// File: contracts/zeppelin/token/ERC20/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: contracts/zeppelin/token/ERC20/ERC20Detailed.sol

pragma solidity ^0.5.0;


/**
 * @dev Optional functions from the ERC20 standard.
 */
contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

// File: contracts/IBridge.sol

pragma solidity ^0.5.0;


interface IBridge {
    function version() external pure returns (string memory);

    function getCrossingPayment() external view returns(uint);

    function calcMaxWithdraw() external view returns (uint);

    /**
     * ERC-20 tokens approve and transferFrom pattern
     * See https://eips.ethereum.org/EIPS/eip-20#transferfrom
     */
    function receiveTokens(address tokenToUse, uint256 amount) external payable returns(bool);

    /**
     * ERC-677 and ERC-223 implementation for Receiving Tokens Contracts
     * See https://github.com/ethereum/EIPs/issues/677 for details
     * See https://github.com/ethereum/EIPs/issues/223 for details
     */
    function tokenFallback(address from, uint amount, bytes calldata userData) external returns(bool);

    /**
     * ERC-777 tokensReceived hook allows to send tokens to a contract and notify it in a single transaction
     * See https://eips.ethereum.org/EIPS/eip-777#motivation for details
     */
    function tokensReceived (
        address operator,
        address from,
        address to,
        uint amount,
        bytes calldata userData,
        bytes calldata operatorData
    ) external;

    function acceptTransfer(
        address originalTokenAddress,
        address receiver, uint256 amount,
        string calldata symbol,
        bytes32 blockHash,
        bytes32 transactionHash,
        uint32 logIndex
    ) external returns(bool);

    function transactionWasProcessed(
        bytes32 _blockHash,
        bytes32 _transactionHash,
        address _receiver,
        uint256 _amount,
        uint32 _logIndex
    ) external view returns(bool);

    event Cross(address indexed _tokenAddress, address indexed _to, uint256 _amount, string _symbol, bytes userData);
    event NewSideToken(address indexed _newSideTokenAddress, address indexed _originalTokenAddress, string _newSymbol);
    event AcceptedCrossTransfer(address indexed _tokenAddress, address indexed _to, uint256 _amount);
    event CrossingPaymentChanged(uint256 _amount);
}

// File: contracts/zeppelin/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: contracts/zeppelin/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/Federation.sol

pragma solidity ^0.5.0;



contract Federation is Ownable {
    uint constant public MAX_MEMBER_COUNT = 50;
    address constant private NULL_ADDRESS = address(0);

    IBridge public bridge;
    address[] public members;
    uint public required;

    mapping (address => bool) public isMember;
    mapping (bytes32 => mapping (address => bool)) public votes;
    mapping(bytes32 => bool) public processed;

    event Voted(address indexed sender, bytes32 indexed transactionId);
    event Executed(bytes32 indexed transactionId);
    event MemberAddition(address indexed member);
    event MemberRemoval(address indexed member);
    event RequirementChange(uint required);

    modifier onlyMember() {
        require(isMember[_msgSender()], "Federation: Caller is not a member of the federation");
        _;
    }

    modifier validRequirement(uint membersCount, uint _required) {
        // solium-disable-next-line max-len
        require(_required <= membersCount && _required != 0 && membersCount != 0, "Federation: Required value is invalid for the current members count");
        _;
    }

    constructor(address[] memory _members, uint _required) public validRequirement(_members.length, _required) {
        members = _members;
        for (uint i = 0; i < _members.length; i++) {
            require(!isMember[_members[i]] && _members[i] != NULL_ADDRESS, "Federation: Members addresses are invalid");
            isMember[_members[i]] = true;
            emit MemberAddition(_members[i]);
        }
        required = _required;
        emit RequirementChange(required);
    }

    function setBridge(address _bridge) external onlyOwner {
        bridge = IBridge(_bridge);
    }

    function voteTransaction(
        address originalTokenAddress,
        address receiver,
        uint256 amount,
        string calldata symbol,
        bytes32 blockHash,
        bytes32 transactionHash,
        uint32 logIndex)
    external onlyMember returns(bool)
    {
        bytes32 transactionId = getTransactionId(originalTokenAddress, receiver, amount, symbol, blockHash, transactionHash, logIndex);
        if (processed[transactionId])
            return true;

        if (votes[transactionId][_msgSender()])
            return true;

        votes[transactionId][_msgSender()] = true;
        emit Voted(_msgSender(), transactionId);

        uint8 transactionCount = getTransactionCount(transactionId);
        if (transactionCount >= required && transactionCount >= members.length / 2 + 1) {
            processed[transactionId] = true;
            bool acceptTransfer = bridge.acceptTransfer(originalTokenAddress, receiver, amount, symbol, blockHash, transactionHash, logIndex);
            require(acceptTransfer, "Federation: Bridge Accept Transfer was not successful");
            emit Executed(transactionId);
            return true;
        }

        return true;
    }

    function getTransactionCount(bytes32 transactionId) public view returns(uint8) {
        uint8 count = 0;
        for (uint8 i = 0; i < members.length; i++) {
            if (votes[transactionId][members[i]])
                count += 1;
        }
        return count;
    }

    function hasVoted(bytes32 transactionId) external view returns(bool)
    {
        return votes[transactionId][_msgSender()];
    }

    function transactionWasProcessed(bytes32 transactionId) external view returns(bool)
    {
        return processed[transactionId];
    }

    function getTransactionId(
        address originalTokenAddress,
        address receiver,
        uint256 amount,
        string memory symbol,
        bytes32 blockHash,
        bytes32 transactionHash,
        uint32 logIndex)
    public pure returns(bytes32)
    {
        return keccak256(abi.encodePacked(originalTokenAddress, receiver, amount, symbol, blockHash, transactionHash, logIndex));
    }

    function addMember(address _newMember) external onlyOwner
    {
        require(_newMember != NULL_ADDRESS, "Federation: Address cannot be empty");
        require(!isMember[_newMember], "Federation: Member already exists");
        require(members.length < MAX_MEMBER_COUNT, "Federation: Already at full capacity");

        isMember[_newMember] = true;
        members.push(_newMember);
        emit MemberAddition(_newMember);
    }

    function removeMember(address _oldMember) external onlyOwner
    {
        require(_oldMember != NULL_ADDRESS, "Federation: Address cannot be empty");
        require(isMember[_oldMember], "Federation: Member does not exists");
        require(members.length > 1, "Federation: Can't remove all the members");

        isMember[_oldMember] = false;
        for (uint i = 0; i < members.length - 1; i++) {
            if (members[i] == _oldMember) {
                members[i] = members[members.length - 1];
                break;
            }
        }
        members.length -= 1;
        emit MemberRemoval(_oldMember);
    }

    function getMembers() external view returns (address[] memory)
    {
        return members;
    }

    function changeRequirement(uint _required) external onlyOwner validRequirement(members.length, _required)
    {
        required = _required;
        emit RequirementChange(_required);
    }

}