/**
 * @notice Execute a transfer with a signed authorization
 * @param from          Payer's address (Authorizer)
 * @param to            Payee's address
 * @param value         Amount to be transferred
 * @param validAfter    The time after which this is valid (unix time)
 * @param validBefore   The time before which this is valid (unix time)
 * @param nonce         Unique nonce
 * @param signature     Unstructured bytes signature signed by an EOA wallet or a contract wallet
 */
function transferWithAuthorization(
    address from,
    address to,
    uint256 value,
    uint256 validAfter,
    uint256 validBefore,
    bytes32 nonce,
    bytes memory signature
) external;

/**
 * @notice Receive a transfer with a signed authorization from the payer
 * @dev This has an additional check to ensure that the payee's address matches
 * the caller of this function to prevent front-running attacks. (See security
 * considerations)
 * @param from          Payer's address (Authorizer)
 * @param to            Payee's address
 * @param value         Amount to be transferred
 * @param validAfter    The time after which this is valid (unix time)
 * @param validBefore   The time before which this is valid (unix time)
 * @param nonce         Unique nonce
 * @param signature     Unstructured bytes signature signed by an EOA wallet or a contract wallet
 */
function receiveWithAuthorization(
    address from,
    address to,
    uint256 value,
    uint256 validAfter,
    uint256 validBefore,
    bytes32 nonce,
    bytes memory signature
) external;

/**
 * @notice Attempt to cancel an authorization
 * @param authorizer    Authorizer's address
 * @param nonce         Nonce of the authorization
 * @param signature     Unstructured bytes signature signed by an EOA wallet or a contract wallet
 */
function cancelAuthorization(
    address authorizer,
    bytes32 nonce,
    bytes memory signature
) external;

function transferWithAuthorization(
    address from,
    address to,
    uint256 value,
    uint256 validAfter,
    uint256 validBefore,
    bytes32 nonce,
    uint8 v,
    bytes32 r,
    bytes32 s
) external {
    transferWithAuthorization(owner, spender, value, deadline, abi.encodePacked(r, s, v));
}

/**
  * @notice Execute a transfer with a signed authorization
  * @dev EOA wallet signatures should be packed in the order of r, s, v.
  * @param from          Payer's address (Authorizer)
  * @param to            Payee's address
  * @param value         Amount to be transferred
  * @param validAfter    The time after which this is valid (unix time)
  * @param validBefore   The time before which this is valid (unix time)
  * @param nonce         Unique nonce
  * @param signature     Signature byte array produced by an EOA wallet or a contract wallet
  */
function _transferWithAuthorization(
    address from,
    address to,
    uint256 value,
    uint256 validAfter,
    uint256 validBefore,
    bytes32 nonce,
    bytes memory signature
) internal {
    require(now > validAfter, "Authorization is not yet valid"); // 授权尚未生效
    require(now < validBefore, "Authorization is expired"); // 授权已过期
    require(!_authorizationStates[authorizer][nonce], "Authorization is used or canceled"); // 授权已使用或已取消

    bytes32 digest = keccak256(abi.encodePacked(
        hex"1901",
        DOMAIN_SEPARATOR,
        keccak256(abi.encode(
            TRANSFER_WITH_AUTHORIZATION_TYPEHASH,
            from,
            to,
            value,
            validAfter,
            validBefore,
            nonce
        ))
    ));
    require(
        // Check for both ECDSA signature and and ERC-1271 signature. A sample SignatureChecker is available at
        // https://github.com/OpenZeppelin/openzeppelin-contracts/blob/7bd2b2a/contracts/utils/cryptography/SignatureChecker.sol
        // 同时检查 ECDSA 签名和 ERC-1271 签名。SignatureChecker 示例可在以下网址获取
        // https://github.com/OpenZeppelin/openzeppelin-contracts/blob/7bd2b2a/contracts/utils/cryptography/SignatureChecker.sol
        SignatureChecker.isValidSignatureNow(
            owner,
            typedDataHash,
            signature
        ),
        "Invalid signature" // 无效签名
    );

    _authorizationStates[authorizer][nonce] = true;
    emit AuthorizationUsed(authorizer, nonce);
    
    _transfer(from, to, value);
}