// File: contracts/MasterChef.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "./interfaces/IERC20Ubiquity.sol";
import "./UbiquityAlgorithmicDollarManager.sol";
import "./interfaces/ITWAPOracle.sol";
import "./interfaces/IERC1155Ubiquity.sol";
import "./interfaces/IUbiquityFormulas.sol";

contract MasterChef {
    using SafeERC20 for IERC20Ubiquity;
    using SafeERC20 for IERC20;
    // Info of each user.
    struct UserInfo {
        uint256 amount; // How many uAD-3CRV LP tokens the user has provided.
        uint256 rewardDebt; // Reward debt. See explanation below.
        //
        // We do some fancy math here. Basically, any point in time, the amount of uGOVs
        // entitled to a user but is pending to be distributed is:
        //
        //   pending reward = (user.amount * pool.accuGOVPerShare) - user.rewardDebt
        //
        // Whenever a user deposits or withdraws LP tokens to a pool. Here's what happens:
        //   1. The pool's `accuGOVPerShare` (and `lastRewardBlock`) gets updated.
        //   2. User receives the pending reward sent to his/her address.
        //   3. User's `amount` gets updated.
        //   4. User's `rewardDebt` gets updated.
    }
    // Info of each pool.
    struct PoolInfo {
        uint256 lastRewardBlock; // Last block number that uGOVs distribution occurs.
        uint256 accuGOVPerShare; // Accumulated uGOVs per share, times 1e12. See below.
    }

    // Ubiquity Manager
    UbiquityAlgorithmicDollarManager public manager;

    // uGOV tokens created per block.
    uint256 public uGOVPerBlock = 1e18;
    // Bonus muliplier for early uGOV makers.
    uint256 public uGOVmultiplier = 1e18;
    uint256 public minPriceDiffToUpdateMultiplier = 1000000000000000;
    uint256 public lastPrice = 1 ether;
    // Info of each pool.
    PoolInfo public pool;
    // Info of each user that stakes LP tokens.
    mapping(address => UserInfo) public userInfo;

    event Deposit(address indexed user, uint256 amount);

    event Withdraw(address indexed user, uint256 amount);

    // ----------- Modifiers -----------
    modifier onlyTokenManager() {
        require(
            manager.hasRole(manager.UBQ_TOKEN_MANAGER_ROLE(), msg.sender),
            "MasterChef: not UBQ manager"
        );
        _;
    }
    modifier onlyBondingContract() {
        require(
            msg.sender == manager.bondingContractAddress(),
            "MasterChef: not Bonding Contract"
        );
        _;
    }

    constructor(address _manager) {
        manager = UbiquityAlgorithmicDollarManager(_manager);
        pool.lastRewardBlock = block.number;
        pool.accuGOVPerShare = 0; // uint256(1e12);
        _updateUGOVMultiplier();
    }

    function setUGOVPerBlock(uint256 _uGOVPerBlock) external onlyTokenManager {
        uGOVPerBlock = _uGOVPerBlock;
    }

    function setMinPriceDiffToUpdateMultiplier(
        uint256 _minPriceDiffToUpdateMultiplier
    ) external onlyTokenManager {
        minPriceDiffToUpdateMultiplier = _minPriceDiffToUpdateMultiplier;
    }

    // Deposit LP tokens to MasterChef for uGOV allocation.
    function deposit(uint256 _amount, address sender)
        external
        onlyBondingContract
    {
        UserInfo storage user = userInfo[sender];
        _updatePool();
        if (user.amount > 0) {
            uint256 pending =
                ((user.amount * pool.accuGOVPerShare) / 1e12) - user.rewardDebt;
            _safeUGOVTransfer(sender, pending);
        }
        /*  pool.lpToken.safeTransferFrom(
            address(msg.sender),
            address(this),
            _amount
        ); */
        user.amount = user.amount + _amount;
        user.rewardDebt = (user.amount * pool.accuGOVPerShare) / 1e12;
        emit Deposit(sender, _amount);
    }

    // Withdraw LP tokens from MasterChef.
    function withdraw(uint256 _amount, address sender)
        external
        onlyBondingContract
    {
        UserInfo storage user = userInfo[sender];
        require(user.amount >= _amount, "MC: amount too high");
        _updatePool();
        uint256 pending =
            ((user.amount * pool.accuGOVPerShare) / 1e12) - user.rewardDebt;
        _safeUGOVTransfer(sender, pending);
        user.amount = user.amount - _amount;
        user.rewardDebt = (user.amount * pool.accuGOVPerShare) / 1e12;
        /*  pool.lpToken.safeTransfer(msg.sender, _amount); */
        emit Withdraw(sender, _amount);
    }

    /// @dev get pending uGOV rewards from MasterChef.
    /// @return amount of pending rewards transfered to msg.sender
    /// @notice only send pending rewards
    function getRewards() external returns (uint256) {
        UserInfo storage user = userInfo[msg.sender];
        _updatePool();
        uint256 pending =
            ((user.amount * pool.accuGOVPerShare) / 1e12) - user.rewardDebt;
        _safeUGOVTransfer(msg.sender, pending);
        user.rewardDebt = (user.amount * pool.accuGOVPerShare) / 1e12;
        return pending;
    }

    // View function to see pending uGOVs on frontend.
    function pendingUGOV(address _user) external view returns (uint256) {
        UserInfo storage user = userInfo[_user];
        uint256 accuGOVPerShare = pool.accuGOVPerShare;
        uint256 lpSupply =
            IERC1155Ubiquity(manager.bondingShareAddress()).totalSupply();

        if (block.number > pool.lastRewardBlock && lpSupply != 0) {
            uint256 multiplier = _getMultiplier();

            uint256 uGOVReward = (multiplier * uGOVPerBlock) / 1e18;
            accuGOVPerShare =
                accuGOVPerShare +
                ((uGOVReward * 1e12) / lpSupply);
        }

        return (user.amount * accuGOVPerShare) / 1e12 - user.rewardDebt;
    }

    // UPDATE uGOV multiplier
    function _updateUGOVMultiplier() internal {
        // (1.05/(1+abs(1-TWAP_PRICE)))
        uint256 currentPrice = _getTwapPrice();

        bool isPriceDiffEnough = false;
        // a minimum price variation is needed to update the multiplier
        if (currentPrice > lastPrice) {
            isPriceDiffEnough =
                currentPrice - lastPrice > minPriceDiffToUpdateMultiplier;
        } else {
            isPriceDiffEnough =
                lastPrice - currentPrice > minPriceDiffToUpdateMultiplier;
        }

        if (isPriceDiffEnough) {
            uGOVmultiplier = IUbiquityFormulas(manager.formulasAddress())
                .ugovMultiply(uGOVmultiplier, currentPrice);
            lastPrice = currentPrice;
        }
    }

    // Update reward variables of the given pool to be up-to-date.
    function _updatePool() internal {
        if (block.number <= pool.lastRewardBlock) {
            return;
        }
        _updateUGOVMultiplier();
        uint256 lpSupply =
            IERC1155Ubiquity(manager.bondingShareAddress()).totalSupply();
        /*  IERC20(manager.stableSwapMetaPoolAddress()).balanceOf(
                manager.bondingContractAddress()
            ); */

        if (lpSupply == 0) {
            pool.lastRewardBlock = block.number;
            return;
        }
        uint256 multiplier = _getMultiplier();
        uint256 uGOVReward = (multiplier * uGOVPerBlock) / 1e18;
        IERC20Ubiquity(manager.governanceTokenAddress()).mint(
            address(this),
            uGOVReward
        );
        // mint another 20% for the treasury
        IERC20Ubiquity(manager.governanceTokenAddress()).mint(
            manager.treasuryAddress(),
            uGOVReward / 5
        );
        pool.accuGOVPerShare =
            pool.accuGOVPerShare +
            ((uGOVReward * 1e12) / lpSupply);
        pool.lastRewardBlock = block.number;
    }

    // Safe uGOV transfer function, just in case if rounding
    // error causes pool to not have enough uGOVs.
    function _safeUGOVTransfer(address _to, uint256 _amount) internal {
        IERC20Ubiquity uGOV = IERC20Ubiquity(manager.governanceTokenAddress());
        uint256 uGOVBal = uGOV.balanceOf(address(this));
        if (_amount > uGOVBal) {
            uGOV.safeTransfer(_to, uGOVBal);
        } else {
            uGOV.safeTransfer(_to, _amount);
        }
    }

    function _getMultiplier() internal view returns (uint256) {
        return (block.number - pool.lastRewardBlock) * uGOVmultiplier;
    }

    function _getTwapPrice() internal view returns (uint256) {
        return
            ITWAPOracle(manager.twapOracleAddress()).consult(
                manager.dollarTokenAddress()
            );
    }
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/interfaces/IERC20Ubiquity.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.3;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/// @title ERC20 Ubiquiti preset interface
/// @author Ubiquity Algorithmic Dollar
interface IERC20Ubiquity is IERC20 {
    // ----------- Events -----------
    event Minting(
        address indexed _to,
        address indexed _minter,
        uint256 _amount
    );

    event Burning(address indexed _burned, uint256 _amount);

    // ----------- State changing api -----------
    function burn(uint256 amount) external;

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    // ----------- Burner only state changing api -----------
    function burnFrom(address account, uint256 amount) external;

    // ----------- Minter only state changing api -----------
    function mint(address account, uint256 amount) external;
}

// File: contracts/UbiquityAlgorithmicDollarManager.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

import "./interfaces/IUbiquityAlgorithmicDollar.sol";
import "./interfaces/ICurveFactory.sol";
import "./interfaces/IMetaPool.sol";

import "./TWAPOracle.sol";

/// @title A central config for the uAD system. Also acts as a central
/// access control manager.
/// @notice For storing constants. For storing variables and allowing them to
/// be changed by the admin (governance)
/// @dev This should be used as a central access control manager which other
/// contracts use to check permissions
contract UbiquityAlgorithmicDollarManager is AccessControl {
    using SafeERC20 for IERC20;

    bytes32 public constant UBQ_MINTER_ROLE = keccak256("UBQ_MINTER_ROLE");
    bytes32 public constant UBQ_BURNER_ROLE = keccak256("UBQ_BURNER_ROLE");

    bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
    bytes32 public constant COUPON_MANAGER_ROLE = keccak256("COUPON_MANAGER");
    bytes32 public constant BONDING_MANAGER_ROLE = keccak256("BONDING_MANAGER");
    bytes32 public constant INCENTIVE_MANAGER_ROLE =
        keccak256("INCENTIVE_MANAGER");
    bytes32 public constant UBQ_TOKEN_MANAGER_ROLE =
        keccak256("UBQ_TOKEN_MANAGER_ROLE");
    address public twapOracleAddress;
    address public debtCouponAddress;
    address public dollarTokenAddress; // uAD
    address public couponCalculatorAddress;
    address public dollarMintingCalculatorAddress;
    address public bondingShareAddress;
    address public bondingContractAddress;
    address public stableSwapMetaPoolAddress;
    address public curve3PoolTokenAddress; // 3CRV
    address public treasuryAddress;
    address public governanceTokenAddress; // uGOV
    address public sushiSwapPoolAddress; // sushi pool uAD-uGOV
    address public masterChefAddress;
    address public formulasAddress;
    address public autoRedeemTokenAddress; // uAR
    address public uarCalculatorAddress; // uAR calculator

    //key = address of couponmanager, value = excessdollardistributor
    mapping(address => address) private _excessDollarDistributors;

    modifier onlyAdmin() {
        require(
            hasRole(DEFAULT_ADMIN_ROLE, msg.sender),
            "uADMGR: Caller is not admin"
        );
        _;
    }

    constructor(address _admin) {
        _setupRole(DEFAULT_ADMIN_ROLE, _admin);
        _setupRole(UBQ_MINTER_ROLE, _admin);
        _setupRole(PAUSER_ROLE, _admin);
        _setupRole(COUPON_MANAGER_ROLE, _admin);
        _setupRole(BONDING_MANAGER_ROLE, _admin);
        _setupRole(INCENTIVE_MANAGER_ROLE, _admin);
        _setupRole(UBQ_TOKEN_MANAGER_ROLE, address(this));
    }

    // TODO Add a generic setter for extra addresses that needs to be linked
    function setTwapOracleAddress(address _twapOracleAddress)
        external
        onlyAdmin
    {
        twapOracleAddress = _twapOracleAddress;
        // to be removed

        TWAPOracle oracle = TWAPOracle(twapOracleAddress);
        oracle.update();
    }

    function setuARTokenAddress(address _uarTokenAddress) external onlyAdmin {
        autoRedeemTokenAddress = _uarTokenAddress;
    }

    function setDebtCouponAddress(address _debtCouponAddress)
        external
        onlyAdmin
    {
        debtCouponAddress = _debtCouponAddress;
    }

    function setIncentiveToUAD(address _account, address _incentiveAddress)
        external
        onlyAdmin
    {
        IUbiquityAlgorithmicDollar(dollarTokenAddress).setIncentiveContract(
            _account,
            _incentiveAddress
        );
    }

    function setDollarTokenAddress(address _dollarTokenAddress)
        external
        onlyAdmin
    {
        dollarTokenAddress = _dollarTokenAddress;
    }

    function setGovernanceTokenAddress(address _governanceTokenAddress)
        external
        onlyAdmin
    {
        governanceTokenAddress = _governanceTokenAddress;
    }

    function setSushiSwapPoolAddress(address _sushiSwapPoolAddress)
        external
        onlyAdmin
    {
        sushiSwapPoolAddress = _sushiSwapPoolAddress;
    }

    function setUARCalculatorAddress(address _uarCalculatorAddress)
        external
        onlyAdmin
    {
        uarCalculatorAddress = _uarCalculatorAddress;
    }

    function setCouponCalculatorAddress(address _couponCalculatorAddress)
        external
        onlyAdmin
    {
        couponCalculatorAddress = _couponCalculatorAddress;
    }

    function setDollarMintingCalculatorAddress(
        address _dollarMintingCalculatorAddress
    ) external onlyAdmin {
        dollarMintingCalculatorAddress = _dollarMintingCalculatorAddress;
    }

    function setExcessDollarsDistributor(
        address debtCouponManagerAddress,
        address excessCouponDistributor
    ) external onlyAdmin {
        _excessDollarDistributors[
            debtCouponManagerAddress
        ] = excessCouponDistributor;
    }

    function setMasterChefAddress(address _masterChefAddress)
        external
        onlyAdmin
    {
        masterChefAddress = _masterChefAddress;
    }

    function setFormulasAddress(address _formulasAddress) external onlyAdmin {
        formulasAddress = _formulasAddress;
    }

    function setBondingShareAddress(address _bondingShareAddress)
        external
        onlyAdmin
    {
        bondingShareAddress = _bondingShareAddress;
    }

    function setStableSwapMetaPoolAddress(address _stableSwapMetaPoolAddress)
        external
        onlyAdmin
    {
        stableSwapMetaPoolAddress = _stableSwapMetaPoolAddress;
    }

    /**
    @notice set the bonding bontract smart contract address
    @dev bonding contract participants deposit  curve LP token
         for a certain duration to earn uGOV and more curve LP token
    @param _bondingContractAddress bonding contract address
     */
    function setBondingContractAddress(address _bondingContractAddress)
        external
        onlyAdmin
    {
        bondingContractAddress = _bondingContractAddress;
    }

    /**
    @notice set the treasury address
    @dev the treasury fund is used to maintain the protocol
    @param _treasuryAddress treasury fund address
     */
    function setTreasuryAddress(address _treasuryAddress) external onlyAdmin {
        treasuryAddress = _treasuryAddress;
    }

    /**
    @notice deploy a new Curve metapools for uAD Token uAD/3Pool
    @dev  From the curve documentation for uncollateralized algorithmic
    stablecoins amplification should be 5-10
    @param _curveFactory MetaPool factory address
    @param _crvBasePool Address of the base pool to use within the new metapool.
    @param _crv3PoolTokenAddress curve 3Pool token Address
    @param _amplificationCoefficient amplification coefficient. The smaller
     it is the closer to a constant product we are.
    @param _fee Trade fee, given as an integer with 1e10 precision.
    */
    function deployStableSwapPool(
        address _curveFactory,
        address _crvBasePool,
        address _crv3PoolTokenAddress,
        uint256 _amplificationCoefficient,
        uint256 _fee
    ) external onlyAdmin {
        // Create new StableSwap meta pool (uAD <-> 3Crv)
        address metaPool =
            ICurveFactory(_curveFactory).deploy_metapool(
                _crvBasePool,
                ERC20(dollarTokenAddress).name(),
                ERC20(dollarTokenAddress).symbol(),
                dollarTokenAddress,
                _amplificationCoefficient,
                _fee
            );
        stableSwapMetaPoolAddress = metaPool;

        // Approve the newly-deployed meta pool to transfer this contract's funds
        uint256 crv3PoolTokenAmount =
            IERC20(_crv3PoolTokenAddress).balanceOf(address(this));
        uint256 uADTokenAmount =
            IERC20(dollarTokenAddress).balanceOf(address(this));

        // safe approve revert if approve from non-zero to non-zero allowance
        IERC20(_crv3PoolTokenAddress).safeApprove(metaPool, 0);
        IERC20(_crv3PoolTokenAddress).safeApprove(
            metaPool,
            crv3PoolTokenAmount
        );

        IERC20(dollarTokenAddress).safeApprove(metaPool, 0);
        IERC20(dollarTokenAddress).safeApprove(metaPool, uADTokenAmount);

        // coin at index 0 is uAD and index 1 is 3CRV
        require(
            IMetaPool(metaPool).coins(0) == dollarTokenAddress &&
                IMetaPool(metaPool).coins(1) == _crv3PoolTokenAddress,
            "uADMGR: COIN_ORDER_MISMATCH"
        );
        // Add the initial liquidity to the StableSwap meta pool
        uint256[2] memory amounts =
            [
                IERC20(dollarTokenAddress).balanceOf(address(this)),
                IERC20(_crv3PoolTokenAddress).balanceOf(address(this))
            ];

        // set curve 3Pool address
        curve3PoolTokenAddress = _crv3PoolTokenAddress;
        IMetaPool(metaPool).add_liquidity(amounts, 0, msg.sender);
    }

    function getExcessDollarsDistributor(address _debtCouponManagerAddress)
        external
        view
        returns (address)
    {
        return _excessDollarDistributors[_debtCouponManagerAddress];
    }
}

// File: contracts/interfaces/ITWAPOracle.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

interface ITWAPOracle {
    function update() external;

    function consult(address token) external view returns (uint256 amountOut);
}

// File: contracts/interfaces/IERC1155Ubiquity.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.3;

import "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";

/// @title ERC1155 Ubiquiti preset interface
/// @author Ubiquity Algorithmic Dollar
interface IERC1155Ubiquity is IERC1155 {
    function mint(
        address to,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) external;

    function mintBatch(
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) external;

    function burn(
        address account,
        uint256 id,
        uint256 value
    ) external;

    function burnBatch(
        address account,
        uint256[] memory ids,
        uint256[] memory values
    ) external;

    function pause() external;

    function unpause() external;

    function totalSupply() external view returns (uint256);

    function exists(uint256 id) external view returns (bool);

    function holderTokens() external view returns (uint256[] memory);
}

// File: contracts/interfaces/IUbiquityFormulas.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

interface IUbiquityFormulas {
    function durationMultiply(
        uint256 _uLP,
        uint256 _weeks,
        uint256 _multiplier
    ) external pure returns (uint256 _shares);

    function bonding(
        uint256 _shares,
        uint256 _currentShareValue,
        uint256 _targetPrice
    ) external pure returns (uint256 _uBOND);

    function redeemBonds(
        uint256 _uBOND,
        uint256 _currentShareValue,
        uint256 _targetPrice
    ) external pure returns (uint256 _uLP);

    function bondPrice(
        uint256 _totalULP,
        uint256 _totalUBOND,
        uint256 _targetPrice
    ) external pure returns (uint256 _priceUBOND);

    function ugovMultiply(uint256 _multiplier, uint256 _price)
        external
        pure
        returns (uint256 _newMultiplier);
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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);
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/access/AccessControl.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";
import "../utils/Strings.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    function hasRole(bytes32 role, address account) external view returns (bool);
    function getRoleAdmin(bytes32 role) external view returns (bytes32);
    function grantRole(bytes32 role, address account) external;
    function revokeRole(bytes32 role, address account) external;
    function renounceRole(bytes32 role, address account) external;
}

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping (address => bool) members;
        bytes32 adminRole;
    }

    mapping (bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{20}) is missing role (0x[0-9a-f]{32})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role, _msgSender());
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId
            || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{20}) is missing role (0x[0-9a-f]{32})$/
     */
    function _checkRole(bytes32 role, address account) internal view {
        if(!hasRole(role, account)) {
            revert(string(abi.encodePacked(
                "AccessControl: account ",
                Strings.toHexString(uint160(account), 20),
                " is missing role ",
                Strings.toHexString(uint256(role), 32)
            )));
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        emit RoleAdminChanged(role, getRoleAdmin(role), adminRole);
        _roles[role].adminRole = adminRole;
    }

    function _grantRole(bytes32 role, address account) private {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) private {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @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, IERC20Metadata {
    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The defaut value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override 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 this function is
     * overridden;
     *
     * 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 override returns (uint8) {
        return 18;
    }

    /**
     * @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);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        _approve(sender, _msgSender(), currentAllowance - amount);

        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] + 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) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        _approve(_msgSender(), spender, currentAllowance - subtractedValue);

        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);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        _balances[sender] = senderBalance - amount;
        _balances[recipient] += 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 += amount;
        _balances[account] += 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);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        _balances[account] = accountBalance - amount;
        _totalSupply -= 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 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 { }
}

// File: contracts/interfaces/IUbiquityAlgorithmicDollar.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.3;

import "./IERC20Ubiquity.sol";

/// @title UAD stablecoin interface
/// @author Ubiquity Algorithmic Dollar
interface IUbiquityAlgorithmicDollar is IERC20Ubiquity {
    event IncentiveContractUpdate(
        address indexed _incentivized,
        address indexed _incentiveContract
    );

    function setIncentiveContract(address account, address incentive) external;

    function incentiveContract(address account) external view returns (address);
}

// File: contracts/interfaces/ICurveFactory.sol



// SPDX-License-Identifier: MIT
// !! THIS FILE WAS AUTOGENERATED BY abi-to-sol. SEE BELOW FOR SOURCE. !!
pragma solidity ^0.8.3;

interface ICurveFactory {
    event BasePoolAdded(address base_pool, address implementat);
    event MetaPoolDeployed(
        address coin,
        address base_pool,
        uint256 A,
        uint256 fee,
        address deployer
    );

    function find_pool_for_coins(address _from, address _to)
        external
        view
        returns (address);

    function find_pool_for_coins(
        address _from,
        address _to,
        uint256 i
    ) external view returns (address);

    function get_n_coins(address _pool)
        external
        view
        returns (uint256, uint256);

    function get_coins(address _pool) external view returns (address[2] memory);

    function get_underlying_coins(address _pool)
        external
        view
        returns (address[8] memory);

    function get_decimals(address _pool)
        external
        view
        returns (uint256[2] memory);

    function get_underlying_decimals(address _pool)
        external
        view
        returns (uint256[8] memory);

    function get_rates(address _pool) external view returns (uint256[2] memory);

    function get_balances(address _pool)
        external
        view
        returns (uint256[2] memory);

    function get_underlying_balances(address _pool)
        external
        view
        returns (uint256[8] memory);

    function get_A(address _pool) external view returns (uint256);

    function get_fees(address _pool) external view returns (uint256, uint256);

    function get_admin_balances(address _pool)
        external
        view
        returns (uint256[2] memory);

    function get_coin_indices(
        address _pool,
        address _from,
        address _to
    )
        external
        view
        returns (
            int128,
            int128,
            bool
        );

    function add_base_pool(
        address _base_pool,
        address _metapool_implementation,
        address _fee_receiver
    ) external;

    function deploy_metapool(
        address _base_pool,
        string memory _name,
        string memory _symbol,
        address _coin,
        uint256 _A,
        uint256 _fee
    ) external returns (address);

    function commit_transfer_ownership(address addr) external;

    function accept_transfer_ownership() external;

    function set_fee_receiver(address _base_pool, address _fee_receiver)
        external;

    function convert_fees() external returns (bool);

    function admin() external view returns (address);

    function future_admin() external view returns (address);

    function pool_list(uint256 arg0) external view returns (address);

    function pool_count() external view returns (uint256);

    function base_pool_list(uint256 arg0) external view returns (address);

    function base_pool_count() external view returns (uint256);

    function fee_receiver(address arg0) external view returns (address);
}

// File: contracts/interfaces/IMetaPool.sol



// SPDX-License-Identifier: UNLICENSED
// !! THIS FILE WAS AUTOGENERATED BY abi-to-sol. SEE BELOW FOR SOURCE. !!
pragma solidity ^0.8.3;

interface IMetaPool {
    event Transfer(
        address indexed sender,
        address indexed receiver,
        uint256 value
    );
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
    event TokenExchange(
        address indexed buyer,
        int128 sold_id,
        uint256 tokens_sold,
        int128 bought_id,
        uint256 tokens_bought
    );
    event TokenExchangeUnderlying(
        address indexed buyer,
        int128 sold_id,
        uint256 tokens_sold,
        int128 bought_id,
        uint256 tokens_bought
    );
    event AddLiquidity(
        address indexed provider,
        uint256[2] token_amounts,
        uint256[2] fees,
        uint256 invariant,
        uint256 token_supply
    );
    event RemoveLiquidity(
        address indexed provider,
        uint256[2] token_amounts,
        uint256[2] fees,
        uint256 token_supply
    );
    event RemoveLiquidityOne(
        address indexed provider,
        uint256 token_amount,
        uint256 coin_amount,
        uint256 token_supply
    );
    event RemoveLiquidityImbalance(
        address indexed provider,
        uint256[2] token_amounts,
        uint256[2] fees,
        uint256 invariant,
        uint256 token_supply
    );
    event CommitNewAdmin(uint256 indexed deadline, address indexed admin);
    event NewAdmin(address indexed admin);
    event CommitNewFee(
        uint256 indexed deadline,
        uint256 fee,
        uint256 admin_fee
    );
    event NewFee(uint256 fee, uint256 admin_fee);
    event RampA(
        uint256 old_A,
        uint256 new_A,
        uint256 initial_time,
        uint256 future_time
    );
    event StopRampA(uint256 A, uint256 t);

    function initialize(
        string memory _name,
        string memory _symbol,
        address _coin,
        uint256 _decimals,
        uint256 _A,
        uint256 _fee,
        address _admin
    ) external;

    function decimals() external view returns (uint256);

    function transfer(address _to, uint256 _value) external returns (bool);

    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    ) external returns (bool);

    function approve(address _spender, uint256 _value) external returns (bool);

    function get_previous_balances() external view returns (uint256[2] memory);

    function get_balances() external view returns (uint256[2] memory);

    function get_twap_balances(
        uint256[2] memory _first_balances,
        uint256[2] memory _last_balances,
        uint256 _time_elapsed
    ) external view returns (uint256[2] memory);

    function get_price_cumulative_last()
        external
        view
        returns (uint256[2] memory);

    function admin_fee() external view returns (uint256);

    function A() external view returns (uint256);

    function A_precise() external view returns (uint256);

    function get_virtual_price() external view returns (uint256);

    function calc_token_amount(uint256[2] memory _amounts, bool _is_deposit)
        external
        view
        returns (uint256);

    function calc_token_amount(
        uint256[2] memory _amounts,
        bool _is_deposit,
        bool _previous
    ) external view returns (uint256);

    function add_liquidity(uint256[2] memory _amounts, uint256 _min_mint_amount)
        external
        returns (uint256);

    function add_liquidity(
        uint256[2] memory _amounts,
        uint256 _min_mint_amount,
        address _receiver
    ) external returns (uint256);

    function get_dy(
        int128 i,
        int128 j,
        uint256 dx
    ) external view returns (uint256);

    function get_dy(
        int128 i,
        int128 j,
        uint256 dx,
        uint256[2] memory _balances
    ) external view returns (uint256);

    function get_dy_underlying(
        int128 i,
        int128 j,
        uint256 dx
    ) external view returns (uint256);

    function get_dy_underlying(
        int128 i,
        int128 j,
        uint256 dx,
        uint256[2] memory _balances
    ) external view returns (uint256);

    function exchange(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy
    ) external returns (uint256);

    function exchange(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy,
        address _receiver
    ) external returns (uint256);

    function exchange_underlying(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy
    ) external returns (uint256);

    function exchange_underlying(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy,
        address _receiver
    ) external returns (uint256);

    function remove_liquidity(
        uint256 _burn_amount,
        uint256[2] memory _min_amounts
    ) external returns (uint256[2] memory);

    function remove_liquidity(
        uint256 _burn_amount,
        uint256[2] memory _min_amounts,
        address _receiver
    ) external returns (uint256[2] memory);

    function remove_liquidity_imbalance(
        uint256[2] memory _amounts,
        uint256 _max_burn_amount
    ) external returns (uint256);

    function remove_liquidity_imbalance(
        uint256[2] memory _amounts,
        uint256 _max_burn_amount,
        address _receiver
    ) external returns (uint256);

    function calc_withdraw_one_coin(uint256 _burn_amount, int128 i)
        external
        view
        returns (uint256);

    function calc_withdraw_one_coin(
        uint256 _burn_amount,
        int128 i,
        bool _previous
    ) external view returns (uint256);

    function remove_liquidity_one_coin(
        uint256 _burn_amount,
        int128 i,
        uint256 _min_received
    ) external returns (uint256);

    function remove_liquidity_one_coin(
        uint256 _burn_amount,
        int128 i,
        uint256 _min_received,
        address _receiver
    ) external returns (uint256);

    function ramp_A(uint256 _future_A, uint256 _future_time) external;

    function stop_ramp_A() external;

    function admin_balances(uint256 i) external view returns (uint256);

    function withdraw_admin_fees() external;

    function admin() external view returns (address);

    function coins(uint256 arg0) external view returns (address);

    function balances(uint256 arg0) external view returns (uint256);

    function fee() external view returns (uint256);

    function block_timestamp_last() external view returns (uint256);

    function initial_A() external view returns (uint256);

    function future_A() external view returns (uint256);

    function initial_A_time() external view returns (uint256);

    function future_A_time() external view returns (uint256);

    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function balanceOf(address arg0) external view returns (uint256);

    function allowance(address arg0, address arg1)
        external
        view
        returns (uint256);

    function totalSupply() external view returns (uint256);
}

// File: contracts/TWAPOracle.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.3;

import "./interfaces/IMetaPool.sol";

contract TWAPOracle {
    address public immutable pool;
    address public immutable token0;
    address public immutable token1;
    uint256 public price0Average;
    uint256 public price1Average;
    uint256 public pricesBlockTimestampLast;
    uint256[2] public priceCumulativeLast;

    constructor(
        address _pool,
        address _uADtoken0,
        address _curve3CRVtoken1
    ) {
        pool = _pool;
        // coin at index 0 is uAD and index 1 is 3CRV
        require(
            IMetaPool(_pool).coins(0) == _uADtoken0 &&
                IMetaPool(_pool).coins(1) == _curve3CRVtoken1,
            "TWAPOracle: COIN_ORDER_MISMATCH"
        );

        token0 = _uADtoken0;
        token1 = _curve3CRVtoken1;

        uint256 _reserve0 = uint112(IMetaPool(_pool).balances(0));
        uint256 _reserve1 = uint112(IMetaPool(_pool).balances(1));

        // ensure that there's liquidity in the pair
        require(_reserve0 != 0 && _reserve1 != 0, "TWAPOracle: NO_RESERVES");
        // ensure that pair balance is perfect
        require(_reserve0 == _reserve1, "TWAPOracle: PAIR_UNBALANCED");
        priceCumulativeLast = IMetaPool(_pool).get_price_cumulative_last();
        pricesBlockTimestampLast = IMetaPool(_pool).block_timestamp_last();

        price0Average = 1 ether;
        price1Average = 1 ether;
    }

    // calculate average price
    function update() external {
        (uint256[2] memory priceCumulative, uint256 blockTimestamp) =
            _currentCumulativePrices();

        if (blockTimestamp - pricesBlockTimestampLast > 0) {
            // get the balances between now and the last price cumulative snapshot
            uint256[2] memory twapBalances =
                IMetaPool(pool).get_twap_balances(
                    priceCumulativeLast,
                    priceCumulative,
                    blockTimestamp - pricesBlockTimestampLast
                );

            // price to exchange amounIn uAD to 3CRV based on TWAP
            price0Average = IMetaPool(pool).get_dy(0, 1, 1 ether, twapBalances);
            // price to exchange amounIn 3CRV to uAD  based on TWAP
            price1Average = IMetaPool(pool).get_dy(1, 0, 1 ether, twapBalances);
            // we update the priceCumulative
            priceCumulativeLast = priceCumulative;
            pricesBlockTimestampLast = blockTimestamp;
        }
    }

    // note this will always return 0 before update has been called successfully
    // for the first time.
    function consult(address token) external view returns (uint256 amountOut) {
        if (token == token0) {
            // price to exchange 1 uAD to 3CRV based on TWAP
            amountOut = price0Average;
        } else {
            require(token == token1, "TWAPOracle: INVALID_TOKEN");
            // price to exchange 1 3CRV to uAD  based on TWAP
            amountOut = price1Average;
        }
    }

    function _currentCumulativePrices()
        internal
        view
        returns (uint256[2] memory priceCumulative, uint256 blockTimestamp)
    {
        priceCumulative = IMetaPool(pool).get_price_cumulative_last();
        blockTimestamp = IMetaPool(pool).block_timestamp_last();
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/*
 * @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 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) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant alphabet = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = alphabet[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: @openzeppelin/contracts/token/ERC1155/IERC1155.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC1155 compliant contract, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1155[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155 is IERC165 {
    /**
     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
     */
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);

    /**
     * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
     * transfers.
     */
    event TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values);

    /**
     * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
     * `approved`.
     */
    event ApprovalForAll(address indexed account, address indexed operator, bool approved);

    /**
     * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
     *
     * If an {URI} event was emitted for `id`, the standard
     * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
     * returned by {IERC1155MetadataURI-uri}.
     */
    event URI(string value, uint256 indexed id);

    /**
     * @dev Returns the amount of tokens of token type `id` owned by `account`.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id) external view returns (uint256);

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids) external view returns (uint256[] memory);

    /**
     * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
     *
     * Emits an {ApprovalForAll} event.
     *
     * Requirements:
     *
     * - `operator` cannot be the caller.
     */
    function setApprovalForAll(address operator, bool approved) external;

    /**
     * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address account, address operator) external view returns (bool);

    /**
     * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
     * - `from` must have a balance of tokens of type `id` of at least `amount`.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external;

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
     *
     * Emits a {TransferBatch} event.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external;
}