/*
* Synthetix - FeePool.sol
*
* https://github.com/Synthetixio/synthetix
* https://synthetix.io
*
* MIT License
* ===========
*
* Copyright (c) 2020 Synthetix
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,	
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/
    
/* ===============================================
* Flattened with Solidifier by Coinage
* 
* https://solidifier.coina.ge
* ===============================================
*/


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       Owned.sol
version:    1.1
author:     Anton Jurisevic
            Dominic Romanowski

date:       2018-2-26

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

An Owned contract, to be inherited by other contracts.
Requires its owner to be explicitly set in the constructor.
Provides an onlyOwner access modifier.

To change owner, the current owner must nominate the next owner,
who then has to accept the nomination. The nomination can be
cancelled before it is accepted by the new owner by having the
previous owner change the nomination (setting it to 0).

-----------------------------------------------------------------
*/

pragma solidity 0.4.25;


/**
 * @title A contract with an owner.
 * @notice Contract ownership can be transferred by first nominating the new owner,
 * who must then accept the ownership, which prevents accidental incorrect ownership transfers.
 */
contract Owned {
    address public owner;
    address public nominatedOwner;

    /**
     * @dev Owned Constructor
     */
    constructor(address _owner) public {
        require(_owner != address(0), "Owner address cannot be 0");
        owner = _owner;
        emit OwnerChanged(address(0), _owner);
    }

    /**
     * @notice Nominate a new owner of this contract.
     * @dev Only the current owner may nominate a new owner.
     */
    function nominateNewOwner(address _owner) external onlyOwner {
        nominatedOwner = _owner;
        emit OwnerNominated(_owner);
    }

    /**
     * @notice Accept the nomination to be owner.
     */
    function acceptOwnership() external {
        require(msg.sender == nominatedOwner, "You must be nominated before you can accept ownership");
        emit OwnerChanged(owner, nominatedOwner);
        owner = nominatedOwner;
        nominatedOwner = address(0);
    }

    modifier onlyOwner {
        require(msg.sender == owner, "Only the contract owner may perform this action");
        _;
    }

    event OwnerNominated(address newOwner);
    event OwnerChanged(address oldOwner, address newOwner);
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       Proxy.sol
version:    1.3
author:     Anton Jurisevic

date:       2018-05-29

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

A proxy contract that, if it does not recognise the function
being called on it, passes all value and call data to an
underlying target contract.

This proxy has the capacity to toggle between DELEGATECALL
and CALL style proxy functionality.

The former executes in the proxy's context, and so will preserve 
msg.sender and store data at the proxy address. The latter will not.
Therefore, any contract the proxy wraps in the CALL style must
implement the Proxyable interface, in order that it can pass msg.sender
into the underlying contract as the state parameter, messageSender.

-----------------------------------------------------------------
*/


contract Proxy is Owned {
    Proxyable public target;
    bool public useDELEGATECALL;

    constructor(address _owner) public Owned(_owner) {}

    function setTarget(Proxyable _target) external onlyOwner {
        target = _target;
        emit TargetUpdated(_target);
    }

    function setUseDELEGATECALL(bool value) external onlyOwner {
        useDELEGATECALL = value;
    }

    function _emit(bytes callData, uint numTopics, bytes32 topic1, bytes32 topic2, bytes32 topic3, bytes32 topic4)
        external
        onlyTarget
    {
        uint size = callData.length;
        bytes memory _callData = callData;

        assembly {
            /* The first 32 bytes of callData contain its length (as specified by the abi). 
             * Length is assumed to be a uint256 and therefore maximum of 32 bytes
             * in length. It is also leftpadded to be a multiple of 32 bytes.
             * This means moving call_data across 32 bytes guarantees we correctly access
             * the data itself. */
            switch numTopics
                case 0 {
                    log0(add(_callData, 32), size)
                }
                case 1 {
                    log1(add(_callData, 32), size, topic1)
                }
                case 2 {
                    log2(add(_callData, 32), size, topic1, topic2)
                }
                case 3 {
                    log3(add(_callData, 32), size, topic1, topic2, topic3)
                }
                case 4 {
                    log4(add(_callData, 32), size, topic1, topic2, topic3, topic4)
                }
        }
    }

    function() external payable {
        if (useDELEGATECALL) {
            assembly {
                /* Copy call data into free memory region. */
                let free_ptr := mload(0x40)
                calldatacopy(free_ptr, 0, calldatasize)

                /* Forward all gas and call data to the target contract. */
                let result := delegatecall(gas, sload(target_slot), free_ptr, calldatasize, 0, 0)
                returndatacopy(free_ptr, 0, returndatasize)

                /* Revert if the call failed, otherwise return the result. */
                if iszero(result) {
                    revert(free_ptr, returndatasize)
                }
                return(free_ptr, returndatasize)
            }
        } else {
            /* Here we are as above, but must send the messageSender explicitly 
             * since we are using CALL rather than DELEGATECALL. */
            target.setMessageSender(msg.sender);
            assembly {
                let free_ptr := mload(0x40)
                calldatacopy(free_ptr, 0, calldatasize)

                /* We must explicitly forward ether to the underlying contract as well. */
                let result := call(gas, sload(target_slot), callvalue, free_ptr, calldatasize, 0, 0)
                returndatacopy(free_ptr, 0, returndatasize)

                if iszero(result) {
                    revert(free_ptr, returndatasize)
                }
                return(free_ptr, returndatasize)
            }
        }
    }

    modifier onlyTarget {
        require(Proxyable(msg.sender) == target, "Must be proxy target");
        _;
    }

    event TargetUpdated(Proxyable newTarget);
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       Proxyable.sol
version:    1.1
author:     Anton Jurisevic

date:       2018-05-15

checked:    Mike Spain
approved:   Samuel Brooks

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

A proxyable contract that works hand in hand with the Proxy contract
to allow for anyone to interact with the underlying contract both
directly and through the proxy.

-----------------------------------------------------------------
*/


// This contract should be treated like an abstract contract
contract Proxyable is Owned {
    /* The proxy this contract exists behind. */
    Proxy public proxy;
    Proxy public integrationProxy;

    /* The caller of the proxy, passed through to this contract.
     * Note that every function using this member must apply the onlyProxy or
     * optionalProxy modifiers, otherwise their invocations can use stale values. */
    address public messageSender;

    constructor(address _proxy, address _owner) public Owned(_owner) {
        proxy = Proxy(_proxy);
        emit ProxyUpdated(_proxy);
    }

    function setProxy(address _proxy) external onlyOwner {
        proxy = Proxy(_proxy);
        emit ProxyUpdated(_proxy);
    }

    function setIntegrationProxy(address _integrationProxy) external onlyOwner {
        integrationProxy = Proxy(_integrationProxy);
    }

    function setMessageSender(address sender) external onlyProxy {
        messageSender = sender;
    }

    modifier onlyProxy {
        require(Proxy(msg.sender) == proxy || Proxy(msg.sender) == integrationProxy, "Only the proxy can call");
        _;
    }

    modifier optionalProxy {
        if (Proxy(msg.sender) != proxy && Proxy(msg.sender) != integrationProxy && messageSender != msg.sender) {
            messageSender = msg.sender;
        }
        _;
    }

    modifier optionalProxy_onlyOwner {
        if (Proxy(msg.sender) != proxy && Proxy(msg.sender) != integrationProxy && messageSender != msg.sender) {
            messageSender = msg.sender;
        }
        require(messageSender == owner, "Owner only function");
        _;
    }

    event ProxyUpdated(address proxyAddress);
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       SelfDestructible.sol
version:    1.2
author:     Anton Jurisevic

date:       2018-05-29

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

This contract allows an inheriting contract to be destroyed after
its owner indicates an intention and then waits for a period
without changing their mind. All ether contained in the contract
is forwarded to a nominated beneficiary upon destruction.

-----------------------------------------------------------------
*/


/**
 * @title A contract that can be destroyed by its owner after a delay elapses.
 */
contract SelfDestructible is Owned {
    uint public initiationTime;
    bool public selfDestructInitiated;
    address public selfDestructBeneficiary;
    uint public constant SELFDESTRUCT_DELAY = 4 weeks;

    /**
     * @dev Constructor
     * @param _owner The account which controls this contract.
     */
    constructor(address _owner) public Owned(_owner) {
        require(_owner != address(0), "Owner must not be zero");
        selfDestructBeneficiary = _owner;
        emit SelfDestructBeneficiaryUpdated(_owner);
    }

    /**
     * @notice Set the beneficiary address of this contract.
     * @dev Only the contract owner may call this. The provided beneficiary must be non-null.
     * @param _beneficiary The address to pay any eth contained in this contract to upon self-destruction.
     */
    function setSelfDestructBeneficiary(address _beneficiary) external onlyOwner {
        require(_beneficiary != address(0), "Beneficiary must not be zero");
        selfDestructBeneficiary = _beneficiary;
        emit SelfDestructBeneficiaryUpdated(_beneficiary);
    }

    /**
     * @notice Begin the self-destruction counter of this contract.
     * Once the delay has elapsed, the contract may be self-destructed.
     * @dev Only the contract owner may call this.
     */
    function initiateSelfDestruct() external onlyOwner {
        initiationTime = now;
        selfDestructInitiated = true;
        emit SelfDestructInitiated(SELFDESTRUCT_DELAY);
    }

    /**
     * @notice Terminate and reset the self-destruction timer.
     * @dev Only the contract owner may call this.
     */
    function terminateSelfDestruct() external onlyOwner {
        initiationTime = 0;
        selfDestructInitiated = false;
        emit SelfDestructTerminated();
    }

    /**
     * @notice If the self-destruction delay has elapsed, destroy this contract and
     * remit any ether it owns to the beneficiary address.
     * @dev Only the contract owner may call this.
     */
    function selfDestruct() external onlyOwner {
        require(selfDestructInitiated, "Self Destruct not yet initiated");
        require(initiationTime + SELFDESTRUCT_DELAY < now, "Self destruct delay not met");
        address beneficiary = selfDestructBeneficiary;
        emit SelfDestructed(beneficiary);
        selfdestruct(beneficiary);
    }

    event SelfDestructTerminated();
    event SelfDestructed(address beneficiary);
    event SelfDestructInitiated(uint selfDestructDelay);
    event SelfDestructBeneficiaryUpdated(address newBeneficiary);
}


/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, reverts on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b, "SafeMath.mul Error");

    return c;
  }

  /**
  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0, "SafeMath.div Error"); // Solidity only automatically asserts when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a, "SafeMath.sub Error");
    uint256 c = a - b;

    return c;
  }

  /**
  * @dev Adds two numbers, reverts on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a, "SafeMath.add Error");

    return c;
  }

  /**
  * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
  * reverts when dividing by zero.
  */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0, "SafeMath.mod Error");
    return a % b;
  }
}


/*

-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       SafeDecimalMath.sol
version:    2.0
author:     Kevin Brown
            Gavin Conway
date:       2018-10-18

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

A library providing safe mathematical operations for division and
multiplication with the capability to round or truncate the results
to the nearest increment. Operations can return a standard precision
or high precision decimal. High precision decimals are useful for
example when attempting to calculate percentages or fractions
accurately.

-----------------------------------------------------------------
*/


/**
 * @title Safely manipulate unsigned fixed-point decimals at a given precision level.
 * @dev Functions accepting uints in this contract and derived contracts
 * are taken to be such fixed point decimals of a specified precision (either standard
 * or high).
 */
library SafeDecimalMath {
    using SafeMath for uint;

    /* Number of decimal places in the representations. */
    uint8 public constant decimals = 18;
    uint8 public constant highPrecisionDecimals = 27;

    /* The number representing 1.0. */
    uint public constant UNIT = 10**uint(decimals);

    /* The number representing 1.0 for higher fidelity numbers. */
    uint public constant PRECISE_UNIT = 10**uint(highPrecisionDecimals);
    uint private constant UNIT_TO_HIGH_PRECISION_CONVERSION_FACTOR = 10**uint(highPrecisionDecimals - decimals);

    /** 
     * @return Provides an interface to UNIT.
     */
    function unit() external pure returns (uint) {
        return UNIT;
    }

    /** 
     * @return Provides an interface to PRECISE_UNIT.
     */
    function preciseUnit() external pure returns (uint) {
        return PRECISE_UNIT;
    }

    /**
     * @return The result of multiplying x and y, interpreting the operands as fixed-point
     * decimals.
     * 
     * @dev A unit factor is divided out after the product of x and y is evaluated,
     * so that product must be less than 2**256. As this is an integer division,
     * the internal division always rounds down. This helps save on gas. Rounding
     * is more expensive on gas.
     */
    function multiplyDecimal(uint x, uint y) internal pure returns (uint) {
        /* Divide by UNIT to remove the extra factor introduced by the product. */
        return x.mul(y) / UNIT;
    }

    /**
     * @return The result of safely multiplying x and y, interpreting the operands
     * as fixed-point decimals of the specified precision unit.
     *
     * @dev The operands should be in the form of a the specified unit factor which will be
     * divided out after the product of x and y is evaluated, so that product must be
     * less than 2**256.
     *
     * Unlike multiplyDecimal, this function rounds the result to the nearest increment.
     * Rounding is useful when you need to retain fidelity for small decimal numbers
     * (eg. small fractions or percentages).
     */
    function _multiplyDecimalRound(uint x, uint y, uint precisionUnit) private pure returns (uint) {
        /* Divide by UNIT to remove the extra factor introduced by the product. */
        uint quotientTimesTen = x.mul(y) / (precisionUnit / 10);

        if (quotientTimesTen % 10 >= 5) {
            quotientTimesTen += 10;
        }

        return quotientTimesTen / 10;
    }

    /**
     * @return The result of safely multiplying x and y, interpreting the operands
     * as fixed-point decimals of a precise unit.
     *
     * @dev The operands should be in the precise unit factor which will be
     * divided out after the product of x and y is evaluated, so that product must be
     * less than 2**256.
     *
     * Unlike multiplyDecimal, this function rounds the result to the nearest increment.
     * Rounding is useful when you need to retain fidelity for small decimal numbers
     * (eg. small fractions or percentages).
     */
    function multiplyDecimalRoundPrecise(uint x, uint y) internal pure returns (uint) {
        return _multiplyDecimalRound(x, y, PRECISE_UNIT);
    }

    /**
     * @return The result of safely multiplying x and y, interpreting the operands
     * as fixed-point decimals of a standard unit.
     *
     * @dev The operands should be in the standard unit factor which will be
     * divided out after the product of x and y is evaluated, so that product must be
     * less than 2**256.
     *
     * Unlike multiplyDecimal, this function rounds the result to the nearest increment.
     * Rounding is useful when you need to retain fidelity for small decimal numbers
     * (eg. small fractions or percentages).
     */
    function multiplyDecimalRound(uint x, uint y) internal pure returns (uint) {
        return _multiplyDecimalRound(x, y, UNIT);
    }

    /**
     * @return The result of safely dividing x and y. The return value is a high
     * precision decimal.
     * 
     * @dev y is divided after the product of x and the standard precision unit
     * is evaluated, so the product of x and UNIT must be less than 2**256. As
     * this is an integer division, the result is always rounded down.
     * This helps save on gas. Rounding is more expensive on gas.
     */
    function divideDecimal(uint x, uint y) internal pure returns (uint) {
        /* Reintroduce the UNIT factor that will be divided out by y. */
        return x.mul(UNIT).div(y);
    }

    /**
     * @return The result of safely dividing x and y. The return value is as a rounded
     * decimal in the precision unit specified in the parameter.
     *
     * @dev y is divided after the product of x and the specified precision unit
     * is evaluated, so the product of x and the specified precision unit must
     * be less than 2**256. The result is rounded to the nearest increment.
     */
    function _divideDecimalRound(uint x, uint y, uint precisionUnit) private pure returns (uint) {
        uint resultTimesTen = x.mul(precisionUnit * 10).div(y);

        if (resultTimesTen % 10 >= 5) {
            resultTimesTen += 10;
        }

        return resultTimesTen / 10;
    }

    /**
     * @return The result of safely dividing x and y. The return value is as a rounded
     * standard precision decimal.
     *
     * @dev y is divided after the product of x and the standard precision unit
     * is evaluated, so the product of x and the standard precision unit must
     * be less than 2**256. The result is rounded to the nearest increment.
     */
    function divideDecimalRound(uint x, uint y) internal pure returns (uint) {
        return _divideDecimalRound(x, y, UNIT);
    }

    /**
     * @return The result of safely dividing x and y. The return value is as a rounded
     * high precision decimal.
     *
     * @dev y is divided after the product of x and the high precision unit
     * is evaluated, so the product of x and the high precision unit must
     * be less than 2**256. The result is rounded to the nearest increment.
     */
    function divideDecimalRoundPrecise(uint x, uint y) internal pure returns (uint) {
        return _divideDecimalRound(x, y, PRECISE_UNIT);
    }

    /**
     * @dev Convert a standard decimal representation to a high precision one.
     */
    function decimalToPreciseDecimal(uint i) internal pure returns (uint) {
        return i.mul(UNIT_TO_HIGH_PRECISION_CONVERSION_FACTOR);
    }

    /**
     * @dev Convert a high precision decimal to a standard decimal representation.
     */
    function preciseDecimalToDecimal(uint i) internal pure returns (uint) {
        uint quotientTimesTen = i / (UNIT_TO_HIGH_PRECISION_CONVERSION_FACTOR / 10);

        if (quotientTimesTen % 10 >= 5) {
            quotientTimesTen += 10;
        }

        return quotientTimesTen / 10;
    }
}


contract AddressResolver is Owned {
    mapping(bytes32 => address) public repository;

    constructor(address _owner) public Owned(_owner) {}

    /* ========== MUTATIVE FUNCTIONS ========== */

    function importAddresses(bytes32[] names, address[] destinations) public onlyOwner {
        require(names.length == destinations.length, "Input lengths must match");

        for (uint i = 0; i < names.length; i++) {
            repository[names[i]] = destinations[i];
        }
    }

    /* ========== VIEWS ========== */

    function getAddress(bytes32 name) public view returns (address) {
        return repository[name];
    }

    function requireAndGetAddress(bytes32 name, string reason) public view returns (address) {
        address _foundAddress = repository[name];
        require(_foundAddress != address(0), reason);
        return _foundAddress;
    }
}


contract MixinResolver is Owned {
    AddressResolver public resolver;

    constructor(address _owner, address _resolver) public Owned(_owner) {
        resolver = AddressResolver(_resolver);
    }

    /* ========== SETTERS ========== */

    function setResolver(AddressResolver _resolver) public onlyOwner {
        resolver = _resolver;
    }
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       State.sol
version:    1.1
author:     Dominic Romanowski
            Anton Jurisevic

date:       2018-05-15

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

This contract is used side by side with external state token
contracts, such as Synthetix and Synth.
It provides an easy way to upgrade contract logic while
maintaining all user balances and allowances. This is designed
to make the changeover as easy as possible, since mappings
are not so cheap or straightforward to migrate.

The first deployed contract would create this state contract,
using it as its store of balances.
When a new contract is deployed, it links to the existing
state contract, whose owner would then change its associated
contract to the new one.

-----------------------------------------------------------------
*/


contract State is Owned {
    // the address of the contract that can modify variables
    // this can only be changed by the owner of this contract
    address public associatedContract;

    constructor(address _owner, address _associatedContract) public Owned(_owner) {
        associatedContract = _associatedContract;
        emit AssociatedContractUpdated(_associatedContract);
    }

    /* ========== SETTERS ========== */

    // Change the associated contract to a new address
    function setAssociatedContract(address _associatedContract) external onlyOwner {
        associatedContract = _associatedContract;
        emit AssociatedContractUpdated(_associatedContract);
    }

    /* ========== MODIFIERS ========== */

    modifier onlyAssociatedContract {
        require(msg.sender == associatedContract, "Only the associated contract can perform this action");
        _;
    }

    /* ========== EVENTS ========== */

    event AssociatedContractUpdated(address associatedContract);
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       TokenState.sol
version:    1.1
author:     Dominic Romanowski
            Anton Jurisevic

date:       2018-05-15

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

A contract that holds the state of an ERC20 compliant token.

This contract is used side by side with external state token
contracts, such as Synthetix and Synth.
It provides an easy way to upgrade contract logic while
maintaining all user balances and allowances. This is designed
to make the changeover as easy as possible, since mappings
are not so cheap or straightforward to migrate.

The first deployed contract would create this state contract,
using it as its store of balances.
When a new contract is deployed, it links to the existing
state contract, whose owner would then change its associated
contract to the new one.

-----------------------------------------------------------------
*/


/**
 * @title ERC20 Token State
 * @notice Stores balance information of an ERC20 token contract.
 */
contract TokenState is State {
    /* ERC20 fields. */
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    /**
     * @dev Constructor
     * @param _owner The address which controls this contract.
     * @param _associatedContract The ERC20 contract whose state this composes.
     */
    constructor(address _owner, address _associatedContract) public State(_owner, _associatedContract) {}

    /* ========== SETTERS ========== */

    /**
     * @notice Set ERC20 allowance.
     * @dev Only the associated contract may call this.
     * @param tokenOwner The authorising party.
     * @param spender The authorised party.
     * @param value The total value the authorised party may spend on the
     * authorising party's behalf.
     */
    function setAllowance(address tokenOwner, address spender, uint value) external onlyAssociatedContract {
        allowance[tokenOwner][spender] = value;
    }

    /**
     * @notice Set the balance in a given account
     * @dev Only the associated contract may call this.
     * @param account The account whose value to set.
     * @param value The new balance of the given account.
     */
    function setBalanceOf(address account, uint value) external onlyAssociatedContract {
        balanceOf[account] = value;
    }
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       ExternStateToken.sol
version:    1.3
author:     Anton Jurisevic
            Dominic Romanowski
            Kevin Brown

date:       2018-05-29

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

A partial ERC20 token contract, designed to operate with a proxy.
To produce a complete ERC20 token, transfer and transferFrom
tokens must be implemented, using the provided _byProxy internal
functions.
This contract utilises an external state for upgradeability.

-----------------------------------------------------------------
*/


/**
 * @title ERC20 Token contract, with detached state and designed to operate behind a proxy.
 */
contract ExternStateToken is SelfDestructible, Proxyable {
    using SafeMath for uint;
    using SafeDecimalMath for uint;

    /* ========== STATE VARIABLES ========== */

    /* Stores balances and allowances. */
    TokenState public tokenState;

    /* Other ERC20 fields. */
    string public name;
    string public symbol;
    uint public totalSupply;
    uint8 public decimals;

    /**
     * @dev Constructor.
     * @param _proxy The proxy associated with this contract.
     * @param _name Token's ERC20 name.
     * @param _symbol Token's ERC20 symbol.
     * @param _totalSupply The total supply of the token.
     * @param _tokenState The TokenState contract address.
     * @param _owner The owner of this contract.
     */
    constructor(
        address _proxy,
        TokenState _tokenState,
        string _name,
        string _symbol,
        uint _totalSupply,
        uint8 _decimals,
        address _owner
    ) public SelfDestructible(_owner) Proxyable(_proxy, _owner) {
        tokenState = _tokenState;

        name = _name;
        symbol = _symbol;
        totalSupply = _totalSupply;
        decimals = _decimals;
    }

    /* ========== VIEWS ========== */

    /**
     * @notice Returns the ERC20 allowance of one party to spend on behalf of another.
     * @param owner The party authorising spending of their funds.
     * @param spender The party spending tokenOwner's funds.
     */
    function allowance(address owner, address spender) public view returns (uint) {
        return tokenState.allowance(owner, spender);
    }

    /**
     * @notice Returns the ERC20 token balance of a given account.
     */
    function balanceOf(address account) public view returns (uint) {
        return tokenState.balanceOf(account);
    }

    /* ========== MUTATIVE FUNCTIONS ========== */

    /**
     * @notice Set the address of the TokenState contract.
     * @dev This can be used to "pause" transfer functionality, by pointing the tokenState at 0x000..
     * as balances would be unreachable.
     */
    function setTokenState(TokenState _tokenState) external optionalProxy_onlyOwner {
        tokenState = _tokenState;
        emitTokenStateUpdated(_tokenState);
    }

    function _internalTransfer(address from, address to, uint value) internal returns (bool) {
        /* Disallow transfers to irretrievable-addresses. */
        require(to != address(0) && to != address(this) && to != address(proxy), "Cannot transfer to this address");

        // Insufficient balance will be handled by the safe subtraction.
        tokenState.setBalanceOf(from, tokenState.balanceOf(from).sub(value));
        tokenState.setBalanceOf(to, tokenState.balanceOf(to).add(value));

        // Emit a standard ERC20 transfer event
        emitTransfer(from, to, value);

        return true;
    }

    /**
     * @dev Perform an ERC20 token transfer. Designed to be called by transfer functions possessing
     * the onlyProxy or optionalProxy modifiers.
     */
    function _transfer_byProxy(address from, address to, uint value) internal returns (bool) {
        return _internalTransfer(from, to, value);
    }

    /**
     * @dev Perform an ERC20 token transferFrom. Designed to be called by transferFrom functions
     * possessing the optionalProxy or optionalProxy modifiers.
     */
    function _transferFrom_byProxy(address sender, address from, address to, uint value) internal returns (bool) {
        /* Insufficient allowance will be handled by the safe subtraction. */
        tokenState.setAllowance(from, sender, tokenState.allowance(from, sender).sub(value));
        return _internalTransfer(from, to, value);
    }

    /**
     * @notice Approves spender to transfer on the message sender's behalf.
     */
    function approve(address spender, uint value) public optionalProxy returns (bool) {
        address sender = messageSender;

        tokenState.setAllowance(sender, spender, value);
        emitApproval(sender, spender, value);
        return true;
    }

    /* ========== EVENTS ========== */

    event Transfer(address indexed from, address indexed to, uint value);
    bytes32 constant TRANSFER_SIG = keccak256("Transfer(address,address,uint256)");

    function emitTransfer(address from, address to, uint value) internal {
        proxy._emit(abi.encode(value), 3, TRANSFER_SIG, bytes32(from), bytes32(to), 0);
    }

    event Approval(address indexed owner, address indexed spender, uint value);
    bytes32 constant APPROVAL_SIG = keccak256("Approval(address,address,uint256)");

    function emitApproval(address owner, address spender, uint value) internal {
        proxy._emit(abi.encode(value), 3, APPROVAL_SIG, bytes32(owner), bytes32(spender), 0);
    }

    event TokenStateUpdated(address newTokenState);
    bytes32 constant TOKENSTATEUPDATED_SIG = keccak256("TokenStateUpdated(address)");

    function emitTokenStateUpdated(address newTokenState) internal {
        proxy._emit(abi.encode(newTokenState), 1, TOKENSTATEUPDATED_SIG, 0, 0, 0);
    }
}


library Math {
    using SafeMath for uint;
    using SafeDecimalMath for uint;

    /**
    * @dev Uses "exponentiation by squaring" algorithm where cost is 0(logN)
    * vs 0(N) for naive repeated multiplication. 
    * Calculates x^n with x as fixed-point and n as regular unsigned int.
    * Calculates to 18 digits of precision with SafeDecimalMath.unit()
    */
    function powDecimal(uint x, uint n) internal pure returns (uint) {
        // https://mpark.github.io/programming/2014/08/18/exponentiation-by-squaring/

        uint result = SafeDecimalMath.unit();
        while (n > 0) {
            if (n % 2 != 0) {
                result = result.multiplyDecimal(x);
            }
            x = x.multiplyDecimal(x);
            n /= 2;
        }
        return result;
    }
}


/**
 * @title SynthetixState interface contract
 * @notice Abstract contract to hold public getters
 */
contract ISynthetixState {
    // A struct for handing values associated with an individual user's debt position
    struct IssuanceData {
        // Percentage of the total debt owned at the time
        // of issuance. This number is modified by the global debt
        // delta array. You can figure out a user's exit price and
        // collateralisation ratio using a combination of their initial
        // debt and the slice of global debt delta which applies to them.
        uint initialDebtOwnership;
        // This lets us know when (in relative terms) the user entered
        // the debt pool so we can calculate their exit price and
        // collateralistion ratio
        uint debtEntryIndex;
    }

    uint[] public debtLedger;
    uint public issuanceRatio;
    mapping(address => IssuanceData) public issuanceData;

    function debtLedgerLength() external view returns (uint);

    function hasIssued(address account) external view returns (bool);

    function incrementTotalIssuerCount() external;

    function decrementTotalIssuerCount() external;

    function setCurrentIssuanceData(address account, uint initialDebtOwnership) external;

    function lastDebtLedgerEntry() external view returns (uint);

    function appendDebtLedgerValue(uint value) external;

    function clearIssuanceData(address account) external;
}


interface ISynth {
    function burn(address account, uint amount) external;

    function issue(address account, uint amount) external;

    function transfer(address to, uint value) external returns (bool);

    function transferFrom(address from, address to, uint value) external returns (bool);

    function transferFromAndSettle(address from, address to, uint value) external returns (bool);

    function balanceOf(address owner) external view returns (uint);
}


/**
 * @title SynthetixEscrow interface
 */
interface ISynthetixEscrow {
    function balanceOf(address account) public view returns (uint);

    function appendVestingEntry(address account, uint quantity) public;
}


/**
 * @title FeePool Interface
 * @notice Abstract contract to hold public getters
 */
contract IFeePool {
    address public FEE_ADDRESS;
    uint public exchangeFeeRate;

    function amountReceivedFromExchange(uint value) external view returns (uint);

    function amountReceivedFromTransfer(uint value) external view returns (uint);

    function recordFeePaid(uint sUSDAmount) external;

    function appendAccountIssuanceRecord(address account, uint lockedAmount, uint debtEntryIndex) external;

    function setRewardsToDistribute(uint amount) external;
}


/**
 * @title ExchangeRates interface
 */
interface IExchangeRates {
    function effectiveValue(bytes32 sourceCurrencyKey, uint sourceAmount, bytes32 destinationCurrencyKey)
        external
        view
        returns (uint);

    function rateForCurrency(bytes32 currencyKey) external view returns (uint);

    function ratesForCurrencies(bytes32[] currencyKeys) external view returns (uint[] memory);

    function rateIsStale(bytes32 currencyKey) external view returns (bool);

    function rateIsFrozen(bytes32 currencyKey) external view returns (bool);

    function anyRateIsStale(bytes32[] currencyKeys) external view returns (bool);

    function getCurrentRoundId(bytes32 currencyKey) external view returns (uint);

    function effectiveValueAtRound(
        bytes32 sourceCurrencyKey,
        uint sourceAmount,
        bytes32 destinationCurrencyKey,
        uint roundIdForSrc,
        uint roundIdForDest
    ) external view returns (uint);

    function getLastRoundIdBeforeElapsedSecs(
        bytes32 currencyKey,
        uint startingRoundId,
        uint startingTimestamp,
        uint timediff
    ) external view returns (uint);

    function ratesAndStaleForCurrencies(bytes32[] currencyKeys) external view returns (uint[], bool);

    function rateAndTimestampAtRound(bytes32 currencyKey, uint roundId) external view returns (uint rate, uint time);
}


interface IExchanger {
    function maxSecsLeftInWaitingPeriod(address account, bytes32 currencyKey) external view returns (uint);

    function feeRateForExchange(bytes32 sourceCurrencyKey, bytes32 destinationCurrencyKey) external view returns (uint);

    function settlementOwing(address account, bytes32 currencyKey)
        external
        view
        returns (uint reclaimAmount, uint rebateAmount);

    function settle(address from, bytes32 currencyKey) external returns (uint reclaimed, uint refunded);

    function exchange(
        address from,
        bytes32 sourceCurrencyKey,
        uint sourceAmount,
        bytes32 destinationCurrencyKey,
        address destinationAddress
    ) external returns (uint amountReceived);

    function calculateAmountAfterSettlement(address from, bytes32 currencyKey, uint amount, uint refunded)
        external
        view
        returns (uint amountAfterSettlement);
}


interface IIssuer {
    function issueSynths(address from, uint amount) external;

    function issueMaxSynths(address from) external;

    function burnSynths(address from, uint amount) external;
}


contract Synth is ExternStateToken, MixinResolver {
    /* ========== STATE VARIABLES ========== */

    // Currency key which identifies this Synth to the Synthetix system
    bytes32 public currencyKey;

    uint8 public constant DECIMALS = 18;

    // Where fees are pooled in sUSD
    address public constant FEE_ADDRESS = 0xfeEFEEfeefEeFeefEEFEEfEeFeefEEFeeFEEFEeF;

    /* ========== CONSTRUCTOR ========== */

    constructor(
        address _proxy,
        TokenState _tokenState,
        string _tokenName,
        string _tokenSymbol,
        address _owner,
        bytes32 _currencyKey,
        uint _totalSupply,
        address _resolver
    )
        public
        ExternStateToken(_proxy, _tokenState, _tokenName, _tokenSymbol, _totalSupply, DECIMALS, _owner)
        MixinResolver(_owner, _resolver)
    {
        require(_proxy != address(0), "_proxy cannot be 0");
        require(_owner != 0, "_owner cannot be 0");

        currencyKey = _currencyKey;
    }

    /* ========== MUTATIVE FUNCTIONS ========== */

    function transfer(address to, uint value) public optionalProxy returns (bool) {
        _ensureCanTransfer(messageSender, value);

        // transfers to FEE_ADDRESS will be exchanged into sUSD and recorded as fee
        if (to == FEE_ADDRESS) {
            return _transferToFeeAddress(to, value);
        }

        // transfers to 0x address will be burned
        if (to == address(0)) {
            return _internalBurn(messageSender, value);
        }

        return super._internalTransfer(messageSender, to, value);
    }

    function transferAndSettle(address to, uint value) public optionalProxy returns (bool) {
        exchanger().settle(messageSender, currencyKey);

        // Save gas instead of calling transferableSynths
        uint balanceAfter = tokenState.balanceOf(messageSender);

        // Reduce the value to transfer if balance is insufficient after reclaimed
        value = value > balanceAfter ? balanceAfter : value;

        return super._internalTransfer(messageSender, to, value);
    }

    function transferFrom(address from, address to, uint value) public optionalProxy returns (bool) {
        _ensureCanTransfer(from, value);

        return _internalTransferFrom(from, to, value);
    }

    function transferFromAndSettle(address from, address to, uint value) public optionalProxy returns (bool) {
        exchanger().settle(from, currencyKey);

        // Save gas instead of calling transferableSynths
        uint balanceAfter = tokenState.balanceOf(from);

        // Reduce the value to transfer if balance is insufficient after reclaimed
        value = value >= balanceAfter ? balanceAfter : value;

        return _internalTransferFrom(from, to, value);
    }

    /**
     * @notice _transferToFeeAddress function
     * non-sUSD synths are exchanged into sUSD via synthInitiatedExchange
     * notify feePool to record amount as fee paid to feePool */
    function _transferToFeeAddress(address to, uint value) internal returns (bool) {
        uint amountInUSD;

        // sUSD can be transferred to FEE_ADDRESS directly
        if (currencyKey == "sUSD") {
            amountInUSD = value;
            super._internalTransfer(messageSender, to, value);
        } else {
            // else exchange synth into sUSD and send to FEE_ADDRESS
            amountInUSD = exchanger().exchange(messageSender, currencyKey, value, "sUSD", FEE_ADDRESS);
        }

        // Notify feePool to record sUSD to distribute as fees
        feePool().recordFeePaid(amountInUSD);

        return true;
    }

    // Allow synthetix to issue a certain number of synths from an account.
    // forward call to _internalIssue
    function issue(address account, uint amount) external onlyInternalContracts {
        _internalIssue(account, amount);
    }

    // Allow synthetix or another synth contract to burn a certain number of synths from an account.
    // forward call to _internalBurn
    function burn(address account, uint amount) external onlyInternalContracts {
        _internalBurn(account, amount);
    }

    function _internalIssue(address account, uint amount) internal {
        tokenState.setBalanceOf(account, tokenState.balanceOf(account).add(amount));
        totalSupply = totalSupply.add(amount);
        emitTransfer(address(0), account, amount);
        emitIssued(account, amount);
    }

    function _internalBurn(address account, uint amount) internal returns (bool) {
        tokenState.setBalanceOf(account, tokenState.balanceOf(account).sub(amount));
        totalSupply = totalSupply.sub(amount);
        emitTransfer(account, address(0), amount);
        emitBurned(account, amount);

        return true;
    }

    // Allow owner to set the total supply on import.
    function setTotalSupply(uint amount) external optionalProxy_onlyOwner {
        totalSupply = amount;
    }

    /* ========== VIEWS ========== */
    function synthetix() internal view returns (ISynthetix) {
        return ISynthetix(resolver.requireAndGetAddress("Synthetix", "Missing Synthetix address"));
    }

    function feePool() internal view returns (IFeePool) {
        return IFeePool(resolver.requireAndGetAddress("FeePool", "Missing FeePool address"));
    }

    function exchanger() internal view returns (IExchanger) {
        return IExchanger(resolver.requireAndGetAddress("Exchanger", "Missing Exchanger address"));
    }

    function issuer() internal view returns (IIssuer) {
        return IIssuer(resolver.requireAndGetAddress("Issuer", "Missing Issuer address"));
    }

    function _ensureCanTransfer(address from, uint value) internal view {
        require(exchanger().maxSecsLeftInWaitingPeriod(from, currencyKey) == 0, "Cannot transfer during waiting period");
        require(transferableSynths(from) >= value, "Transfer requires settle");
    }

    function transferableSynths(address account) public view returns (uint) {
        (uint reclaimAmount, ) = exchanger().settlementOwing(account, currencyKey);

        // Note: ignoring rebate amount here because a settle() is required in order to
        // allow the transfer to actually work

        uint balance = tokenState.balanceOf(account);

        if (reclaimAmount > balance) {
            return 0;
        } else {
            return balance.sub(reclaimAmount);
        }
    }

    /* ========== INTERNAL FUNCTIONS ========== */

    function _internalTransferFrom(address from, address to, uint value) internal returns (bool) {
        // Skip allowance update in case of infinite allowance
        if (tokenState.allowance(from, messageSender) != uint(-1)) {
            // Reduce the allowance by the amount we're transferring.
            // The safeSub call will handle an insufficient allowance.
            tokenState.setAllowance(from, messageSender, tokenState.allowance(from, messageSender).sub(value));
        }

        return super._internalTransfer(from, to, value);
    }

    /* ========== MODIFIERS ========== */

    modifier onlyInternalContracts() {
        bool isSynthetix = msg.sender == address(synthetix());
        bool isFeePool = msg.sender == address(feePool());
        bool isExchanger = msg.sender == address(exchanger());
        bool isIssuer = msg.sender == address(issuer());

        require(
            isSynthetix || isFeePool || isExchanger || isIssuer,
            "Only Synthetix, FeePool, Exchanger or Issuer contracts allowed"
        );
        _;
    }

    /* ========== EVENTS ========== */
    event Issued(address indexed account, uint value);
    bytes32 private constant ISSUED_SIG = keccak256("Issued(address,uint256)");

    function emitIssued(address account, uint value) internal {
        proxy._emit(abi.encode(value), 2, ISSUED_SIG, bytes32(account), 0, 0);
    }

    event Burned(address indexed account, uint value);
    bytes32 private constant BURNED_SIG = keccak256("Burned(address,uint256)");

    function emitBurned(address account, uint value) internal {
        proxy._emit(abi.encode(value), 2, BURNED_SIG, bytes32(account), 0, 0);
    }
}


/**
 * @title Synthetix interface contract
 * @notice Abstract contract to hold public getters
 * @dev pseudo interface, actually declared as contract to hold the public getters
 */


contract ISynthetix {
    // ========== PUBLIC STATE VARIABLES ==========

    uint public totalSupply;

    mapping(bytes32 => Synth) public synths;

    mapping(address => bytes32) public synthsByAddress;

    // ========== PUBLIC FUNCTIONS ==========

    function balanceOf(address account) public view returns (uint);

    function transfer(address to, uint value) public returns (bool);

    function transferFrom(address from, address to, uint value) public returns (bool);

    function exchange(bytes32 sourceCurrencyKey, uint sourceAmount, bytes32 destinationCurrencyKey)
        external
        returns (uint amountReceived);

    function issueSynths(uint amount) external;

    function issueMaxSynths() external;

    function burnSynths(uint amount) external;

    function settle(bytes32 currencyKey) external returns (uint reclaimed, uint refunded);

    function collateralisationRatio(address issuer) public view returns (uint);

    function totalIssuedSynths(bytes32 currencyKey) public view returns (uint);

    function totalIssuedSynthsExcludeEtherCollateral(bytes32 currencyKey) public view returns (uint);

    function debtBalanceOf(address issuer, bytes32 currencyKey) public view returns (uint);

    function remainingIssuableSynths(address issuer) public view returns (uint, uint);

    function isWaitingPeriod(bytes32 currencyKey) external view returns (bool);

    function emitSynthExchange(
        address account,
        bytes32 fromCurrencyKey,
        uint fromAmount,
        bytes32 toCurrencyKey,
        uint toAmount,
        address toAddress
    ) external;

    function emitExchangeReclaim(address account, bytes32 currencyKey, uint amount) external;

    function emitExchangeRebate(address account, bytes32 currencyKey, uint amount) external;
}


/*
-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

The SNX supply schedule contract determines the amount of SNX tokens
mintable over the course of 195 weeks.

Exponential Decay Inflation Schedule

Synthetix.mint() function is used to mint the inflationary supply.

The mechanics for Inflation Smoothing and Terminal Inflation 
have been defined in these sips
https://sips.synthetix.io/sips/sip-23
https://sips.synthetix.io/sips/sip-24

The previous SNX Inflation Supply Schedule is at 
https://etherscan.io/address/0xA3de830b5208851539De8e4FF158D635E8f36FCb#code

-----------------------------------------------------------------
*/


/**
 * @title SupplySchedule contract
 */
contract SupplySchedule is Owned {
    using SafeMath for uint;
    using SafeDecimalMath for uint;
    using Math for uint;

    // Time of the last inflation supply mint event
    uint public lastMintEvent;

    // Counter for number of weeks since the start of supply inflation
    uint public weekCounter;

    // The number of SNX rewarded to the caller of Synthetix.mint()
    uint public minterReward = 200 * SafeDecimalMath.unit();

    // The initial weekly inflationary supply is 75m / 52 until the start of the decay rate.
    // 75e6 * SafeDecimalMath.unit() / 52
    uint public constant INITIAL_WEEKLY_SUPPLY = 1442307692307692307692307;

    // Address of the SynthetixProxy for the onlySynthetix modifier
    address public synthetixProxy;

    // Max SNX rewards for minter
    uint public constant MAX_MINTER_REWARD = 200 * SafeDecimalMath.unit();

    // How long each inflation period is before mint can be called
    uint public constant MINT_PERIOD_DURATION = 1 weeks;

    uint public constant INFLATION_START_DATE = 1551830400; // 2019-03-06T00:00:00+00:00
    uint public constant MINT_BUFFER = 1 days;
    uint8 public constant SUPPLY_DECAY_START = 40; // Week 40
    uint8 public constant SUPPLY_DECAY_END = 234; //  Supply Decay ends on Week 234 (inclusive of Week 234 for a total of 195 weeks of inflation decay)

    // Weekly percentage decay of inflationary supply from the first 40 weeks of the 75% inflation rate
    uint public constant DECAY_RATE = 12500000000000000; // 1.25% weekly

    // Percentage growth of terminal supply per annum
    uint public constant TERMINAL_SUPPLY_RATE_ANNUAL = 25000000000000000; // 2.5% pa

    constructor(address _owner, uint _lastMintEvent, uint _currentWeek) public Owned(_owner) {
        lastMintEvent = _lastMintEvent;
        weekCounter = _currentWeek;
    }

    // ========== VIEWS ==========

    /**    
    * @return The amount of SNX mintable for the inflationary supply
    */
    function mintableSupply() external view returns (uint) {
        uint totalAmount;

        if (!isMintable()) {
            return totalAmount;
        }

        uint remainingWeeksToMint = weeksSinceLastIssuance();

        uint currentWeek = weekCounter;

        // Calculate total mintable supply from exponential decay function
        // The decay function stops after week 234
        while (remainingWeeksToMint > 0) {
            currentWeek++;

            if (currentWeek < SUPPLY_DECAY_START) {
                // If current week is before supply decay we add initial supply to mintableSupply
                totalAmount = totalAmount.add(INITIAL_WEEKLY_SUPPLY);
                remainingWeeksToMint--;
            } else if (currentWeek <= SUPPLY_DECAY_END) {
                // if current week before supply decay ends we add the new supply for the week
                // diff between current week and (supply decay start week - 1)
                uint decayCount = currentWeek.sub(SUPPLY_DECAY_START - 1);

                totalAmount = totalAmount.add(tokenDecaySupplyForWeek(decayCount));
                remainingWeeksToMint--;
            } else {
                // Terminal supply is calculated on the total supply of Synthetix including any new supply
                // We can compound the remaining week's supply at the fixed terminal rate
                uint totalSupply = ISynthetix(synthetixProxy).totalSupply();
                uint currentTotalSupply = totalSupply.add(totalAmount);

                totalAmount = totalAmount.add(terminalInflationSupply(currentTotalSupply, remainingWeeksToMint));
                remainingWeeksToMint = 0;
            }
        }

        return totalAmount;
    }

    /**
    * @return A unit amount of decaying inflationary supply from the INITIAL_WEEKLY_SUPPLY
    * @dev New token supply reduces by the decay rate each week calculated as supply = INITIAL_WEEKLY_SUPPLY * () 
    */
    function tokenDecaySupplyForWeek(uint counter) public pure returns (uint) {
        // Apply exponential decay function to number of weeks since
        // start of inflation smoothing to calculate diminishing supply for the week.
        uint effectiveDecay = (SafeDecimalMath.unit().sub(DECAY_RATE)).powDecimal(counter);
        uint supplyForWeek = INITIAL_WEEKLY_SUPPLY.multiplyDecimal(effectiveDecay);

        return supplyForWeek;
    }

    /**
    * @return A unit amount of terminal inflation supply
    * @dev Weekly compound rate based on number of weeks     
    */
    function terminalInflationSupply(uint totalSupply, uint numOfWeeks) public pure returns (uint) {
        // rate = (1 + weekly rate) ^ num of weeks
        uint effectiveCompoundRate = SafeDecimalMath.unit().add(TERMINAL_SUPPLY_RATE_ANNUAL.div(52)).powDecimal(numOfWeeks);

        // return Supply * (effectiveRate - 1) for extra supply to issue based on number of weeks
        return totalSupply.multiplyDecimal(effectiveCompoundRate.sub(SafeDecimalMath.unit()));
    }

    /**    
    * @dev Take timeDiff in seconds (Dividend) and MINT_PERIOD_DURATION as (Divisor)
    * @return Calculate the numberOfWeeks since last mint rounded down to 1 week
    */
    function weeksSinceLastIssuance() public view returns (uint) {
        // Get weeks since lastMintEvent
        // If lastMintEvent not set or 0, then start from inflation start date.
        uint timeDiff = lastMintEvent > 0 ? now.sub(lastMintEvent) : now.sub(INFLATION_START_DATE);
        return timeDiff.div(MINT_PERIOD_DURATION);
    }

    /**
     * @return boolean whether the MINT_PERIOD_DURATION (7 days)
     * has passed since the lastMintEvent.
     * */
    function isMintable() public view returns (bool) {
        if (now - lastMintEvent > MINT_PERIOD_DURATION) {
            return true;
        }
        return false;
    }

    // ========== MUTATIVE FUNCTIONS ==========

    /**
     * @notice Record the mint event from Synthetix by incrementing the inflation 
     * week counter for the number of weeks minted (probabaly always 1)
     * and store the time of the event.
     * @param supplyMinted the amount of SNX the total supply was inflated by.
     * */
    function recordMintEvent(uint supplyMinted) external onlySynthetix returns (bool) {
        uint numberOfWeeksIssued = weeksSinceLastIssuance();

        // add number of weeks minted to weekCounter
        weekCounter = weekCounter.add(numberOfWeeksIssued);

        // Update mint event to latest week issued (start date + number of weeks issued * seconds in week)
        // 1 day time buffer is added so inflation is minted after feePeriod closes
        lastMintEvent = INFLATION_START_DATE.add(weekCounter.mul(MINT_PERIOD_DURATION)).add(MINT_BUFFER);

        emit SupplyMinted(supplyMinted, numberOfWeeksIssued, lastMintEvent, now);
        return true;
    }

    /**
     * @notice Sets the reward amount of SNX for the caller of the public 
     * function Synthetix.mint(). 
     * This incentivises anyone to mint the inflationary supply and the mintr 
     * Reward will be deducted from the inflationary supply and sent to the caller.
     * @param amount the amount of SNX to reward the minter.
     * */
    function setMinterReward(uint amount) external onlyOwner {
        require(amount <= MAX_MINTER_REWARD, "Reward cannot exceed max minter reward");
        minterReward = amount;
        emit MinterRewardUpdated(minterReward);
    }

    // ========== SETTERS ========== */

    /**
     * @notice Set the SynthetixProxy should it ever change.
     * SupplySchedule requires Synthetix address as it has the authority
     * to record mint event.
     * */
    function setSynthetixProxy(ISynthetix _synthetixProxy) external onlyOwner {
        require(_synthetixProxy != address(0), "Address cannot be 0");
        synthetixProxy = _synthetixProxy;
        emit SynthetixProxyUpdated(synthetixProxy);
    }

    // ========== MODIFIERS ==========

    /**
     * @notice Only the Synthetix contract is authorised to call this function
     * */
    modifier onlySynthetix() {
        require(
            msg.sender == address(Proxy(synthetixProxy).target()),
            "Only the synthetix contract can perform this action"
        );
        _;
    }

    /* ========== EVENTS ========== */
    /**
     * @notice Emitted when the inflationary supply is minted
     * */
    event SupplyMinted(uint supplyMinted, uint numberOfWeeksIssued, uint lastMintEvent, uint timestamp);

    /**
     * @notice Emitted when the SNX minter reward amount is updated
     * */
    event MinterRewardUpdated(uint newRewardAmount);

    /**
     * @notice Emitted when setSynthetixProxy is called changing the Synthetix Proxy address
     * */
    event SynthetixProxyUpdated(address newAddress);
}


/**
 * @title RewardsDistribution interface
 */
interface IRewardsDistribution {
    function distributeRewards(uint amount) external;
}


contract IEtherCollateral {
    uint256 public totalIssuedSynths;
}


/**
 * @title Synthetix ERC20 contract.
 * @notice The Synthetix contracts not only facilitates transfers, exchanges, and tracks balances,
 * but it also computes the quantity of fees each synthetix holder is entitled to.
 */
contract Synthetix is ExternStateToken, MixinResolver {
    // ========== STATE VARIABLES ==========

    // Available Synths which can be used with the system
    Synth[] public availableSynths;
    mapping(bytes32 => Synth) public synths;
    mapping(address => bytes32) public synthsByAddress;

    string constant TOKEN_NAME = "Synthetix Network Token";
    string constant TOKEN_SYMBOL = "SNX";
    uint8 constant DECIMALS = 18;
    bytes32 constant sUSD = "sUSD";

    // ========== CONSTRUCTOR ==========

    /**
     * @dev Constructor
     * @param _proxy The main token address of the Proxy contract. This will be ProxyERC20.sol
     * @param _tokenState Address of the external immutable contract containing token balances.
     * @param _owner The owner of this contract.
     * @param _totalSupply On upgrading set to reestablish the current total supply (This should be in SynthetixState if ever updated)
     * @param _resolver The address of the Synthetix Address Resolver
     */
    constructor(address _proxy, TokenState _tokenState, address _owner, uint _totalSupply, address _resolver)
        public
        ExternStateToken(_proxy, _tokenState, TOKEN_NAME, TOKEN_SYMBOL, _totalSupply, DECIMALS, _owner)
        MixinResolver(_owner, _resolver)
    {}

    /* ========== VIEWS ========== */

    function exchanger() internal view returns (IExchanger) {
        return IExchanger(resolver.requireAndGetAddress("Exchanger", "Missing Exchanger address"));
    }

    function etherCollateral() internal view returns (IEtherCollateral) {
        return IEtherCollateral(resolver.requireAndGetAddress("EtherCollateral", "Missing EtherCollateral address"));
    }

    function issuer() internal view returns (IIssuer) {
        return IIssuer(resolver.requireAndGetAddress("Issuer", "Missing Issuer address"));
    }

    function synthetixState() internal view returns (ISynthetixState) {
        return ISynthetixState(resolver.requireAndGetAddress("SynthetixState", "Missing SynthetixState address"));
    }

    function exchangeRates() internal view returns (IExchangeRates) {
        return IExchangeRates(resolver.requireAndGetAddress("ExchangeRates", "Missing ExchangeRates address"));
    }

    function feePool() internal view returns (IFeePool) {
        return IFeePool(resolver.requireAndGetAddress("FeePool", "Missing FeePool address"));
    }

    function supplySchedule() internal view returns (SupplySchedule) {
        return SupplySchedule(resolver.requireAndGetAddress("SupplySchedule", "Missing SupplySchedule address"));
    }

    function rewardEscrow() internal view returns (ISynthetixEscrow) {
        return ISynthetixEscrow(resolver.requireAndGetAddress("RewardEscrow", "Missing RewardEscrow address"));
    }

    function synthetixEscrow() internal view returns (ISynthetixEscrow) {
        return ISynthetixEscrow(resolver.requireAndGetAddress("SynthetixEscrow", "Missing SynthetixEscrow address"));
    }

    function rewardsDistribution() internal view returns (IRewardsDistribution) {
        return
            IRewardsDistribution(
                resolver.requireAndGetAddress("RewardsDistribution", "Missing RewardsDistribution address")
            );
    }

    /**
     * @notice Total amount of synths issued by the system, priced in currencyKey
     * @param currencyKey The currency to value the synths in
     */
    function _totalIssuedSynths(bytes32 currencyKey, bool excludeEtherCollateral) internal view returns (uint) {
        IExchangeRates exRates = exchangeRates();
        uint total = 0;
        uint currencyRate = exRates.rateForCurrency(currencyKey);

        (uint[] memory rates, bool anyRateStale) = exRates.ratesAndStaleForCurrencies(availableCurrencyKeys());
        require(!anyRateStale, "Rates are stale");

        for (uint i = 0; i < availableSynths.length; i++) {
            // What's the total issued value of that synth in the destination currency?
            // Note: We're not using exchangeRates().effectiveValue() because we don't want to go get the
            //       rate for the destination currency and check if it's stale repeatedly on every
            //       iteration of the loop
            uint totalSynths = availableSynths[i].totalSupply();

            // minus total issued synths from Ether Collateral from sETH.totalSupply()
            if (excludeEtherCollateral && availableSynths[i] == synths["sETH"]) {
                totalSynths = totalSynths.sub(etherCollateral().totalIssuedSynths());
            }

            uint synthValue = totalSynths.multiplyDecimalRound(rates[i]);
            total = total.add(synthValue);
        }

        return total.divideDecimalRound(currencyRate);
    }

    /**
     * @notice Total amount of synths issued by the system priced in currencyKey
     * @param currencyKey The currency to value the synths in
     */
    function totalIssuedSynths(bytes32 currencyKey) public view returns (uint) {
        return _totalIssuedSynths(currencyKey, false);
    }

    /**
     * @notice Total amount of synths issued by the system priced in currencyKey, excluding ether collateral
     * @param currencyKey The currency to value the synths in
     */
    function totalIssuedSynthsExcludeEtherCollateral(bytes32 currencyKey) public view returns (uint) {
        return _totalIssuedSynths(currencyKey, true);
    }

    /**
     * @notice Returns the currencyKeys of availableSynths for rate checking
     */
    function availableCurrencyKeys() public view returns (bytes32[]) {
        bytes32[] memory currencyKeys = new bytes32[](availableSynths.length);

        for (uint i = 0; i < availableSynths.length; i++) {
            currencyKeys[i] = synthsByAddress[availableSynths[i]];
        }

        return currencyKeys;
    }

    /**
     * @notice Returns the count of available synths in the system, which you can use to iterate availableSynths
     */
    function availableSynthCount() public view returns (uint) {
        return availableSynths.length;
    }

    function isWaitingPeriod(bytes32 currencyKey) external view returns (bool) {
        return exchanger().maxSecsLeftInWaitingPeriod(messageSender, currencyKey) > 0;
    }

    // ========== MUTATIVE FUNCTIONS ==========

    /**
     * @notice Add an associated Synth contract to the Synthetix system
     * @dev Only the contract owner may call this.
     */
    function addSynth(Synth synth) external optionalProxy_onlyOwner {
        bytes32 currencyKey = synth.currencyKey();

        require(synths[currencyKey] == Synth(0), "Synth already exists");
        require(synthsByAddress[synth] == bytes32(0), "Synth address already exists");

        availableSynths.push(synth);
        synths[currencyKey] = synth;
        synthsByAddress[synth] = currencyKey;
    }

    /**
     * @notice Remove an associated Synth contract from the Synthetix system
     * @dev Only the contract owner may call this.
     */
    function removeSynth(bytes32 currencyKey) external optionalProxy_onlyOwner {
        require(synths[currencyKey] != address(0), "Synth does not exist");
        require(synths[currencyKey].totalSupply() == 0, "Synth supply exists");
        require(currencyKey != sUSD, "Cannot remove synth");

        // Save the address we're removing for emitting the event at the end.
        address synthToRemove = synths[currencyKey];

        // Remove the synth from the availableSynths array.
        for (uint i = 0; i < availableSynths.length; i++) {
            if (availableSynths[i] == synthToRemove) {
                delete availableSynths[i];

                // Copy the last synth into the place of the one we just deleted
                // If there's only one synth, this is synths[0] = synths[0].
                // If we're deleting the last one, it's also a NOOP in the same way.
                availableSynths[i] = availableSynths[availableSynths.length - 1];

                // Decrease the size of the array by one.
                availableSynths.length--;

                break;
            }
        }

        // And remove it from the synths mapping
        delete synthsByAddress[synths[currencyKey]];
        delete synths[currencyKey];

        // Note: No event here as Synthetix contract exceeds max contract size
        // with these events, and it's unlikely people will need to
        // track these events specifically.
    }

    /**
     * @notice ERC20 transfer function.
     */
    function transfer(address to, uint value) public optionalProxy returns (bool) {
        // Ensure they're not trying to exceed their staked SNX amount
        require(value <= transferableSynthetix(messageSender), "Cannot transfer staked or escrowed SNX");

        // Perform the transfer: if there is a problem an exception will be thrown in this call.
        _transfer_byProxy(messageSender, to, value);

        return true;
    }

    /**
     * @notice ERC20 transferFrom function.
     */
    function transferFrom(address from, address to, uint value) public optionalProxy returns (bool) {
        // Ensure they're not trying to exceed their locked amount
        require(value <= transferableSynthetix(from), "Cannot transfer staked or escrowed SNX");

        // Perform the transfer: if there is a problem,
        // an exception will be thrown in this call.
        return _transferFrom_byProxy(messageSender, from, to, value);
    }

    function issueSynths(uint amount) external optionalProxy {
        return issuer().issueSynths(messageSender, amount);
    }

    function issueMaxSynths() external optionalProxy {
        return issuer().issueMaxSynths(messageSender);
    }

    function burnSynths(uint amount) external optionalProxy {
        return issuer().burnSynths(messageSender, amount);
    }

    function exchange(bytes32 sourceCurrencyKey, uint sourceAmount, bytes32 destinationCurrencyKey)
        external
        optionalProxy
        returns (uint amountReceived)
    {
        return exchanger().exchange(messageSender, sourceCurrencyKey, sourceAmount, destinationCurrencyKey, messageSender);
    }

    function settle(bytes32 currencyKey) external optionalProxy returns (uint reclaimed, uint refunded) {
        return exchanger().settle(messageSender, currencyKey);
    }

    // ========== Issuance/Burning ==========

    /**
     * @notice The maximum synths an issuer can issue against their total synthetix quantity.
     * This ignores any already issued synths, and is purely giving you the maximimum amount the user can issue.
     */
    function maxIssuableSynths(address _issuer)
        public
        view
        returns (
            // We don't need to check stale rates here as effectiveValue will do it for us.
            uint
        )
    {
        // What is the value of their SNX balance in the destination currency?
        uint destinationValue = exchangeRates().effectiveValue("SNX", collateral(_issuer), sUSD);

        // They're allowed to issue up to issuanceRatio of that value
        return destinationValue.multiplyDecimal(synthetixState().issuanceRatio());
    }

    /**
     * @notice The current collateralisation ratio for a user. Collateralisation ratio varies over time
     * as the value of the underlying Synthetix asset changes,
     * e.g. based on an issuance ratio of 20%. if a user issues their maximum available
     * synths when they hold $10 worth of Synthetix, they will have issued $2 worth of synths. If the value
     * of Synthetix changes, the ratio returned by this function will adjust accordingly. Users are
     * incentivised to maintain a collateralisation ratio as close to the issuance ratio as possible by
     * altering the amount of fees they're able to claim from the system.
     */
    function collateralisationRatio(address _issuer) public view returns (uint) {
        uint totalOwnedSynthetix = collateral(_issuer);
        if (totalOwnedSynthetix == 0) return 0;

        uint debtBalance = debtBalanceOf(_issuer, "SNX");
        return debtBalance.divideDecimalRound(totalOwnedSynthetix);
    }

    /**
     * @notice If a user issues synths backed by SNX in their wallet, the SNX become locked. This function
     * will tell you how many synths a user has to give back to the system in order to unlock their original
     * debt position. This is priced in whichever synth is passed in as a currency key, e.g. you can price
     * the debt in sUSD, or any other synth you wish.
     */
    function debtBalanceOf(address _issuer, bytes32 currencyKey)
        public
        view
        returns (
            // Don't need to check for stale rates here because totalIssuedSynths will do it for us
            uint
        )
    {
        ISynthetixState state = synthetixState();

        // What was their initial debt ownership?
        uint initialDebtOwnership;
        uint debtEntryIndex;
        (initialDebtOwnership, debtEntryIndex) = state.issuanceData(_issuer);

        // If it's zero, they haven't issued, and they have no debt.
        if (initialDebtOwnership == 0) return 0;

        // Figure out the global debt percentage delta from when they entered the system.
        // This is a high precision integer of 27 (1e27) decimals.
        uint currentDebtOwnership = state
            .lastDebtLedgerEntry()
            .divideDecimalRoundPrecise(state.debtLedger(debtEntryIndex))
            .multiplyDecimalRoundPrecise(initialDebtOwnership);

        // What's the total value of the system excluding ETH backed synths in their requested currency?
        uint totalSystemValue = totalIssuedSynthsExcludeEtherCollateral(currencyKey);

        // Their debt balance is their portion of the total system value.
        uint highPrecisionBalance = totalSystemValue.decimalToPreciseDecimal().multiplyDecimalRoundPrecise(
            currentDebtOwnership
        );

        // Convert back into 18 decimals (1e18)
        return highPrecisionBalance.preciseDecimalToDecimal();
    }

    /**
     * @notice The remaining synths an issuer can issue against their total synthetix balance.
     * @param _issuer The account that intends to issue
     */
    function remainingIssuableSynths(address _issuer)
        public
        view
        returns (
            // Don't need to check for synth existing or stale rates because maxIssuableSynths will do it for us.
            uint,
            uint
        )
    {
        uint alreadyIssued = debtBalanceOf(_issuer, sUSD);
        uint maxIssuable = maxIssuableSynths(_issuer);

        if (alreadyIssued >= maxIssuable) {
            maxIssuable = 0;
        } else {
            maxIssuable = maxIssuable.sub(alreadyIssued);
        }
        return (maxIssuable, alreadyIssued);
    }

    /**
     * @notice The total SNX owned by this account, both escrowed and unescrowed,
     * against which synths can be issued.
     * This includes those already being used as collateral (locked), and those
     * available for further issuance (unlocked).
     */
    function collateral(address account) public view returns (uint) {
        uint balance = tokenState.balanceOf(account);

        if (synthetixEscrow() != address(0)) {
            balance = balance.add(synthetixEscrow().balanceOf(account));
        }

        if (rewardEscrow() != address(0)) {
            balance = balance.add(rewardEscrow().balanceOf(account));
        }

        return balance;
    }

    /**
     * @notice The number of SNX that are free to be transferred for an account.
     * @dev Escrowed SNX are not transferable, so they are not included
     * in this calculation.
     * @notice SNX rate not stale is checked within debtBalanceOf
     */
    function transferableSynthetix(address account)
        public
        view
        rateNotStale("SNX") // SNX is not a synth so is not checked in totalIssuedSynths
        returns (uint)
    {
        // How many SNX do they have, excluding escrow?
        // Note: We're excluding escrow here because we're interested in their transferable amount
        // and escrowed SNX are not transferable.
        uint balance = tokenState.balanceOf(account);

        // How many of those will be locked by the amount they've issued?
        // Assuming issuance ratio is 20%, then issuing 20 SNX of value would require
        // 100 SNX to be locked in their wallet to maintain their collateralisation ratio
        // The locked synthetix value can exceed their balance.
        uint lockedSynthetixValue = debtBalanceOf(account, "SNX").divideDecimalRound(synthetixState().issuanceRatio());

        // If we exceed the balance, no SNX are transferable, otherwise the difference is.
        if (lockedSynthetixValue >= balance) {
            return 0;
        } else {
            return balance.sub(lockedSynthetixValue);
        }
    }

    /**
     * @notice Mints the inflationary SNX supply. The inflation shedule is
     * defined in the SupplySchedule contract.
     * The mint() function is publicly callable by anyone. The caller will
     receive a minter reward as specified in supplySchedule.minterReward().
     */
    function mint() external returns (bool) {
        require(rewardsDistribution() != address(0), "RewardsDistribution not set");

        SupplySchedule _supplySchedule = supplySchedule();
        IRewardsDistribution _rewardsDistribution = rewardsDistribution();

        uint supplyToMint = _supplySchedule.mintableSupply();
        require(supplyToMint > 0, "No supply is mintable");

        // record minting event before mutation to token supply
        _supplySchedule.recordMintEvent(supplyToMint);

        // Set minted SNX balance to RewardEscrow's balance
        // Minus the minterReward and set balance of minter to add reward
        uint minterReward = _supplySchedule.minterReward();
        // Get the remainder
        uint amountToDistribute = supplyToMint.sub(minterReward);

        // Set the token balance to the RewardsDistribution contract
        tokenState.setBalanceOf(_rewardsDistribution, tokenState.balanceOf(_rewardsDistribution).add(amountToDistribute));
        emitTransfer(this, _rewardsDistribution, amountToDistribute);

        // Kick off the distribution of rewards
        _rewardsDistribution.distributeRewards(amountToDistribute);

        // Assign the minters reward.
        tokenState.setBalanceOf(msg.sender, tokenState.balanceOf(msg.sender).add(minterReward));
        emitTransfer(this, msg.sender, minterReward);

        totalSupply = totalSupply.add(supplyToMint);

        return true;
    }

    // ========== MODIFIERS ==========

    modifier rateNotStale(bytes32 currencyKey) {
        require(!exchangeRates().rateIsStale(currencyKey), "Rate stale or not a synth");
        _;
    }

    modifier onlyExchanger() {
        require(msg.sender == address(exchanger()), "Only the exchanger contract can invoke this function");
        _;
    }

    // ========== EVENTS ==========
    /* solium-disable */
    event SynthExchange(
        address indexed account,
        bytes32 fromCurrencyKey,
        uint256 fromAmount,
        bytes32 toCurrencyKey,
        uint256 toAmount,
        address toAddress
    );
    bytes32 constant SYNTHEXCHANGE_SIG = keccak256("SynthExchange(address,bytes32,uint256,bytes32,uint256,address)");

    function emitSynthExchange(
        address account,
        bytes32 fromCurrencyKey,
        uint256 fromAmount,
        bytes32 toCurrencyKey,
        uint256 toAmount,
        address toAddress
    ) external onlyExchanger {
        proxy._emit(
            abi.encode(fromCurrencyKey, fromAmount, toCurrencyKey, toAmount, toAddress),
            2,
            SYNTHEXCHANGE_SIG,
            bytes32(account),
            0,
            0
        );
    }

    event ExchangeReclaim(address indexed account, bytes32 currencyKey, uint amount);
    bytes32 constant EXCHANGERECLAIM_SIG = keccak256("ExchangeReclaim(address,bytes32,uint256)");

    function emitExchangeReclaim(address account, bytes32 currencyKey, uint256 amount) external onlyExchanger {
        proxy._emit(abi.encode(currencyKey, amount), 2, EXCHANGERECLAIM_SIG, bytes32(account), 0, 0);
    }

    event ExchangeRebate(address indexed account, bytes32 currencyKey, uint amount);
    bytes32 constant EXCHANGEREBATE_SIG = keccak256("ExchangeRebate(address,bytes32,uint256)");

    function emitExchangeRebate(address account, bytes32 currencyKey, uint256 amount) external onlyExchanger {
        proxy._emit(abi.encode(currencyKey, amount), 2, EXCHANGEREBATE_SIG, bytes32(account), 0, 0);
    }
    /* solium-enable */
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       LimitedSetup.sol
version:    1.1
author:     Anton Jurisevic

date:       2018-05-15

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

A contract with a limited setup period. Any function modified
with the setup modifier will cease to work after the
conclusion of the configurable-length post-construction setup period.

-----------------------------------------------------------------
*/


/**
 * @title Any function decorated with the modifier this contract provides
 * deactivates after a specified setup period.
 */
contract LimitedSetup {
    uint setupExpiryTime;

    /**
     * @dev LimitedSetup Constructor.
     * @param setupDuration The time the setup period will last for.
     */
    constructor(uint setupDuration) public {
        setupExpiryTime = now + setupDuration;
    }

    modifier onlyDuringSetup {
        require(now < setupExpiryTime, "Can only perform this action during setup");
        _;
    }
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       FeePoolState.sol
version:    1.0
author:     Clinton Ennis
            Jackson Chan
date:       2019-04-05

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

The FeePoolState simply stores the accounts issuance ratio for
each fee period in the FeePool.

This is used to calculate the correct allocation of fees/rewards
owed to minters of the stablecoin total supply

-----------------------------------------------------------------
*/


contract FeePoolState is SelfDestructible, LimitedSetup {
    using SafeMath for uint;
    using SafeDecimalMath for uint;

    /* ========== STATE VARIABLES ========== */

    uint8 public constant FEE_PERIOD_LENGTH = 6;

    address public feePool;

    // The IssuanceData activity that's happened in a fee period.
    struct IssuanceData {
        uint debtPercentage;
        uint debtEntryIndex;
    }

    // The IssuanceData activity that's happened in a fee period.
    mapping(address => IssuanceData[FEE_PERIOD_LENGTH]) public accountIssuanceLedger;

    /**
     * @dev Constructor.
     * @param _owner The owner of this contract.
     */
    constructor(address _owner, IFeePool _feePool) public SelfDestructible(_owner) LimitedSetup(6 weeks) {
        feePool = _feePool;
    }

    /* ========== SETTERS ========== */

    /**
     * @notice set the FeePool contract as it is the only authority to be able to call
     * appendAccountIssuanceRecord with the onlyFeePool modifer
     * @dev Must be set by owner when FeePool logic is upgraded
     */
    function setFeePool(IFeePool _feePool) external onlyOwner {
        feePool = _feePool;
    }

    /* ========== VIEWS ========== */

    /**
     * @notice Get an accounts issuanceData for
     * @param account users account
     * @param index Index in the array to retrieve. Upto FEE_PERIOD_LENGTH
     */
    function getAccountsDebtEntry(address account, uint index)
        public
        view
        returns (uint debtPercentage, uint debtEntryIndex)
    {
        require(index < FEE_PERIOD_LENGTH, "index exceeds the FEE_PERIOD_LENGTH");

        debtPercentage = accountIssuanceLedger[account][index].debtPercentage;
        debtEntryIndex = accountIssuanceLedger[account][index].debtEntryIndex;
    }

    /**
     * @notice Find the oldest debtEntryIndex for the corresponding closingDebtIndex
     * @param account users account
     * @param closingDebtIndex the last periods debt index on close
     */
    function applicableIssuanceData(address account, uint closingDebtIndex) external view returns (uint, uint) {
        IssuanceData[FEE_PERIOD_LENGTH] memory issuanceData = accountIssuanceLedger[account];

        // We want to use the user's debtEntryIndex at when the period closed
        // Find the oldest debtEntryIndex for the corresponding closingDebtIndex
        for (uint i = 0; i < FEE_PERIOD_LENGTH; i++) {
            if (closingDebtIndex >= issuanceData[i].debtEntryIndex) {
                return (issuanceData[i].debtPercentage, issuanceData[i].debtEntryIndex);
            }
        }
    }

    /* ========== MUTATIVE FUNCTIONS ========== */

    /**
     * @notice Logs an accounts issuance data in the current fee period which is then stored historically
     * @param account Message.Senders account address
     * @param debtRatio Debt of this account as a percentage of the global debt.
     * @param debtEntryIndex The index in the global debt ledger. synthetix.synthetixState().issuanceData(account)
     * @param currentPeriodStartDebtIndex The startingDebtIndex of the current fee period
     * @dev onlyFeePool to call me on synthetix.issue() & synthetix.burn() calls to store the locked SNX
     * per fee period so we know to allocate the correct proportions of fees and rewards per period
      accountIssuanceLedger[account][0] has the latest locked amount for the current period. This can be update as many time
      accountIssuanceLedger[account][1-2] has the last locked amount for a previous period they minted or burned
     */
    function appendAccountIssuanceRecord(
        address account,
        uint debtRatio,
        uint debtEntryIndex,
        uint currentPeriodStartDebtIndex
    ) external onlyFeePool {
        // Is the current debtEntryIndex within this fee period
        if (accountIssuanceLedger[account][0].debtEntryIndex < currentPeriodStartDebtIndex) {
            // If its older then shift the previous IssuanceData entries periods down to make room for the new one.
            issuanceDataIndexOrder(account);
        }

        // Always store the latest IssuanceData entry at [0]
        accountIssuanceLedger[account][0].debtPercentage = debtRatio;
        accountIssuanceLedger[account][0].debtEntryIndex = debtEntryIndex;
    }

    /**
     * @notice Pushes down the entire array of debt ratios per fee period
     */
    function issuanceDataIndexOrder(address account) private {
        for (uint i = FEE_PERIOD_LENGTH - 2; i < FEE_PERIOD_LENGTH; i--) {
            uint next = i + 1;
            accountIssuanceLedger[account][next].debtPercentage = accountIssuanceLedger[account][i].debtPercentage;
            accountIssuanceLedger[account][next].debtEntryIndex = accountIssuanceLedger[account][i].debtEntryIndex;
        }
    }

    /**
     * @notice Import issuer data from synthetixState.issuerData on FeePeriodClose() block #
     * @dev Only callable by the contract owner, and only for 6 weeks after deployment.
     * @param accounts Array of issuing addresses
     * @param ratios Array of debt ratios
     * @param periodToInsert The Fee Period to insert the historical records into
     * @param feePeriodCloseIndex An accounts debtEntryIndex is valid when within the fee peroid,
     * since the input ratio will be an average of the pervious periods it just needs to be
     * > recentFeePeriods[periodToInsert].startingDebtIndex
     * < recentFeePeriods[periodToInsert - 1].startingDebtIndex
     */
    function importIssuerData(address[] accounts, uint[] ratios, uint periodToInsert, uint feePeriodCloseIndex)
        external
        onlyOwner
        onlyDuringSetup
    {
        require(accounts.length == ratios.length, "Length mismatch");

        for (uint i = 0; i < accounts.length; i++) {
            accountIssuanceLedger[accounts[i]][periodToInsert].debtPercentage = ratios[i];
            accountIssuanceLedger[accounts[i]][periodToInsert].debtEntryIndex = feePeriodCloseIndex;
            emit IssuanceDebtRatioEntry(accounts[i], ratios[i], feePeriodCloseIndex);
        }
    }

    /* ========== MODIFIERS ========== */

    modifier onlyFeePool {
        require(msg.sender == address(feePool), "Only the FeePool contract can perform this action");
        _;
    }

    /* ========== Events ========== */
    event IssuanceDebtRatioEntry(address indexed account, uint debtRatio, uint feePeriodCloseIndex);
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       EternalStorage.sol
version:    1.0
author:     Clinton Ennise
            Jackson Chan

date:       2019-02-01

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

This contract is used with external state storage contracts for
decoupled data storage.

Implements support for storing a keccak256 key and value pairs. It is
the more flexible and extensible option. This ensures data schema
changes can be implemented without requiring upgrades to the
storage contract

The first deployed storage contract would create this eternal storage.
Favour use of keccak256 key over sha3 as future version of solidity
> 0.5.0 will be deprecated.

-----------------------------------------------------------------
*/


/**
 * @notice  This contract is based on the code available from this blog
 * https://blog.colony.io/writing-upgradeable-contracts-in-solidity-6743f0eecc88/
 * Implements support for storing a keccak256 key and value pairs. It is the more flexible
 * and extensible option. This ensures data schema changes can be implemented without
 * requiring upgrades to the storage contract.
 */
contract EternalStorage is State {
    constructor(address _owner, address _associatedContract) public State(_owner, _associatedContract) {}

    /* ========== DATA TYPES ========== */
    mapping(bytes32 => uint) UIntStorage;
    mapping(bytes32 => string) StringStorage;
    mapping(bytes32 => address) AddressStorage;
    mapping(bytes32 => bytes) BytesStorage;
    mapping(bytes32 => bytes32) Bytes32Storage;
    mapping(bytes32 => bool) BooleanStorage;
    mapping(bytes32 => int) IntStorage;

    // UIntStorage;
    function getUIntValue(bytes32 record) external view returns (uint) {
        return UIntStorage[record];
    }

    function setUIntValue(bytes32 record, uint value) external onlyAssociatedContract {
        UIntStorage[record] = value;
    }

    function deleteUIntValue(bytes32 record) external onlyAssociatedContract {
        delete UIntStorage[record];
    }

    // StringStorage
    function getStringValue(bytes32 record) external view returns (string memory) {
        return StringStorage[record];
    }

    function setStringValue(bytes32 record, string value) external onlyAssociatedContract {
        StringStorage[record] = value;
    }

    function deleteStringValue(bytes32 record) external onlyAssociatedContract {
        delete StringStorage[record];
    }

    // AddressStorage
    function getAddressValue(bytes32 record) external view returns (address) {
        return AddressStorage[record];
    }

    function setAddressValue(bytes32 record, address value) external onlyAssociatedContract {
        AddressStorage[record] = value;
    }

    function deleteAddressValue(bytes32 record) external onlyAssociatedContract {
        delete AddressStorage[record];
    }

    // BytesStorage
    function getBytesValue(bytes32 record) external view returns (bytes memory) {
        return BytesStorage[record];
    }

    function setBytesValue(bytes32 record, bytes value) external onlyAssociatedContract {
        BytesStorage[record] = value;
    }

    function deleteBytesValue(bytes32 record) external onlyAssociatedContract {
        delete BytesStorage[record];
    }

    // Bytes32Storage
    function getBytes32Value(bytes32 record) external view returns (bytes32) {
        return Bytes32Storage[record];
    }

    function setBytes32Value(bytes32 record, bytes32 value) external onlyAssociatedContract {
        Bytes32Storage[record] = value;
    }

    function deleteBytes32Value(bytes32 record) external onlyAssociatedContract {
        delete Bytes32Storage[record];
    }

    // BooleanStorage
    function getBooleanValue(bytes32 record) external view returns (bool) {
        return BooleanStorage[record];
    }

    function setBooleanValue(bytes32 record, bool value) external onlyAssociatedContract {
        BooleanStorage[record] = value;
    }

    function deleteBooleanValue(bytes32 record) external onlyAssociatedContract {
        delete BooleanStorage[record];
    }

    // IntStorage
    function getIntValue(bytes32 record) external view returns (int) {
        return IntStorage[record];
    }

    function setIntValue(bytes32 record, int value) external onlyAssociatedContract {
        IntStorage[record] = value;
    }

    function deleteIntValue(bytes32 record) external onlyAssociatedContract {
        delete IntStorage[record];
    }
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       FeePoolEternalStorage.sol
version:    1.0
author:     Clinton Ennis
            Jackson Chan
date:       2019-04-05

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

The FeePoolEternalStorage is for any state the FeePool contract
needs to persist between upgrades to the FeePool logic.

Please see EternalStorage.sol

-----------------------------------------------------------------
*/


contract FeePoolEternalStorage is EternalStorage, LimitedSetup {
    bytes32 constant LAST_FEE_WITHDRAWAL = "last_fee_withdrawal";

    /**
     * @dev Constructor.
     * @param _owner The owner of this contract.
     */
    constructor(address _owner, address _feePool) public EternalStorage(_owner, _feePool) LimitedSetup(6 weeks) {}

    /**
     * @notice Import data from FeePool.lastFeeWithdrawal
     * @dev Only callable by the contract owner, and only for 6 weeks after deployment.
     * @param accounts Array of addresses that have claimed
     * @param feePeriodIDs Array feePeriodIDs with the accounts last claim
     */
    function importFeeWithdrawalData(address[] accounts, uint[] feePeriodIDs) external onlyOwner onlyDuringSetup {
        require(accounts.length == feePeriodIDs.length, "Length mismatch");

        for (uint8 i = 0; i < accounts.length; i++) {
            this.setUIntValue(keccak256(abi.encodePacked(LAST_FEE_WITHDRAWAL, accounts[i])), feePeriodIDs[i]);
        }
    }
}


/*
-----------------------------------------------------------------
FILE INFORMATION
-----------------------------------------------------------------

file:       DelegateApprovals.sol
version:    1.0
author:     Jackson Chan
checked:    Clinton Ennis
date:       2019-05-01

-----------------------------------------------------------------
MODULE DESCRIPTION
-----------------------------------------------------------------

The approval state contract is designed to allow a wallet to
authorise another address to perform actions, on a contract,
on their behalf. This could be an automated service
that would help a wallet claim fees / rewards on their behalf.

The concept is similar to the ERC20 interface where a wallet can
approve an authorised party to spend on the authorising party's
behalf in the allowance interface.

Withdrawing approval deletes the approval for the given delegate.

This contract inherits state for upgradeability / associated
contract.

-----------------------------------------------------------------
*/


contract DelegateApprovals is State {
    // Approvals - [authoriser][delegate]
    // Each authoriser can have multiple delegates
    mapping(address => mapping(address => bool)) public approval;

    /**
     * @dev Constructor
     * @param _owner The address which controls this contract.
     * @param _associatedContract The contract whose approval state this composes.
     */
    constructor(address _owner, address _associatedContract) public State(_owner, _associatedContract) {}

    function setApproval(address authoriser, address delegate) external onlyAssociatedContract {
        approval[authoriser][delegate] = true;
        emit Approval(authoriser, delegate);
    }

    function withdrawApproval(address authoriser, address delegate) external onlyAssociatedContract {
        delete approval[authoriser][delegate];
        emit WithdrawApproval(authoriser, delegate);
    }

    /* ========== EVENTS ========== */

    event Approval(address indexed authoriser, address delegate);
    event WithdrawApproval(address indexed authoriser, address delegate);
}


contract FeePool is Proxyable, SelfDestructible, LimitedSetup, MixinResolver {
    using SafeMath for uint;
    using SafeDecimalMath for uint;

    // A percentage fee charged on each exchange between currencies.
    uint public exchangeFeeRate;

    // Exchange fee may not exceed 10%.
    uint public constant MAX_EXCHANGE_FEE_RATE = SafeDecimalMath.unit() / 10;

    // Where fees are pooled in sUSD.
    address public constant FEE_ADDRESS = 0xfeEFEEfeefEeFeefEEFEEfEeFeefEEFeeFEEFEeF;

    // sUSD currencyKey. Fees stored and paid in sUSD
    bytes32 private sUSD = "sUSD";

    // This struct represents the issuance activity that's happened in a fee period.
    struct FeePeriod {
        uint64 feePeriodId;
        uint64 startingDebtIndex;
        uint64 startTime;
        uint feesToDistribute;
        uint feesClaimed;
        uint rewardsToDistribute;
        uint rewardsClaimed;
    }

    // The last 2 fee periods are all that you can claim from.
    // These are stored and managed from [0], such that [0] is always
    // the current avtive fee period which is not claimable until the
    // public function closeCurrentFeePeriod() is called closing the
    // current weeks collected fees. [1] is last weeks feeperiod and
    // [2] is the oldest fee period that users can claim for.
    uint8 public constant FEE_PERIOD_LENGTH = 3;

    FeePeriod[FEE_PERIOD_LENGTH] private _recentFeePeriods;
    uint256 private _currentFeePeriod;

    // How long a fee period lasts at a minimum. It is required for
    // anyone to roll over the periods, so they are not guaranteed
    // to roll over at exactly this duration, but the contract enforces
    // that they cannot roll over any quicker than this duration.
    uint public feePeriodDuration = 1 weeks;
    // The fee period must be between 1 day and 60 days.
    uint public constant MIN_FEE_PERIOD_DURATION = 1 days;
    uint public constant MAX_FEE_PERIOD_DURATION = 60 days;

    // Users are unable to claim fees if their collateralisation ratio drifts out of target treshold
    uint public targetThreshold = (1 * SafeDecimalMath.unit()) / 100;

    /* ========== ETERNAL STORAGE CONSTANTS ========== */

    bytes32 private constant LAST_FEE_WITHDRAWAL = "last_fee_withdrawal";

    constructor(address _proxy, address _owner, uint _exchangeFeeRate, address _resolver)
        public
        SelfDestructible(_owner)
        Proxyable(_proxy, _owner)
        LimitedSetup(3 weeks)
        MixinResolver(_owner, _resolver)
    {
        // Constructed fee rates should respect the maximum fee rates.
        require(_exchangeFeeRate <= MAX_EXCHANGE_FEE_RATE, "Exchange fee rate max exceeded");

        exchangeFeeRate = _exchangeFeeRate;

        // Set our initial fee period
        _recentFeePeriodsStorage(0).feePeriodId = 1;
        _recentFeePeriodsStorage(0).startTime = uint64(now);
    }

    /* ========== VIEWS ========== */

    function synthetix() internal view returns (ISynthetix) {
        return ISynthetix(resolver.requireAndGetAddress("Synthetix", "Missing Synthetix address"));
    }

    function feePoolState() internal view returns (FeePoolState) {
        return FeePoolState(resolver.requireAndGetAddress("FeePoolState", "Missing FeePoolState address"));
    }

    function feePoolEternalStorage() internal view returns (FeePoolEternalStorage) {
        require(resolver.getAddress("FeePoolEternalStorage") != address(0), "Missing FeePoolEternalStorage address");
        return FeePoolEternalStorage(resolver.getAddress("FeePoolEternalStorage"));
    }

    function exchanger() internal view returns (IExchanger) {
        return IExchanger(resolver.requireAndGetAddress("Exchanger", "Missing Exchanger address"));
    }

    function issuer() internal view returns (IIssuer) {
        return IIssuer(resolver.requireAndGetAddress("Issuer", "Missing Issuer address"));
    }

    function synthetixState() internal view returns (ISynthetixState) {
        return ISynthetixState(resolver.requireAndGetAddress("SynthetixState", "Missing SynthetixState address"));
    }

    function rewardEscrow() internal view returns (ISynthetixEscrow) {
        return ISynthetixEscrow(resolver.requireAndGetAddress("RewardEscrow", "Missing RewardEscrow address"));
    }

    function delegateApprovals() internal view returns (DelegateApprovals) {
        return DelegateApprovals(resolver.requireAndGetAddress("DelegateApprovals", "Missing DelegateApprovals address"));
    }

    function recentFeePeriods(uint index)
        external
        view
        returns (
            uint64 feePeriodId,
            uint64 startingDebtIndex,
            uint64 startTime,
            uint feesToDistribute,
            uint feesClaimed,
            uint rewardsToDistribute,
            uint rewardsClaimed
        )
    {
        FeePeriod memory feePeriod = _recentFeePeriodsStorage(index);
        return (
            feePeriod.feePeriodId,
            feePeriod.startingDebtIndex,
            feePeriod.startTime,
            feePeriod.feesToDistribute,
            feePeriod.feesClaimed,
            feePeriod.rewardsToDistribute,
            feePeriod.rewardsClaimed
        );
    }

    function _recentFeePeriodsStorage(uint index) internal view returns (FeePeriod storage) {
        return _recentFeePeriods[(_currentFeePeriod + index) % FEE_PERIOD_LENGTH];
    }

    /* ========== MUTATIVE FUNCTIONS ========== */

    /**
     * @notice Logs an accounts issuance data per fee period
     * @param account Message.Senders account address
     * @param debtRatio Debt percentage this account has locked after minting or burning their synth
     * @param debtEntryIndex The index in the global debt ledger. synthetixState.issuanceData(account)
     * @dev onlyIssuer to call me on synthetix.issue() & synthetix.burn() calls to store the locked SNX
     * per fee period so we know to allocate the correct proportions of fees and rewards per period
     */
    function appendAccountIssuanceRecord(address account, uint debtRatio, uint debtEntryIndex) external onlyIssuer {
        feePoolState().appendAccountIssuanceRecord(
            account,
            debtRatio,
            debtEntryIndex,
            _recentFeePeriodsStorage(0).startingDebtIndex
        );

        emitIssuanceDebtRatioEntry(account, debtRatio, debtEntryIndex, _recentFeePeriodsStorage(0).startingDebtIndex);
    }

    /**
     * @notice Set the exchange fee, anywhere within the range 0-10%.
     * @dev The fee rate is in decimal format, with UNIT being the value of 100%.
     */
    function setExchangeFeeRate(uint _exchangeFeeRate) external optionalProxy_onlyOwner {
        require(_exchangeFeeRate < MAX_EXCHANGE_FEE_RATE, "rate < MAX_EXCHANGE_FEE_RATE");
        exchangeFeeRate = _exchangeFeeRate;
    }

    /**
     * @notice Set the fee period duration
     */
    function setFeePeriodDuration(uint _feePeriodDuration) external optionalProxy_onlyOwner {
        require(_feePeriodDuration >= MIN_FEE_PERIOD_DURATION, "value < MIN_FEE_PERIOD_DURATION");
        require(_feePeriodDuration <= MAX_FEE_PERIOD_DURATION, "value > MAX_FEE_PERIOD_DURATION");

        feePeriodDuration = _feePeriodDuration;

        emitFeePeriodDurationUpdated(_feePeriodDuration);
    }

    function setTargetThreshold(uint _percent) external optionalProxy_onlyOwner {
        require(_percent >= 0, "Threshold should be positive");
        require(_percent <= 50, "Threshold too high");
        targetThreshold = _percent.mul(SafeDecimalMath.unit()).div(100);
    }

    /**
     * @notice The Exchanger contract informs us when fees are paid.
     * @param amount susd amount in fees being paid.
     */
    function recordFeePaid(uint amount) external onlyExchangerOrSynth {
        // Keep track off fees in sUSD in the open fee pool period.
        _recentFeePeriodsStorage(0).feesToDistribute = _recentFeePeriodsStorage(0).feesToDistribute.add(amount);
    }

    /**
     * @notice The RewardsDistribution contract informs us how many SNX rewards are sent to RewardEscrow to be claimed.
     */
    function setRewardsToDistribute(uint amount) external {
        address rewardsAuthority = resolver.getAddress("RewardsDistribution");
        require(messageSender == rewardsAuthority || msg.sender == rewardsAuthority, "Caller is not rewardsAuthority");
        // Add the amount of SNX rewards to distribute on top of any rolling unclaimed amount
        _recentFeePeriodsStorage(0).rewardsToDistribute = _recentFeePeriodsStorage(0).rewardsToDistribute.add(amount);
    }

    /**
     * @notice Close the current fee period and start a new one.
     */
    function closeCurrentFeePeriod() external {
        require(_recentFeePeriodsStorage(0).startTime <= (now - feePeriodDuration), "Too early to close fee period");

        FeePeriod storage secondLastFeePeriod = _recentFeePeriodsStorage(FEE_PERIOD_LENGTH - 2);
        FeePeriod storage lastFeePeriod = _recentFeePeriodsStorage(FEE_PERIOD_LENGTH - 1);

        // Any unclaimed fees from the last period in the array roll back one period.
        // Because of the subtraction here, they're effectively proportionally redistributed to those who
        // have already claimed from the old period, available in the new period.
        // The subtraction is important so we don't create a ticking time bomb of an ever growing
        // number of fees that can never decrease and will eventually overflow at the end of the fee pool.
        _recentFeePeriodsStorage(FEE_PERIOD_LENGTH - 2).feesToDistribute = lastFeePeriod
            .feesToDistribute
            .sub(lastFeePeriod.feesClaimed)
            .add(secondLastFeePeriod.feesToDistribute);
        _recentFeePeriodsStorage(FEE_PERIOD_LENGTH - 2).rewardsToDistribute = lastFeePeriod
            .rewardsToDistribute
            .sub(lastFeePeriod.rewardsClaimed)
            .add(secondLastFeePeriod.rewardsToDistribute);

        // Shift the previous fee periods across to make room for the new one.
        _currentFeePeriod = _currentFeePeriod.add(FEE_PERIOD_LENGTH).sub(1).mod(FEE_PERIOD_LENGTH);

        // Clear the first element of the array to make sure we don't have any stale values.
        delete _recentFeePeriods[_currentFeePeriod];

        // Open up the new fee period.
        // Increment periodId from the recent closed period feePeriodId
        _recentFeePeriodsStorage(0).feePeriodId = uint64(uint256(_recentFeePeriodsStorage(1).feePeriodId).add(1));
        _recentFeePeriodsStorage(0).startingDebtIndex = uint64(synthetixState().debtLedgerLength());
        _recentFeePeriodsStorage(0).startTime = uint64(now);

        emitFeePeriodClosed(_recentFeePeriodsStorage(1).feePeriodId);
    }

    /**
    * @notice Claim fees for last period when available or not already withdrawn.
    */
    function claimFees() external optionalProxy returns (bool) {
        return _claimFees(messageSender);
    }

    /**
    * @notice Delegated claimFees(). Call from the deletegated address
    * and the fees will be sent to the claimingForAddress.
    * approveClaimOnBehalf() must be called first to approve the deletage address
    * @param claimingForAddress The account you are claiming fees for
    */
    function claimOnBehalf(address claimingForAddress) external optionalProxy returns (bool) {
        require(delegateApprovals().approval(claimingForAddress, messageSender), "Not approved to claim on behalf");

        return _claimFees(claimingForAddress);
    }

    function _claimFees(address claimingAddress) internal returns (bool) {
        uint rewardsPaid = 0;
        uint feesPaid = 0;
        uint availableFees;
        uint availableRewards;

        // Address won't be able to claim fees if it is too far below the target c-ratio.
        // It will need to burn synths then try claiming again.
        require(isFeesClaimable(claimingAddress), "C-Ratio below penalty threshold");

        // Get the claimingAddress available fees and rewards
        (availableFees, availableRewards) = feesAvailable(claimingAddress);

        require(
            availableFees > 0 || availableRewards > 0,
            "No fees or rewards available for period, or fees already claimed"
        );

        // Record the address has claimed for this period
        _setLastFeeWithdrawal(claimingAddress, _recentFeePeriodsStorage(1).feePeriodId);

        if (availableFees > 0) {
            // Record the fee payment in our recentFeePeriods
            feesPaid = _recordFeePayment(availableFees);

            // Send them their fees
            _payFees(claimingAddress, feesPaid);
        }

        if (availableRewards > 0) {
            // Record the reward payment in our recentFeePeriods
            rewardsPaid = _recordRewardPayment(availableRewards);

            // Send them their rewards
            _payRewards(claimingAddress, rewardsPaid);
        }

        emitFeesClaimed(claimingAddress, feesPaid, rewardsPaid);

        return true;
    }

    /**
    * @notice Admin function to import the FeePeriod data from the previous contract
    */
    function importFeePeriod(
        uint feePeriodIndex,
        uint feePeriodId,
        uint startingDebtIndex,
        uint startTime,
        uint feesToDistribute,
        uint feesClaimed,
        uint rewardsToDistribute,
        uint rewardsClaimed
    ) public optionalProxy_onlyOwner onlyDuringSetup {
        require(startingDebtIndex <= synthetixState().debtLedgerLength(), "Cannot import bad data");

        _recentFeePeriods[_currentFeePeriod.add(feePeriodIndex).mod(FEE_PERIOD_LENGTH)] = FeePeriod({
            feePeriodId: uint64(feePeriodId),
            startingDebtIndex: uint64(startingDebtIndex),
            startTime: uint64(startTime),
            feesToDistribute: feesToDistribute,
            feesClaimed: feesClaimed,
            rewardsToDistribute: rewardsToDistribute,
            rewardsClaimed: rewardsClaimed
        });
    }

    /**
    * @notice Owner can escrow SNX. Owner to send the tokens to the RewardEscrow
    * @param account Address to escrow tokens for
    * @param quantity Amount of tokens to escrow
    */
    function appendVestingEntry(address account, uint quantity) public optionalProxy_onlyOwner {
        // Transfer SNX from messageSender to the Reward Escrow
        synthetix().transferFrom(messageSender, rewardEscrow(), quantity);

        // Create Vesting Entry
        rewardEscrow().appendVestingEntry(account, quantity);
    }

    /**
    * @notice One time onlyOwner call to convert all XDR balance in the FEE_ADDRESS to sUSD
    */
    function convertXDRFeesTosUSD(address exchangeRatesAddress) public optionalProxy_onlyOwner {
        // Get the ExchageRates address with the XDR rate (its not in the new one)
        address _exchangeRates = 0xE95Ef4e7a04d2fB05cb625c62CA58da10112c605;
        if (exchangeRatesAddress != 0) {
            _exchangeRates = exchangeRatesAddress;
        }

        Synth xdrSynth = synthetix().synths("XDR");
        Synth sUSDSynth = synthetix().synths(sUSD);

        // FeePools XDR Balance
        uint xdrAmount = xdrSynth.balanceOf(FEE_ADDRESS);

        // How much sUSD should be minted from the XDR's
        uint sUSDAmount = IExchangeRates(_exchangeRates).effectiveValue("XDR", xdrAmount, sUSD);

        // Burn the XDRs
        xdrSynth.burn(FEE_ADDRESS, xdrAmount);

        // Mint their new synths
        sUSDSynth.issue(FEE_ADDRESS, sUSDAmount);

        // Convert FeePeriods To sUSD
        for (uint i = 0; i < FEE_PERIOD_LENGTH; i++) {
            uint feesToDistribute = IExchangeRates(_exchangeRates).effectiveValue(
                "XDR",
                _recentFeePeriodsStorage(i).feesToDistribute,
                sUSD
            );
            uint feesClaimed = IExchangeRates(_exchangeRates).effectiveValue(
                "XDR",
                _recentFeePeriodsStorage(i).feesClaimed,
                sUSD
            );
            _recentFeePeriodsStorage(i).feesToDistribute = feesToDistribute;
            _recentFeePeriodsStorage(i).feesClaimed = feesClaimed;
        }
    }

    /**
    * @notice Approve an address to be able to claim your fees to your account on your behalf.
    * This is intended to be able to delegate a mobile wallet to call the function to claim fees to
    * your cold storage wallet
    * @param account The hot/mobile/contract address that will call claimFees your accounts behalf
    */
    function approveClaimOnBehalf(address account) public optionalProxy {
        require(account != address(0), "Can't delegate to address(0)");
        delegateApprovals().setApproval(messageSender, account);
    }

    /**
    * @notice Remove the permission to call claimFees your accounts behalf
    * @param account The hot/mobile/contract address to remove permission
    */
    function removeClaimOnBehalf(address account) public optionalProxy {
        delegateApprovals().withdrawApproval(messageSender, account);
    }

    /**
     * @notice Record the fee payment in our recentFeePeriods.
     * @param sUSDAmount The amount of fees priced in sUSD.
     */
    function _recordFeePayment(uint sUSDAmount) internal returns (uint) {
        // Don't assign to the parameter
        uint remainingToAllocate = sUSDAmount;

        uint feesPaid;
        // Start at the oldest period and record the amount, moving to newer periods
        // until we've exhausted the amount.
        // The condition checks for overflow because we're going to 0 with an unsigned int.
        for (uint i = FEE_PERIOD_LENGTH - 1; i < FEE_PERIOD_LENGTH; i--) {
            uint feesAlreadyClaimed = _recentFeePeriodsStorage(i).feesClaimed;
            uint delta = _recentFeePeriodsStorage(i).feesToDistribute.sub(feesAlreadyClaimed);

            if (delta > 0) {
                // Take the smaller of the amount left to claim in the period and the amount we need to allocate
                uint amountInPeriod = delta < remainingToAllocate ? delta : remainingToAllocate;

                _recentFeePeriodsStorage(i).feesClaimed = feesAlreadyClaimed.add(amountInPeriod);
                remainingToAllocate = remainingToAllocate.sub(amountInPeriod);
                feesPaid = feesPaid.add(amountInPeriod);

                // No need to continue iterating if we've recorded the whole amount;
                if (remainingToAllocate == 0) return feesPaid;

                // We've exhausted feePeriods to distribute and no fees remain in last period
                // User last to claim would in this scenario have their remainder slashed
                if (i == 0 && remainingToAllocate > 0) {
                    remainingToAllocate = 0;
                }
            }
        }

        return feesPaid;
    }

    /**
     * @notice Record the reward payment in our recentFeePeriods.
     * @param snxAmount The amount of SNX tokens.
     */
    function _recordRewardPayment(uint snxAmount) internal returns (uint) {
        // Don't assign to the parameter
        uint remainingToAllocate = snxAmount;

        uint rewardPaid;

        // Start at the oldest period and record the amount, moving to newer periods
        // until we've exhausted the amount.
        // The condition checks for overflow because we're going to 0 with an unsigned int.
        for (uint i = FEE_PERIOD_LENGTH - 1; i < FEE_PERIOD_LENGTH; i--) {
            uint toDistribute = _recentFeePeriodsStorage(i).rewardsToDistribute.sub(
                _recentFeePeriodsStorage(i).rewardsClaimed
            );

            if (toDistribute > 0) {
                // Take the smaller of the amount left to claim in the period and the amount we need to allocate
                uint amountInPeriod = toDistribute < remainingToAllocate ? toDistribute : remainingToAllocate;

                _recentFeePeriodsStorage(i).rewardsClaimed = _recentFeePeriodsStorage(i).rewardsClaimed.add(amountInPeriod);
                remainingToAllocate = remainingToAllocate.sub(amountInPeriod);
                rewardPaid = rewardPaid.add(amountInPeriod);

                // No need to continue iterating if we've recorded the whole amount;
                if (remainingToAllocate == 0) return rewardPaid;

                // We've exhausted feePeriods to distribute and no rewards remain in last period
                // User last to claim would in this scenario have their remainder slashed
                // due to rounding up of PreciseDecimal
                if (i == 0 && remainingToAllocate > 0) {
                    remainingToAllocate = 0;
                }
            }
        }
        return rewardPaid;
    }

    /**
    * @notice Send the fees to claiming address.
    * @param account The address to send the fees to.
    * @param sUSDAmount The amount of fees priced in sUSD.
    */
    function _payFees(address account, uint sUSDAmount) internal notFeeAddress(account) {
        // Checks not really possible but rather gaurds for the internal code.
        require(
            account != address(0) ||
                account != address(this) ||
                account != address(proxy) ||
                account != address(synthetix()),
            "Can't send fees to this address"
        );

        // Grab the sUSD Synth
        Synth sUSDSynth = synthetix().synths(sUSD);

        // NOTE: we do not control the FEE_ADDRESS so it is not possible to do an
        // ERC20.approve() transaction to allow this feePool to call ERC20.transferFrom
        // to the accounts address

        // Burn the source amount
        sUSDSynth.burn(FEE_ADDRESS, sUSDAmount);

        // Mint their new synths
        sUSDSynth.issue(account, sUSDAmount);
    }

    /**
    * @notice Send the rewards to claiming address - will be locked in rewardEscrow.
    * @param account The address to send the fees to.
    * @param snxAmount The amount of SNX.
    */
    function _payRewards(address account, uint snxAmount) internal notFeeAddress(account) {
        require(account != address(0), "Account can't be 0");
        require(account != address(this), "Can't send rewards to fee pool");
        require(account != address(proxy), "Can't send rewards to proxy");
        require(account != address(synthetix()), "Can't send rewards to synthetix");

        // Record vesting entry for claiming address and amount
        // SNX already minted to rewardEscrow balance
        rewardEscrow().appendVestingEntry(account, snxAmount);
    }

    /**
     * @notice The amount the recipient will receive if you send a certain number of tokens.
     * function used by Depot and stub will return value amount inputted.
     * @param value The amount of tokens you intend to send.
     */
    function amountReceivedFromTransfer(uint value) external pure returns (uint) {
        return value;
    }

    /**
     * @notice Calculate the fee charged on top of a value being sent via an exchange
     * @return Return the fee charged
     */
    function exchangeFeeIncurred(uint value) public view returns (uint) {
        return value.multiplyDecimal(exchangeFeeRate);

        // Exchanges less than the reciprocal of exchangeFeeRate should be completely eaten up by fees.
        // This is on the basis that exchanges less than this value will result in a nil fee.
        // Probably too insignificant to worry about, but the following code will achieve it.
        //      if (fee == 0 && exchangeFeeRate != 0) {
        //          return _value;
        //      }
        //      return fee;
    }

    /**
     * @notice The amount the recipient will receive if you are performing an exchange and the
     * destination currency will be worth a certain number of tokens.
     * @param value The amount of destination currency tokens they received after the exchange.
     */
    function amountReceivedFromExchange(uint value) external view returns (uint) {
        return value.multiplyDecimal(SafeDecimalMath.unit().sub(exchangeFeeRate));
    }

    /**
     * @notice The total fees available in the system to be withdrawnn in sUSD
     */
    function totalFeesAvailable() external view returns (uint) {
        uint totalFees = 0;

        // Fees in fee period [0] are not yet available for withdrawal
        for (uint i = 1; i < FEE_PERIOD_LENGTH; i++) {
            totalFees = totalFees.add(_recentFeePeriodsStorage(i).feesToDistribute);
            totalFees = totalFees.sub(_recentFeePeriodsStorage(i).feesClaimed);
        }

        return totalFees;
    }

    /**
     * @notice The total SNX rewards available in the system to be withdrawn
     */
    function totalRewardsAvailable() external view returns (uint) {
        uint totalRewards = 0;

        // Rewards in fee period [0] are not yet available for withdrawal
        for (uint i = 1; i < FEE_PERIOD_LENGTH; i++) {
            totalRewards = totalRewards.add(_recentFeePeriodsStorage(i).rewardsToDistribute);
            totalRewards = totalRewards.sub(_recentFeePeriodsStorage(i).rewardsClaimed);
        }

        return totalRewards;
    }

    /**
     * @notice The fees available to be withdrawn by a specific account, priced in sUSD
     * @dev Returns two amounts, one for fees and one for SNX rewards
     */
    function feesAvailable(address account) public view returns (uint, uint) {
        // Add up the fees
        uint[2][FEE_PERIOD_LENGTH] memory userFees = feesByPeriod(account);

        uint totalFees = 0;
        uint totalRewards = 0;

        // Fees & Rewards in fee period [0] are not yet available for withdrawal
        for (uint i = 1; i < FEE_PERIOD_LENGTH; i++) {
            totalFees = totalFees.add(userFees[i][0]);
            totalRewards = totalRewards.add(userFees[i][1]);
        }

        // And convert totalFees to sUSD
        // Return totalRewards as is in SNX amount
        return (totalFees, totalRewards);
    }

    /**
     * @notice Check if a particular address is able to claim fees right now
     * @param account The address you want to query for
     */
    function isFeesClaimable(address account) public view returns (bool) {
        // Threshold is calculated from ratio % above the target ratio (issuanceRatio).
        //  0  <  10%:   Claimable
        // 10% > above:  Unable to claim
        uint ratio = synthetix().collateralisationRatio(account);
        uint targetRatio = synthetixState().issuanceRatio();

        // Claimable if collateral ratio below target ratio
        if (ratio < targetRatio) {
            return true;
        }

        // Calculate the threshold for collateral ratio before fees can't be claimed.
        uint ratio_threshold = targetRatio.multiplyDecimal(SafeDecimalMath.unit().add(targetThreshold));

        // Not claimable if collateral ratio above threshold
        if (ratio > ratio_threshold) {
            return false;
        }

        return true;
    }

    /**
     * @notice Calculates fees by period for an account, priced in sUSD
     * @param account The address you want to query the fees for
     */
    function feesByPeriod(address account) public view returns (uint[2][FEE_PERIOD_LENGTH] memory results) {
        // What's the user's debt entry index and the debt they owe to the system at current feePeriod
        uint userOwnershipPercentage;
        uint debtEntryIndex;
        FeePoolState _feePoolState = feePoolState();

        (userOwnershipPercentage, debtEntryIndex) = _feePoolState.getAccountsDebtEntry(account, 0);

        // If they don't have any debt ownership and they never minted, they don't have any fees.
        // User ownership can reduce to 0 if user burns all synths,
        // however they could have fees applicable for periods they had minted in before so we check debtEntryIndex.
        if (debtEntryIndex == 0 && userOwnershipPercentage == 0) return;

        // The [0] fee period is not yet ready to claim, but it is a fee period that they can have
        // fees owing for, so we need to report on it anyway.
        uint feesFromPeriod;
        uint rewardsFromPeriod;
        (feesFromPeriod, rewardsFromPeriod) = _feesAndRewardsFromPeriod(0, userOwnershipPercentage, debtEntryIndex);

        results[0][0] = feesFromPeriod;
        results[0][1] = rewardsFromPeriod;

        // Retrieve user's last fee claim by periodId
        uint lastFeeWithdrawal = getLastFeeWithdrawal(account);

        // Go through our fee periods from the oldest feePeriod[FEE_PERIOD_LENGTH - 1] and figure out what we owe them.
        // Condition checks for periods > 0
        for (uint i = FEE_PERIOD_LENGTH - 1; i > 0; i--) {
            uint next = i - 1;
            uint nextPeriodStartingDebtIndex = _recentFeePeriodsStorage(next).startingDebtIndex;

            // We can skip the period, as no debt minted during period (next period's startingDebtIndex is still 0)
            if (nextPeriodStartingDebtIndex > 0 && lastFeeWithdrawal < _recentFeePeriodsStorage(i).feePeriodId) {
                // We calculate a feePeriod's closingDebtIndex by looking at the next feePeriod's startingDebtIndex
                // we can use the most recent issuanceData[0] for the current feePeriod
                // else find the applicableIssuanceData for the feePeriod based on the StartingDebtIndex of the period
                uint closingDebtIndex = uint256(nextPeriodStartingDebtIndex).sub(1);

                // Gas optimisation - to reuse debtEntryIndex if found new applicable one
                // if applicable is 0,0 (none found) we keep most recent one from issuanceData[0]
                // return if userOwnershipPercentage = 0)
                (userOwnershipPercentage, debtEntryIndex) = _feePoolState.applicableIssuanceData(account, closingDebtIndex);

                (feesFromPeriod, rewardsFromPeriod) = _feesAndRewardsFromPeriod(i, userOwnershipPercentage, debtEntryIndex);

                results[i][0] = feesFromPeriod;
                results[i][1] = rewardsFromPeriod;
            }
        }
    }

    /**
     * @notice ownershipPercentage is a high precision decimals uint based on
     * wallet's debtPercentage. Gives a precise amount of the feesToDistribute
     * for fees in the period. Precision factor is removed before results are
     * returned.
     * @dev The reported fees owing for the current period [0] are just a
     * running balance until the fee period closes
     */
    function _feesAndRewardsFromPeriod(uint period, uint ownershipPercentage, uint debtEntryIndex)
        internal
        view
        returns (uint, uint)
    {
        // If it's zero, they haven't issued, and they have no fees OR rewards.
        if (ownershipPercentage == 0) return (0, 0);

        uint debtOwnershipForPeriod = ownershipPercentage;

        // If period has closed we want to calculate debtPercentage for the period
        if (period > 0) {
            uint closingDebtIndex = uint256(_recentFeePeriodsStorage(period - 1).startingDebtIndex).sub(1);
            debtOwnershipForPeriod = _effectiveDebtRatioForPeriod(closingDebtIndex, ownershipPercentage, debtEntryIndex);
        }

        // Calculate their percentage of the fees / rewards in this period
        // This is a high precision integer.
        uint feesFromPeriod = _recentFeePeriodsStorage(period).feesToDistribute.multiplyDecimal(debtOwnershipForPeriod);

        uint rewardsFromPeriod = _recentFeePeriodsStorage(period).rewardsToDistribute.multiplyDecimal(
            debtOwnershipForPeriod
        );

        return (feesFromPeriod.preciseDecimalToDecimal(), rewardsFromPeriod.preciseDecimalToDecimal());
    }

    function _effectiveDebtRatioForPeriod(uint closingDebtIndex, uint ownershipPercentage, uint debtEntryIndex)
        internal
        view
        returns (uint)
    {
        // Figure out their global debt percentage delta at end of fee Period.
        // This is a high precision integer.
        ISynthetixState _synthetixState = synthetixState();
        uint feePeriodDebtOwnership = _synthetixState
            .debtLedger(closingDebtIndex)
            .divideDecimalRoundPrecise(_synthetixState.debtLedger(debtEntryIndex))
            .multiplyDecimalRoundPrecise(ownershipPercentage);

        return feePeriodDebtOwnership;
    }

    function effectiveDebtRatioForPeriod(address account, uint period) external view returns (uint) {
        require(period != 0, "Current period is not closed yet");
        require(period < FEE_PERIOD_LENGTH, "Exceeds the FEE_PERIOD_LENGTH");

        // If the period being checked is uninitialised then return 0. This is only at the start of the system.
        if (_recentFeePeriodsStorage(period - 1).startingDebtIndex == 0) return 0;

        uint closingDebtIndex = uint256(_recentFeePeriodsStorage(period - 1).startingDebtIndex).sub(1);

        uint ownershipPercentage;
        uint debtEntryIndex;
        (ownershipPercentage, debtEntryIndex) = feePoolState().applicableIssuanceData(account, closingDebtIndex);

        // internal function will check closingDebtIndex has corresponding debtLedger entry
        return _effectiveDebtRatioForPeriod(closingDebtIndex, ownershipPercentage, debtEntryIndex);
    }

    /**
     * @notice Get the feePeriodID of the last claim this account made
     * @param _claimingAddress account to check the last fee period ID claim for
     * @return uint of the feePeriodID this account last claimed
     */
    function getLastFeeWithdrawal(address _claimingAddress) public view returns (uint) {
        return feePoolEternalStorage().getUIntValue(keccak256(abi.encodePacked(LAST_FEE_WITHDRAWAL, _claimingAddress)));
    }

    /**
    * @notice Calculate the collateral ratio before user is blocked from claiming.
    */
    function getPenaltyThresholdRatio() public view returns (uint) {
        uint targetRatio = synthetixState().issuanceRatio();

        return targetRatio.multiplyDecimal(SafeDecimalMath.unit().add(targetThreshold));
    }

    /**
     * @notice Set the feePeriodID of the last claim this account made
     * @param _claimingAddress account to set the last feePeriodID claim for
     * @param _feePeriodID the feePeriodID this account claimed fees for
     */
    function _setLastFeeWithdrawal(address _claimingAddress, uint _feePeriodID) internal {
        feePoolEternalStorage().setUIntValue(
            keccak256(abi.encodePacked(LAST_FEE_WITHDRAWAL, _claimingAddress)),
            _feePeriodID
        );
    }

    /* ========== Modifiers ========== */
    modifier onlyExchangerOrSynth {
        bool isExchanger = msg.sender == address(exchanger());
        bool isSynth = synthetix().synthsByAddress(msg.sender) != bytes32(0);

        require(isExchanger || isSynth, "Only Exchanger, Synths Authorised");
        _;
    }

    modifier onlyIssuer {
        require(msg.sender == address(issuer()), "FeePool: Only Issuer Authorised");
        _;
    }

    modifier onlyExchanger {
        require(msg.sender == address(exchanger()), "FeePool: Only Exchanger Authorised");
        _;
    }

    modifier notFeeAddress(address account) {
        require(account != FEE_ADDRESS, "Fee address not allowed");
        _;
    }

    /* ========== Proxy Events ========== */

    event IssuanceDebtRatioEntry(
        address indexed account,
        uint debtRatio,
        uint debtEntryIndex,
        uint feePeriodStartingDebtIndex
    );
    bytes32 private constant ISSUANCEDEBTRATIOENTRY_SIG = keccak256(
        "IssuanceDebtRatioEntry(address,uint256,uint256,uint256)"
    );

    function emitIssuanceDebtRatioEntry(
        address account,
        uint debtRatio,
        uint debtEntryIndex,
        uint feePeriodStartingDebtIndex
    ) internal {
        proxy._emit(
            abi.encode(debtRatio, debtEntryIndex, feePeriodStartingDebtIndex),
            2,
            ISSUANCEDEBTRATIOENTRY_SIG,
            bytes32(account),
            0,
            0
        );
    }

    event ExchangeFeeUpdated(uint newFeeRate);
    bytes32 private constant EXCHANGEFEEUPDATED_SIG = keccak256("ExchangeFeeUpdated(uint256)");

    function emitExchangeFeeUpdated(uint newFeeRate) internal {
        proxy._emit(abi.encode(newFeeRate), 1, EXCHANGEFEEUPDATED_SIG, 0, 0, 0);
    }

    event FeePeriodDurationUpdated(uint newFeePeriodDuration);
    bytes32 private constant FEEPERIODDURATIONUPDATED_SIG = keccak256("FeePeriodDurationUpdated(uint256)");

    function emitFeePeriodDurationUpdated(uint newFeePeriodDuration) internal {
        proxy._emit(abi.encode(newFeePeriodDuration), 1, FEEPERIODDURATIONUPDATED_SIG, 0, 0, 0);
    }

    event FeePeriodClosed(uint feePeriodId);
    bytes32 private constant FEEPERIODCLOSED_SIG = keccak256("FeePeriodClosed(uint256)");

    function emitFeePeriodClosed(uint feePeriodId) internal {
        proxy._emit(abi.encode(feePeriodId), 1, FEEPERIODCLOSED_SIG, 0, 0, 0);
    }

    event FeesClaimed(address account, uint sUSDAmount, uint snxRewards);
    bytes32 private constant FEESCLAIMED_SIG = keccak256("FeesClaimed(address,uint256,uint256)");

    function emitFeesClaimed(address account, uint sUSDAmount, uint snxRewards) internal {
        proxy._emit(abi.encode(account, sUSDAmount, snxRewards), 1, FEESCLAIMED_SIG, 0, 0, 0);
    }
}