// File: contracts/AelinDeal.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;

import "./AelinERC20.sol";
import "./interfaces/IAelinDeal.sol";
import "./MinimalProxyFactory.sol";
import "./AelinFeeEscrow.sol";

contract AelinDeal is AelinERC20, MinimalProxyFactory, IAelinDeal {
    using SafeERC20 for IERC20;
    uint256 public maxTotalSupply;

    address public underlyingDealToken;
    uint256 public underlyingDealTokenTotal;
    uint256 public totalUnderlyingClaimed;
    address public holder;
    address public futureHolder;
    address public aelinTreasuryAddress;

    uint256 public underlyingPerDealExchangeRate;

    address public aelinPool;
    uint256 public vestingCliffExpiry;
    uint256 public vestingCliffPeriod;
    uint256 public vestingPeriod;
    uint256 public vestingExpiry;
    uint256 public holderFundingExpiry;

    bool private calledInitialize;
    address public aelinEscrowAddress;
    AelinFeeEscrow public aelinFeeEscrow;

    bool public depositComplete;
    mapping(address => uint256) public amountVested;

    Timeline public openRedemption;
    Timeline public proRataRedemption;

    /**
     * @dev the constructor will always be blank due to the MinimalProxyFactory pattern
     * this allows the underlying logic of this contract to only be deployed once
     * and each new deal created is simply a storage wrapper
     */
    constructor() {}

    /**
     * @dev the initialize method replaces the constructor setup and can only be called once
     * NOTE the deal tokens wrapping the underlying are always 18 decimals
     */
    function initialize(
        string calldata _poolName,
        string calldata _poolSymbol,
        DealData calldata _dealData,
        address _aelinTreasuryAddress,
        address _aelinEscrowAddress
    ) external initOnce {
        _setNameSymbolAndDecimals(
            string(abi.encodePacked("aeDeal-", _poolName)),
            string(abi.encodePacked("aeD-", _poolSymbol)),
            DEAL_TOKEN_DECIMALS
        );

        holder = _dealData.holder;
        underlyingDealToken = _dealData.underlyingDealToken;
        underlyingDealTokenTotal = _dealData.underlyingDealTokenTotal;
        maxTotalSupply = _dealData.maxDealTotalSupply;

        aelinPool = msg.sender;
        vestingCliffPeriod = _dealData.vestingCliffPeriod;
        vestingPeriod = _dealData.vestingPeriod;
        proRataRedemption.period = _dealData.proRataRedemptionPeriod;
        openRedemption.period = _dealData.openRedemptionPeriod;
        holderFundingExpiry = _dealData.holderFundingDuration;
        aelinTreasuryAddress = _aelinTreasuryAddress;
        aelinEscrowAddress = _aelinEscrowAddress;

        depositComplete = false;

        /**
         * calculates the amount of underlying deal tokens you get per wrapped deal token accepted
         */
        underlyingPerDealExchangeRate = (_dealData.underlyingDealTokenTotal * 1e18) / maxTotalSupply;
        emit SetHolder(_dealData.holder);
    }

    modifier initOnce() {
        require(!calledInitialize, "can only initialize once");
        calledInitialize = true;
        _;
    }

    modifier finalizeDeposit() {
        require(block.timestamp < holderFundingExpiry, "deposit past deadline");
        require(!depositComplete, "deposit already complete");
        _;
    }

    /**
     * @dev the holder may change their address
     */
    function setHolder(address _holder) external onlyHolder {
        require(_holder != address(0));
        futureHolder = _holder;
    }

    function acceptHolder() external {
        require(msg.sender == futureHolder, "only future holder can access");
        holder = futureHolder;
        emit SetHolder(futureHolder);
    }

    /**
     * @dev the holder finalizes the deal for the pool created by the
     * sponsor by depositing funds using this method.
     *
     * NOTE if the deposit was completed with a transfer instead of this method
     * the deposit still needs to be finalized by calling this method with
     * _underlyingDealTokenAmount set to 0
     */
    function depositUnderlying(uint256 _underlyingDealTokenAmount) external finalizeDeposit lock returns (bool) {
        if (_underlyingDealTokenAmount > 0) {
            uint256 currentBalance = IERC20(underlyingDealToken).balanceOf(address(this));
            IERC20(underlyingDealToken).safeTransferFrom(msg.sender, address(this), _underlyingDealTokenAmount);
            uint256 balanceAfterTransfer = IERC20(underlyingDealToken).balanceOf(address(this));
            uint256 underlyingDealTokenAmount = balanceAfterTransfer - currentBalance;

            emit DepositDealToken(underlyingDealToken, msg.sender, underlyingDealTokenAmount);
        }

        if (IERC20(underlyingDealToken).balanceOf(address(this)) >= underlyingDealTokenTotal) {
            depositComplete = true;
            proRataRedemption.start = block.timestamp;
            proRataRedemption.expiry = block.timestamp + proRataRedemption.period;
            vestingCliffExpiry = block.timestamp + proRataRedemption.period + openRedemption.period + vestingCliffPeriod;
            vestingExpiry = vestingCliffExpiry + vestingPeriod;

            if (openRedemption.period > 0) {
                openRedemption.start = proRataRedemption.expiry;
                openRedemption.expiry = proRataRedemption.expiry + openRedemption.period;
            }

            address aelinEscrowStorageProxy = _cloneAsMinimalProxy(aelinEscrowAddress, "Could not create new escrow");
            aelinFeeEscrow = AelinFeeEscrow(aelinEscrowStorageProxy);
            aelinFeeEscrow.initialize(aelinTreasuryAddress, underlyingDealToken);

            emit DealFullyFunded(
                aelinPool,
                proRataRedemption.start,
                proRataRedemption.expiry,
                openRedemption.start,
                openRedemption.expiry
            );
            return true;
        }
        return false;
    }

    /**
     * @dev the holder can withdraw any amount accidentally deposited over
     * the amount needed to fulfill the deal or all amount if deposit was not completed
     */
    function withdraw() external onlyHolder {
        uint256 withdrawAmount;
        if (!depositComplete && block.timestamp >= holderFundingExpiry) {
            withdrawAmount = IERC20(underlyingDealToken).balanceOf(address(this));
        } else {
            withdrawAmount =
                IERC20(underlyingDealToken).balanceOf(address(this)) -
                (underlyingDealTokenTotal - totalUnderlyingClaimed);
        }
        IERC20(underlyingDealToken).safeTransfer(holder, withdrawAmount);
        emit WithdrawUnderlyingDealToken(underlyingDealToken, holder, withdrawAmount);
    }

    /**
     * @dev after the redemption period has ended the holder can withdraw
     * the excess funds remaining from purchasers who did not accept the deal
     *
     * Requirements:
     * - both the pro rata and open redemption windows are no longer active
     */
    function withdrawExpiry() external onlyHolder {
        require(proRataRedemption.expiry > 0, "redemption period not started");
        require(
            openRedemption.expiry > 0
                ? block.timestamp >= openRedemption.expiry
                : block.timestamp >= proRataRedemption.expiry,
            "redeem window still active"
        );
        uint256 withdrawAmount = IERC20(underlyingDealToken).balanceOf(address(this)) -
            ((underlyingPerDealExchangeRate * totalSupply()) / 1e18);
        IERC20(underlyingDealToken).safeTransfer(holder, withdrawAmount);
        emit WithdrawUnderlyingDealToken(underlyingDealToken, holder, withdrawAmount);
    }

    modifier onlyHolder() {
        require(msg.sender == holder, "only holder can access");
        _;
    }

    modifier onlyPool() {
        require(msg.sender == aelinPool, "only AelinPool can access");
        _;
    }

    /**
     * @dev a view showing the number of claimable deal tokens and the
     * amount of the underlying deal token a purchser gets in return
     */
    function claimableTokens(address purchaser)
        public
        view
        returns (uint256 underlyingClaimable, uint256 dealTokensClaimable)
    {
        underlyingClaimable = 0;
        dealTokensClaimable = 0;

        uint256 maxTime = block.timestamp > vestingExpiry ? vestingExpiry : block.timestamp;
        if (
            balanceOf(purchaser) > 0 &&
            (maxTime > vestingCliffExpiry || (maxTime == vestingCliffExpiry && vestingPeriod == 0))
        ) {
            uint256 timeElapsed = maxTime - vestingCliffExpiry;

            dealTokensClaimable = vestingPeriod == 0
                ? balanceOf(purchaser)
                : ((balanceOf(purchaser) + amountVested[purchaser]) * timeElapsed) / vestingPeriod - amountVested[purchaser];
            underlyingClaimable = (underlyingPerDealExchangeRate * dealTokensClaimable) / 1e18;
        }
    }

    /**
     * @dev allows a user to claim their underlying deal tokens or a partial amount
     * of their underlying tokens once they have vested according to the schedule
     * created by the sponsor
     */
    function claim() external returns (uint256) {
        return _claim(msg.sender);
    }

    function _claim(address recipient) internal returns (uint256) {
        (uint256 underlyingDealTokensClaimed, uint256 dealTokensClaimed) = claimableTokens(recipient);
        if (dealTokensClaimed > 0) {
            amountVested[recipient] += dealTokensClaimed;
            totalUnderlyingClaimed += underlyingDealTokensClaimed;
            _burn(recipient, dealTokensClaimed);
            IERC20(underlyingDealToken).safeTransfer(recipient, underlyingDealTokensClaimed);
            emit ClaimedUnderlyingDealToken(underlyingDealToken, recipient, underlyingDealTokensClaimed);
        }
        return dealTokensClaimed;
    }

    /**
     * @dev allows the purchaser to mint deal tokens. this method is also used
     * to send deal tokens to the sponsor. It may only be called from the pool
     * contract that created this deal
     */
    function mint(address dst, uint256 dealTokenAmount) external onlyPool {
        require(depositComplete, "deposit not complete");
        _mint(dst, dealTokenAmount);
    }

    /**
     * @dev allows the protocol to handle protocol fees coming in deal tokens.
     * It may only be called from the pool contract that created this deal
     */
    function protocolMint(uint256 dealTokenAmount) external onlyPool {
        require(depositComplete, "deposit not complete");
        uint256 underlyingProtocolFees = (underlyingPerDealExchangeRate * dealTokenAmount) / 1e18;
        IERC20(underlyingDealToken).safeTransfer(address(aelinFeeEscrow), underlyingProtocolFees);
    }

    modifier blockTransfer() {
        require(msg.sender == aelinTreasuryAddress, "cannot transfer deal tokens");
        _;
    }

    /**
     * @dev a function only the treasury can use so they can send both the all
     * unvested deal tokens as well as all the vested underlying deal tokens in a
     * single transaction for distribution to $AELIN stakers.
     */
    function treasuryTransfer(address recipient) external returns (bool) {
        require(msg.sender == aelinTreasuryAddress, "only Rewards address can access");
        (uint256 underlyingClaimable, uint256 claimableDealTokens) = claimableTokens(msg.sender);
        transfer(recipient, balanceOf(msg.sender) - claimableDealTokens);
        IERC20(underlyingDealToken).safeTransferFrom(msg.sender, recipient, underlyingClaimable);
        return true;
    }

    /**
     * @dev below are helpers for transferring deal tokens. NOTE the token holder transferring
     * the deal tokens must pay the gas to claim their vested tokens first, which will burn their vested deal
     * tokens. They must also pay for the receivers claim and burn any of their vested tokens in order to ensure
     * the claim calculation is always accurate for all parties in the system
     */
    function transferMax(address recipient) external blockTransfer returns (bool) {
        (, uint256 claimableDealTokens) = claimableTokens(msg.sender);
        return transfer(recipient, balanceOf(msg.sender) - claimableDealTokens);
    }

    function transferFromMax(address sender, address recipient) external blockTransfer returns (bool) {
        (, uint256 claimableDealTokens) = claimableTokens(sender);
        return transferFrom(sender, recipient, balanceOf(sender) - claimableDealTokens);
    }

    function transfer(address recipient, uint256 amount) public virtual override blockTransfer returns (bool) {
        _claim(msg.sender);
        _claim(recipient);
        return super.transfer(recipient, amount);
    }

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override blockTransfer returns (bool) {
        _claim(sender);
        _claim(recipient);
        return super.transferFrom(sender, recipient, amount);
    }

    event SetHolder(address indexed holder);
    event DealFullyFunded(
        address indexed poolAddress,
        uint256 proRataRedemptionStart,
        uint256 proRataRedemptionExpiry,
        uint256 openRedemptionStart,
        uint256 openRedemptionExpiry
    );
    event DepositDealToken(
        address indexed underlyingDealTokenAddress,
        address indexed depositor,
        uint256 underlyingDealTokenAmount
    );
    event WithdrawUnderlyingDealToken(
        address indexed underlyingDealTokenAddress,
        address indexed depositor,
        uint256 underlyingDealTokenAmount
    );
    event ClaimedUnderlyingDealToken(
        address indexed underlyingDealTokenAddress,
        address indexed recipient,
        uint256 underlyingDealTokensClaimed
    );
}

// File: contracts/AelinERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;

import {ERC20, IERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";

interface IERC20Decimals {
    function decimals() external view returns (uint8);
}

/**
 * @dev a standard ERC20 contract that is extended with a few methods
 * described in detail below
 */
contract AelinERC20 is ERC20 {
    bool setInfo;
    /**
     * @dev Due to the constructor being empty for the MinimalProxy architecture we need
     * to set the name and symbol in the initializer which requires these custom variables
     */
    string private _custom_name;
    string private _custom_symbol;
    uint8 private _custom_decimals;
    bool private locked;
    uint8 constant DEAL_TOKEN_DECIMALS = 18;

    constructor() ERC20("", "") {}

    modifier initInfoOnce() {
        require(!setInfo, "can only initialize once");
        _;
    }

    /**
     * @dev Due to the constructor being empty for the MinimalProxy architecture we need
     * to set the name, symbol, and decimals in the initializer which requires this
     * custom logic for name(), symbol(), decimals(), and _setNameSymbolAndDecimals()
     */
    function name() public view virtual override returns (string memory) {
        return _custom_name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _custom_symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return _custom_decimals;
    }

    function _setNameSymbolAndDecimals(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) internal initInfoOnce returns (bool) {
        _custom_name = _name;
        _custom_symbol = _symbol;
        _custom_decimals = _decimals;
        setInfo = true;
        emit AelinToken(_name, _symbol, _decimals);
        return true;
    }

    /**
     * @dev Add this to prevent reentrancy attacks on purchasePoolTokens and depositUnderlying
     * source: https://quantstamp.com/blog/how-the-dforce-hacker-used-reentrancy-to-steal-25-million
     * uniswap implementation: https://github.com/Uniswap/v2-core/blob/master/contracts/UniswapV2Pair.sol#L31-L36
     */
    modifier lock() {
        require(!locked, "AelinV1: LOCKED");
        locked = true;
        _;
        locked = false;
    }

    event AelinToken(string name, string symbol, uint8 decimals);
}

// File: contracts/interfaces/IAelinDeal.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;

interface IAelinDeal {
    struct DealData {
        address underlyingDealToken;
        uint256 underlyingDealTokenTotal;
        uint256 vestingPeriod;
        uint256 vestingCliffPeriod;
        uint256 proRataRedemptionPeriod;
        uint256 openRedemptionPeriod;
        address holder;
        uint256 maxDealTotalSupply;
        uint256 holderFundingDuration;
    }

    struct Timeline {
        uint256 period;
        uint256 start;
        uint256 expiry;
    }
}

// File: contracts/MinimalProxyFactory.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.7;

// https://docs.synthetix.io/contracts/source/contracts/minimalproxyfactory
// https://blog.openzeppelin.com/deep-dive-into-the-minimal-proxy-contract/
contract MinimalProxyFactory {
    function _cloneAsMinimalProxy(address _base, string memory _revertMsg) internal returns (address clone) {
        bytes memory createData = _generateMinimalProxyCreateData(_base);

        assembly {
            clone := create(
                0, // no value
                add(createData, 0x20), // data
                55 // data is always 55 bytes (10 constructor + 45 code)
            )
        }

        // If CREATE fails for some reason, address(0) is returned
        require(clone != address(0), _revertMsg);
    }

    function _generateMinimalProxyCreateData(address _base) internal pure returns (bytes memory) {
        return
            abi.encodePacked(
                //---- constructor -----
                bytes10(0x3d602d80600a3d3981f3),
                //---- proxy code -----
                bytes10(0x363d3d373d3d3d363d73),
                _base,
                bytes15(0x5af43d82803e903d91602b57fd5bf3)
            );
    }
}

// File: contracts/AelinFeeEscrow.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

contract AelinFeeEscrow {
    using SafeERC20 for IERC20;
    uint256 public vestingExpiry;
    address public treasury;
    address public futureTreasury;
    address public escrowedToken;

    bool private calledInitialize;

    /**
     * @dev the constructor will always be blank due to the MinimalProxyFactory pattern
     * this allows the underlying logic of this contract to only be deployed once
     * and each new escrow created is simply a storage wrapper
     */
    constructor() {}

    /**
     * @dev the treasury may change their address
     */
    function setTreasury(address _treasury) external onlyTreasury {
        require(_treasury != address(0));
        futureTreasury = _treasury;
    }

    function acceptTreasury() external {
        require(msg.sender == futureTreasury, "only future treasury can access");
        treasury = futureTreasury;
        emit SetTreasury(futureTreasury);
    }

    function initialize(address _treasury, address _escrowedToken) external initOnce {
        treasury = _treasury;
        vestingExpiry = block.timestamp;
        escrowedToken = _escrowedToken;
        emit InitializeEscrow(msg.sender, _treasury, vestingExpiry, escrowedToken);
    }

    modifier initOnce() {
        require(!calledInitialize, "can only initialize once");
        calledInitialize = true;
        _;
    }

    modifier onlyTreasury() {
        require(msg.sender == treasury, "only treasury can access");
        _;
    }

    function delayEscrow() external onlyTreasury {
        require(vestingExpiry < block.timestamp + 90 days, "can only extend by 90 days");
        vestingExpiry = block.timestamp + 90 days;
        emit DelayEscrow(vestingExpiry);
    }

    /**
     * @dev transfer all the escrow tokens to the treasury
     */
    function withdrawToken() external onlyTreasury {
        require(block.timestamp > vestingExpiry, "cannot access funds yet");
        uint256 balance = IERC20(escrowedToken).balanceOf(address(this));
        IERC20(escrowedToken).safeTransfer(treasury, balance);
    }

    event SetTreasury(address indexed treasury);
    event InitializeEscrow(
        address indexed dealAddress,
        address indexed treasury,
        uint256 vestingExpiry,
        address indexed escrowedToken
    );
    event DelayEscrow(uint256 vestingExpiry);
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/ERC20.sol)

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 Contracts guidelines: functions revert
 * instead 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 default 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:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, 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}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, 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}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, 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) {
        address owner = _msgSender();
        _approve(owner, spender, _allowances[owner][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) {
        address owner = _msgSender();
        uint256 currentAllowance = _allowances[owner][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `sender` to `recipient`.
     *
     * This 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:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _balances[to] += amount;

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, 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:
     *
     * - `account` 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);

        _afterTokenTransfer(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");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(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 Spend `amount` form the allowance of `owner` toward `spender`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - 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 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 Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        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/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

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/utils/Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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) {
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

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'
        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
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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");

        (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");

        (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");

        (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");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}