contract TokenWhitelist is ENSResolvable, Controllable, Transferrable {
    using strings for *;
    using SafeMath for uint256;
    using BytesUtils for bytes;

    event UpdatedTokenRate(address _sender, address _token, uint _rate);

    event UpdatedTokenLoadable(address _sender, address _token, bool _loadable);
    event UpdatedTokenRedeemable(address _sender, address _token, bool _redeemable);

    event AddedToken(address _sender, address _token, string _symbol, uint _magnitude, bool _loadable, bool _redeemable);
    event RemovedToken(address _sender, address _token);

    event AddedMethodId(bytes4 _methodId);
    event RemovedMethodId(bytes4 _methodId);
    event AddedExclusiveMethod(address _token, bytes4 _methodId);
    event RemovedExclusiveMethod(address _token, bytes4 _methodId);

    event Claimed(address _to, address _asset, uint _amount);

    /// @dev these are the methods whitelisted by default in executeTransaction() for protected tokens
    bytes4 private constant _APPROVE = 0x095ea7b3; // keccak256(approve(address,uint256)) => 0x095ea7b3
    bytes4 private constant _BURN = 0x42966c68; // keccak256(burn(uint256)) => 0x42966c68
    bytes4 private constant _TRANSFER= 0xa9059cbb; // keccak256(transfer(address,uint256)) => 0xa9059cbb
    bytes4 private constant _TRANSFER_FROM = 0x23b872dd; // keccak256(transferFrom(address,address,uint256)) => 0x23b872dd

    struct Token {
        string symbol;    // Token symbol
        uint magnitude;   // 10^decimals
        uint rate;        // Token exchange rate in wei
        bool available;   // Flags if the token is available or not
        bool loadable;    // Flags if token is loadable to the TokenCard
        bool redeemable;    // Flags if token is redeemable in the TKN Holder contract
        uint lastUpdate;  // Time of the last rate update
    }

    mapping(address => Token) private _tokenInfoMap;

    // @notice specifies whitelisted methodIds for protected tokens in wallet's excuteTranaction() e.g. keccak256(transfer(address,uint256)) => 0xa9059cbb
    mapping(bytes4 => bool) private _methodIdWhitelist;

    address[] private _tokenAddressArray;

    /// @notice keeping track of how many redeemable tokens are in the tokenWhitelist
    uint private _redeemableCounter;

    /// @notice Address of the stablecoin.
    address private _stablecoin;

    /// @notice is registered ENS node identifying the oracle contract.
    bytes32 private _oracleNode;

    /// @notice Constructor initializes ENSResolvable, and Controllable.
    /// @param _ens_ is the ENS registry address.
    /// @param _oracleNode_ is the ENS node of the Oracle.
    /// @param _controllerNode_ is our Controllers node.
    /// @param _stablecoinAddress_ is the address of the stablecoint used by the wallet for the card load limit.
    constructor(address _ens_, bytes32 _oracleNode_, bytes32 _controllerNode_, address _stablecoinAddress_) ENSResolvable(_ens_) Controllable(_controllerNode_) public {
        _oracleNode = _oracleNode_;
        _stablecoin = _stablecoinAddress_;
        //a priori ERC20 whitelisted methods
        _methodIdWhitelist[_APPROVE] = true;
        _methodIdWhitelist[_BURN] = true;
        _methodIdWhitelist[_TRANSFER] = true;
        _methodIdWhitelist[_TRANSFER_FROM] = true;
    }

    modifier onlyAdminOrOracle() {
        address oracleAddress = _ensResolve(_oracleNode);
        require (_isAdmin(msg.sender) || msg.sender == oracleAddress, "either oracle or admin");
        _;
    }

    /// @notice Add ERC20 tokens to the list of whitelisted tokens.
    /// @param _tokens ERC20 token contract addresses.
    /// @param _symbols ERC20 token names.
    /// @param _magnitude 10 to the power of number of decimal places used by each ERC20 token.
    /// @param _loadable is a bool that states whether or not a token is loadable to the TokenCard.
    /// @param _redeemable is a bool that states whether or not a token is redeemable in the TKN Holder Contract.
    /// @param _lastUpdate is a unit representing an ISO datetime e.g. 20180913153211.
    function addTokens(address[] calldata _tokens, bytes32[] calldata _symbols, uint[] calldata _magnitude, bool[] calldata _loadable, bool[] calldata _redeemable, uint _lastUpdate) external onlyAdmin {
        // Require that all parameters have the same length.
        require(_tokens.length == _symbols.length && _tokens.length == _magnitude.length && _tokens.length == _loadable.length && _tokens.length == _loadable.length, "parameter lengths do not match");
        // Add each token to the list of supported tokens.
        for (uint i = 0; i < _tokens.length; i++) {
            // Require that the token isn't already available.
            require(!_tokenInfoMap[_tokens[i]].available, "token already available");
            // Store the intermediate values.
            string memory symbol = _symbols[i].toSliceB32().toString();
            // Add the token to the token list.
            _tokenInfoMap[_tokens[i]] = Token({
                symbol : symbol,
                magnitude : _magnitude[i],
                rate : 0,
                available : true,
                loadable : _loadable[i],
                redeemable: _redeemable[i],
                lastUpdate : _lastUpdate
                });
            // Add the token address to the address list.
            _tokenAddressArray.push(_tokens[i]);
            //if the token is redeemable increase the redeemableCounter
            if (_redeemable[i]){
                _redeemableCounter = _redeemableCounter.add(1);
            }
            // Emit token addition event.
            emit AddedToken(msg.sender, _tokens[i], symbol, _magnitude[i], _loadable[i], _redeemable[i]);
        }
    }

    /// @notice Remove ERC20 tokens from the whitelist of tokens.
    /// @param _tokens ERC20 token contract addresses.
    function removeTokens(address[] calldata _tokens) external onlyAdmin {
        // Delete each token object from the list of supported tokens based on the addresses provided.
        for (uint i = 0; i < _tokens.length; i++) {
            // Store the token address.
            address token = _tokens[i];
            //token must be available, reverts on duplicates as well
            require(_tokenInfoMap[token].available, "token is not available");
            //if the token is redeemable decrease the redeemableCounter
            if (_tokenInfoMap[token].redeemable){
                _redeemableCounter = _redeemableCounter.sub(1);
            }
            // Delete the token object.
            delete _tokenInfoMap[token];
            // Remove the token address from the address list.
            for (uint j = 0; j < _tokenAddressArray.length.sub(1); j++) {
                if (_tokenAddressArray[j] == token) {
                    _tokenAddressArray[j] = _tokenAddressArray[_tokenAddressArray.length.sub(1)];
                    break;
                }
            }
            _tokenAddressArray.length--;
            // Emit token removal event.
            emit RemovedToken(msg.sender, token);
        }
    }

    /// @notice based on the method it returns the recipient address and amount/value, ERC20 specific.
    /// @param _data is the transaction payload.
    function getERC20RecipientAndAmount(address _token, bytes calldata _data) external view returns (address, uint) {
        // Require that there exist enough bytes for encoding at least a method signature + data in the transaction payload:
        // 4 (signature)  + 32(address or uint256)
        require(_data.length >= 4 + 32, "not enough method-encoding bytes");
        // Get the method signature
        bytes4 signature = _data._bytesToBytes4(0);
        // Check if method Id is supported
        require(isERC20MethodSupported(_token, signature), "unsupported method");
        // returns the recipient's address and amount is the value to be transferred
        if (signature == _BURN) {
            // 4 (signature) + 32(uint256)
            return (_token, _data._bytesToUint256(4));
        } else if (signature == _TRANSFER_FROM) {
            // 4 (signature) + 32(address) + 32(address) + 32(uint256)
            require(_data.length >= 4 + 32 + 32 + 32, "not enough data for transferFrom");
            return ( _data._bytesToAddress(4 + 32 + 12), _data._bytesToUint256(4 + 32 + 32));
        } else { //transfer or approve
            // 4 (signature) + 32(address) + 32(uint)
            require(_data.length >= 4 + 32 + 32, "not enough data for transfer/appprove");
            return (_data._bytesToAddress(4 + 12), _data._bytesToUint256(4 + 32));
        }
    }

    /// @notice Toggles whether or not a token is loadable or not.
    function setTokenLoadable(address _token, bool _loadable) external onlyAdmin {
        // Require that the token exists.
        require(_tokenInfoMap[_token].available, "token is not available");

        // this sets the loadable flag to the value passed in
        _tokenInfoMap[_token].loadable = _loadable;

        emit UpdatedTokenLoadable(msg.sender, _token, _loadable);
    }

    /// @notice Toggles whether or not a token is redeemable or not.
    function setTokenRedeemable(address _token, bool _redeemable) external onlyAdmin {
        // Require that the token exists.
        require(_tokenInfoMap[_token].available, "token is not available");

        // this sets the redeemable flag to the value passed in
        _tokenInfoMap[_token].redeemable = _redeemable;

        emit UpdatedTokenRedeemable(msg.sender, _token, _redeemable);
    }

    /// @notice Update ERC20 token exchange rate.
    /// @param _token ERC20 token contract address.
    /// @param _rate ERC20 token exchange rate in wei.
    /// @param _updateDate date for the token updates. This will be compared to when oracle updates are received.
    function updateTokenRate(address _token, uint _rate, uint _updateDate) external onlyAdminOrOracle {
        // Require that the token exists.
        require(_tokenInfoMap[_token].available, "token is not available");
        // Update the token's rate.
        _tokenInfoMap[_token].rate = _rate;
        // Update the token's last update timestamp.
        _tokenInfoMap[_token].lastUpdate = _updateDate;
        // Emit the rate update event.
        emit UpdatedTokenRate(msg.sender, _token, _rate);
    }

    //// @notice Withdraw tokens from the smart contract to the specified account.
    function claim(address payable _to, address _asset, uint _amount) external onlyAdmin {
        _safeTransfer(_to, _asset, _amount);
        emit Claimed(_to, _asset, _amount);
    }

    /// @notice This returns all of the fields for a given token.
    /// @param _a is the address of a given token.
    /// @return string of the token's symbol.
    /// @return uint of the token's magnitude.
    /// @return uint of the token's exchange rate to ETH.
    /// @return bool whether the token is available.
    /// @return bool whether the token is loadable to the TokenCard.
    /// @return bool whether the token is redeemable to the TKN Holder Contract.
    /// @return uint of the lastUpdated time of the token's exchange rate.
    function getTokenInfo(address _a) external view returns (string memory, uint256, uint256, bool, bool, bool, uint256) {
        Token storage tokenInfo = _tokenInfoMap[_a];
        return (tokenInfo.symbol, tokenInfo.magnitude, tokenInfo.rate, tokenInfo.available, tokenInfo.loadable, tokenInfo.redeemable, tokenInfo.lastUpdate);
    }

    /// @notice This returns all of the fields for our StableCoin.
    /// @return string of the token's symbol.
    /// @return uint of the token's magnitude.
    /// @return uint of the token's exchange rate to ETH.
    /// @return bool whether the token is available.
    /// @return bool whether the token is loadable to the TokenCard.
    /// @return bool whether the token is redeemable to the TKN Holder Contract.
    /// @return uint of the lastUpdated time of the token's exchange rate.
    function getStablecoinInfo() external view returns (string memory, uint256, uint256, bool, bool, bool, uint256) {
        Token storage stablecoinInfo = _tokenInfoMap[_stablecoin];
        return (stablecoinInfo.symbol, stablecoinInfo.magnitude, stablecoinInfo.rate, stablecoinInfo.available, stablecoinInfo.loadable, stablecoinInfo.redeemable, stablecoinInfo.lastUpdate);
    }

    /// @notice This returns an array of all whitelisted token addresses.
    /// @return address[] of whitelisted tokens.
    function tokenAddressArray() external view returns (address[] memory) {
        return _tokenAddressArray;
    }

    /// @notice This returns an array of all redeemable token addresses.
    /// @return address[] of redeemable tokens.
    function redeemableTokens() external view returns (address[] memory) {
        address[] memory redeemableAddresses = new address[](_redeemableCounter);
        uint redeemableIndex = 0;
        for (uint i = 0; i < _tokenAddressArray.length; i++) {
            address token = _tokenAddressArray[i];
            if (_tokenInfoMap[token].redeemable){
                redeemableAddresses[redeemableIndex] = token;
                redeemableIndex += 1;
            }
        }
        return redeemableAddresses;
    }


    /// @notice This returns true if a method Id is supported for the specific token.
    /// @return true if _methodId is supported in general or just for the specific token.
    function isERC20MethodSupported(address _token, bytes4 _methodId) public view returns (bool) {
        require(_tokenInfoMap[_token].available, "non-existing token");
        return (_methodIdWhitelist[_methodId]);
    }

    /// @notice This returns true if the method is supported for all protected tokens.
    /// @return true if _methodId is in the method whitelist.
    function isERC20MethodWhitelisted(bytes4 _methodId) external view returns (bool) {
        return (_methodIdWhitelist[_methodId]);
    }

    /// @notice This returns the number of redeemable tokens.
    /// @return current # of redeemables.
    function redeemableCounter() external view returns (uint) {
        return _redeemableCounter;
    }

    /// @notice This returns the address of our stablecoin of choice.
    /// @return the address of the stablecoin contract.
    function stablecoin() external view returns (address) {
        return _stablecoin;
    }

    /// @notice this returns the node hash of our Oracle.
    /// @return the oracle node registered in ENS.
    function oracleNode() external view returns (bytes32) {
        return _oracleNode;
    }
}
/// @title TokenWhitelist stores a list of tokens used by the Consumer Contract Wallet, the Oracle, the TKN Holder and the TKN Licence Contract
function getStablecoinInfo() external view returns (string memory, uint256, uint256, bool, bool, bool, uint256) {
    Token storage stablecoinInfo = _tokenInfoMap[_stablecoin];
    return (stablecoinInfo.symbol, stablecoinInfo.magnitude, stablecoinInfo.rate, stablecoinInfo.available, stablecoinInfo.loadable, stablecoinInfo.redeemable, stablecoinInfo.lastUpdate);
}

/// @notice This returns all of the fields for our StableCoin.
/// @return string of the token's symbol.
/// @return uint of the token's magnitude.
/// @return uint of the token's exchange rate to ETH.
/// @return bool whether the token is available.
/// @return bool whether the token is loadable to the TokenCard.
/// @return bool whether the token is redeemable to the TKN Holder Contract.
/// @return uint of the lastUpdated time of the token's exchange rate.