// SPDX-License-Identifier: MIT

pragma solidity =0.8.4;

import '../utils/RetrieveTokensFeature.sol';
import '../interfaces/IERC20UpgradeableBurnable.sol';

/**
 * Contract to handle a seed sale of diversify
 */
contract SeedSaleRound is RetrieveTokensFeature {
    // The State of the seed sale
    enum State {
        Setup,
        Active,
        Refunding,
        Closed
    }

    // ERC20 basic token contract being held
    IERC20UpgradeableBurnable private _token;

    // Balance sheet of the invested weis
    mapping(address => uint256) private _balances;

    // Tracks the state of the seedsale
    State private _state;

    //  Start date of seedsale (unix timestamp)
    uint256 private _startDate;

    // the duration of the seed sale (seconds)
    uint256 private _duration;

    // beneficiary of tokens (weis) after the sale ends
    address private _beneficiary;

    // How many token units a buyer gets per wei (wei)
    uint256 private _rate;

    // Supply of seed round in momos
    uint256 private _totalSupply;

    // The total supply in wei
    uint256 private _weiTotalSupply;

    // Amount of wei raised
    uint256 private _weiRaised;

    // Amount of wei to raise
    uint256 private _weiGoal;

    // Min investment limit per transaction (wei)
    uint256 private _weiMinTransactionLimit;

    // Max investment limit for investor, zero(0) for unlimited (wei)
    uint256 private _weiMaxInvestmentLimit;

    // Locking period of tokens if sale was successful (seconds)
    uint256 private _lockingPeriod;

    /*
     * Event seedsale announced
     * @param startDate when the sales start
     * @param rate How many token units a buyer gets per wei
     * @param weiGoal amount of wei to reach for success
     * @param weiMinTransactionLimit min investment limit per transaction
     * @param weiMaxInvestmentLimit max investment limit for investor
     * @param totalSupply of momos in the round
     * @param duration the duration of the seed sale in seconds
     * @param lockingPeriod Locking period of tokens in seconds if sale was successful
     */
    event Setup(
        uint256 startDate,
        uint256 rate,
        uint256 weiGoal,
        uint256 weiMinTransactionLimit,
        uint256 weiMaxInvestmentLimit,
        uint256 totalSupply,
        uint256 duration,
        uint256 lockingPeriod
    );

    /*
     * Event for seedsale closed logging
     */
    event Closed();

    /*
     * Event for refunds enabled
     */
    event RefundsEnabled();

    /*
     * Event for logging the refund
     * @param beneficiary who get the refund
     * @param weiAmount weis refunded
     */
    event Refunded(address indexed beneficiary, uint256 weiAmount);

    /*
     * Event for token purchase logging
     * @param purchaser who paid for the tokens
     * @param value weis paid for purchase
     * @param amount amount of tokens purchased
     */
    event TokenPurchased(address indexed purchaser, uint256 value, uint256 amount);

    /**
     * Create a new instance of the seed sale
     */
    constructor() {
        _state = State.Setup;
    }

    /**
     * @return the state of the sales round
     */
    function state() public view returns (State) {
        return _state;
    }

    /**
     * @return the token being held.
     */
    function token() public view returns (IERC20UpgradeableBurnable) {
        return _token;
    }

    /**
     * @return  the start date of seedsale (unix timestamp)
     */
    function startDate() public view returns (uint256) {
        return _startDate;
    }

    /**
     * @return  the duration of seedsale (seconds)
     */
    function duration() public view returns (uint256) {
        return _duration;
    }

    /**
     * @return the beneficiary of the tokens.
     */
    function beneficiary() public view returns (address) {
        return _beneficiary;
    }

    /**
     * @return the rate how many momos one get per gwei
     */
    function rate() public view returns (uint256) {
        return _rate;
    }

    /**
     * @return  Supply of seed round in momos
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @return the total supply in wei
     */
    function weiTotalSupply() public view returns (uint256) {
        return _weiTotalSupply;
    }

    /**
     * @return the amount of wei raised
     */
    function weiRaised() public view returns (uint256) {
        return _weiRaised;
    }

    /**
     * @return the wei min transaction limit
     */
    function weiMinTransactionLimit() public view returns (uint256) {
        return _weiMinTransactionLimit;
    }

    /**
     * @return the wei Max Investment Limit
     */
    function weiMaxInvestmentLimit() public view returns (uint256) {
        return _weiMaxInvestmentLimit;
    }

    /**
     * @return the locking period time in seconds
     */
    function lockingPeriod() public view returns (uint256) {
        return _lockingPeriod;
    }

    /**
     * @return the goal of wei to raise
     */
    function weiGoal() public view returns (uint256) {
        return _weiGoal;
    }

    /**
     * @return the balance of momos for the given address
     */
    function balanceOf(address address_) public view returns (uint256) {
        return _getMomoAmount(_balances[address_]);
    }

    /**
     * @dev setup the sale
     * @param beneficiary_ beneficiary of tokens (weis) after the sale ends
     * @param startDate_ The date in a unix timestamp when the seedsale starts
     * @param duration_ the duration of the seed sale in seconds
     * @param lockingPeriod_ Locking period of tokens in seconds if sale was successful
     * @param rate_ How many momos a buyer gets per wei
     * @param weiGoal_ The goal in wei to reach for round success
     * @param weiMinTransactionLimit_ Min investment limit per transaction
     * @param weiMaxInvestmentLimit_  Max investment limit per investor, zero for unlimited
     * @param token_ The div token
     */

    function setup(
        address beneficiary_,
        uint256 startDate_,
        uint256 duration_,
        uint256 lockingPeriod_,
        uint256 rate_,
        uint256 weiGoal_,
        uint256 weiMinTransactionLimit_,
        uint256 weiMaxInvestmentLimit_,
        IERC20UpgradeableBurnable token_
    ) public onlyOwner {
        require(_state == State.Setup, 'Seed already started');
        require(beneficiary_ != address(0), 'Beneficary not specified');
        require(duration_ > 0, 'Duration needs to be bigger than 0');
        require(address(token_) != address(0), 'Token must be set');
        require(token_.balanceOf(address(this)) > 0, 'Seedsale has no amount for the given token');
        require(rate_ > 0, 'Rate needs to be bigger than 0');
        require(weiGoal_ > 0, 'Goal needs to be bigger than 0');

        _beneficiary = beneficiary_;
        _duration = duration_;
        _lockingPeriod = lockingPeriod_;
        _token = token_;
        _rate = rate_;
        _startDate = startDate_;
        _totalSupply = _token.balanceOf(address(this));
        _weiTotalSupply = _totalSupply / _rate;
        _weiGoal = weiGoal_;
        _weiMinTransactionLimit = weiMinTransactionLimit_;
        _weiMaxInvestmentLimit = weiMaxInvestmentLimit_;
        _state = State.Active;

        emit Setup(
            _startDate,
            _rate,
            _weiGoal,
            _weiMinTransactionLimit,
            _weiMaxInvestmentLimit,
            _totalSupply,
            _duration,
            _lockingPeriod
        );
    }

    /**
     * @dev token purchase
     */
    function buyTokens() public payable {
        require(_state != State.Setup, 'SeedSale not ready');
        require(block.timestamp > _startDate, 'SeedSale not started');

        require(_state == State.Active, 'SeedSale not active');
        require(block.timestamp < _startDate + _duration, 'End duration reached');
        require(_msgSender() != address(0), 'Address 0 as sender is not allowed');

        uint256 weiAmount = msg.value;
        require(weiAmount != 0, 'Wei amount cant be zero');

        // limit the minimum amount for one transaction (WEI)
        require(weiAmount >= _weiMinTransactionLimit, 'Transaction doesnt reach minTransactionLimit');
        require(_weiRaised + weiAmount <= _weiTotalSupply, 'Transaction overeaches totalSupply');

        // limit the maximum amount that one user can spend during sale (WEI),
        // if initalized with 0, we allow unlimited
        if (_weiMaxInvestmentLimit > 0) {
            uint256 maxAllowableValue = _weiMaxInvestmentLimit - _balances[_msgSender()];
            require(weiAmount <= maxAllowableValue, 'Transaction exceeds investment limit!');
        }

        // calculate token amount for event
        uint256 tokens = _getMomoAmount(weiAmount);

        // update state
        _weiRaised += weiAmount;

        _balances[_msgSender()] = _balances[_msgSender()] + msg.value;
        emit TokenPurchased(_msgSender(), weiAmount, tokens);
    }

    /**
     * Closes the sale, when enduration reached
     */
    function close() public onlyOwner {
        require(_state == State.Active, 'Seedsale needs to be active state');
        require(block.timestamp >= _startDate + _duration, 'End duration not reached');

        if (_weiRaised >= _weiGoal) {
            _state = State.Closed;
            emit Closed();
            retrieveETH(payable(beneficiary()));
            // Burn remaining tokens
            uint256 momosSold = _getMomoAmount(_weiRaised);
            _token.burn(totalSupply() - momosSold);
        } else {
            _state = State.Refunding;
            emit RefundsEnabled();
        }
    }

    /**
     * @dev Investors can claim refunds here if crowdsale is unsuccessful
     */
    function claimRefund(address payable investor) public {
        require(_state == State.Refunding, 'Refunding disabled');
        uint256 balanceValue = _balances[investor];
        _balances[investor] = 0;
        investor.transfer(balanceValue);
        emit Refunded(investor, balanceValue);
    }

    /**
     * @dev payout the freezed amount of token
     */
    function retrieveFreezedTokens() public {
        require(_state == State.Closed, 'Sale not closed');
        require(block.timestamp >= (_startDate + _duration + _lockingPeriod), 'Seed locking period not ended');
        uint256 momoAmount = _getMomoAmount(_balances[_msgSender()]);
        _balances[_msgSender()] = 0;
        _token.transfer(_msgSender(), momoAmount);
    }

    /**
     * @dev retrieve wrongly assigned tokens
     */
    function retrieveTokens(address to, address anotherToken) public override onlyOwner {
        require(address(_token) != anotherToken, 'You should only use this method to withdraw extraneous tokens.');
        require(to == beneficiary(), 'You can only transfer tokens to the beneficiary');
        super.retrieveTokens(to, anotherToken);
    }

    /**
     * @dev retrieve wrongly assigned tokens
     */
    function retrieveETH(address payable to) public override onlyOwner {
        require(_state == State.Closed, 'Only allowed when closed');
        require(to == beneficiary(), 'You can only transfer tokens to the beneficiary');
        super.retrieveETH(to);
    }

    /**
     * @param _weiAmount Value in wei to momos
     * @return Number of token (momo's) one receives for the _weiAmount
     */
    function _getMomoAmount(uint256 _weiAmount) internal view returns (uint256) {
        return _weiAmount * rate();
    }
}

// SPDX-License-Identifier: MIT

pragma solidity =0.8.4;
import '@openzeppelin/contracts/utils/Context.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';

/**
 * Contract that provides ETH and  ERC20 token retriever authorised by the owner
 */
contract RetrieveTokensFeature is Context, Ownable {
    using SafeERC20 for IERC20;

    /**
     * @dev Allows to transfer the whole amount of the given token to a receiver
     */
    function retrieveTokens(address to, address anotherToken) public virtual onlyOwner {
        IERC20 alienToken = IERC20(anotherToken);
        alienToken.safeTransfer(to, alienToken.balanceOf(address(this)));
    }

    /**
     * @dev Allows to transfer contract's ETH to a receiver
     */
    function retrieveETH(address payable to) public virtual onlyOwner {
        to.transfer(address(this).balance);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity =0.8.4;
import '@openzeppelin/contracts-upgradeable/interfaces/IERC20Upgradeable.sol';

/**
 * Wrapper around IERC20 to interact with burn function
 */
interface IERC20UpgradeableBurnable is IERC20Upgradeable {
    /**
     * @dev Destroys `amount` tokens from the caller.
     *
     * See {ERC20-_burn}.
     */
    function burn(uint256 amount) external returns (bool);

    /**
     * @dev Destroys `amount` tokens from `account`, deducting from the caller's
     * allowance.
     *
     * See {ERC20-_burn} and {ERC20-allowance}.
     *
     * Requirements:
     *
     * - the caller must have allowance for ``accounts``'s tokens of at least
     * `amount`.
     */
    function burnFrom(address account, uint256 amount) external returns (bool);
}

// 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) {
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _setOwner(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// 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'
        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");
        }
    }
}

// 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);
}

// 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;
        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");

        (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);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../token/ERC20/IERC20Upgradeable.sol";

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20Upgradeable {
    /**
     * @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);
}
{"success": true, "error": null, "results": {"detectors": [{"check": "unchecked-transfer", "impact": "High", "confidence": "Medium"}, {"check": "unused-return", "impact": "Medium", "confidence": "Medium"}]}}