contract SignedOperationProxy is
    OnlySolo,
    Ownable
{
    using SafeMath for uint256;

    // ============ Constants ============

    bytes32 constant private FILE = "SignedOperationProxy";

    // EIP191 header for EIP712 prefix
    bytes2 constant private EIP191_HEADER = 0x1901;

    // EIP712 Domain Name value
    string constant private EIP712_DOMAIN_NAME = "SignedOperationProxy";

    // EIP712 Domain Version value
    string constant private EIP712_DOMAIN_VERSION = "1.1";

    // EIP712 encodeType of EIP712Domain
    bytes constant private EIP712_DOMAIN_STRING = abi.encodePacked(
        "EIP712Domain(",
        "string name,",
        "string version,",
        "uint256 chainId,",
        "address verifyingContract",
        ")"
    );

    // EIP712 encodeType of Operation
    bytes constant private EIP712_OPERATION_STRING = abi.encodePacked(
        "Operation(",
        "Action[] actions,",
        "uint256 expiration,",
        "uint256 salt,",
        "address sender,",
        "address signer",
        ")"
    );

    // EIP712 encodeType of Action
    bytes constant private EIP712_ACTION_STRING = abi.encodePacked(
        "Action(",
        "uint8 actionType,",
        "address accountOwner,",
        "uint256 accountNumber,",
        "AssetAmount assetAmount,",
        "uint256 primaryMarketId,",
        "uint256 secondaryMarketId,",
        "address otherAddress,",
        "address otherAccountOwner,",
        "uint256 otherAccountNumber,",
        "bytes data",
        ")"
    );

    // EIP712 encodeType of AssetAmount
    bytes constant private EIP712_ASSET_AMOUNT_STRING = abi.encodePacked(
        "AssetAmount(",
        "bool sign,",
        "uint8 denomination,",
        "uint8 ref,",
        "uint256 value",
        ")"
    );

    // EIP712 typeHash of EIP712Domain
    /* solium-disable-next-line indentation */
    bytes32 constant private EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
        EIP712_DOMAIN_STRING
    ));

    // EIP712 typeHash of Operation
    /* solium-disable-next-line indentation */
    bytes32 constant private EIP712_OPERATION_HASH = keccak256(abi.encodePacked(
        EIP712_OPERATION_STRING,
        EIP712_ACTION_STRING,
        EIP712_ASSET_AMOUNT_STRING
    ));

    // EIP712 typeHash of Action
    /* solium-disable-next-line indentation */
    bytes32 constant private EIP712_ACTION_HASH = keccak256(abi.encodePacked(
        EIP712_ACTION_STRING,
        EIP712_ASSET_AMOUNT_STRING
    ));

    // EIP712 typeHash of AssetAmount
    /* solium-disable-next-line indentation */
    bytes32 constant private EIP712_ASSET_AMOUNT_HASH = keccak256(abi.encodePacked(
        EIP712_ASSET_AMOUNT_STRING
    ));

    // ============ Structs ============

    struct OperationHeader {
        uint256 expiration;
        uint256 salt;
        address sender;
        address signer;
    }

    struct Authorization {
        uint256 numActions;
        OperationHeader header;
        bytes signature;
    }

    // ============ Events ============

    event ContractStatusSet(
        bool operational
    );

    event LogOperationExecuted(
        bytes32 indexed operationHash,
        address indexed signer,
        address indexed sender
    );

    event LogOperationCanceled(
        bytes32 indexed operationHash,
        address indexed canceler
    );

    // ============ Immutable Storage ============

    // Hash of the EIP712 Domain Separator data
    bytes32 public EIP712_DOMAIN_HASH;

    // ============ Mutable Storage ============

     // true if this contract can process operationss
    bool public g_isOperational;

    // operation hash => was executed (or canceled)
    mapping (bytes32 => bool) public g_invalidated;

    // ============ Constructor ============

    constructor (
        address soloMargin,
        uint256 chainId
    )
        public
        OnlySolo(soloMargin)
    {
        g_isOperational = true;

        /* solium-disable-next-line indentation */
        EIP712_DOMAIN_HASH = keccak256(abi.encode(
            EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH,
            keccak256(bytes(EIP712_DOMAIN_NAME)),
            keccak256(bytes(EIP712_DOMAIN_VERSION)),
            chainId,
            address(this)
        ));
    }

    // ============ Admin Functions ============

     /**
     * The owner can shut down the exchange.
     */
    function shutDown()
        external
        onlyOwner
    {
        g_isOperational = false;
        emit ContractStatusSet(false);
    }

     /**
     * The owner can start back up the exchange.
     */
    function startUp()
        external
        onlyOwner
    {
        g_isOperational = true;
        emit ContractStatusSet(true);
    }

    // ============ Public Functions ============

    /**
     * Allows a signer to permanently cancel an operation on-chain.
     *
     * @param  accounts  The accounts involved in the operation
     * @param  actions   The actions involved in the operation
     * @param  auth      The unsigned authorization of the operation
     */
    function cancel(
        Account.Info[] memory accounts,
        Actions.ActionArgs[] memory actions,
        Authorization memory auth
    )
        public
    {
        bytes32 operationHash = getOperationHash(
            accounts,
            actions,
            auth,
            0
        );
        Require.that(
            auth.header.signer == msg.sender,
            FILE,
            "Canceler must be signer"
        );
        g_invalidated[operationHash] = true;
        emit LogOperationCanceled(operationHash, msg.sender);
    }

    /**
     * Submits an operation to SoloMargin. Actions for accounts that the msg.sender does not control
     * must be authorized by a signed message. Each authorization can apply to multiple actions at
     * once which must occur in-order next to each other. An empty authorization must be supplied
     * explicitly for each group of actions that do not require a signed message.
     *
     * @param  accounts  The accounts to forward to SoloMargin.operate()
     * @param  actions   The actions to forward to SoloMargin.operate()
     * @param  auths     The signed authorizations for each group of actions
     *                   (or unsigned if msg.sender is already authorized)
     */
    function operate(
        Account.Info[] memory accounts,
        Actions.ActionArgs[] memory actions,
        Authorization[] memory auths
    )
        public
    {
        Require.that(
            g_isOperational,
            FILE,
            "Contract is not operational"
        );

        // cache the index of the first action for this auth
        uint256 actionStartIdx = 0;

        // loop over all auths
        for (uint256 authIdx = 0; authIdx < auths.length; authIdx++) {
            Authorization memory auth = auths[authIdx];

            // require that the message is not expired
            Require.that(
                auth.header.expiration == 0 || auth.header.expiration >= block.timestamp,
                FILE,
                "Signed operation is expired",
                authIdx
            );

            // require that the sender matches the authorization
            Require.that(
                auth.header.sender == address(0) || auth.header.sender == msg.sender,
                FILE,
                "Operation sender mismatch",
                authIdx
            );

            // consider the signer to be msg.sender unless there is a signature
            address signer = msg.sender;

            // if there is a signature, then validate it
            if (auth.signature.length != 0) {
                // get the hash of the operation
                bytes32 operationHash = getOperationHash(
                    accounts,
                    actions,
                    auth,
                    actionStartIdx
                );

                // require that this message is still valid
                Require.that(
                    !g_invalidated[operationHash],
                    FILE,
                    "Hash already used or canceled",
                    operationHash
                );

                // get the signer
                signer = TypedSignature.recover(operationHash, auth.signature);

                // require that this signer matches the authorization
                Require.that(
                    auth.header.signer == signer,
                    FILE,
                    "Invalid signature"
                );

                // consider this operationHash to be used (and therefore no longer valid)
                g_invalidated[operationHash] = true;
                emit LogOperationExecuted(operationHash, signer, msg.sender);
            }

            // cache the index of the first action after this auth
            uint256 actionEndIdx = actionStartIdx.add(auth.numActions);

            // loop over all actions for which this auth applies
            for (uint256 actionIdx = actionStartIdx; actionIdx < actionEndIdx; actionIdx++) {
                // validate primary account
                Actions.ActionArgs memory action = actions[actionIdx];
                validateAccountOwner(accounts[action.accountId].owner, signer);

                // validate second account in the case of a transfer
                if (action.actionType == Actions.ActionType.Transfer) {
                    validateAccountOwner(accounts[action.otherAccountId].owner, signer);
                }
            }

            // update actionStartIdx
            actionStartIdx = actionEndIdx;
        }

        // require that all actions are signed or from msg.sender
        Require.that(
            actionStartIdx == actions.length,
            FILE,
            "Not all actions are signed"
        );

        // send the operation
        SOLO_MARGIN.operate(accounts, actions);
    }

    // ============ Getters ============

    /**
     * Returns a bool for each operation. True if the operation is invalid (from being canceled or
     * previously executed).
     */
    function getOperationsAreInvalid(
        bytes32[] memory operationHashes
    )
        public
        view
        returns(bool[] memory)
    {
        uint256 numOperations = operationHashes.length;
        bool[] memory output = new bool[](numOperations);

        for (uint256 i = 0; i < numOperations; i++) {
            output[i] = g_invalidated[operationHashes[i]];
        }
        return output;
    }

    // ============ Private Helper Functions ============

    /**
     * Validates that either the signer or the msg.sender are the accountOwner (or that either are
     * localOperators of the accountOwner).
     */
    function validateAccountOwner(
        address accountOwner,
        address signer
    )
        private
        view
    {
        bool valid =
            msg.sender == accountOwner
            || signer == accountOwner
            || SOLO_MARGIN.getIsLocalOperator(accountOwner, msg.sender)
            || SOLO_MARGIN.getIsLocalOperator(accountOwner, signer);

        Require.that(
            valid,
            FILE,
            "Signer not authorized",
            signer
        );
    }

    /**
     * Returns the EIP712 hash of an Operation message.
     */
    function getOperationHash(
        Account.Info[] memory accounts,
        Actions.ActionArgs[] memory actions,
        Authorization memory auth,
        uint256 startIdx
    )
        private
        view
        returns (bytes32)
    {
        // get the bytes32 hash of each action, then packed together
        bytes32 actionsEncoding = getActionsEncoding(
            accounts,
            actions,
            auth,
            startIdx
        );

        // compute the EIP712 hashStruct of an Operation struct
        /* solium-disable-next-line indentation */
        bytes32 structHash = keccak256(abi.encode(
            EIP712_OPERATION_HASH,
            actionsEncoding,
            auth.header
        ));

        // compute eip712 compliant hash
        /* solium-disable-next-line indentation */
        return keccak256(abi.encodePacked(
            EIP191_HEADER,
            EIP712_DOMAIN_HASH,
            structHash
        ));
    }

    /**
     * Returns the EIP712 encodeData of an Action struct array.
     */
    function getActionsEncoding(
        Account.Info[] memory accounts,
        Actions.ActionArgs[] memory actions,
        Authorization memory auth,
        uint256 startIdx
    )
        private
        pure
        returns (bytes32)
    {
        // store hash of each action
        bytes32[] memory actionsBytes = new bytes32[](auth.numActions);

        // for each action that corresponds to the auth
        for (uint256 i = 0; i < auth.numActions; i++) {
            Actions.ActionArgs memory action = actions[startIdx + i];

            // if action type has no second account, assume null account
            Account.Info memory otherAccount =
                (Actions.getAccountLayout(action.actionType) == Actions.AccountLayout.OnePrimary)
                ? Account.Info({ owner: address(0), number: 0 })
                : accounts[action.otherAccountId];

            // compute the individual hash for the action
            /* solium-disable-next-line indentation */
            actionsBytes[i] = getActionHash(
                action,
                accounts[action.accountId],
                otherAccount
            );
        }

        return keccak256(abi.encodePacked(actionsBytes));
    }

    /**
     * Returns the EIP712 hashStruct of an Action struct.
     */
    function getActionHash(
        Actions.ActionArgs memory action,
        Account.Info memory primaryAccount,
        Account.Info memory secondaryAccount
    )
        private
        pure
        returns (bytes32)
    {
        /* solium-disable-next-line indentation */
        return keccak256(abi.encode(
            EIP712_ACTION_HASH,
            action.actionType,
            primaryAccount.owner,
            primaryAccount.number,
            getAssetAmountHash(action.amount),
            action.primaryMarketId,
            action.secondaryMarketId,
            action.otherAddress,
            secondaryAccount.owner,
            secondaryAccount.number,
            keccak256(action.data)
        ));
    }

    /**
     * Returns the EIP712 hashStruct of an AssetAmount struct.
     */
    function getAssetAmountHash(
        Types.AssetAmount memory amount
    )
        private
        pure
        returns (bytes32)
    {
        /* solium-disable-next-line indentation */
        return keccak256(abi.encode(
            EIP712_ASSET_AMOUNT_HASH,
            amount.sign,
            amount.denomination,
            amount.ref,
            amount.value
        ));
    }
}
/**
 * @title SignedOperationProxy
 * @author dYdX
 *
 * Contract for sending operations on behalf of others
 */
function startUp()
        external
        onlyOwner
    {
        g_isOperational = true;
        emit ContractStatusSet(true);
    }
/**
 * The owner can start back up the exchange.
 */