// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (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
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import { IAxelarGateway } from '../interfaces/IAxelarGateway.sol';
import { IAxelarExecutable } from '../interfaces/IAxelarExecutable.sol';

contract AxelarExecutable is IAxelarExecutable {
    IAxelarGateway public immutable gateway;

    constructor(address gateway_) {
        if (gateway_ == address(0)) revert InvalidAddress();

        gateway = IAxelarGateway(gateway_);
    }

    function execute(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes calldata payload
    ) external override {
        bytes32 payloadHash = keccak256(payload);
        if (!gateway.validateContractCall(commandId, sourceChain, sourceAddress, payloadHash))
            revert NotApprovedByGateway();
        _execute(sourceChain, sourceAddress, payload);
    }

    function executeWithToken(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes calldata payload,
        string calldata tokenSymbol,
        uint256 amount
    ) external override {
        bytes32 payloadHash = keccak256(payload);
        if (
            !gateway.validateContractCallAndMint(
                commandId,
                sourceChain,
                sourceAddress,
                payloadHash,
                tokenSymbol,
                amount
            )
        ) revert NotApprovedByGateway();

        _executeWithToken(sourceChain, sourceAddress, payload, tokenSymbol, amount);
    }

    function _execute(
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes calldata payload
    ) internal virtual {}

    function _executeWithToken(
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes calldata payload,
        string calldata tokenSymbol,
        uint256 amount
    ) internal virtual {}
}

// 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;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import { IAxelarGateway } from '../interfaces/IAxelarGateway.sol';

interface IAxelarExecutable {
    error InvalidAddress();
    error NotApprovedByGateway();

    function gateway() external view returns (IAxelarGateway);

    function execute(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes calldata payload
    ) external;

    function executeWithToken(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes calldata payload,
        string calldata tokenSymbol,
        uint256 amount
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

// This should be owned by the microservice that is paying for gas.
interface IAxelarGasService {
    error NothingReceived();
    error TransferFailed();
    error InvalidAddress();

    event GasPaidForContractCall(
        address indexed sourceAddress,
        string destinationChain,
        string destinationAddress,
        bytes32 indexed payloadHash,
        address gasToken,
        uint256 gasFeeAmount,
        address refundAddress
    );

    event GasPaidForContractCallWithToken(
        address indexed sourceAddress,
        string destinationChain,
        string destinationAddress,
        bytes32 indexed payloadHash,
        string symbol,
        uint256 amount,
        address gasToken,
        uint256 gasFeeAmount,
        address refundAddress
    );

    event NativeGasPaidForContractCall(
        address indexed sourceAddress,
        string destinationChain,
        string destinationAddress,
        bytes32 indexed payloadHash,
        uint256 gasFeeAmount,
        address refundAddress
    );

    event NativeGasPaidForContractCallWithToken(
        address indexed sourceAddress,
        string destinationChain,
        string destinationAddress,
        bytes32 indexed payloadHash,
        string symbol,
        uint256 amount,
        uint256 gasFeeAmount,
        address refundAddress
    );

    event GasAdded(
        bytes32 indexed txHash,
        uint256 indexed logIndex,
        address gasToken,
        uint256 gasFeeAmount,
        address refundAddress
    );

    event NativeGasAdded(bytes32 indexed txHash, uint256 indexed logIndex, uint256 gasFeeAmount, address refundAddress);

    // This is called on the source chain before calling the gateway to execute a remote contract.
    function payGasForContractCall(
        address sender,
        string calldata destinationChain,
        string calldata destinationAddress,
        bytes calldata payload,
        address gasToken,
        uint256 gasFeeAmount,
        address refundAddress
    ) external;

    // This is called on the source chain before calling the gateway to execute a remote contract.
    function payGasForContractCallWithToken(
        address sender,
        string calldata destinationChain,
        string calldata destinationAddress,
        bytes calldata payload,
        string calldata symbol,
        uint256 amount,
        address gasToken,
        uint256 gasFeeAmount,
        address refundAddress
    ) external;

    // This is called on the source chain before calling the gateway to execute a remote contract.
    function payNativeGasForContractCall(
        address sender,
        string calldata destinationChain,
        string calldata destinationAddress,
        bytes calldata payload,
        address refundAddress
    ) external payable;

    // This is called on the source chain before calling the gateway to execute a remote contract.
    function payNativeGasForContractCallWithToken(
        address sender,
        string calldata destinationChain,
        string calldata destinationAddress,
        bytes calldata payload,
        string calldata symbol,
        uint256 amount,
        address refundAddress
    ) external payable;

    function addGas(
        bytes32 txHash,
        uint256 txIndex,
        address gasToken,
        uint256 gasFeeAmount,
        address refundAddress
    ) external;

    function addNativeGas(
        bytes32 txHash,
        uint256 logIndex,
        address refundAddress
    ) external payable;

    function collectFees(address payable receiver, address[] calldata tokens) external;

    function refund(
        address payable receiver,
        address token,
        uint256 amount
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IAxelarGateway {
    /**********\
    |* Errors *|
    \**********/

    error NotSelf();
    error NotProxy();
    error InvalidCodeHash();
    error SetupFailed();
    error InvalidAuthModule();
    error InvalidTokenDeployer();
    error InvalidAmount();
    error InvalidChainId();
    error InvalidCommands();
    error TokenDoesNotExist(string symbol);
    error TokenAlreadyExists(string symbol);
    error TokenDeployFailed(string symbol);
    error TokenContractDoesNotExist(address token);
    error BurnFailed(string symbol);
    error MintFailed(string symbol);
    error InvalidSetMintLimitsParams();
    error ExceedMintLimit(string symbol);

    /**********\
    |* Events *|
    \**********/

    event TokenSent(
        address indexed sender,
        string destinationChain,
        string destinationAddress,
        string symbol,
        uint256 amount
    );

    event ContractCall(
        address indexed sender,
        string destinationChain,
        string destinationContractAddress,
        bytes32 indexed payloadHash,
        bytes payload
    );

    event ContractCallWithToken(
        address indexed sender,
        string destinationChain,
        string destinationContractAddress,
        bytes32 indexed payloadHash,
        bytes payload,
        string symbol,
        uint256 amount
    );

    event Executed(bytes32 indexed commandId);

    event TokenDeployed(string symbol, address tokenAddresses);

    event ContractCallApproved(
        bytes32 indexed commandId,
        string sourceChain,
        string sourceAddress,
        address indexed contractAddress,
        bytes32 indexed payloadHash,
        bytes32 sourceTxHash,
        uint256 sourceEventIndex
    );

    event ContractCallApprovedWithMint(
        bytes32 indexed commandId,
        string sourceChain,
        string sourceAddress,
        address indexed contractAddress,
        bytes32 indexed payloadHash,
        string symbol,
        uint256 amount,
        bytes32 sourceTxHash,
        uint256 sourceEventIndex
    );

    event TokenMintLimitUpdated(string symbol, uint256 limit);

    event OperatorshipTransferred(bytes newOperatorsData);

    event Upgraded(address indexed implementation);

    /********************\
    |* Public Functions *|
    \********************/

    function sendToken(
        string calldata destinationChain,
        string calldata destinationAddress,
        string calldata symbol,
        uint256 amount
    ) external;

    function callContract(
        string calldata destinationChain,
        string calldata contractAddress,
        bytes calldata payload
    ) external;

    function callContractWithToken(
        string calldata destinationChain,
        string calldata contractAddress,
        bytes calldata payload,
        string calldata symbol,
        uint256 amount
    ) external;

    function isContractCallApproved(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        address contractAddress,
        bytes32 payloadHash
    ) external view returns (bool);

    function isContractCallAndMintApproved(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        address contractAddress,
        bytes32 payloadHash,
        string calldata symbol,
        uint256 amount
    ) external view returns (bool);

    function validateContractCall(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes32 payloadHash
    ) external returns (bool);

    function validateContractCallAndMint(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes32 payloadHash,
        string calldata symbol,
        uint256 amount
    ) external returns (bool);

    /***********\
    |* Getters *|
    \***********/

    function authModule() external view returns (address);

    function tokenDeployer() external view returns (address);

    function tokenMintLimit(string memory symbol) external view returns (uint256);

    function tokenMintAmount(string memory symbol) external view returns (uint256);

    function allTokensFrozen() external view returns (bool);

    function implementation() external view returns (address);

    function tokenAddresses(string memory symbol) external view returns (address);

    function tokenFrozen(string memory symbol) external view returns (bool);

    function isCommandExecuted(bytes32 commandId) external view returns (bool);

    function adminEpoch() external view returns (uint256);

    function adminThreshold(uint256 epoch) external view returns (uint256);

    function admins(uint256 epoch) external view returns (address[] memory);

    /*******************\
    |* Admin Functions *|
    \*******************/

    function setTokenMintLimits(string[] calldata symbols, uint256[] calldata limits) external;

    function upgrade(
        address newImplementation,
        bytes32 newImplementationCodeHash,
        bytes calldata setupParams
    ) external;

    /**********************\
    |* External Functions *|
    \**********************/

    function setup(bytes calldata params) external;

    function execute(bytes calldata input) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// 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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);
}

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


import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/finance/PaymentSplitter.sol";
import "@openzeppelin/contracts/security/Pausable.sol";

import {AxelarExecutable} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/executables/AxelarExecutable.sol";
import {IAxelarGateway} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/interfaces/IAxelarGateway.sol";
import {IAxelarGasService} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/interfaces/IAxelarGasService.sol";
import {StringToAddress, AddressToString} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/StringAddressUtils.sol";

/**
 * @title Junkyard
 * @author Razmo
 * @notice Deployed on Ethereum, this contract manages the fishing and claim attempts
 * @dev Ethereum and Polygon contracts are communicating through Axelar and the Junkbot
 */
contract Junkyard is Ownable, PaymentSplitter, Pausable, AxelarExecutable {
    using StringToAddress for string;
    using AddressToString for address;

    IAxelarGasService public immutable GAS_RECEIVER;

    string public managerAddress;
    string public managerChain;
    string public storageAddress;
    string public storageChain;
    uint256 internal fishingNonce = 0;

    uint8 private constant CLAIM_ACTION = 1;
    uint8 private constant VALIDATE_ACTION = 2;

    // List fishing quantity and price
    mapping(uint256 => uint256) public prices;

    event NewFishingEntry(address indexed, uint256, bytes32); // who, quantity, uid
    event PricesChange(uint256, uint256); // quantity, new price
    event NewClaim(uint256 indexed, address, uint256); // requestId, sender, tokenUID
    event ContractValueUpdate(string, string); // value name, new value

    constructor(
        address[] memory jkdPayees,
        uint256[] memory jkdShares,
        address _gateway,
        address _gasReceiver
    ) PaymentSplitter(jkdPayees, jkdShares) AxelarExecutable(_gateway) {
        if (_gasReceiver == address(0)) revert InvalidAddress();

        prices[1] = 0.01 ether;
        prices[3] = 0.02 ether;
        prices[7] = 0.04 ether;
        prices[15] = 0.06 ether;
        prices[40] = 0.12 ether;
        prices[60] = 0.15 ether;

        GAS_RECEIVER = IAxelarGasService(_gasReceiver);
    }

    /**
     * @notice Fishing attempt to win a valuable NFT, the player needs to pay an entry fee
     * @dev Emit an event intercepted by the Junkbot and call the Manager from Polygon through Axelar
     * @param _qt Quantity of NFTs selected by the player to be fished in the Junkyard
     */
    function fishing(uint256 _qt) external payable whenNotPaused {
        require(prices[_qt] != 0, "Quantity not available");
        require(msg.value == prices[_qt], "Entry fee is incorrect");

        bytes32 uid = getUID();

        bytes memory actionPayload = abi.encode(uid, msg.sender, _qt);
        bytes memory payload = abi.encode(VALIDATE_ACTION, actionPayload);

        GAS_RECEIVER.payNativeGasForContractCall{value: msg.value}(
            address(this),
            "Polygon",
            managerAddress,
            payload,
            address(this)
        );
        gateway.callContract("Polygon", managerAddress, payload);

        emit NewFishingEntry(msg.sender, _qt, uid);
    }

    /**
     * @notice Claim an NFT won by a player after a fishing attempt
     * @dev Call the Manager through Axelar for on-chain verification
     * @param requestId RequestId of the fishing attempt from which the player wants to claim the NFT
     * @param tokenUID Claimed NFT UID
     */
    function claim(
        uint256 requestId,
        uint256 tokenUID
    ) external payable {
        require(msg.value > 0, "No value sent");

        bytes memory actionPayload = abi.encode(
            requestId,
            tokenUID,
            msg.sender
        );
        bytes memory payload = abi.encode(CLAIM_ACTION, actionPayload);

        // Player pays for Polygon transaction on Axelar
        GAS_RECEIVER.payNativeGasForContractCall{value: msg.value}(
            address(this),
            managerChain,
            managerAddress,
            payload,
            address(this)
        );

        gateway.callContract(managerChain, managerAddress, payload);

        emit NewClaim(requestId, msg.sender, tokenUID);
    }

    /**
     * @notice Batch transfer NFTs from users to the contract
     * @dev Require users to approve the contract to transfer NFTs on their behalf
     * @param tokenAddresses Array of ERC721 token contract addresses
     * @param tokenIds Array of corresponding token IDs
     */
    function batchTransferNFTs(address[] memory tokenAddresses, uint256[] memory tokenIds) external whenNotPaused {
        require(tokenAddresses.length == tokenIds.length, "Input arrays length mismatch");

        for (uint256 i = 0; i < tokenAddresses.length; i++) {
            IERC721(tokenAddresses[i]).transferFrom(msg.sender, storageAddress.toAddress(), tokenIds[i]);
        }
    }

    /**
     * @notice Change the fishing price
     * @param _qt Fishing quantity
     * @param _newPrice New price
     */
    function setPrice(uint256 _qt, uint256 _newPrice) external onlyOwner {
        prices[_qt] = _newPrice;

        emit PricesChange(_qt, _newPrice);
    }

    /**
     * @notice Update the address of the Manager
     * @param newManagerAddr New address
     */
    function setManagerAddress(string memory newManagerAddr)
        external
        onlyOwner
    {
        managerAddress = newManagerAddr;

        emit ContractValueUpdate('managerAddress', newManagerAddr);
    }

    /**
     * @notice Update the name of the chain of the Manager
     * @param newManagerChain New chain
     */
    function setManagerChain(string memory newManagerChain) external onlyOwner {
        managerChain = newManagerChain;

        emit ContractValueUpdate('managerChain', newManagerChain);
    }

    /**
     * @notice Update the address of the Storage
     * @param newStorageAddr New address
     */
    function setStorageAddress(string memory newStorageAddr)
        external
        onlyOwner
    {
        storageAddress = newStorageAddr;

        emit ContractValueUpdate('storageAddress', newStorageAddr);
    }

    /**
     * @notice Update the name of the chain of the Storage
     * @param newStorageChain New chain
     */
    function setStorageChain(string memory newStorageChain) external onlyOwner {
        storageChain = newStorageChain;

        emit ContractValueUpdate('storageChain', newStorageChain);
    }

    /// @notice Pause the contract
    function pause() external onlyOwner {
        _pause();
    }

    /// @notice Unpause the contract
    function unpause() external onlyOwner {
        _unpause();
    }

    /**
     * @notice Generate an UID for each fishing entry
     */
    function getUID() private returns (bytes32) {
        bytes32 uid = (
            keccak256(
                abi.encodePacked(fishingNonce, block.number - 1, msg.sender)
            )
        );
        fishingNonce++;

        return uid;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (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 Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        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);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (finance/PaymentSplitter.sol)

pragma solidity ^0.8.0;

import "../token/ERC20/utils/SafeERC20.sol";
import "../utils/Address.sol";
import "../utils/Context.sol";

/**
 * @title PaymentSplitter
 * @dev This contract allows to split Ether payments among a group of accounts. The sender does not need to be aware
 * that the Ether will be split in this way, since it is handled transparently by the contract.
 *
 * The split can be in equal parts or in any other arbitrary proportion. The way this is specified is by assigning each
 * account to a number of shares. Of all the Ether that this contract receives, each account will then be able to claim
 * an amount proportional to the percentage of total shares they were assigned. The distribution of shares is set at the
 * time of contract deployment and can't be updated thereafter.
 *
 * `PaymentSplitter` follows a _pull payment_ model. This means that payments are not automatically forwarded to the
 * accounts but kept in this contract, and the actual transfer is triggered as a separate step by calling the {release}
 * function.
 *
 * NOTE: This contract assumes that ERC20 tokens will behave similarly to native tokens (Ether). Rebasing tokens, and
 * tokens that apply fees during transfers, are likely to not be supported as expected. If in doubt, we encourage you
 * to run tests before sending real value to this contract.
 */
contract PaymentSplitter is Context {
    event PayeeAdded(address account, uint256 shares);
    event PaymentReleased(address to, uint256 amount);
    event ERC20PaymentReleased(IERC20 indexed token, address to, uint256 amount);
    event PaymentReceived(address from, uint256 amount);

    uint256 private _totalShares;
    uint256 private _totalReleased;

    mapping(address => uint256) private _shares;
    mapping(address => uint256) private _released;
    address[] private _payees;

    mapping(IERC20 => uint256) private _erc20TotalReleased;
    mapping(IERC20 => mapping(address => uint256)) private _erc20Released;

    /**
     * @dev Creates an instance of `PaymentSplitter` where each account in `payees` is assigned the number of shares at
     * the matching position in the `shares` array.
     *
     * All addresses in `payees` must be non-zero. Both arrays must have the same non-zero length, and there must be no
     * duplicates in `payees`.
     */
    constructor(address[] memory payees, uint256[] memory shares_) payable {
        require(payees.length == shares_.length, "PaymentSplitter: payees and shares length mismatch");
        require(payees.length > 0, "PaymentSplitter: no payees");

        for (uint256 i = 0; i < payees.length; i++) {
            _addPayee(payees[i], shares_[i]);
        }
    }

    /**
     * @dev The Ether received will be logged with {PaymentReceived} events. Note that these events are not fully
     * reliable: it's possible for a contract to receive Ether without triggering this function. This only affects the
     * reliability of the events, and not the actual splitting of Ether.
     *
     * To learn more about this see the Solidity documentation for
     * https://solidity.readthedocs.io/en/latest/contracts.html#fallback-function[fallback
     * functions].
     */
    receive() external payable virtual {
        emit PaymentReceived(_msgSender(), msg.value);
    }

    /**
     * @dev Getter for the total shares held by payees.
     */
    function totalShares() public view returns (uint256) {
        return _totalShares;
    }

    /**
     * @dev Getter for the total amount of Ether already released.
     */
    function totalReleased() public view returns (uint256) {
        return _totalReleased;
    }

    /**
     * @dev Getter for the total amount of `token` already released. `token` should be the address of an IERC20
     * contract.
     */
    function totalReleased(IERC20 token) public view returns (uint256) {
        return _erc20TotalReleased[token];
    }

    /**
     * @dev Getter for the amount of shares held by an account.
     */
    function shares(address account) public view returns (uint256) {
        return _shares[account];
    }

    /**
     * @dev Getter for the amount of Ether already released to a payee.
     */
    function released(address account) public view returns (uint256) {
        return _released[account];
    }

    /**
     * @dev Getter for the amount of `token` tokens already released to a payee. `token` should be the address of an
     * IERC20 contract.
     */
    function released(IERC20 token, address account) public view returns (uint256) {
        return _erc20Released[token][account];
    }

    /**
     * @dev Getter for the address of the payee number `index`.
     */
    function payee(uint256 index) public view returns (address) {
        return _payees[index];
    }

    /**
     * @dev Getter for the amount of payee's releasable Ether.
     */
    function releasable(address account) public view returns (uint256) {
        uint256 totalReceived = address(this).balance + totalReleased();
        return _pendingPayment(account, totalReceived, released(account));
    }

    /**
     * @dev Getter for the amount of payee's releasable `token` tokens. `token` should be the address of an
     * IERC20 contract.
     */
    function releasable(IERC20 token, address account) public view returns (uint256) {
        uint256 totalReceived = token.balanceOf(address(this)) + totalReleased(token);
        return _pendingPayment(account, totalReceived, released(token, account));
    }

    /**
     * @dev Triggers a transfer to `account` of the amount of Ether they are owed, according to their percentage of the
     * total shares and their previous withdrawals.
     */
    function release(address payable account) public virtual {
        require(_shares[account] > 0, "PaymentSplitter: account has no shares");

        uint256 payment = releasable(account);

        require(payment != 0, "PaymentSplitter: account is not due payment");

        _released[account] += payment;
        _totalReleased += payment;

        Address.sendValue(account, payment);
        emit PaymentReleased(account, payment);
    }

    /**
     * @dev Triggers a transfer to `account` of the amount of `token` tokens they are owed, according to their
     * percentage of the total shares and their previous withdrawals. `token` must be the address of an IERC20
     * contract.
     */
    function release(IERC20 token, address account) public virtual {
        require(_shares[account] > 0, "PaymentSplitter: account has no shares");

        uint256 payment = releasable(token, account);

        require(payment != 0, "PaymentSplitter: account is not due payment");

        _erc20Released[token][account] += payment;
        _erc20TotalReleased[token] += payment;

        SafeERC20.safeTransfer(token, account, payment);
        emit ERC20PaymentReleased(token, account, payment);
    }

    /**
     * @dev internal logic for computing the pending payment of an `account` given the token historical balances and
     * already released amounts.
     */
    function _pendingPayment(
        address account,
        uint256 totalReceived,
        uint256 alreadyReleased
    ) private view returns (uint256) {
        return (totalReceived * _shares[account]) / _totalShares - alreadyReleased;
    }

    /**
     * @dev Add a new payee to the contract.
     * @param account The address of the payee to add.
     * @param shares_ The number of shares owned by the payee.
     */
    function _addPayee(address account, uint256 shares_) private {
        require(account != address(0), "PaymentSplitter: account is the zero address");
        require(shares_ > 0, "PaymentSplitter: shares are 0");
        require(_shares[account] == 0, "PaymentSplitter: account already has shares");

        _payees.push(account);
        _shares[account] = shares_;
        _totalShares = _totalShares + shares_;
        emit PayeeAdded(account, shares_);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/draft-IERC20Permit.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));
        }
    }

    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

library StringToAddress {
    error InvalidAddressString();

    function toAddress(string memory addressString) internal pure returns (address) {
        bytes memory stringBytes = bytes(addressString);
        uint160 addressNumber = 0;
        uint8 stringByte;

        if (stringBytes.length != 42 || stringBytes[0] != '0' || stringBytes[1] != 'x') revert InvalidAddressString();

        for (uint256 i = 2; i < 42; ++i) {
            stringByte = uint8(stringBytes[i]);

            if ((stringByte >= 97) && (stringByte <= 102)) stringByte -= 87;
            else if ((stringByte >= 65) && (stringByte <= 70)) stringByte -= 55;
            else if ((stringByte >= 48) && (stringByte <= 57)) stringByte -= 48;
            else revert InvalidAddressString();

            addressNumber |= uint160(uint256(stringByte) << ((41 - i) << 2));
        }
        return address(addressNumber);
    }
}

library AddressToString {
    function toString(address addr) internal pure returns (string memory) {
        bytes memory addressBytes = abi.encodePacked(addr);
        uint256 length = addressBytes.length;
        bytes memory characters = '0123456789abcdef';
        bytes memory stringBytes = new bytes(2 + addressBytes.length * 2);

        stringBytes[0] = '0';
        stringBytes[1] = 'x';

        for (uint256 i; i < length; ++i) {
            stringBytes[2 + i * 2] = characters[uint8(addressBytes[i] >> 4)];
            stringBytes[3 + i * 2] = characters[uint8(addressBytes[i] & 0x0f)];
        }
        return string(stringBytes);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

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