// File: contracts/lending/Vault.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;

import "../IUSDI.sol";
import "./IVault.sol";
import "./IVaultController.sol";

import "../_external/CompLike.sol";
import "../_external/IERC20.sol";
import "../_external/Context.sol";
import "../_external/openzeppelin/SafeERC20Upgradeable.sol";

/// @title Vault
/// @notice our implentation of maker-vault like vault
/// major differences:
/// 1. multi-collateral
/// 2. generate interest in USDi
/// 3. can delegate voting power of contained tokens
contract Vault is IVault, Context {
  using SafeERC20Upgradeable for IERC20;

  /// @title VaultInfo struct
  /// @notice this struct is used to store the vault metadata
  /// this should reduce the cost of minting by ~15,000
  /// by limiting us to max 2**96-1 vaults
  struct VaultInfo {
    uint96 id;
    address minter;
  }
  /// @notice Metadata of vault, aka the id & the minter's address
  VaultInfo public _vaultInfo;
  IVaultController public immutable _controller;

  /// @notice this is the unscaled liability of the vault.
  /// the number is meaningless on its own, and must be combined with the factor taken from
  /// the vaultController in order to find the true liabilitiy
  uint256 public _baseLiability;

  /// @notice checks if _msgSender is the controller of the vault
  modifier onlyVaultController() {
    require(_msgSender() == address(_controller), "sender not VaultController");
    _;
  }

  /// @notice checks if _msgSender is the minter of the vault
  modifier onlyMinter() {
    require(_msgSender() == _vaultInfo.minter, "sender not minter");
    _;
  }

  /// @notice must be called by VaultController, else it will not be registered as a vault in system
  /// @param id_ unique id of the vault, ever increasing and tracked by VaultController
  /// @param minter_ address of the person who created this vault
  /// @param controller_address address of the VaultController
  constructor(
    uint96 id_,
    address minter_,
    address controller_address
  ) {
    _vaultInfo = VaultInfo(id_, minter_);
    _controller = IVaultController(controller_address);
  }

  /// @notice minter of the vault
  /// @return address of minter
  function minter() external view override returns (address) {
    return _vaultInfo.minter;
  }

  /// @notice id of the vault
  /// @return address of minter
  function id() external view override returns (uint96) {
    return _vaultInfo.id;
  }

  /// @notice current vault base liability
  /// @return base liability of vault
  function baseLiability() external view override returns (uint256) {
    return _baseLiability;
  }

  /// @notice get vaults balance of an erc20 token
  /// @param addr address of the erc20 token
  /// @dev scales wBTC up to normal erc20 size
  function tokenBalance(address addr) external view override returns (uint256) {
    return IERC20(addr).balanceOf(address(this));
  }

  /// @notice withdraw an erc20 token from the vault
  /// this can only be called by the minter
  /// the withdraw will be denied if ones vault would become insolvent
  /// @param token_address address of erc20 token
  /// @param amount amount of erc20 token to withdraw
  function withdrawErc20(address token_address, uint256 amount) external override onlyMinter {
    // transfer the token to the owner
    SafeERC20Upgradeable.safeTransfer(IERC20Upgradeable(token_address), _msgSender(), amount);
    //  check if the account is solvent
    require(_controller.checkVault(_vaultInfo.id), "over-withdrawal");
    emit Withdraw(token_address, amount);
  }

  /// @notice delegate the voting power of a comp-like erc20 token to another address
  /// @param delegatee address that will receive the votes
  /// @param token_address address of comp-like erc20 token
  function delegateCompLikeTo(address delegatee, address token_address) external override onlyMinter {
    CompLike(token_address).delegate(delegatee);
  }

  /// @notice function used by the VaultController to transfer tokens
  /// callable by the VaultController only
  /// @param _token token to transfer
  /// @param _to person to send the coins to
  /// @param _amount amount of coins to move
  function controllerTransfer(
    address _token,
    address _to,
    uint256 _amount
  ) external override onlyVaultController {
    SafeERC20Upgradeable.safeTransfer(IERC20Upgradeable(_token), _to, _amount);
  }

  /// @notice function used by the VaultController to reduce a vault's liability
  /// callable by the VaultController only
  /// @param increase true to increase, false to decrease
  /// @param base_amount change in base liability
  function modifyLiability(bool increase, uint256 base_amount) external override onlyVaultController returns (uint256) {
    if (increase) {
      _baseLiability = _baseLiability + base_amount;
    } else {
      // require statement only valid for repayment
      require(_baseLiability >= base_amount, "repay too much");
      _baseLiability = _baseLiability - base_amount;
    }
    return _baseLiability;
  }
}

// File: contracts/IUSDI.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;

import "./_external/IERC20Metadata.sol";

/// @title USDI Events
/// @notice interface which contains any events which the USDI contract emits
interface USDIEvents {
  event Deposit(address indexed _from, uint256 _value);
  event Withdraw(address indexed _from, uint256 _value);
  event Mint(address to, uint256 _value);
  event Burn(address from, uint256 _value);
  event Donation(address indexed _from, uint256 _value, uint256 _totalSupply);
}

/// @title USDI Interface
/// @notice extends USDIEvents and IERC20Metadata
interface IUSDI is IERC20Metadata, USDIEvents {
  /// @notice initializer specifies the reserveAddress
  function initialize(address reserveAddress) external;

  // getters
  function reserveRatio() external view returns (uint192);

  function reserveAddress() external view returns (address);

  // owner
  function owner() external view returns (address);

  // business
  function deposit(uint256 usdc_amount) external;

  function depositTo(uint256 usdc_amount, address target) external;

  function withdraw(uint256 usdc_amount) external;

  function withdrawTo(uint256 usdc_amount, address target) external;

  function withdrawAll() external;

  function withdrawAllTo(address target) external;

  function donate(uint256 usdc_amount) external;

  function donateReserve() external;

  // admin functions

  function setPauser(address pauser_) external;

  function pauser() external view returns (address);

  function pause() external;

  function unpause() external;

  function mint(uint256 usdc_amount) external;

  function burn(uint256 usdc_amount) external;

  function setVaultController(address vault_master_address) external;

  function getVaultController() external view returns (address);

  // functions for the vault controller to call
  function vaultControllerBurn(address target, uint256 amount) external;

  function vaultControllerMint(address target, uint256 amount) external;

  function vaultControllerTransfer(address target, uint256 usdc_amount) external;

  function vaultControllerDonate(uint256 amount) external;
}

// File: contracts/lending/IVault.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;

// @title Vault Events
/// @notice interface which contains any events which the Vault contract emits
interface VaultEvents {
  event Deposit(address token_address, uint256 amount);
  event Withdraw(address token_address, uint256 amount);
}

/// @title Vault Interface
/// @notice extends VaultEvents
interface IVault is VaultEvents {
  /// @notice value of _baseLiability
  function baseLiability() external view returns (uint256);
  /// @notice value of _vaultInfo.minter
  function minter() external view returns (address);
  /// @notice value of _vaultInfo.id
  function id() external view returns (uint96);
  /// @notice value of _tokenBalance
  function tokenBalance(address) external view returns (uint256);

  // business logic

  function withdrawErc20(address token_address, uint256 amount) external;
  function delegateCompLikeTo(address compLikeDelegatee, address compLikeToken) external;

  // administrative functions
  function controllerTransfer(
    address _token,
    address _to,
    uint256 _amount
  ) external;

  function modifyLiability(bool increase, uint256 base_amount) external returns (uint256);
}

// File: contracts/lending/IVaultController.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;

// @title VaultController Events
/// @notice interface which contains any events which the VaultController contract emits
interface VaultControllerEvents {
  event InterestEvent(uint64 epoch, uint192 amount, uint256 curve_val);
  event NewProtocolFee(uint256 protocol_fee);
  event RegisteredErc20(address token_address, uint256 LTVe4, address oracle_address, uint256 liquidationIncentivee4);
  event UpdateRegisteredErc20(
    address token_address,
    uint256 LTVe4,
    address oracle_address,
    uint256 liquidationIncentivee4
  );
  event NewVault(address vault_address, uint256 vaultId, address vaultOwner);
  event RegisterOracleMaster(address oracleMasterAddress);
  event RegisterCurveMaster(address curveMasterAddress);
  event BorrowUSDi(uint256 vaultId, address vaultAddress, uint256 borrowAmount);
  event RepayUSDi(uint256 vaultId, address vaultAddress, uint256 repayAmount);
  event Liquidate(uint256 vaultId, address asset_address, uint256 usdi_to_repurchase, uint256 tokens_to_liquidate);
}

/// @title VaultController Interface
/// @notice extends VaultControllerEvents
interface IVaultController is VaultControllerEvents {
  // initializer
  function initialize() external;

  // view functions

  function tokensRegistered() external view returns (uint256);

  function vaultsMinted() external view returns (uint96);

  function lastInterestTime() external view returns (uint64);

  function totalBaseLiability() external view returns (uint192);

  function interestFactor() external view returns (uint192);

  function protocolFee() external view returns (uint192);

  function vaultAddress(uint96 id) external view returns (address);

  function vaultIDs(address wallet) external view returns (uint96[] memory);

  function amountToSolvency(uint96 id) external view returns (uint256);

  function vaultLiability(uint96 id) external view returns (uint192);

  function vaultBorrowingPower(uint96 id) external view returns (uint192);

  function tokensToLiquidate(uint96 id, address token) external view returns (uint256);

  function checkVault(uint96 id) external view returns (bool);

  struct VaultSummary {
    uint96 id;
    uint192 borrowingPower;
    uint192 vaultLiability;
    address[] tokenAddresses;
    uint256[] tokenBalances;
  }

  function vaultSummaries(uint96 start, uint96 stop) external view returns (VaultSummary[] memory);

  // interest calculations
  function calculateInterest() external returns (uint256);

  // vault management business
  function mintVault() external returns (address);

  function liquidateVault(
    uint96 id,
    address asset_address,
    uint256 tokenAmount
  ) external returns (uint256);

  function borrowUsdi(uint96 id, uint192 amount) external;

  function borrowUSDIto(
    uint96 id,
    uint192 amount,
    address target
  ) external;

  function borrowUSDCto(
    uint96 id,
    uint192 usdc_amount,
    address target
  ) external;

  function repayUSDi(uint96 id, uint192 amount) external;

  function repayAllUSDi(uint96 id) external;

  // admin
  function pause() external;

  function unpause() external;

  function getOracleMaster() external view returns (address);

  function registerOracleMaster(address master_oracle_address) external;

  function getCurveMaster() external view returns (address);

  function registerCurveMaster(address master_curve_address) external;

  function changeProtocolFee(uint192 new_protocol_fee) external;

  function registerErc20(
    address token_address,
    uint256 LTV,
    address oracle_address,
    uint256 liquidationIncentive
  ) external;

  function registerUSDi(address usdi_address) external;

  function updateRegisteredErc20(
    address token_address,
    uint256 LTV,
    address oracle_address,
    uint256 liquidationIncentive
  ) external;
}

// File: contracts/_external/CompLike.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;

interface CompLike {
  function delegate(address delegatee) external;
}

// File: contracts/_external/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.9;

/**
 * @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 token decimals.
   */
  function decimals() external view returns (uint8);

  /**
   * @dev Returns the amount of tokens owned by `account`.
   */
  function balanceOf(address account) external view returns (uint256);

  /**
   * @dev Moves `amount` tokens from the caller's account to `recipient`.
   *
   * Returns a boolean value indicating whether the operation succeeded.
   *
   * Emits a {Transfer} event.
   */
  function transfer(address recipient, uint256 amount) external returns (bool);

  /**
   * @dev Returns the remaining number of tokens that `spender` will be
   * allowed to spend on behalf of `owner` through {transferFrom}. This is
   * zero by default.
   *
   * This value changes when {approve} or {transferFrom} are called.
   */
  function allowance(address owner, address spender) external view returns (uint256);

  /**
   * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
   *
   * Returns a boolean value indicating whether the operation succeeded.
   *
   * IMPORTANT: Beware that changing an allowance with this method brings the risk
   * that someone may use both the old and the new allowance by unfortunate
   * transaction ordering. One possible solution to mitigate this race
   * condition is to first reduce the spender's allowance to 0 and set the
   * desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   *
   * Emits an {Approval} event.
   */
  function approve(address spender, uint256 amount) external returns (bool);

  /**
   * @dev Moves `amount` tokens from `sender` to `recipient` using the
   * allowance mechanism. `amount` is then deducted from the caller's
   * allowance.
   *
   * Returns a boolean value indicating whether the operation succeeded.
   *
   * Emits a {Transfer} event.
   */
  function transferFrom(
    address sender,
    address recipient,
    uint256 amount
  ) external returns (bool);

  /**
   * @dev Emitted when `value` tokens are moved from one account (`from`) to
   * another (`to`).
   *
   * Note that `value` may be zero.
   */
  event Transfer(address indexed from, address indexed to, uint256 value);

  /**
   * @dev Emitted when the allowance of a `spender` for an `owner` is set by
   * a call to {approve}. `value` is the new allowance.
   */
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: contracts/_external/Context.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
  function _msgSender() internal view virtual returns (address) {
    return msg.sender;
  }

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

// File: contracts/_external/openzeppelin/SafeERC20Upgradeable.sol



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

pragma solidity ^0.8.0;

import "./IERC20Upgradeable.sol";
import "./AddressUpgradeable.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 SafeERC20Upgradeable {
    using AddressUpgradeable for address;

    function safeTransfer(
        IERC20Upgradeable token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20Upgradeable 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(
        IERC20Upgradeable 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(
        IERC20Upgradeable 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(
        IERC20Upgradeable 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(IERC20Upgradeable 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/_external/IERC20Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.9;

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: contracts/_external/openzeppelin/IERC20Upgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/IERC20.sol)

pragma solidity 0.8.9;

/**
 * @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);
}

// File: contracts/_external/openzeppelin/AddressUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (utils/Address.sol)

pragma solidity 0.8.9;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
  /**
   * @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 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);
      }
    }
  }
}