// File: contracts/strategies/anchor/AnchorStrat.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import './AnchorConstants.sol';
import './AnchorStratBase.sol';

contract AnchorStrat is AnchorStratBase {
    constructor()
        AnchorStratBase(
            Config({
                tokens: [
                    IERC20Metadata(AnchorConstants.DAI_ADDRESS),
                    IERC20Metadata(AnchorConstants.USDC_ADDRESS),
                    IERC20Metadata(AnchorConstants.USDT_ADDRESS)
                ],
                aTokens: [
                    IERC20Metadata(AnchorConstants.aDAI_ADDRESS),
                    IERC20Metadata(AnchorConstants.aUSDC_ADDRESS),
                    IERC20Metadata(AnchorConstants.aUSDT_ADDRESS)
                ],
                aTokenPools: [
                    IConversionPool(AnchorConstants.aDAI_POOL_ADDRESS),
                    IConversionPool(AnchorConstants.aUSDC_POOL_ADDRESS),
                    IConversionPool(AnchorConstants.aUSDT_POOL_ADDRESS)
                ]
            })
        )
    {}
}

// File: contracts/strategies/anchor/AnchorConstants.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

library AnchorConstants {
    address internal constant DAI_ADDRESS = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
    address internal constant aDAI_ADDRESS = 0x23afFce94d2A6736DE456a25eB8Cc96612Ca55CA;
    address internal constant aDAI_POOL_ADDRESS = 0x83dd0a8E6F3A51c4cCA6c3f95721f9926DD9e7E7;

    address internal constant USDC_ADDRESS = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
    address internal constant aUSDC_ADDRESS = 0x94eAd8f528A3aF425de14cfdDA727B218915687C;
    address internal constant aUSDC_POOL_ADDRESS = 0x53fD7e8fEc0ac80cf93aA872026EadF50cB925f3;

    address internal constant USDT_ADDRESS = 0xdAC17F958D2ee523a2206206994597C13D831ec7;
    address internal constant aUSDT_ADDRESS = 0x54E076dBa023251854f4C29ea750566528734B2d;
    address internal constant aUSDT_POOL_ADDRESS = 0xEd8C41774E71f9BF0c2C223d3a3554F496656D16;
}

// File: contracts/strategies/anchor/AnchorStratBase.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol';
import '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';

import '../../interfaces/IZunami.sol';
import './IConversionPool.sol';
import './IExchangeRateFeeder.sol';

contract AnchorStratBase is Ownable {
    using SafeERC20 for IERC20Metadata;

    enum WithdrawalType {
        Base,
        OneCoin
    }

    struct Config {
        IERC20Metadata[3] tokens;
        IERC20Metadata[3] aTokens;
        IConversionPool[3] aTokenPools;
    }

    Config internal _config;

    IZunami public zunami;

    uint256 public constant PRICE_DENOMINATOR = 1e18;

    address public feeDistributor;
    uint256[3] public managementFees;

    uint256[3] public decimalsMultipliers;

    event AccruedManagementFees(uint256[3] managementFees);

    /**
     * @dev Throws if called by any account other than the Zunami
     */
    modifier onlyZunami() {
        require(_msgSender() == address(zunami), 'must be called by Zunami contract');
        _;
    }

    constructor(Config memory config_) {
        _config = config_;

        for (uint256 i; i < 3; i++) {
            decimalsMultipliers[i] = calcTokenDecimalsMultiplier(_config.tokens[i]);
        }

        feeDistributor = _msgSender();
    }

    /**
     * @dev Returns deposited amount in USD.
     * If deposit failed return zero
     * @return Returns deposited amount in USD.
     * @param amounts - amounts in stablecoins that user deposit
     */
    function deposit(uint256[3] memory amounts) external returns (uint256) {
        uint256 addedHoldings;
        for (uint256 i = 0; i < 3; i++) {
            if(amounts[i] == 0) continue;

            uint256 beforeATokenBalance = _config.aTokens[i].balanceOf(address(this));

            _config.tokens[i].safeIncreaseAllowance(address(_config.aTokenPools[i]), amounts[i]);
            _config.aTokenPools[i].deposit(amounts[i]);

            IExchangeRateFeeder feeder = IExchangeRateFeeder(_config.aTokenPools[i].feeder());
            uint256 pER = feeder.exchangeRateOf(address(_config.tokens[i]), false);
            addedHoldings += ((_config.aTokens[i].balanceOf(address(this)) - beforeATokenBalance) * pER) / PRICE_DENOMINATOR;
        }

        return addedHoldings;
    }

    function initWithdrawAll() external onlyOwner {
        for (uint256 i = 0; i < 3; i++) {
            uint256 aTokenBalance = _config.aTokens[i].balanceOf(address(this));
            if(aTokenBalance == 0) continue;
            _config.aTokens[i].safeIncreaseAllowance(
                address(_config.aTokenPools[i]),
                aTokenBalance
            );
            _config.aTokenPools[i].redeem(aTokenBalance, 0);
        }
    }

    /**
     * @dev can be called by Zunami contract.
     * This function need for moveFunds between strategys.
     */
    function withdrawAll() external onlyZunami {
        // initWithdrawAll has to be called before
        transferAllTokensOut(address(zunami));
    }

    function transferAllTokensOut(address withdrawer) internal {
        uint256 transferAmount;
        for (uint256 i = 0; i < 3; i++) {
            uint256 tokenStratBalance = _config.tokens[i].balanceOf(address(this));
            if(tokenStratBalance == 0) continue;
            require( tokenStratBalance > managementFees[i], "Zunami: Not enough strategy balance");
            unchecked {
                transferAmount = tokenStratBalance - managementFees[i];
            }
            if (transferAmount > 0) {
                _config.tokens[i].safeTransfer(withdrawer, transferAmount);
            }
        }
    }

    /**
     * @dev Returns true if withdraw success and false if fail.
     * Withdraw failed when user removingCrvLps < requiredCrvLPs (wrong minAmounts)
     * @return Returns true if withdraw success and false if fail.
     * @param withdrawer - address of user that deposit funds
     * @param userRatioOfCrvLps - user's Ratio of ZLP for withdraw
     * @param tokenAmounts -  array of amounts stablecoins that user want minimum receive
     */
    function withdraw(
        address withdrawer,
        uint256 userRatioOfCrvLps, // multiplied by 1e18
        uint256[3] memory tokenAmounts,
        WithdrawalType withdrawalType,
        uint128 tokenIndex
    ) external virtual onlyZunami returns (bool) {
        require(userRatioOfCrvLps > 0 && userRatioOfCrvLps <= PRICE_DENOMINATOR, 'Wrong lp Ratio');
        require(withdrawalType == WithdrawalType.Base, 'Only base');

        for (uint256 i = 0; i < 3; i++) {
            uint256 removingATokenBalance = (_config.aTokens[i].balanceOf(address(this)) *
                userRatioOfCrvLps) / PRICE_DENOMINATOR;
            if(removingATokenBalance == 0) continue;

            _config.aTokens[i].safeIncreaseAllowance(
                address(_config.aTokenPools[i]),
                removingATokenBalance
            );

            _config.aTokenPools[i].redeem(removingATokenBalance, tokenAmounts[i]);

            IExchangeRateFeeder feeder = IExchangeRateFeeder(_config.aTokenPools[i].feeder());
            uint256 pER = feeder.exchangeRateOf(address(_config.tokens[i]), true);

            uint256 transferAmount = (removingATokenBalance * pER) / PRICE_DENOMINATOR / decimalsMultipliers[i];
            if (transferAmount > 0) {
                _config.tokens[i].safeTransfer(withdrawer, transferAmount);
            }
        }

        return true;
    }

    function calcTokenDecimalsMultiplier(IERC20Metadata token) internal view returns (uint256) {
        uint8 decimals = token.decimals();
        require(decimals <= 18, 'Zunami: wrong token decimals');
        if (decimals == 18) return 1;
        return 10**(18 - decimals);
    }

    function autoCompound() public onlyZunami {
        // Calcs automaticly
    }

    /**
     * @dev Returns total USD holdings in strategy.
     * return amount is lpBalance x lpPrice + cvx x cvxPrice + _config.crv * crvPrice.
     * @return Returns total USD holdings in strategy
     */
    function totalHoldings() public view virtual returns (uint256) {
        uint256 tokensHoldings = 0;
        for (uint256 i = 0; i < 3; i++) {
            IExchangeRateFeeder feeder = IExchangeRateFeeder(_config.aTokenPools[i].feeder());
            uint256 pER = feeder.exchangeRateOf(address(_config.tokens[i]), false);
            tokensHoldings += _config.tokens[i].balanceOf(address(this)) * decimalsMultipliers[i] +
                (_config.aTokens[i].balanceOf(address(this)) * pER) / PRICE_DENOMINATOR;
        }
        return tokensHoldings;
    }

    function accrueManagementFees(uint256[3] memory newManagementFees) public onlyOwner {
        for (uint256 i = 0; i < 3; i++) {
            managementFees[i] += newManagementFees[i];
        }
        emit AccruedManagementFees(newManagementFees);
    }

    /**
     * @dev dev claim managementFees from strategy.
     * when tx completed managementFees = 0
     */
    function claimManagementFees() public returns (uint256 totalClaimedFees) {
        for (uint256 i = 0; i < 3; i++) {
            uint256 tokenBalance = _config.tokens[i].balanceOf(address(this));
            uint256 transferBalance = managementFees[i] > tokenBalance ? tokenBalance : managementFees[i];
            totalClaimedFees += transferBalance * decimalsMultipliers[i];
            if (transferBalance > 0) {
                _config.tokens[i].safeTransfer(feeDistributor, transferBalance);
            }
            managementFees[i] = 0;
        }

        return totalClaimedFees;
    }

    /**
     * @dev disable renounceOwnership for safety
     */
    function renounceOwnership() public view override onlyOwner {
        revert('The strategy must have an owner');
    }

    /**
     * @dev dev set Zunami (main contract) address
     * @param zunamiAddr - address of main contract (Zunami)
     */
    function setZunami(address zunamiAddr) external onlyOwner {
        zunami = IZunami(zunamiAddr);
    }

    /**
     * @dev governance can withdraw all stuck funds in emergency case
     * @param _token - IERC20Metadata token that should be fully withdraw from Strategy
     */
    function withdrawStuckToken(IERC20Metadata _token) external onlyOwner {
        uint256 tokenBalance = _token.balanceOf(address(this));
        if (tokenBalance > 0) {
            _token.safeTransfer(_msgSender(), tokenBalance);
        }
    }

    /**
     * @dev governance can set feeDistributor address for distribute protocol fees
     * @param _feeDistributor - address feeDistributor that be used for claim fees
     */
    function changeFeeDistributor(address _feeDistributor) external onlyOwner {
        feeDistributor = _feeDistributor;
    }

    function calcWithdrawOneCoin(uint256 userRatioOfCrvLps, uint128 tokenIndex)
    external
    view
    returns (uint256 tokenAmount){
        //Don't support
        return 0;
    }

    function calcSharesAmount(uint256[3] memory tokenAmounts, bool isDeposit)
    external
    view
    returns (uint256 sharesAmount) {
        //Don't support
        return 0;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

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() {
        _transferOwnership(_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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// 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/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: contracts/interfaces/IZunami.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IZunami {
    function totalDeposited() external returns (uint256);

    function deposited(address account) external returns (uint256);

    function totalHoldings() external returns (uint256);

    function calcManagementFee(uint256 amount) external returns (uint256);
}

// File: contracts/strategies/anchor/IConversionPool.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IConversionPool {
    function deposit(uint256 _amount) external;

    function deposit(uint256 _amount, uint256 _minAmountOut) external;

    function redeem(uint256 _amount) external;

    function redeem(uint256 _amount, uint256 _minAmountOut) external;

    function feeder() external view returns (address);
}

// File: contracts/strategies/anchor/IExchangeRateFeeder.sol



//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IExchangeRateFeeder {
    event RateUpdated(
        address indexed _operator,
        address indexed _token,
        uint256 _before,
        uint256 _after,
        uint256 _updateCount
    );

    enum Status {
        NEUTRAL,
        RUNNING,
        STOPPED
    }

    struct Token {
        Status status;
        uint256 exchangeRate;
        uint256 period;
        uint256 weight;
        uint256 lastUpdatedAt;
    }

    function exchangeRateOf(address _token, bool _simulate) external view returns (uint256);

    function update(address _token) external;
}

// 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/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/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);
            }
        }
    }
}