contract ISignatureValidator {

   // Allowed signature types.
    enum SignatureType {
        Illegal,                     // 0x00, default value
        Invalid,                     // 0x01
        EIP712,                      // 0x02
        EthSign,                     // 0x03
        Wallet,                      // 0x04
        Validator,                   // 0x05
        PreSigned,                   // 0x06
        EIP1271Wallet,               // 0x07
        NSignatureTypes              // 0x08, number of signature types. Always leave at end.
    }

    event SignatureValidatorApproval(
        address indexed signerAddress,     // Address that approves or disapproves a contract to verify signatures.
        address indexed validatorAddress,  // Address of signature validator contract.
        bool isApproved                    // Approval or disapproval of validator contract.
    );

    /// @dev Approves a hash on-chain.
    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
    /// @param hash Any 32-byte hash.
    function preSign(bytes32 hash)
        external
        payable;

    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
    /// @param validatorAddress Address of Validator contract.
    /// @param approval Approval or disapproval of  Validator contract.
    function setSignatureValidatorApproval(
        address validatorAddress,
        bool approval
    )
        external
        payable;

    /// @dev Verifies that a hash has been signed by the given signer.
    /// @param hash Any 32-byte hash.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return isValid `true` if the signature is valid for the given hash and signer.
    function isValidHashSignature(
        bytes32 hash,
        address signerAddress,
        bytes memory signature
    )
        public
        view
        returns (bool isValid);

    /// @dev Verifies that a signature for an order is valid.
    /// @param order The order.
    /// @param signature Proof that the order has been signed by signer.
    /// @return isValid true if the signature is valid for the given order and signer.
    function isValidOrderSignature(
        LibOrder.Order memory order,
        bytes memory signature
    )
        public
        view
        returns (bool isValid);

    /// @dev Verifies that a signature for a transaction is valid.
    /// @param transaction The transaction.
    /// @param signature Proof that the order has been signed by signer.
    /// @return isValid true if the signature is valid for the given transaction and signer.
    function isValidTransactionSignature(
        LibZeroExTransaction.ZeroExTransaction memory transaction,
        bytes memory signature
    )
        public
        view
        returns (bool isValid);

    /// @dev Verifies that an order, with provided order hash, has been signed
    ///      by the given signer.
    /// @param order The order.
    /// @param orderHash The hash of the order.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return isValid True if the signature is valid for the given order and signer.
    function _isValidOrderWithHashSignature(
        LibOrder.Order memory order,
        bytes32 orderHash,
        bytes memory signature
    )
        internal
        view
        returns (bool isValid);

    /// @dev Verifies that a transaction, with provided order hash, has been signed
    ///      by the given signer.
    /// @param transaction The transaction.
    /// @param transactionHash The hash of the transaction.
    /// @param signature Proof that the hash has been signed by signer.
    /// @return isValid True if the signature is valid for the given transaction and signer.
    function _isValidTransactionWithHashSignature(
        LibZeroExTransaction.ZeroExTransaction memory transaction,
        bytes32 transactionHash,
        bytes memory signature
    )
        internal
        view
        returns (bool isValid);
}
function preSign(bytes32 hash)
    external
    payable;

/// @dev Approves a hash on-chain.
///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
/// @param hash Any 32-byte hash.