pragma solidity ^0.5.4;

/**
 * ERC20 contract interface.
 */
contract ERC20 {
    function totalSupply() public view returns (uint);
    function decimals() public view returns (uint);
    function balanceOf(address tokenOwner) public view returns (uint balance);
    function allowance(address tokenOwner, address spender) public view returns (uint remaining);
    function transfer(address to, uint tokens) public returns (bool success);
    function approve(address spender, uint tokens) public returns (bool success);
    function transferFrom(address from, address to, uint tokens) public returns (bool success);
}

/**
 * @title Module
 * @dev Interface for a module. 
 * A module MUST implement the addModule() method to ensure that a wallet with at least one module
 * can never end up in a "frozen" state.
 * @author Julien Niset - <julien@argent.xyz>
 */
interface Module {
    function init(BaseWallet _wallet) external;
    function addModule(BaseWallet _wallet, Module _module) external;
    function recoverToken(address _token) external;
}

/**
 * @title BaseWallet
 * @dev Simple modular wallet that authorises modules to call its invoke() method.
 * Based on https://gist.github.com/Arachnid/a619d31f6d32757a4328a428286da186 by 
 * @author Julien Niset - <julien@argent.xyz>
 */
contract BaseWallet {
    address public implementation;
    address public owner;
    mapping (address => bool) public authorised;
    mapping (bytes4 => address) public enabled;
    uint public modules;
    function init(address _owner, address[] calldata _modules) external;
    function authoriseModule(address _module, bool _value) external;
    function enableStaticCall(address _module, bytes4 _method) external;
    function setOwner(address _newOwner) external;
    function invoke(address _target, uint _value, bytes calldata _data) external returns (bytes memory _result);
}

/**
 * @title ModuleRegistry
 * @dev Registry of authorised modules. 
 * Modules must be registered before they can be authorised on a wallet.
 * @author Julien Niset - <julien@argent.xyz>
 */
contract ModuleRegistry {
    function registerModule(address _module, bytes32 _name) external;
    function deregisterModule(address _module) external;
    function registerUpgrader(address _upgrader, bytes32 _name) external;
    function deregisterUpgrader(address _upgrader) external;
    function recoverToken(address _token) external;
    function moduleInfo(address _module) external view returns (bytes32);
    function upgraderInfo(address _upgrader) external view returns (bytes32);
    function isRegisteredModule(address _module) external view returns (bool);
    function isRegisteredModule(address[] calldata _modules) external view returns (bool);
    function isRegisteredUpgrader(address _upgrader) external view returns (bool);
}

contract TokenPriceProvider {
    mapping(address => uint256) public cachedPrices;
    function setPrice(ERC20 _token, uint256 _price) public;
    function setPriceForTokenList(ERC20[] calldata _tokens, uint256[] calldata _prices) external;
    function getEtherValue(uint256 _amount, address _token) external view returns (uint256);
}

/**
 * @title GuardianStorage
 * @dev Contract storing the state of wallets related to guardians and lock.
 * The contract only defines basic setters and getters with no logic. Only modules authorised
 * for a wallet can modify its state.
 * @author Julien Niset - <julien@argent.xyz>
 * @author Olivier Van Den Biggelaar - <olivier@argent.xyz>
 */
contract GuardianStorage {
    function addGuardian(BaseWallet _wallet, address _guardian) external;
    function revokeGuardian(BaseWallet _wallet, address _guardian) external;
    function guardianCount(BaseWallet _wallet) external view returns (uint256);
    function getGuardians(BaseWallet _wallet) external view returns (address[] memory);
    function isGuardian(BaseWallet _wallet, address _guardian) external view returns (bool);
    function setLock(BaseWallet _wallet, uint256 _releaseAfter) external;
    function isLocked(BaseWallet _wallet) external view returns (bool);
    function getLock(BaseWallet _wallet) external view returns (uint256);
    function getLocker(BaseWallet _wallet) external view returns (address);
}

/**
 * @title TransferStorage
 * @dev Contract storing the state of wallets related to transfers (limit and whitelist).
 * The contract only defines basic setters and getters with no logic. Only modules authorised
 * for a wallet can modify its state.
 * @author Julien Niset - <julien@argent.xyz>
 */
contract TransferStorage {
    function setWhitelist(BaseWallet _wallet, address _target, uint256 _value) external;
    function getWhitelist(BaseWallet _wallet, address _target) external view returns (uint256);
}

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

    /**
    * @dev Multiplies two numbers, reverts on overflow.
    */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
    * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0); // Solidity only automatically asserts when dividing by 0
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
    * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
    * @dev Adds two numbers, reverts on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
    * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }

    /**
    * @dev Returns ceil(a / b).
    */
    function ceil(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a / b;
        if(a % b == 0) {
            return c;
        }
        else {
            return c + 1;
        }
    }
}

library GuardianUtils {

    /**
    * @dev Checks if an address is an account guardian or an account authorised to sign on behalf of a smart-contract guardian
    * given a list of guardians.
    * @param _guardians the list of guardians
    * @param _guardian the address to test
    * @return true and the list of guardians minus the found guardian upon success, false and the original list of guardians if not found.
    */
    function isGuardian(address[] memory _guardians, address _guardian) internal view returns (bool, address[] memory) {
        if(_guardians.length == 0 || _guardian == address(0)) {
            return (false, _guardians);
        }
        bool isFound = false;
        address[] memory updatedGuardians = new address[](_guardians.length - 1);
        uint256 index = 0;
        for (uint256 i = 0; i < _guardians.length; i++) {
            if(!isFound) {
                // check if _guardian is an account guardian
                if(_guardian == _guardians[i]) {
                    isFound = true;
                    continue;
                }
                // check if _guardian is the owner of a smart contract guardian
                if(isContract(_guardians[i]) && isGuardianOwner(_guardians[i], _guardian)) {
                    isFound = true;
                    continue;
                }
            }
            if(index < updatedGuardians.length) {
                updatedGuardians[index] = _guardians[i];
                index++;
            }
        }
        return isFound ? (true, updatedGuardians) : (false, _guardians);
    }

   /**
    * @dev Checks if an address is a contract.
    * @param _addr The address.
    */
    function isContract(address _addr) internal view returns (bool) {
        uint32 size;
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            size := extcodesize(_addr)
        }
        return (size > 0);
    }

    /**
    * @dev Checks if an address is the owner of a guardian contract. 
    * The method does not revert if the call to the owner() method consumes more then 5000 gas. 
    * @param _guardian The guardian contract
    * @param _owner The owner to verify.
    */
    function isGuardianOwner(address _guardian, address _owner) internal view returns (bool) {
        address owner = address(0);
        bytes4 sig = bytes4(keccak256("owner()"));
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            let ptr := mload(0x40)
            mstore(ptr,sig)
            let result := staticcall(5000, _guardian, ptr, 0x20, ptr, 0x20)
            if eq(result, 1) {
                owner := mload(ptr)
            }
        }
        return owner == _owner;
    }
} 

/**
 * @title BaseModule
 * @dev Basic module that contains some methods common to all modules.
 * @author Julien Niset - <julien@argent.im>
 */
contract BaseModule is Module {

    // Empty calldata
    bytes constant internal EMPTY_BYTES = "";

    // The adddress of the module registry.
    ModuleRegistry internal registry;
    // The address of the Guardian storage
    GuardianStorage internal guardianStorage;

    /**
     * @dev Throws if the wallet is locked.
     */
    modifier onlyWhenUnlocked(BaseWallet _wallet) {
        // solium-disable-next-line security/no-block-members
        require(!guardianStorage.isLocked(_wallet), "BM: wallet must be unlocked");
        _;
    }

    event ModuleCreated(bytes32 name);
    event ModuleInitialised(address wallet);

    constructor(ModuleRegistry _registry, GuardianStorage _guardianStorage, bytes32 _name) public {
        registry = _registry;
        guardianStorage = _guardianStorage;
        emit ModuleCreated(_name);
    }

    /**
     * @dev Throws if the sender is not the target wallet of the call.
     */
    modifier onlyWallet(BaseWallet _wallet) {
        require(msg.sender == address(_wallet), "BM: caller must be wallet");
        _;
    }

    /**
     * @dev Throws if the sender is not the owner of the target wallet or the module itself.
     */
    modifier onlyWalletOwner(BaseWallet _wallet) {
        require(msg.sender == address(this) || isOwner(_wallet, msg.sender), "BM: must be an owner for the wallet");
        _;
    }

    /**
     * @dev Throws if the sender is not the owner of the target wallet.
     */
    modifier strictOnlyWalletOwner(BaseWallet _wallet) {
        require(isOwner(_wallet, msg.sender), "BM: msg.sender must be an owner for the wallet");
        _;
    }

    /**
     * @dev Inits the module for a wallet by logging an event.
     * The method can only be called by the wallet itself.
     * @param _wallet The wallet.
     */
    function init(BaseWallet _wallet) public onlyWallet(_wallet) {
        emit ModuleInitialised(address(_wallet));
    }

    /**
     * @dev Adds a module to a wallet. First checks that the module is registered.
     * @param _wallet The target wallet.
     * @param _module The modules to authorise.
     */
    function addModule(BaseWallet _wallet, Module _module) external strictOnlyWalletOwner(_wallet) {
        require(registry.isRegisteredModule(address(_module)), "BM: module is not registered");
        _wallet.authoriseModule(address(_module), true);
    }

    /**
    * @dev Utility method enbaling anyone to recover ERC20 token sent to the
    * module by mistake and transfer them to the Module Registry. 
    * @param _token The token to recover.
    */
    function recoverToken(address _token) external {
        uint total = ERC20(_token).balanceOf(address(this));
        ERC20(_token).transfer(address(registry), total);
    }

    /**
     * @dev Helper method to check if an address is the owner of a target wallet.
     * @param _wallet The target wallet.
     * @param _addr The address.
     */
    function isOwner(BaseWallet _wallet, address _addr) internal view returns (bool) {
        return _wallet.owner() == _addr;
    }

    /**
     * @dev Helper method to invoke a wallet.
     * @param _wallet The target wallet.
     * @param _to The target address for the transaction.
     * @param _value The value of the transaction.
     * @param _data The data of the transaction.
     */
    function invokeWallet(address _wallet, address _to, uint256 _value, bytes memory _data) internal returns (bytes memory _res) {
        bool success;
        // solium-disable-next-line security/no-call-value
        (success, _res) = _wallet.call(abi.encodeWithSignature("invoke(address,uint256,bytes)", _to, _value, _data));
        if(success && _res.length > 0) { //_res is empty if _wallet is an "old" BaseWallet that can't return output values
            (_res) = abi.decode(_res, (bytes));
        } else if (_res.length > 0) {
            // solium-disable-next-line security/no-inline-assembly
            assembly {
                returndatacopy(0, 0, returndatasize)
                revert(0, returndatasize)
            }
        } else if(!success) {
            revert("BM: wallet invoke reverted");
        }
    }
}

/**
 * @title RelayerModule
 * @dev Base module containing logic to execute transactions signed by eth-less accounts and sent by a relayer.
 * @author Julien Niset - <julien@argent.im>
 */
contract RelayerModule is BaseModule {

    uint256 constant internal BLOCKBOUND = 10000;

    mapping (address => RelayerConfig) public relayer;

    struct RelayerConfig {
        uint256 nonce;
        mapping (bytes32 => bool) executedTx;
    }

    event TransactionExecuted(address indexed wallet, bool indexed success, bytes32 signedHash);

    /**
     * @dev Throws if the call did not go through the execute() method.
     */
    modifier onlyExecute {
        require(msg.sender == address(this), "RM: must be called via execute()");
        _;
    }

    /* ***************** Abstract method ************************* */

    /**
    * @dev Gets the number of valid signatures that must be provided to execute a
    * specific relayed transaction.
    * @param _wallet The target wallet.
    * @param _data The data of the relayed transaction.
    * @return The number of required signatures.
    */
    function getRequiredSignatures(BaseWallet _wallet, bytes memory _data) internal view returns (uint256);

    /**
    * @dev Validates the signatures provided with a relayed transaction.
    * The method MUST throw if one or more signatures are not valid.
    * @param _wallet The target wallet.
    * @param _data The data of the relayed transaction.
    * @param _signHash The signed hash representing the relayed transaction.
    * @param _signatures The signatures as a concatenated byte array.
    */
    function validateSignatures(BaseWallet _wallet, bytes memory _data, bytes32 _signHash, bytes memory _signatures) internal view returns (bool);

    /* ************************************************************ */

    /**
    * @dev Executes a relayed transaction.
    * @param _wallet The target wallet.
    * @param _data The data for the relayed transaction
    * @param _nonce The nonce used to prevent replay attacks.
    * @param _signatures The signatures as a concatenated byte array.
    * @param _gasPrice The gas price to use for the gas refund.
    * @param _gasLimit The gas limit to use for the gas refund.
    */
    function execute(
        BaseWallet _wallet,
        bytes calldata _data,
        uint256 _nonce,
        bytes calldata _signatures,
        uint256 _gasPrice,
        uint256 _gasLimit
    )
        external
        returns (bool success)
    {
        uint startGas = gasleft();
        bytes32 signHash = getSignHash(address(this), address(_wallet), 0, _data, _nonce, _gasPrice, _gasLimit);
        require(checkAndUpdateUniqueness(_wallet, _nonce, signHash), "RM: Duplicate request");
        require(verifyData(address(_wallet), _data), "RM: the wallet authorized is different then the target of the relayed data");
        uint256 requiredSignatures = getRequiredSignatures(_wallet, _data);
        if((requiredSignatures * 65) == _signatures.length) {
            if(verifyRefund(_wallet, _gasLimit, _gasPrice, requiredSignatures)) {
                if(requiredSignatures == 0 || validateSignatures(_wallet, _data, signHash, _signatures)) {
                    // solium-disable-next-line security/no-call-value
                    (success,) = address(this).call(_data);
                    refund(_wallet, startGas - gasleft(), _gasPrice, _gasLimit, requiredSignatures, msg.sender);
                }
            }
        }
        emit TransactionExecuted(address(_wallet), success, signHash);
    }

    /**
    * @dev Gets the current nonce for a wallet.
    * @param _wallet The target wallet.
    */
    function getNonce(BaseWallet _wallet) external view returns (uint256 nonce) {
        return relayer[address(_wallet)].nonce;
    }

    /**
    * @dev Generates the signed hash of a relayed transaction according to ERC 1077.
    * @param _from The starting address for the relayed transaction (should be the module)
    * @param _to The destination address for the relayed transaction (should be the wallet)
    * @param _value The value for the relayed transaction
    * @param _data The data for the relayed transaction
    * @param _nonce The nonce used to prevent replay attacks.
    * @param _gasPrice The gas price to use for the gas refund.
    * @param _gasLimit The gas limit to use for the gas refund.
    */
    function getSignHash(
        address _from,
        address _to,
        uint256 _value,
        bytes memory _data,
        uint256 _nonce,
        uint256 _gasPrice,
        uint256 _gasLimit
    )
        internal
        pure
        returns (bytes32)
    {
        return keccak256(
            abi.encodePacked(
                "\x19Ethereum Signed Message:\n32",
                keccak256(abi.encodePacked(byte(0x19), byte(0), _from, _to, _value, _data, _nonce, _gasPrice, _gasLimit))
        ));
    }

    /**
    * @dev Checks if the relayed transaction is unique.
    * @param _wallet The target wallet.
    * @param _nonce The nonce
    * @param _signHash The signed hash of the transaction
    */
    function checkAndUpdateUniqueness(BaseWallet _wallet, uint256 _nonce, bytes32 _signHash) internal returns (bool) {
        if(relayer[address(_wallet)].executedTx[_signHash] == true) {
            return false;
        }
        relayer[address(_wallet)].executedTx[_signHash] = true;
        return true;
    }

    /**
    * @dev Checks that a nonce has the correct format and is valid.
    * It must be constructed as nonce = {block number}{timestamp} where each component is 16 bytes.
    * @param _wallet The target wallet.
    * @param _nonce The nonce
    */
    function checkAndUpdateNonce(BaseWallet _wallet, uint256 _nonce) internal returns (bool) {
        if(_nonce <= relayer[address(_wallet)].nonce) {
            return false;
        }
        uint256 nonceBlock = (_nonce & 0xffffffffffffffffffffffffffffffff00000000000000000000000000000000) >> 128;
        if(nonceBlock > block.number + BLOCKBOUND) {
            return false;
        }
        relayer[address(_wallet)].nonce = _nonce;
        return true;
    }

    /**
    * @dev Recovers the signer at a given position from a list of concatenated signatures.
    * @param _signedHash The signed hash
    * @param _signatures The concatenated signatures.
    * @param _index The index of the signature to recover.
    */
    function recoverSigner(bytes32 _signedHash, bytes memory _signatures, uint _index) internal pure returns (address) {
        uint8 v;
        bytes32 r;
        bytes32 s;
        // we jump 32 (0x20) as the first slot of bytes contains the length
        // we jump 65 (0x41) per signature
        // for v we load 32 bytes ending with v (the first 31 come from s) then apply a mask
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            r := mload(add(_signatures, add(0x20,mul(0x41,_index))))
            s := mload(add(_signatures, add(0x40,mul(0x41,_index))))
            v := and(mload(add(_signatures, add(0x41,mul(0x41,_index)))), 0xff)
        }
        require(v == 27 || v == 28);
        return ecrecover(_signedHash, v, r, s);
    }

    /**
    * @dev Refunds the gas used to the Relayer. 
    * For security reasons the default behavior is to not refund calls with 0 or 1 signatures. 
    * @param _wallet The target wallet.
    * @param _gasUsed The gas used.
    * @param _gasPrice The gas price for the refund.
    * @param _gasLimit The gas limit for the refund.
    * @param _signatures The number of signatures used in the call.
    * @param _relayer The address of the Relayer.
    */
    function refund(BaseWallet _wallet, uint _gasUsed, uint _gasPrice, uint _gasLimit, uint _signatures, address _relayer) internal {
        uint256 amount = 29292 + _gasUsed; // 21000 (transaction) + 7620 (execution of refund) + 672 to log the event + _gasUsed
        // only refund if gas price not null, more than 1 signatures, gas less than gasLimit
        if(_gasPrice > 0 && _signatures > 1 && amount <= _gasLimit) {
            if(_gasPrice > tx.gasprice) {
                amount = amount * tx.gasprice;
            }
            else {
                amount = amount * _gasPrice;
            }
            invokeWallet(address(_wallet), _relayer, amount, EMPTY_BYTES);
        }
    }

    /**
    * @dev Returns false if the refund is expected to fail.
    * @param _wallet The target wallet.
    * @param _gasUsed The expected gas used.
    * @param _gasPrice The expected gas price for the refund.
    */
    function verifyRefund(BaseWallet _wallet, uint _gasUsed, uint _gasPrice, uint _signatures) internal view returns (bool) {
        if(_gasPrice > 0
            && _signatures > 1
            && (address(_wallet).balance < _gasUsed * _gasPrice || _wallet.authorised(address(this)) == false)) {
            return false;
        }
        return true;
    }

    /**
    * @dev Checks that the wallet address provided as the first parameter of the relayed data is the same
    * as the wallet passed as the input of the execute() method. 
    @return false if the addresses are different.
    */
    function verifyData(address _wallet, bytes memory _data) private pure returns (bool) {
        require(_data.length >= 36, "RM: Invalid dataWallet");
        address dataWallet;
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            //_data = {length:32}{sig:4}{_wallet:32}{...}
            dataWallet := mload(add(_data, 0x24))
        }
        return dataWallet == _wallet;
    }

    /**
    * @dev Parses the data to extract the method signature.
    */
    function functionPrefix(bytes memory _data) internal pure returns (bytes4 prefix) {
        require(_data.length >= 4, "RM: Invalid functionPrefix");
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            prefix := mload(add(_data, 0x20))
        }
    }
}

/**
 * @title BaseTransfer
 * @dev Module containing internal methods to execute or approve transfers
 * @author Olivier VDB - <olivier@argent.xyz>
 */
contract BaseTransfer is BaseModule {

    // Mock token address for ETH
    address constant internal ETH_TOKEN = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

    // *************** Events *************************** //

    event Transfer(address indexed wallet, address indexed token, uint256 indexed amount, address to, bytes data);
    event Approved(address indexed wallet, address indexed token, uint256 amount, address spender);
    event CalledContract(address indexed wallet, address indexed to, uint256 amount, bytes data);

    // *************** Internal Functions ********************* //

    /**
    * @dev Helper method to transfer ETH or ERC20 for a wallet.
    * @param _wallet The target wallet.
    * @param _token The ERC20 address.
    * @param _to The recipient.
    * @param _value The amount of ETH to transfer
    * @param _data The data to *log* with the transfer.
    */
    function doTransfer(BaseWallet _wallet, address _token, address _to, uint256 _value, bytes memory _data) internal {
        if(_token == ETH_TOKEN) {
            invokeWallet(address(_wallet), _to, _value, EMPTY_BYTES);
        }
        else {
            bytes memory methodData = abi.encodeWithSignature("transfer(address,uint256)", _to, _value);
            invokeWallet(address(_wallet), _token, 0, methodData);
        }
        emit Transfer(address(_wallet), _token, _value, _to, _data);
    }

    /**
    * @dev Helper method to approve spending the ERC20 of a wallet.
    * @param _wallet The target wallet.
    * @param _token The ERC20 address.
    * @param _spender The spender address.
    * @param _value The amount of token to transfer.
    */
    function doApproveToken(BaseWallet _wallet, address _token, address _spender, uint256 _value) internal {
        bytes memory methodData = abi.encodeWithSignature("approve(address,uint256)", _spender, _value);
        invokeWallet(address(_wallet), _token, 0, methodData);
        emit Approved(address(_wallet), _token, _value, _spender);
    }

    /**
    * @dev Helper method to call an external contract.
    * @param _wallet The target wallet.
    * @param _contract The contract address.
    * @param _value The ETH value to transfer.
    * @param _data The method data.
    */
    function doCallContract(BaseWallet _wallet, address _contract, uint256 _value, bytes memory _data) internal {
        invokeWallet(address(_wallet), _contract, _value, _data);
        emit CalledContract(address(_wallet), _contract, _value, _data);
    }
}

/**
 * @title ApprovedTransfer
 * @dev Module to transfer tokens (ETH or ERC20) with the approval of guardians.
 * @author Julien Niset - <julien@argent.im>
 */
contract ApprovedTransfer is BaseModule, RelayerModule, BaseTransfer {

    bytes32 constant NAME = "ApprovedTransfer";

    constructor(ModuleRegistry _registry, GuardianStorage _guardianStorage) BaseModule(_registry, _guardianStorage, NAME) public {

    }

    /**
    * @dev transfers tokens (ETH or ERC20) from a wallet.
    * @param _wallet The target wallet.
    * @param _token The address of the token to transfer.
    * @param _to The destination address
    * @param _amount The amoutnof token to transfer
    * @param _data  The data for the transaction (only for ETH transfers)
    */
    function transferToken(
        BaseWallet _wallet,
        address _token,
        address _to,
        uint256 _amount,
        bytes calldata _data
    )
        external
        onlyExecute
        onlyWhenUnlocked(_wallet)
    {
        doTransfer(_wallet, _token, _to, _amount, _data);
    }

    /**
    * @dev call a contract.
    * @param _wallet The target wallet.
    * @param _contract The address of the contract.
    * @param _value The amount of ETH to transfer as part of call
    * @param _data The encoded method data
    */
    function callContract(
        BaseWallet _wallet,
        address _contract,
        uint256 _value,
        bytes calldata _data
    )
        external
        onlyExecute
        onlyWhenUnlocked(_wallet)
    {
        require(!_wallet.authorised(_contract) && _contract != address(_wallet), "AT: Forbidden contract");
        doCallContract(_wallet, _contract, _value, _data);
    }

    // *************** Implementation of RelayerModule methods ********************* //

    function validateSignatures(
        BaseWallet _wallet,
        bytes memory /* _data */,
        bytes32 _signHash,
        bytes memory _signatures
    )
        internal
        view
        returns (bool)
    {
        address lastSigner = address(0);
        address[] memory guardians = guardianStorage.getGuardians(_wallet);
        bool isGuardian = false;
        for (uint8 i = 0; i < _signatures.length / 65; i++) {
            address signer = recoverSigner(_signHash, _signatures, i);
            if(i == 0) {
                // AT: first signer must be owner
                if(!isOwner(_wallet, signer)) {
                    return false;
                }
            }
            else {
                // "AT: signers must be different"
                if(signer <= lastSigner) {
                    return false;
                }
                lastSigner = signer;
                (isGuardian, guardians) = GuardianUtils.isGuardian(guardians, signer);
                // "AT: signatures not valid"
                if(!isGuardian) {
                    return false;
                }
            }
        }
        return true;
    }

    function getRequiredSignatures(BaseWallet _wallet, bytes memory /* _data */) internal view returns (uint256) {
        // owner  + [n/2] guardians
        return  1 + SafeMath.ceil(guardianStorage.guardianCount(_wallet), 2);
    }
}

{
  "compilationTarget": {
    "ApprovedTransfer.sol": "ApprovedTransfer"
  },
  "evmVersion": "byzantium",
  "libraries": {},
  "optimizer": {
    "enabled": true,
    "runs": 999
  },
  "remappings": []
}