// File: src/WETHGateway.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;

import "openzeppelin-upgradeable/contracts/proxy/utils/Initializable.sol";

import "./interfaces/IOmniToken.sol";
import "./interfaces/IWETH9.sol";
import "./interfaces/IWithUnderlying.sol";
import "./SubAccount.sol";

/**
 * @title WETHGateway
 * @notice Handles native ETH deposits directly to contract through WETH, but does not handle native ETH withdrawals.
 * @dev This contract serves as a gateway for handling deposits of native ETH, which are then wrapped into WETH tokens.
 */
contract WETHGateway is Initializable {
    using SubAccount for address;

    address public oweth;
    address public weth;
    uint96 private constant SUBACCOUNT_ID = 0;

    event Deposit(bytes32 indexed account, uint8 indexed trancheId, uint256 amount, uint256 share);

    /**
     * @notice Initializes the contract with the OWETH contract address.
     * @param _oweth The address of the OWETH contract.
     */
    function initialize(address _oweth) external initializer {
        address _weth = IWithUnderlying(_oweth).underlying();
        IWETH9(_weth).approve(_oweth, type(uint256).max);
        oweth = _oweth;
        weth = _weth;
    }

    /**
     * @notice Deposits native ETH to the contract, wraps it into WETH tokens, and handles the deposit operation
     * through the Omni Token contract.
     * @dev The function is payable to accept ETH deposits.
     * @param _subId The subscription ID related to the depositor's account.
     * @param _trancheId The identifier of the tranche where the deposit is occurring.
     * @return share The number of shares received in exchange for the deposited ETH.
     */
    function deposit(uint96 _subId, uint8 _trancheId) external payable returns (uint256 share) {
        bytes32 to = msg.sender.toAccount(_subId);
        IWETH9(weth).deposit{value: msg.value}();
        share = IOmniToken(oweth).deposit(SUBACCOUNT_ID, _trancheId, msg.value);
        IOmniToken(oweth).transfer(SUBACCOUNT_ID, to, _trancheId, share);
        emit Deposit(to, _trancheId, msg.value, share);
    }

    /**
     * @notice Fallback function that reverts if ETH is sent directly to the contract.
     * @dev Any attempts to send ETH directly to the contract will cause a transaction revert.
     */
    receive() external payable {
        revert("This contract should not accept ETH directly.");
    }
}

// File: lib/openzeppelin-contracts-upgradeable/contracts/proxy/utils/Initializable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (proxy/utils/Initializable.sol)

pragma solidity ^0.8.2;

import "../../utils/AddressUpgradeable.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
 * case an upgrade adds a module that needs to be initialized.
 *
 * For example:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * contract MyToken is ERC20Upgradeable {
 *     function initialize() initializer public {
 *         __ERC20_init("MyToken", "MTK");
 *     }
 * }
 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
 *     function initializeV2() reinitializer(2) public {
 *         __ERC20Permit_init("MyToken");
 *     }
 * }
 * ```
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() {
 *     _disableInitializers();
 * }
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     * @custom:oz-retyped-from bool
     */
    uint8 private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Triggered when the contract has been initialized or reinitialized.
     */
    event Initialized(uint8 version);

    /**
     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
     * `onlyInitializing` functions can be used to initialize parent contracts.
     *
     * Similar to `reinitializer(1)`, except that functions marked with `initializer` can be nested in the context of a
     * constructor.
     *
     * Emits an {Initialized} event.
     */
    modifier initializer() {
        bool isTopLevelCall = !_initializing;
        require(
            (isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
            "Initializable: contract is already initialized"
        );
        _initialized = 1;
        if (isTopLevelCall) {
            _initializing = true;
        }
        _;
        if (isTopLevelCall) {
            _initializing = false;
            emit Initialized(1);
        }
    }

    /**
     * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
     * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
     * used to initialize parent contracts.
     *
     * A reinitializer may be used after the original initialization step. This is essential to configure modules that
     * are added through upgrades and that require initialization.
     *
     * When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
     * cannot be nested. If one is invoked in the context of another, execution will revert.
     *
     * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
     * a contract, executing them in the right order is up to the developer or operator.
     *
     * WARNING: setting the version to 255 will prevent any future reinitialization.
     *
     * Emits an {Initialized} event.
     */
    modifier reinitializer(uint8 version) {
        require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
        _initialized = version;
        _initializing = true;
        _;
        _initializing = false;
        emit Initialized(version);
    }

    /**
     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
     * {initializer} and {reinitializer} modifiers, directly or indirectly.
     */
    modifier onlyInitializing() {
        require(_initializing, "Initializable: contract is not initializing");
        _;
    }

    /**
     * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
     * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
     * to any version. It is recommended to use this to lock implementation contracts that are designed to be called
     * through proxies.
     *
     * Emits an {Initialized} event the first time it is successfully executed.
     */
    function _disableInitializers() internal virtual {
        require(!_initializing, "Initializable: contract is initializing");
        if (_initialized < type(uint8).max) {
            _initialized = type(uint8).max;
            emit Initialized(type(uint8).max);
        }
    }

    /**
     * @dev Internal function that returns the initialized version. Returns `_initialized`
     */
    function _getInitializedVersion() internal view returns (uint8) {
        return _initialized;
    }

    /**
     * @dev Internal function that returns the initialized version. Returns `_initializing`
     */
    function _isInitializing() internal view returns (bool) {
        return _initializing;
    }
}

// File: src/interfaces/IOmniToken.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.19;

import "./IOmniTokenBase.sol";

/**
 * @title IOmniToken
 * @notice Interface for the OmniToken contract which manages deposits, withdrawals, borrowings, and repayments within the Omni protocol.
 */
interface IOmniToken is IOmniTokenBase {
    /// Events
    event Accrue();
    event Deposit(bytes32 indexed account, uint8 indexed trancheId, uint256 amount, uint256 share);
    event Withdraw(bytes32 indexed account, uint8 indexed trancheId, uint256 amount, uint256 share);
    event Borrow(bytes32 indexed account, uint8 indexed trancheId, uint256 amount, uint256 share);
    event Repay(bytes32 indexed account, address indexed payer, uint8 indexed trancheId, uint256 amount, uint256 share);
    event Seize(bytes32 indexed account, bytes32 indexed to, uint256 amount, uint256[] seizedShares);
    event SetTrancheCount(uint8 trancheCount);
    event SetTrancheBorrowCaps(uint256[] borrowCaps);
    event SocializedLoss(bytes32 indexed account, uint8 indexed trancheId, uint256 amount, uint256 share);
    event Transfer(bytes32 indexed from, bytes32 indexed to, uint8 indexed trancheId, uint256 share);

    /**
     * @notice Gets the address of the OmniPool contract.
     * @return The address of the OmniPool contract.
     */
    function omniPool() external view returns (address);

    /**
     * @notice Gets the address of the Interest Rate Model (IRM) contract.
     * @return The address of the IRM contract.
     */
    function irm() external view returns (address);

    /**
     * @notice Gets the last accrual time.
     * @return The timestamp of the last accrual time.
     */
    function lastAccrualTime() external view returns (uint256);

    /**
     * @notice Gets the count of tranches.
     * @return The total number of tranches.
     */
    function trancheCount() external view returns (uint8);

    /**
     * @notice Gets the reserve receiver.
     * @return The bytes32 identifier of the reserve receiver.
     */
    function reserveReceiver() external view returns (bytes32);

    /**
     * @notice Gets the borrow cap for a specific tranche.
     * @param _trancheId The ID of the tranche for which to retrieve the borrow cap.
     * @return The borrow cap for the specified tranche.
     */
    function getBorrowCap(uint8 _trancheId) external view returns (uint256);

    /**
     * @notice Accrues interest for all tranches, calculates and distributes the interest among the depositors and updates tranche balances.
     * The function also handles reserve payments. This method needs to be called before any deposit, withdrawal, borrow, or repayment actions to update the state of the contract.
     * @dev Interest is paid out proportionately to more risky tranche deposits per tranche
     */
    function accrue() external;

    /**
     * @notice Deposits a specified amount into a specified tranche.
     * @param _subId Sub-account identifier for the depositor.
     * @param _trancheId Identifier of the tranche to deposit into.
     * @param _amount Amount to deposit.
     * @return share Amount of deposit shares received in exchange for the deposit.
     */
    function deposit(uint96 _subId, uint8 _trancheId, uint256 _amount) external returns (uint256 share);

    /**
     * @notice Withdraws funds from a specified tranche.
     * @param _subId The ID of the sub-account.
     * @param _trancheId The ID of the tranche.
     * @param _share The share of the user in the tranche.
     * @return amount The amount of funds withdrawn.
     */
    function withdraw(uint96 _subId, uint8 _trancheId, uint256 _share) external returns (uint256 amount);

    /**
     * @notice Borrows funds from a specified tranche.
     * @param _account The account of the user.
     * @param _trancheId The ID of the tranche.
     * @param _amount The amount to borrow.
     * @return share The share of the borrowed amount in the tranche.
     */
    function borrow(bytes32 _account, uint8 _trancheId, uint256 _amount) external returns (uint256 share);

    /**
     * @notice Repays borrowed funds.
     * @param _account The account of the user.
     * @param _payer The account that will pay the borrowed amount.
     * @param _trancheId The ID of the tranche.
     * @param _amount The amount to repay.
     * @return amount The amount of the repaid amount in the tranche.
     */
    function repay(bytes32 _account, address _payer, uint8 _trancheId, uint256 _amount)
        external
        returns (uint256 amount);

    /**
     * @notice Transfers specified shares from one account to another within a specified tranche.
     * @param _subId The subscription ID related to the sender's account.
     * @param _to The account identifier to which shares are being transferred.
     * @param _trancheId The identifier of the tranche where the transfer is occurring.
     * @param _shares The amount of shares to transfer.
     * @return A boolean value indicating whether the transfer was successful.
     */
    function transfer(uint96 _subId, bytes32 _to, uint8 _trancheId, uint256 _shares) external returns (bool);

    /**
     * @notice Distributes the bad debt loss in a tranche among all tranche members. This function should only be called by the OmniPool.
     * @param _account The account that incurred a loss.
     * @param _trancheId The ID of the tranche.
     */
    function socializeLoss(bytes32 _account, uint8 _trancheId) external;

    /**
     * @notice Computes the borrowing amount of a specific account in the underlying asset for a given borrow tier.
     * @dev The division is ceiling division.
     * @param _account The account identifier for which the borrowing amount is to be computed.
     * @param _borrowTier The borrow tier identifier from which the borrowing amount is to be computed.
     * @return The borrowing amount of the account in the underlying asset for the given borrow tier.
     */
    function getAccountBorrowInUnderlying(bytes32 _account, uint8 _borrowTier) external view returns (uint256);

    /**
     * @notice Retrieves the deposit and borrow shares for a specific account in a specific tranche.
     * @param _account The account identifier.
     * @param _trancheId The tranche identifier.
     * @return depositShare The deposit share.
     * @return borrowShare The borrow share.
     */
    function getAccountSharesByTranche(bytes32 _account, uint8 _trancheId)
        external
        view
        returns (uint256 depositShare, uint256 borrowShare);

    /**
     * @notice Sets the borrow caps for each tranche.
     * @param _borrowCaps An array of borrow caps in the underlying's decimals.
     */
    function setTrancheBorrowCaps(uint256[] calldata _borrowCaps) external;

    /**
     * @notice Sets the number of tranches.
     * @param _trancheCount The new tranche count.
     */
    function setTrancheCount(uint8 _trancheCount) external;

    /**
     * @notice Fetches and updates the reserve receiver from the OmniPool contract.
     */
    function fetchReserveReceiver() external;
}

// File: src/interfaces/IWETH9.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity 0.8.19;

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

/// @title Interface for WETH9
interface IWETH9 is IERC20 {
    /// @notice Deposit ether to get wrapped ether
    function deposit() external payable;

    /// @notice Withdraw wrapped ether to get ether
    function withdraw(uint256) external;
}

// File: src/interfaces/IWithUnderlying.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.19;

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

/**
 * @title IWithUnderlying
 * @notice Interface for the WithUnderlying contract to handle the inflow and outflow of ERC20 tokens.
 */
interface IWithUnderlying {
    /**
     * @notice Gets the address of the underlying ERC20 token.
     * @return The address of the underlying ERC20 token.
     */
    function underlying() external view returns (address);
}

// File: src/SubAccount.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.19;

/**
 * @title SubAccount
 * @notice This library provides utility functions to handle sub-accounts using bytes32 types, where id is most significant bytes.
 */
library SubAccount {
    /**
     * @notice Combines an address and a sub-account identifier into a bytes32 account representation.
     * @param _sender The address component.
     * @param _subId The sub-account identifier component.
     * @return A bytes32 representation of the account.
     */
    function toAccount(address _sender, uint96 _subId) internal pure returns (bytes32) {
        return bytes32(uint256(uint160(_sender)) | (uint256(_subId) << 160));
    }

    /**
     * @notice Extracts the address component from a bytes32 account representation.
     * @param _account The bytes32 representation of the account.
     * @return The address component.
     */
    function toAddress(bytes32 _account) internal pure returns (address) {
        return address(uint160(uint256(_account)));
    }

    /**
     * @notice Extracts the sub-account identifier component from a bytes32 account representation.
     * @param _account The bytes32 representation of the account.
     * @return The sub-account identifier component.
     */
    function toSubId(bytes32 _account) internal pure returns (uint96) {
        return uint96(uint256(_account) >> 160);
    }
}

// File: lib/openzeppelin-contracts-upgradeable/contracts/utils/AddressUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [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 functionCallWithValue(target, data, 0, "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");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or 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 {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // 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
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// File: src/interfaces/IOmniTokenBase.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.19;

/**
 * @title IOmniTokenBase
 * @notice Base interface shared by the IOmniToken and IOmniTokenNoBorrow interfaces.
 */
interface IOmniTokenBase {
    /**
     * @notice Retrieves the total deposit amount for a specific account.
     * @param _account The account identifier.
     * @return The total deposit amount.
     */
    function getAccountDepositInUnderlying(bytes32 _account) external view returns (uint256);

    /**
     * @notice Calculates the total deposited amount for a specific owner across sub-accounts. This funciton is for wallets and Etherscan to pick up balances.
     * @param _owner The address of the owner.
     * @return The total deposited amount.
     */
    function balanceOf(address _owner) external view returns (uint256);

    /**
     * @notice Seizes funds from a user's account in the event of a liquidation. This is a priveleged function only callable by the OmniPool and must be implemented carefully.
     * @param _account The account from which funds will be seized.
     * @param _to The account to which seized funds will be sent.
     * @param _amount The amount of funds to seize.
     * @return The shares seized from each tranche.
     */
    function seize(bytes32 _account, bytes32 _to, uint256 _amount) external returns (uint256[] memory);
}

// File: lib/openzeppelin-contracts/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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);
}