// SPDX-License-Identifier: MIT
pragma solidity ^0.7.4;


/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}


/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, 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-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) public {
        _name = name_;
        _symbol = symbol_;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal virtual {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

/*

  Proxy registry; keeps a mapping of AuthenticatedProxy contracts and mapping of contracts authorized to access them.  
  
  Abstracted away from the Exchange (a) to reduce Exchange attack surface and (b) so that the Exchange contract can be upgraded without users needing to transfer assets to new proxies.

*/
contract ProxyRegistry is Ownable {

    /* DelegateProxy implementation contract. Must be initialized. */
    address public delegateProxyImplementation;

    /* Authenticated proxies by user. */
    mapping(address => OwnableDelegateProxy) public proxies;

    /* Contracts pending access. */
    mapping(address => uint) public pending;

    /* Contracts allowed to call those proxies. */
    mapping(address => bool) public contracts;

    /* Delay period for adding an authenticated contract.
       This mitigates a particular class of potential attack on the Erax DAO (which owns this registry) - if at any point the value of assets held by proxy contracts exceeded the value of half the WYV supply (votes in the DAO),
       a malicious but rational attacker could buy half the Erax and grant themselves access to all the proxy contracts. A delay period renders this attack nonthreatening - given two weeks, if that happened, users would have
       plenty of time to notice and transfer their assets.
    */
    uint public DELAY_PERIOD = 2 weeks;

    /**
     * Start the process to enable access for specified contract. Subject to delay period.
     *
     * @dev ProxyRegistry owner only
     * @param addr Address to which to grant permissions
     */
    function startGrantAuthentication (address addr)
    public
    onlyOwner
    {
        require(!contracts[addr] && pending[addr] == 0,"31");
        pending[addr] = block.timestamp;
    }

    /**
     * End the process to nable access for specified contract after delay period has passed.
     *
     * @dev ProxyRegistry owner only
     * @param addr Address to which to grant permissions
     */
    function endGrantAuthentication (address addr)
    public
    onlyOwner
    {
        require(!contracts[addr] && pending[addr] != 0 && ((pending[addr] + DELAY_PERIOD) < block.timestamp),"32");
        pending[addr] = 0;
        contracts[addr] = true;
    }


    /**
   Joe add
   **/
    function grantAuthentication (address addr)
    public
    onlyOwner
    {
        require(!contracts[addr],"33");

        contracts[addr] = true;
    }

    /**
     * Revoke access for specified contract. Can be done instantly.
     *
     * @dev ProxyRegistry owner only
     * @param addr Address of which to revoke permissions
     */
    function revokeAuthentication (address addr)
    public
    onlyOwner
    {
        contracts[addr] = false;
    }

    /**
     * Register a proxy contract with this registry
     *
     * @dev Must be called by the user which the proxy is for, creates a new AuthenticatedProxy
     * @return proxy New AuthenticatedProxy contract
     */
    function registerProxy()
    public
    returns (OwnableDelegateProxy proxy)
    {
        require(address(proxies[msg.sender]) == address(0),"34");
        proxy = new OwnableDelegateProxy(msg.sender, delegateProxyImplementation, abi.encodeWithSignature("initialize(address,address)", msg.sender, address(this)));
        proxies[msg.sender] = proxy;
        return proxy;
    }

}

/*

  Token recipient. Modified very slightly from the example on http://ethereum.org/dao (just to index log parameters).

*/
/**
 * @title TokenRecipient
 * @author Project Erax Developers
 */
contract TokenRecipient {
    event ReceivedEther(address indexed sender, uint amount);
    event ReceivedTokens(address indexed from, uint256 value, address indexed token, bytes extraData);

    /**
     * @dev Receive tokens and generate a log event
     * @param from Address from which to transfer tokens
     * @param value Amount of tokens to transfer
     * @param token Address of token
     * @param extraData Additional data to log
     */
    function receiveApproval(address from, uint256 value, address token, bytes memory extraData) public {
        ERC20 t = ERC20(token);
        require(t.transferFrom(from, address(this), value),"4");
        emit ReceivedTokens(from, value, token, extraData);
    }

    /**
     * @dev Receive Ether and generate a log event
     */
    receive() payable external {
        emit ReceivedEther(msg.sender, msg.value);
    }
}

/**
 * @title Proxy
 * @dev Gives the possibility to delegate any call to a foreign implementation.
 */
abstract contract Proxy {

  /**
  * @dev Tells the address of the implementation where every call will be delegated.
  * @return address of the implementation to which it will be delegated
  */
  function implementation() public virtual view returns (address);

  /**
  * @dev Tells the type of proxy (EIP 897)
  * @return proxyTypeId Type of proxy, 2 for upgradeable proxy
  */
  function proxyType() public virtual pure returns (uint256 proxyTypeId);

  /**
  * @dev Fallback function allowing to perform a delegatecall to the given implementation.
  * This function will return whatever the implementation call returns
  */
  fallback () payable external {
    address _impl = implementation();
    require(_impl != address(0),"40");

    assembly {
      let ptr := mload(0x40)
      calldatacopy(ptr, 0, calldatasize())
      let result := delegatecall(gas(), _impl, ptr, calldatasize(), 0, 0)
      let size := returndatasize()
      returndatacopy(ptr, 0, size)

      switch result
      case 0 { revert(ptr, size) }
      default { return(ptr, size) }
    }
  }
}

/**
 * @title OwnedUpgradeabilityStorage
 * @dev This contract keeps track of the upgradeability owner
 */
contract OwnedUpgradeabilityStorage is Proxy{

  // Current implementation
  address internal _implementation;

  // Owner of the contract
  address private _upgradeabilityOwner;

  /**
   * @dev Tells the address of the owner
   * @return the address of the owner
   */
  function upgradeabilityOwner() public view returns (address) {
    return _upgradeabilityOwner;
  }

  /**
   * @dev Sets the address of the owner
   */
  function setUpgradeabilityOwner(address newUpgradeabilityOwner) internal {
    _upgradeabilityOwner = newUpgradeabilityOwner;
  }

  /**
  * @dev Tells the address of the current implementation
  * @return address of the current implementation
  */
  function implementation() public override view returns (address) {
    return _implementation;
  }

  /**
  * @dev Tells the proxy type (EIP 897)
  * @return proxyTypeId Proxy type, 2 for forwarding proxy
  */
  function proxyType() public override pure returns (uint256 proxyTypeId) {
    return 2;
  }
}

/*

  Proxy contract to hold access to assets on behalf of a user (e.g. ERC20 approve) and execute calls under particular conditions.

*/
/**
 * @title AuthenticatedProxy
 * @author Project Erax Developers
 */
contract AuthenticatedProxy is TokenRecipient, OwnedUpgradeabilityStorage {

    /* Whether initialized. */
    bool initialized = false;

    /* Address which owns this proxy. */
    address public user;

    /* Associated registry with contract authentication information. */
    ProxyRegistry public registry;

    /* Whether access has been revoked. */
    bool public revoked;

    /* Delegate call could be used to atomically transfer multiple assets owned by the proxy contract with one order. */
    enum HowToCall { Call, DelegateCall }

    /* Event fired when the proxy access is revoked or unrevoked. */
    event Revoked(bool revoked);

    /**
     * Initialize an AuthenticatedProxy
     *
     * @param addrUser Address of user on whose behalf this proxy will act
     * @param addrRegistry Address of ProxyRegistry contract which will manage this proxy
     */
    function initialize (address addrUser, ProxyRegistry addrRegistry)
    public
    {
        require(!initialized,"26");
        initialized = true;
        user = addrUser;
        registry = addrRegistry;
    }

    /**
     * Set the revoked flag (allows a user to revoke ProxyRegistry access)
     *
     * @dev Can be called by the user only
     * @param revoke Whether or not to revoke access
     */
    function setRevoke(bool revoke)
    public
    {
        require(msg.sender == user,"27");
        revoked = revoke;
        emit Revoked(revoke);
    }

    /**
     * Execute a message call from the proxy contract
     *
     * @dev Can be called by the user, or by a contract authorized by the registry as long as the user has not revoked access
     * @param dest Address to which the call will be sent
     * @param howToCall Which kind of call to make
     * @param callData Calldata to send
     * @return result Result of the call (success or failure)
     */
    function proxy(address dest, HowToCall howToCall, bytes memory callData)
    public
    returns (bool result)
    {
        require(msg.sender == user || (!revoked && registry.contracts(msg.sender)),"28");
        if (howToCall == HowToCall.Call) {
            (result, ) = dest.call(callData);
        } else if (howToCall == HowToCall.DelegateCall) {
            (result, ) = dest.delegatecall(callData);
        }
        return result;
    }

    /**
     * Execute a message call and assert success
     *
     * @dev Same functionality as `proxy`, just asserts the return value
     * @param dest Address to which the call will be sent
     * @param howToCall What kind of call to make
     * @param callData Calldata to send
     */
    function proxyAssert(address dest, HowToCall howToCall, bytes memory callData)
    public
    {
        require(proxy(dest, howToCall, callData),"29");
    }

}

/**
 * @title OwnedUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with basic authorization control functionalities
 */
contract OwnedUpgradeabilityProxy is OwnedUpgradeabilityStorage {
  /**
  * @dev Event to show ownership has been transferred
  * @param previousOwner representing the address of the previous owner
  * @param newOwner representing the address of the new owner
  */
  event ProxyOwnershipTransferred(address previousOwner, address newOwner);

  /**
  * @dev This event will be emitted every time the implementation gets upgraded
  * @param implementation representing the address of the upgraded implementation
  */
  event Upgraded(address indexed implementation);

  /**
  * @dev Upgrades the implementation address
  * @param implementation representing the address of the new implementation to be set
  */
  function _upgradeTo(address implementation) internal {
    require(_implementation != implementation,"36");
    _implementation = implementation;
    emit Upgraded(implementation);
  }

  /**
  * @dev Throws if called by any account other than the owner.
  */
  modifier onlyProxyOwner() {
    require(msg.sender == proxyOwner(),"37");
    _;
  }

  /**
   * @dev Tells the address of the proxy owner
   * @return the address of the proxy owner
   */
  function proxyOwner() public view returns (address) {
    return upgradeabilityOwner();
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function transferProxyOwnership(address newOwner) public onlyProxyOwner {
    require(newOwner != address(0),"38");
    emit ProxyOwnershipTransferred(proxyOwner(), newOwner);
    setUpgradeabilityOwner(newOwner);
  }

  /**
   * @dev Allows the upgradeability owner to upgrade the current implementation of the proxy.
   * @param implementation representing the address of the new implementation to be set.
   */
  function upgradeTo(address implementation) public onlyProxyOwner {
    _upgradeTo(implementation);
  }

  /**
   * @dev Allows the upgradeability owner to upgrade the current implementation of the proxy
   * and delegatecall the new implementation for initialization.
   * @param implementation representing the address of the new implementation to be set.
   * @param data represents the msg.data to bet sent in the low level call. This parameter may include the function
   * signature of the implementation to be called with the needed payload
   */
  function upgradeToAndCall(address implementation, bytes memory data) payable public onlyProxyOwner {
    upgradeTo(implementation);
    (bool result, ) = address(this).delegatecall(data);
    require(result,"39");
  }
}

/*

  EraxOwnableDelegateProxy

*/
contract OwnableDelegateProxy is OwnedUpgradeabilityProxy {

    constructor(address owner, address initialImplementation, bytes memory callData)
    {
        setUpgradeabilityOwner(owner);
        _upgradeTo(initialImplementation);
        (bool result, ) = initialImplementation.delegatecall(callData);
        require(result,"30");
    }

}

/*

  Token transfer proxy. Uses the authentication table of a ProxyRegistry contract to grant ERC20 `transferFrom` access.
  This means that users only need to authorize the proxy contract once for all future protocol versions.

*/
contract TokenTransferProxy {

    /* Authentication registry. */
    ProxyRegistry public registry;

    /**
     * Call ERC20 `transferFrom`
     *
     * @dev Authenticated contract only
     * @param token ERC20 token address
     * @param from From address
     * @param to To address
     * @param amount Transfer amount
     */
    function transferFrom(address token, address from, address to, uint amount)
    public
    returns (bool)
    {
        require(registry.contracts(msg.sender),"35");
        return ERC20(token).transferFrom(from, to, amount);
    }

}

/*

  Various functions for manipulating arrays in Solidity.
  This library is completely inlined and does not need to be deployed or linked.

*/
/**
 * @title ArrayUtils
 * @author Project Erax Developers
 */
library ArrayUtils {

    /**
     * Replace bytes in an array with bytes in another array, guarded by a bitmask
     * Efficiency of this function is a bit unpredictable because of the EVM's word-specific model (arrays under 32 bytes will be slower)
     * 
     * @dev Mask must be the size of the byte array. A nonzero byte means the byte array can be changed.
     * @param array The original array
     * @param desired The target array
     * @param mask The mask specifying which bits can be changed
     * return The updated byte array (the parameter will be modified inplace)
     */
    function guardedArrayReplace(bytes memory array, bytes memory desired, bytes memory mask)
    internal
    pure
    {
        require(array.length == desired.length,"2");
        require(array.length == mask.length,"3");

        uint words = array.length / 0x20;
        uint index = words * 0x20;
        assert(index / 0x20 == words);
        uint i;

        for (i = 0; i < words; i++) {
            /* Conceptually: array[i] = (!mask[i] && array[i]) || (mask[i] && desired[i]), bitwise in word chunks. */
            assembly {
                let commonIndex := mul(0x20, add(1, i))
                let maskValue := mload(add(mask, commonIndex))
                mstore(add(array, commonIndex), or(and(not(maskValue), mload(add(array, commonIndex))), and(maskValue, mload(add(desired, commonIndex)))))
            }
        }

        /* Deal with the last section of the byte array. */
        if (words > 0) {
            /* This overlaps with bytes already set but is still more efficient than iterating through each of the remaining bytes individually. */
            i = words;
            assembly {
                let commonIndex := mul(0x20, add(1, i))
                let maskValue := mload(add(mask, commonIndex))
                mstore(add(array, commonIndex), or(and(not(maskValue), mload(add(array, commonIndex))), and(maskValue, mload(add(desired, commonIndex)))))
            }
        } else {
            /* If the byte array is shorter than a word, we must unfortunately do the whole thing bytewise.
               (bounds checks could still probably be optimized away in assembly, but this is a rare case) */
            for (i = index; i < array.length; i++) {
                array[i] = ((mask[i] ^ 0xff) & array[i]) | (mask[i] & desired[i]);
            }
        }
    }

    /**
     * Test if two arrays are equal
     * Source: https://github.com/GNSPS/solidity-bytes-utils/blob/master/contracts/BytesLib.sol
     * 
     * @dev Arrays must be of equal length, otherwise will return false
     * @param a First array
     * @param b Second array
     * @return Whether or not all bytes in the arrays are equal
     */
    function arrayEq(bytes memory a, bytes memory b)
    internal
    pure
    returns (bool)
    {
        bool success = true;

        assembly {
            let length := mload(a)

        // if lengths don't match the arrays are not equal
            switch eq(length, mload(b))
            case 1 {
            // cb is a circuit breaker in the for loop since there's
            //  no said feature for inline assembly loops
            // cb = 1 - don't breaker
            // cb = 0 - break
                let cb := 1

                let mc := add(a, 0x20)
                let end := add(mc, length)

                for {
                    let cc := add(b, 0x20)
                // the next line is the loop condition:
                // while(uint(mc < end) + cb == 2)
                } eq(add(lt(mc, end), cb), 2) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                // if any of these checks fails then arrays are not equal
                    if iszero(eq(mload(mc), mload(cc))) {
                    // unsuccess:
                        success := 0
                        cb := 0
                    }
                }
            }
            default {
            // unsuccess:
                success := 0
            }
        }

        return success;
    }

    /**
     * Unsafe write byte array into a memory location
     *
     * @param index Memory location
     * @param source Byte array to write
     * @return End memory index
     */
    function unsafeWriteBytes(uint index, bytes memory source)
    internal
    pure
    returns (uint)
    {
        if (source.length > 0) {
            assembly {
                let length := mload(source)
                let end := add(source, add(0x20, length))
                let arrIndex := add(source, 0x20)
                let tempIndex := index
                for { } eq(lt(arrIndex, end), 1) {
                    arrIndex := add(arrIndex, 0x20)
                    tempIndex := add(tempIndex, 0x20)
                } {
                    mstore(tempIndex, mload(arrIndex))
                }
                index := add(index, length)
            }
        }
        return index;
    }

    /**
     * Unsafe write address into a memory location
     *
     * @param index Memory location
     * @param source Address to write
     * @return End memory index
     */
    function unsafeWriteAddress(uint index, address source)
    internal
    pure
    returns (uint)
    {
        //0.8.3
        //uint256 conv = uint256(uint160((source))) << 0x60;
        uint256 conv = uint256(source) << 0x60;
        assembly {
            mstore(index, conv)
            index := add(index, 0x14)
        }
        return index;
    }

    /**
     * Unsafe write uint into a memory location
     *
     * @param index Memory location
     * @param source uint to write
     * @return End memory index
     */
    function unsafeWriteUint(uint index, uint source)
    internal
    pure
    returns (uint)
    {
        assembly {
            mstore(index, source)
            index := add(index, 0x20)
        }
        return index;
    }

    /**
     * Unsafe write uint8 into a memory location
     *
     * @param index Memory location
     * @param source uint8 to write
     * @return End memory index
     */
    function unsafeWriteUint8(uint index, uint8 source)
    internal
    pure
    returns (uint)
    {
        assembly {
            mstore8(index, source)
            index := add(index, 0x1)
        }
        return index;
    }

}

/*

  Simple contract extension to provide a contract-global reentrancy guard on functions.

*/
/**
 * @title ReentrancyGuarded
 * @author Project Erax Developers
 */
contract ReentrancyGuarded {

    bool reentrancyLock = false;

    /* Prevent a contract function from being reentrant-called. */
    modifier reentrancyGuard {
        if (reentrancyLock) {
            revert();
        }
        reentrancyLock = true;
        _;
        reentrancyLock = false;
    }

}

/*

  Abstract over fixed-price sales and Dutch auctions, with the intent of easily supporting additional methods of sale later.

  Separated into a library for convenience, all the functions are inlined.

*/
//import "@openzeppelin/contracts/utils/math/SafeMath.sol";
/**
 * @title SaleKindInterface
 * @author Project Erax Developers
 */
library SaleKindInterface {

    /**
     * Side: buy or sell.
     */
    enum Side { Buy, Sell }

    /**
     * Currently supported kinds of sale: fixed price, Dutch auction. 
     * English auctions cannot be supported without stronger escrow guarantees.
     * Future interesting options: Vickrey auction, nonlinear Dutch auctions.
     */
    enum SaleKind { FixedPrice, DutchAuction }

    /**
     * @dev Check whether the parameters of a sale are valid
     * @param saleKind Kind of sale
     * @param expirationTime Order expiration time
     * @return Whether the parameters were valid
     */
    function validateParameters(SaleKind saleKind, uint expirationTime)
    pure
    internal
    returns (bool)
    {
        /* Auctions must have a set expiration date. */
        return (saleKind == SaleKind.FixedPrice || expirationTime > 0);
    }

    /**
     * @dev Return whether or not an order can be settled
     * @dev Precondition: parameters have passed validateParameters
     * @param listingTime Order listing time
     * @param expirationTime Order expiration time
     */
    function canSettleOrder(uint listingTime, uint expirationTime)
    view
    internal
    returns (bool)
    {
        return (listingTime < block.timestamp) && (expirationTime == 0 || block.timestamp < expirationTime);
    }

    /**
     * @dev Calculate the settlement price of an order
     * @dev Precondition: parameters have passed validateParameters.
     * @param side Order side
     * @param saleKind Method of sale
     * @param basePrice Order base price
     * @param extra Order extra price data
     * @param listingTime Order listing time
     * @param expirationTime Order expiration time
     */
    function calculateFinalPrice(Side side, SaleKind saleKind, uint basePrice, uint extra, uint listingTime, uint expirationTime)
    view
    internal
    returns (uint finalPrice)
    {
        if (saleKind == SaleKind.FixedPrice) {
            return basePrice;
        } else if (saleKind == SaleKind.DutchAuction) {
            uint diff = SafeMath.div(SafeMath.mul(extra, SafeMath.sub(block.timestamp, listingTime)), SafeMath.sub(expirationTime, listingTime));
            if (side == Side.Sell) {
                /* Sell-side - start price: basePrice. End price: basePrice - extra. */
                return SafeMath.sub(basePrice, diff);
            } else {
                /* Buy-side - start price: basePrice. End price: basePrice + extra. */
                return SafeMath.add(basePrice, diff);
            }
        }
    }

}

/**
 * @title ExchangeCore
 * @author Project Erax Developers
 */
contract ExchangeCore is ReentrancyGuarded, Ownable {

    /* The token used to pay exchange fees. */
    ERC20 public exchangeToken;

    /* User registry. */
    ProxyRegistry public registry;

    /* Token transfer proxy. */
    TokenTransferProxy public tokenTransferProxy;

    /* Cancelled / finalized orders, by hash. */
    mapping(bytes32 => bool) public cancelledOrFinalized;

    /* Orders verified by on-chain approval (alternative to ECDSA signatures so that smart contracts can place orders directly). */
    mapping(bytes32 => bool) public approvedOrders;

    /* For split fee orders, minimum required protocol maker fee, in basis points. Paid to owner (who can change it). */
    uint public minimumMakerProtocolFee = 0;

    /* For split fee orders, minimum required protocol taker fee, in basis points. Paid to owner (who can change it). */
    uint public minimumTakerProtocolFee = 0;

    /* Recipient of protocol fees. */
    address public protocolFeeRecipient;

    /* Fee method: protocol fee or split fee. */
    enum FeeMethod { ProtocolFee, SplitFee }

    /* Inverse basis point. */
    uint public constant INVERSE_BASIS_POINT = 10000;

    /* An ECDSA signature. */
    struct Sig {
        /* v parameter */
        uint8 v;
        /* r parameter */
        bytes32 r;
        /* s parameter */
        bytes32 s;
    }

    /* An order on the exchange. */
    struct Order {
        /* Exchange address, intended as a versioning mechanism. */
        address exchange;
        /* Order maker address. */
        address maker;
        /* Order taker address, if specified. */
        address taker;
        /* Maker relayer fee of the order, unused for taker order. */
        uint makerRelayerFee;
        /* Taker relayer fee of the order, or maximum taker fee for a taker order. */
        uint takerRelayerFee;
        /* Maker protocol fee of the order, unused for taker order. */
        uint makerProtocolFee;
        /* Taker protocol fee of the order, or maximum taker fee for a taker order. */
        uint takerProtocolFee;
        /* Order fee recipient or zero address for taker order. */
        address feeRecipient;
        /* Fee method (protocol token or split fee). */
        FeeMethod feeMethod;
        /* Side (buy/sell). */
        SaleKindInterface.Side side;
        /* Kind of sale. */
        SaleKindInterface.SaleKind saleKind;
        /* Target. */
        address target;
        /* HowToCall. */
        AuthenticatedProxy.HowToCall howToCall;
        /* Calldata. */
        bytes callData;
        /* Calldata replacement pattern, or an empty byte array for no replacement. */
        bytes replacementPattern;
        /* Agent who can help sell the good. */
        address agent;
        /* Agent fee nee to be charged. */
        uint agentFee;
        /* Token used to pay for the order, or the zero-address as a sentinel value for Ether. */
        address paymentToken;
        /* Base price of the order (in paymentTokens). */
        uint basePrice;
        /* Auction extra parameter - minimum bid increment for English auctions, starting/ending price difference. */
        uint extra;
        /* Listing timestamp. */
        uint listingTime;
        /* Expiration timestamp - 0 for no expiry. */
        uint expirationTime;
        /* Order salt, used to prevent duplicate hashes. */
        uint salt;
        }

        event OrderApprovedPartOne    (bytes32 indexed hash, address exchange, address indexed maker, address taker, uint makerRelayerFee, uint takerRelayerFee, uint makerProtocolFee, uint takerProtocolFee, address indexed feeRecipient, FeeMethod feeMethod, SaleKindInterface.Side side, SaleKindInterface.SaleKind saleKind, address target);
        event OrderApprovedPartTwo    (bytes32 indexed hash, AuthenticatedProxy.HowToCall howToCall, bytes callData, bytes replacementPattern, address agent, uint agentFee, address paymentToken, uint basePrice, uint extra, uint listingTime, uint expirationTime, uint salt, bool orderbookInclusionDesired);
        event OrderCancelled          (bytes32 indexed hash);
        event OrdersMatched           (bytes32 buyHash, bytes32 sellHash, address indexed maker, address indexed taker, uint price, bytes32 indexed metadata);

        /**
         * @dev Change the minimum maker fee paid to the protocol (owner only)
         * @param newMinimumMakerProtocolFee New fee to set in basis points
         */
        function changeMinimumMakerProtocolFee(uint newMinimumMakerProtocolFee)
        public
        onlyOwner
        {
            minimumMakerProtocolFee = newMinimumMakerProtocolFee;
        }

        /**
         * @dev Change the minimum taker fee paid to the protocol (owner only)
         * @param newMinimumTakerProtocolFee New fee to set in basis points
         */
        function changeMinimumTakerProtocolFee(uint newMinimumTakerProtocolFee)
        public
        onlyOwner
        {
            minimumTakerProtocolFee = newMinimumTakerProtocolFee;
        }

        /**
         * @dev Change the protocol fee recipient (owner only)
         * @param newProtocolFeeRecipient New protocol fee recipient address
         */
        function changeProtocolFeeRecipient(address newProtocolFeeRecipient)
        public
        onlyOwner
        {
            protocolFeeRecipient = newProtocolFeeRecipient;
        }

        /**
         * @dev Transfer tokens
         * @param token Token to transfer
         * @param from Address to charge fees
         * @param to Address to receive fees
         * @param amount Amount of protocol tokens to charge
         */
        function transferTokens(address token, address from, address to, uint amount)
        internal
        {
            if (amount > 0) {
                require(tokenTransferProxy.transferFrom(token, from, to, amount),"5");
            }
        }

        /**
         * @dev Charge a fee in protocol tokens
         * @param from Address to charge fees
         * @param to Address to receive fees
         * @param amount Amount of protocol tokens to charge
         */
        function chargeProtocolFee(address from, address to, uint amount)
        internal
        {
            transferTokens(address(exchangeToken), from, to, amount);
        }


        /**
         * Calculate size of an order struct when tightly packed
         *
         * @param order Order to calculate size of
         * @return Size in bytes
         */
        function sizeOf(Order memory order)
        internal
        pure
        returns (uint)
        {
            return ((0x14 * 7) + (0x20 * 10) + 4 + order.callData.length + order.replacementPattern.length);
        }

        /**
         * @dev Hash an order, returning the canonical order hash, without the message prefix
         * @param order Order to hash
         * @return hash Hash of order
         */
        function hashOrder(Order memory order)
        internal
        pure
        returns (bytes32 hash)
        {
            /* Unfortunately abi.encodePacked doesn't work here, stack size constraints. */
            uint size = sizeOf(order);
            bytes memory array = new bytes(size);
            uint index;
            assembly {
                index := add(array, 0x20)
            }
            index = ArrayUtils.unsafeWriteAddress(index, order.exchange);
            index = ArrayUtils.unsafeWriteAddress(index, order.maker);
            index = ArrayUtils.unsafeWriteAddress(index, order.taker);
            index = ArrayUtils.unsafeWriteUint(index, order.makerRelayerFee);
            index = ArrayUtils.unsafeWriteUint(index, order.takerRelayerFee);
            index = ArrayUtils.unsafeWriteUint(index, order.makerProtocolFee);
            index = ArrayUtils.unsafeWriteUint(index, order.takerProtocolFee);
            index = ArrayUtils.unsafeWriteAddress(index, order.feeRecipient);
            index = ArrayUtils.unsafeWriteUint8(index, uint8(order.feeMethod));
            index = ArrayUtils.unsafeWriteUint8(index, uint8(order.side));
            index = ArrayUtils.unsafeWriteUint8(index, uint8(order.saleKind));
            index = ArrayUtils.unsafeWriteAddress(index, order.target);
            index = ArrayUtils.unsafeWriteUint8(index, uint8(order.howToCall));
            index = ArrayUtils.unsafeWriteBytes(index, order.callData);
            index = ArrayUtils.unsafeWriteBytes(index, order.replacementPattern);
            index = ArrayUtils.unsafeWriteAddress(index, order.agent);
            index = ArrayUtils.unsafeWriteUint(index, order.agentFee);
            index = ArrayUtils.unsafeWriteAddress(index, order.paymentToken);
            index = ArrayUtils.unsafeWriteUint(index, order.basePrice);
            index = ArrayUtils.unsafeWriteUint(index, order.extra);
            index = ArrayUtils.unsafeWriteUint(index, order.listingTime);
            index = ArrayUtils.unsafeWriteUint(index, order.expirationTime);
            index = ArrayUtils.unsafeWriteUint(index, order.salt);
            assembly {
                hash := keccak256(add(array, 0x20), size)
            }
            return hash;
        }

        /**
         * @dev Hash an order, returning the hash that a client must sign, including the standard message prefix
         * @param order Order to hash
         * @return Hash of message prefix and order hash per Ethereum format
         */
        function hashToSign(Order memory order)
        internal
        pure
        returns (bytes32)
        {
            return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hashOrder(order)));
        }

        /**
         * @dev Assert an order is valid and return its hash
         * @param order Order to validate
         * @param sig ECDSA signature
         */
        function requireValidOrder(Order memory order, Sig memory sig)
        internal
        view
        returns (bytes32)
        {
            bytes32 hash = hashToSign(order);
            require(validateOrder(hash, order, sig),"6");
            return hash;
        }

        /**
         * @dev Validate order parameters (does *not* check signature validity)
         * @param order Order to validate
         */
        function validateOrderParameters(Order memory order)
        internal
        view
        returns (bool)
        {
            /* Order must be targeted at this protocol version (this Exchange contract). */
            if (order.exchange != address(this)) {
                return false;
            }

            /* Order must possess valid sale kind parameter combination. */
            if (!SaleKindInterface.validateParameters(order.saleKind, order.expirationTime)) {
                return false;
            }

            /* If using the split fee method, order must have sufficient protocol fees. */
            if (order.feeMethod == FeeMethod.SplitFee && (order.makerProtocolFee < minimumMakerProtocolFee || order.takerProtocolFee < minimumTakerProtocolFee)) {
                return false;
            }

            return true;
        }

        /**
         * @dev Validate a provided previously approved / signed order, hash, and signature.
         * @param hash Order hash (already calculated, passed to avoid recalculation)
         * @param order Order to validate
         * @param sig ECDSA signature
         */
        function validateOrder(bytes32 hash, Order memory order, Sig memory sig)
        internal
        view
        returns (bool)
        {
            /* Not done in an if-conditional to prevent unnecessary ecrecover evaluation, which seems to happen even though it should short-circuit. */

            /* Order must have valid parameters. */
            if (!validateOrderParameters(order)) {
                return false;
            }

            /* Order must have not been canceled or already filled. */
            if (cancelledOrFinalized[hash]) {
                return false;
            }

            /* Order authentication. Order must be either:
            /* (a) previously approved */
            if (approvedOrders[hash]) {
                return true;
            }

            /* or (b) ECDSA-signed by maker. */
            if (ecrecover(hash, sig.v, sig.r, sig.s) == order.maker) {
                return true;
            }

            return false;
        }

        /**
         * @dev Approve an order and optionally mark it for orderbook inclusion. Must be called by the maker of the order
         * @param order Order to approve
         * @param orderbookInclusionDesired Whether orderbook providers should include the order in their orderbooks
         */
        function approveOrder(Order memory order, bool orderbookInclusionDesired)
        internal
        {
            /* CHECKS */

            /* Assert sender is authorized to approve order. */
            require(msg.sender == order.maker,"7");

            /* Calculate order hash. */
            bytes32 hash = hashToSign(order);

            /* Assert order has not already been approved. */
            require(!approvedOrders[hash],"8");

            /* EFFECTS */

            /* Mark order as approved. */
            approvedOrders[hash] = true;

            /* Log approval event. Must be split in two due to Solidity stack size limitations. */
            {
                emit OrderApprovedPartOne(hash, order.exchange, order.maker, order.taker, order.makerRelayerFee, order.takerRelayerFee, order.makerProtocolFee, order.takerProtocolFee, order.feeRecipient, order.feeMethod, order.side, order.saleKind, order.target);
            }
            {
                emit OrderApprovedPartTwo(hash, order.howToCall, order.callData, order.replacementPattern, order.agent, order.agentFee, order.paymentToken, order.basePrice, order.extra, order.listingTime, order.expirationTime, order.salt, orderbookInclusionDesired);
            }
        }

        /**
         * @dev Cancel an order, preventing it from being matched. Must be called by the maker of the order
         * @param order Order to cancel
         * @param sig ECDSA signature
         */
        function cancelOrder(Order memory order, Sig memory sig)
        internal
        {
            /* CHECKS */

            /* Calculate order hash. */
            bytes32 hash = requireValidOrder(order, sig);

            /* Assert sender is authorized to cancel order. */
            require(msg.sender == order.maker,"9");

            /* EFFECTS */

            /* Mark order as cancelled, preventing it from being matched. */
            cancelledOrFinalized[hash] = true;

            /* Log cancel event. */
            emit OrderCancelled(hash);
        }

        /**
         * @dev Calculate the current price of an order (convenience function)
         * @param order Order to calculate the price of
         * @return The current price of the order
         */
        function calculateCurrentPrice (Order memory order)
        internal
        view
        returns (uint)
        {
            return SaleKindInterface.calculateFinalPrice(order.side, order.saleKind, order.basePrice, order.extra, order.listingTime, order.expirationTime);
        }

        /**
         * @dev Calculate the price two orders would match at, if in fact they would match (otherwise fail)
         * @param buy Buy-side order
         * @param sell Sell-side order
         * @return Match price
         */
        function calculateMatchPrice(Order memory buy, Order memory sell)
        view
        internal
        returns (uint)
        {
            /* Calculate sell price. */
            uint sellPrice = SaleKindInterface.calculateFinalPrice(sell.side, sell.saleKind, sell.basePrice, sell.extra, sell.listingTime, sell.expirationTime);

            /* Calculate buy price. */
            uint buyPrice = SaleKindInterface.calculateFinalPrice(buy.side, buy.saleKind, buy.basePrice, buy.extra, buy.listingTime, buy.expirationTime);

            /* Require price cross. */
            require(buyPrice >= sellPrice,"10");

            /* Maker/taker priority. */
            return sell.feeRecipient != address(0) ? sellPrice : buyPrice;
        }

        /**
         * @dev Execute all ERC20 token / Ether transfers associated with an order match (fees and buyer => seller transfer)
         * @param buy Buy-side order
         * @param sell Sell-side order
         */
        function executeFundsTransfer(Order memory buy, Order memory sell)
        internal
        returns (uint)
        {
            /* Only payable in the special case of unwrapped Ether. */
            if (sell.paymentToken != address(0)) {
                require(msg.value == 0,"11");
            }

            /* Calculate match price. */
            uint price = calculateMatchPrice(buy, sell);

            /* If paying using a token (not Ether), transfer tokens. This is done prior to fee payments to that a seller will have tokens before being charged fees. */
            if (price > 0 && sell.paymentToken != address(0)) {
                transferTokens(sell.paymentToken, buy.maker, sell.maker, price);
            }

            /* Amount that will be received by seller (for Ether). */
            uint receiveAmount = price;

            /* Amount that must be sent by buyer (for Ether). */
            uint requiredAmount = price;

            /* Determine maker/taker and charge fees accordingly. */
            if (sell.feeRecipient != address(0)) {
                /* Sell-side order is maker. */

                /* Assert taker fee is less than or equal to maximum fee specified by buyer. */
                require(sell.takerRelayerFee <= buy.takerRelayerFee,"12");

                if (sell.feeMethod == FeeMethod.SplitFee) {
                    /* Assert taker fee is less than or equal to maximum fee specified by buyer. */
                    require(sell.takerProtocolFee <= buy.takerProtocolFee,"13");

                    /* Maker fees are deducted from the token amount that the maker receives. Taker fees are extra tokens that must be paid by the taker. */

                    if (sell.makerRelayerFee > 0) {
                        uint makerRelayerFee = SafeMath.div(SafeMath.mul(sell.makerRelayerFee, price), INVERSE_BASIS_POINT);
                        if (sell.paymentToken == address(0)) {
                            receiveAmount = SafeMath.sub(receiveAmount, makerRelayerFee);
                            payable(sell.feeRecipient).transfer(makerRelayerFee);
                        } else {
                            transferTokens(sell.paymentToken, sell.maker, sell.feeRecipient, makerRelayerFee);
                        }
                    }

                    if (sell.takerRelayerFee > 0) {
                        uint takerRelayerFee = SafeMath.div(SafeMath.mul(sell.takerRelayerFee, price), INVERSE_BASIS_POINT);
                        if (sell.paymentToken == address(0)) {
                            requiredAmount = SafeMath.add(requiredAmount, takerRelayerFee);
                            payable(sell.feeRecipient).transfer(takerRelayerFee);
                        } else {
                            transferTokens(sell.paymentToken, buy.maker, sell.feeRecipient, takerRelayerFee);
                        }
                    }

                    if (sell.makerProtocolFee > 0) {
                        uint makerProtocolFee = SafeMath.div(SafeMath.mul(sell.makerProtocolFee, price), INVERSE_BASIS_POINT);
                        if (sell.paymentToken == address(0)) {
                            receiveAmount = SafeMath.sub(receiveAmount, makerProtocolFee);
                            payable(protocolFeeRecipient).transfer(makerProtocolFee);
                        } else {
                            transferTokens(sell.paymentToken, sell.maker, protocolFeeRecipient, makerProtocolFee);
                        }
                    }

                    if (sell.takerProtocolFee > 0) {
                        uint takerProtocolFee = SafeMath.div(SafeMath.mul(sell.takerProtocolFee, price), INVERSE_BASIS_POINT);
                        if (sell.paymentToken == address(0)) {
                            requiredAmount = SafeMath.add(requiredAmount, takerProtocolFee);
                            payable(protocolFeeRecipient).transfer(takerProtocolFee);
                        } else {
                            transferTokens(sell.paymentToken, buy.maker, protocolFeeRecipient, takerProtocolFee);
                        }
                    }

                } else {
                        /* Charge maker fee to seller. */
                        chargeProtocolFee(sell.maker, sell.feeRecipient, sell.makerRelayerFee);

                        /* Charge taker fee to buyer. */
                        chargeProtocolFee(buy.maker, sell.feeRecipient, sell.takerRelayerFee);
                    }
            } else {
                /* Buy-side order is maker. */

                /* Assert taker fee is less than or equal to maximum fee specified by seller. */
                require(buy.takerRelayerFee <= sell.takerRelayerFee,"14");

                if (sell.feeMethod == FeeMethod.SplitFee) {
                    /* The Exchange does not escrow Ether, so direct Ether can only be used to with sell-side maker / buy-side taker orders. */
                    require(sell.paymentToken != address(0),"15");

                    /* Assert taker fee is less than or equal to maximum fee specified by seller. */
                    require(buy.takerProtocolFee <= sell.takerProtocolFee,"16");

                    if (buy.makerRelayerFee > 0) {
                        uint makerRelayerFee = SafeMath.div(SafeMath.mul(buy.makerRelayerFee, price), INVERSE_BASIS_POINT);
                        transferTokens(sell.paymentToken, buy.maker, buy.feeRecipient, makerRelayerFee);
                    }

                    if (buy.takerRelayerFee > 0) {
                        uint takerRelayerFee = SafeMath.div(SafeMath.mul(buy.takerRelayerFee, price), INVERSE_BASIS_POINT);
                        transferTokens(sell.paymentToken, sell.maker, buy.feeRecipient, takerRelayerFee);
                    }

                    if (buy.makerProtocolFee > 0) {
                        uint makerProtocolFee = SafeMath.div(SafeMath.mul(buy.makerProtocolFee, price), INVERSE_BASIS_POINT);
                        transferTokens(sell.paymentToken, buy.maker, protocolFeeRecipient, makerProtocolFee);
                    }

                    if (buy.takerProtocolFee > 0) {
                        uint takerProtocolFee = SafeMath.div(SafeMath.mul(buy.takerProtocolFee, price), INVERSE_BASIS_POINT);
                        transferTokens(sell.paymentToken, sell.maker, protocolFeeRecipient, takerProtocolFee);
                    }

                } else {
                    /* Charge maker fee to buyer. */
                    chargeProtocolFee(buy.maker, buy.feeRecipient, buy.makerRelayerFee);

                    /* Charge taker fee to seller. */
                    chargeProtocolFee(sell.maker, buy.feeRecipient, buy.takerRelayerFee);
                }
            }

            if (sell.paymentToken == address(0)) {
                /* Special-case Ether, order must be matched by buyer. */
                require(msg.value >= requiredAmount,"17");
                payable(sell.maker).transfer(receiveAmount);
                /* Allow overshoot for variable-price auctions, refund difference. */
                uint diff = SafeMath.sub(msg.value, requiredAmount);
                if (diff > 0) {
                    payable(buy.maker).transfer(diff);
                }
            }

            /* This contract should never hold Ether, however, we cannot assert this, since it is impossible to prevent anyone from sending Ether e.g. with selfdestruct. */

            return price;
        }

        /**
         * @dev Return whether or not two orders can be matched with each other by basic parameters (does not check order signatures / calldata or perform static calls)
         * @param buy Buy-side order
         * @param sell Sell-side order
         * @return Whether or not the two orders can be matched
         */
        function ordersCanMatch(Order memory buy, Order memory sell)
        internal
        view
        returns (bool)
        {
            return (
            /* Must be opposite-side. */
            (buy.side == SaleKindInterface.Side.Buy && sell.side == SaleKindInterface.Side.Sell) &&
            /* Must use same fee method. */
            (buy.feeMethod == sell.feeMethod) &&
            /* Must use same payment token. */
            (buy.paymentToken == sell.paymentToken) &&
            /* Must match maker/taker addresses. */
            (sell.taker == address(0) || sell.taker == buy.maker) &&
            (buy.taker == address(0) || buy.taker == sell.maker) &&
            /* One must be maker and the other must be taker (no bool XOR in Solidity). */
            ((sell.feeRecipient == address(0) && buy.feeRecipient != address(0)) || (sell.feeRecipient != address(0) && buy.feeRecipient == address(0))) &&
            /* Must match target. */
            (buy.target == sell.target) &&
            /* Must match howToCall. */
            (buy.howToCall == sell.howToCall) &&
            /* Buy-side order must be settleable. */
            SaleKindInterface.canSettleOrder(buy.listingTime, buy.expirationTime) &&
            /* Sell-side order must be settleable. */
            SaleKindInterface.canSettleOrder(sell.listingTime, sell.expirationTime)
            );
        }

        /**
         * @dev Atomically match two orders, ensuring validity of the match, and execute all associated state transitions. Protected against reentrancy by a contract-global lock.
         * @param buy Buy-side order
         * @param buySig Buy-side order signature
         * @param sell Sell-side order
         * @param sellSig Sell-side order signature
         */
        function atomicMatch(Order memory buy, Sig memory buySig, Order memory sell, Sig memory sellSig, bytes32 metadata)
        internal
        reentrancyGuard
        {
            /* CHECKS */

            /* Ensure buy order validity and calculate hash if necessary. */
            bytes32 buyHash;
            if (buy.maker == msg.sender) {
                require(validateOrderParameters(buy),"18");
            } else {
                buyHash = requireValidOrder(buy, buySig);
            }

            /* Ensure sell order validity and calculate hash if necessary. */
            bytes32 sellHash;
            if (sell.maker == msg.sender) {
                require(validateOrderParameters(sell),"19");
            } else {
                sellHash = requireValidOrder(sell, sellSig);
            }

            /* Must be matchable. */
            require(ordersCanMatch(buy, sell),"20");

            /* Target must exist (prevent malicious selfdestructs just prior to order settlement). */
            uint size;
            address target = sell.target;
            assembly {
                size := extcodesize(target)
            }
            require(size > 0,"21");

            /* Must match calldata after replacement, if specified. */
            if (buy.replacementPattern.length > 0) {
                ArrayUtils.guardedArrayReplace(buy.callData, sell.callData, buy.replacementPattern);
            }
            if (sell.replacementPattern.length > 0) {
                ArrayUtils.guardedArrayReplace(sell.callData, buy.callData, sell.replacementPattern);
            }
            require(ArrayUtils.arrayEq(buy.callData, sell.callData),"22");

            /* Retrieve delegateProxy contract. */
            OwnableDelegateProxy delegateProxy = registry.proxies(sell.maker);

            /* Proxy must exist. */
            require(address(delegateProxy) != address(0),"23");

            /* Assert implementation. */
            require(delegateProxy.implementation() == registry.delegateProxyImplementation(),"24");

            /* Access the passthrough AuthenticatedProxy. */
            AuthenticatedProxy proxy = AuthenticatedProxy(payable(delegateProxy));

            /* EFFECTS */

            /* Mark previously signed or approved orders as finalized. */
            if (msg.sender != buy.maker) {
                cancelledOrFinalized[buyHash] = true;
            }
            if (msg.sender != sell.maker) {
                cancelledOrFinalized[sellHash] = true;
            }

            /* INTERACTIONS */

            /* Execute funds transfer and pay fees. */
            uint price = executeFundsTransfer(buy, sell);

            /* Execute specified call through proxy. */
            require(proxy.proxy(sell.target, sell.howToCall, sell.callData),"25");


            /* Log match event. */
            emit OrdersMatched(buyHash, sellHash, sell.feeRecipient != address(0) ? sell.maker : buy.maker, sell.feeRecipient != address(0) ? buy.maker : sell.maker, price, metadata);
        }

}

/*
  
  Exchange contract. This is an outer contract with public or convenience functions and includes no state-modifying functions.
 
*/
/**
 * @title Exchange
 * @author Project Erax Developers
 */
contract Exchange is ExchangeCore {

    /**
     * @dev Call hashOrder - Solidity ABI encoding limitation workaround, hopefully temporary.
     */
    function hashOrder_(
        address[7] memory addrs,
        uint[10] memory uints,
        FeeMethod feeMethod,
        SaleKindInterface.Side side,
        SaleKindInterface.SaleKind saleKind,
        AuthenticatedProxy.HowToCall howToCall,
        bytes memory callData,
        bytes memory replacementPattern)
    public
    pure
    returns (bytes32)
    {
        return hashOrder(
        Order(addrs[0], addrs[1], addrs[2], uints[0], uints[1], uints[2], uints[3], addrs[3], feeMethod, side, saleKind, addrs[4], howToCall, callData, replacementPattern, addrs[5], uints[9], addrs[6], uints[4], uints[5], uints[6], uints[7], uints[8])
        );
    }


    /**
     * @dev Call validateOrderParameters - Solidity ABI encoding limitation workaround, hopefully temporary.
     */
    function validateOrderParameters_ (
        address[7] memory addrs,
        uint[10] memory uints,
        FeeMethod feeMethod,
        SaleKindInterface.Side side,
        SaleKindInterface.SaleKind saleKind,
        AuthenticatedProxy.HowToCall howToCall,
        bytes memory callData,
        bytes memory replacementPattern)
    view
    public
    returns (bool)
    {
        Order memory order = Order(addrs[0], addrs[1], addrs[2], uints[0], uints[1], uints[2], uints[3], addrs[3], feeMethod, side, saleKind, addrs[4], howToCall, callData, replacementPattern, addrs[5], uints[9], addrs[6], uints[4], uints[5], uints[6], uints[7], uints[8]);
        return validateOrderParameters(
            order
        );
    }


    /**
     * @dev Call cancelOrder - Solidity ABI encoding limitation workaround, hopefully temporary.
     */
    function cancelOrder_(
        address[7] memory addrs,
        uint[10] memory uints,
        FeeMethod feeMethod,
        SaleKindInterface.Side side,
        SaleKindInterface.SaleKind saleKind,
        AuthenticatedProxy.HowToCall howToCall,
        bytes memory callData,
        bytes memory replacementPattern,
        uint8 v,
        bytes32 r,
        bytes32 s)
    public
    {

        return cancelOrder(
        Order(addrs[0], addrs[1], addrs[2], uints[0], uints[1], uints[2], uints[3], addrs[3], feeMethod, side, saleKind, addrs[4], howToCall, callData, replacementPattern, addrs[5], uints[9], addrs[6], uints[4], uints[5], uints[6], uints[7], uints[8]),
    Sig(v, r, s)
        );
    }


    /**
     * @dev Call atomicMatch - Solidity ABI encoding limitation workaround, hopefully temporary.
     */
    function atomicMatch_(
        address[14] memory addrs,
        uint[20] memory uints,
        uint8[8] memory feeMethodsSidesKindsHowToCalls,
        bytes memory calldataBuy,
        bytes memory calldataSell,
        bytes memory replacementPatternBuy,
        bytes memory replacementPatternSell,
        uint8[2] memory vs,
        bytes32[5] memory rssMetadata)
    public
    payable
    {

        return atomicMatch(
            Order(addrs[0], addrs[1], addrs[2], uints[0], uints[1], uints[2], uints[3], addrs[3], FeeMethod(feeMethodsSidesKindsHowToCalls[0]), SaleKindInterface.Side(feeMethodsSidesKindsHowToCalls[1]), SaleKindInterface.SaleKind(feeMethodsSidesKindsHowToCalls[2]), addrs[4], AuthenticatedProxy.HowToCall(feeMethodsSidesKindsHowToCalls[3]), calldataBuy, replacementPatternBuy, addrs[5], uints[9], addrs[6], uints[4], uints[5], uints[6], uints[7], uints[8]),
            Sig(vs[0], rssMetadata[0], rssMetadata[1]),
            Order(addrs[7], addrs[8], addrs[9], uints[10], uints[11], uints[12], uints[13], addrs[10], FeeMethod(feeMethodsSidesKindsHowToCalls[4]), SaleKindInterface.Side(feeMethodsSidesKindsHowToCalls[5]), SaleKindInterface.SaleKind(feeMethodsSidesKindsHowToCalls[6]), addrs[11], AuthenticatedProxy.HowToCall(feeMethodsSidesKindsHowToCalls[7]), calldataSell, replacementPatternSell, addrs[12], uints[19], addrs[13], uints[14], uints[15], uints[16], uints[17], uints[18]),
            Sig(vs[1], rssMetadata[2], rssMetadata[3]),
            rssMetadata[4]
        );
    }

}

/*

  << Project Erax Exchange >>

*/
/**
 * @title EraxExchange
 * @author Project Erax Developers
 */
contract EraxExchange is Exchange {

    string public constant name = "Erax";

    string public constant version = "1.0.0";

    string public constant codename = "Init";

    /**
     * @dev Initialize a EraxExchange instance
     * @param registryAddress Address of the registry instance which this Exchange instance will use
     * @param tokenAddress Address of the token used for protocol fees
     */
    constructor (ProxyRegistry registryAddress, TokenTransferProxy tokenTransferProxyAddress, ERC20 tokenAddress, address protocolFeeAddress) {
        registry = registryAddress;
        tokenTransferProxy = tokenTransferProxyAddress;
        exchangeToken = tokenAddress;
        protocolFeeRecipient = protocolFeeAddress;
    }

}