// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;
pragma experimental ABIEncoderV2;

import { SafeMath } from "@openzeppelin/contracts-v3/math/SafeMath.sol";
import { IERC20 } from "@openzeppelin/contracts-v3/token/ERC20/IERC20.sol";
import { Initializable } from "@openzeppelin/contracts-v3/proxy/Initializable.sol";
import { SafeERC20 } from "@openzeppelin/contracts-v3/token/ERC20/SafeERC20.sol";
import { TORN } from "./TORN/TORN.sol";
import { TornadoStakingRewards } from "./TornadoStakingRewards.sol";
import { ITornadoInstance } from "./interfaces/ITornadoInstance.sol";

interface IENS {
    function owner(bytes32 node) external view returns (address);
}

/*
 * @dev Solidity implementation of the ENS namehash algorithm.
 *
 * Warning! Does not normalize or validate names before hashing.
 * Original version can be found here https://github.com/JonahGroendal/ens-namehash/
 */
library ENSNamehash {
    function namehash(bytes memory domain) internal pure returns (bytes32) {
        return namehash(domain, 0);
    }

    function namehash(bytes memory domain, uint256 i) internal pure returns (bytes32) {
        if (domain.length <= i) return 0x0000000000000000000000000000000000000000000000000000000000000000;

        uint256 len = labelLength(domain, i);

        return keccak256(abi.encodePacked(namehash(domain, i + len + 1), keccak(domain, i, len)));
    }

    function labelLength(bytes memory domain, uint256 i) private pure returns (uint256) {
        uint256 len;
        while (i + len != domain.length && domain[i + len] != 0x2e) {
            len++;
        }
        return len;
    }

    function keccak(bytes memory data, uint256 offset, uint256 len) private pure returns (bytes32 ret) {
        require(offset + len <= data.length);
        assembly {
            ret := keccak256(add(add(data, 32), offset), len)
        }
    }
}

interface IFeeManager {
    function instanceFeeWithUpdate(ITornadoInstance _instance) external returns (uint160);
}

struct RelayerState {
    uint256 balance;
    bytes32 ensHash;
}

/**
 * @notice Registry contract, one of the main contracts of this protocol upgrade.
 *         The contract should store relayers' addresses and data attributed to the
 *         master address of the relayer. This data includes the relayers stake and
 *         his ensHash.
 *         A relayers master address has a number of subaddresses called "workers",
 *         these are all addresses which burn stake in communication with the proxy.
 *         If a relayer is not registered, he is not displayed on the frontend.
 * @dev CONTRACT RISKS:
 *      - if setter functions are compromised, relayer metadata would be at risk, including the noted amount of his balance
 *      - if burn function is compromised, relayers run the risk of being unable to handle withdrawals
 *      - the above risk also applies to the nullify balance function
 *
 */
contract RelayerRegistry is Initializable {
    using SafeMath for uint256;
    using SafeERC20 for TORN;
    using ENSNamehash for bytes;

    TORN public immutable torn;
    address public immutable governance;
    IENS public immutable ens;
    TornadoStakingRewards public immutable staking;
    IFeeManager public immutable feeManager;

    address public tornadoRouter;
    uint256 public minStakeAmount;

    mapping(address => RelayerState) public relayers;
    mapping(address => address) public workers;

    event RelayerBalanceNullified(address relayer);
    event WorkerRegistered(address relayer, address worker);
    event WorkerUnregistered(address relayer, address worker);
    event StakeAddedToRelayer(address relayer, uint256 amountStakeAdded);
    event StakeBurned(address relayer, uint256 amountBurned);
    event MinimumStakeAmount(uint256 minStakeAmount);
    event RouterRegistered(address tornadoRouter);
    event RelayerRegistered(bytes32 relayer, string ensName, address relayerAddress, uint256 stakedAmount);
    event RelayerUnregistered(address relayer);

    modifier onlyGovernance() {
        require(msg.sender == governance, "only governance");
        _;
    }

    modifier onlyTornadoRouter() {
        require(msg.sender == tornadoRouter, "only proxy");
        _;
    }

    modifier onlyRelayer(address sender, address relayer) {
        require(workers[sender] == relayer, "only relayer");
        _;
    }

    constructor(address _torn, address _governance, address _ens, address _staking, address _feeManager) public {
        torn = TORN(_torn);
        governance = _governance;
        ens = IENS(_ens);
        staking = TornadoStakingRewards(_staking);
        feeManager = IFeeManager(_feeManager);
    }

    /**
     * @notice initialize function for upgradeability
     * @dev this contract will be deployed behind a proxy and should not assign values at logic address,
     *      params left out because self explainable
     *
     */
    function initialize(address _tornadoRouter) external initializer {
        tornadoRouter = _tornadoRouter;
    }

    /**
     * @notice This function should register a master address and optionally a set of workeres for a relayer + metadata
     * @dev Relayer can't steal other relayers workers since they are registered, and a wallet (msg.sender check) can always unregister itself
     * @param ensName ens name of the relayer
     * @param stake the initial amount of stake in TORN the relayer is depositing
     *
     */
    function register(string calldata ensName, uint256 stake, address[] calldata workersToRegister) external {
        _register(msg.sender, ensName, stake, workersToRegister);
    }

    /**
     * @dev Register function equivalent with permit-approval instead of regular approve.
     *
     */
    function registerPermit(
        string calldata ensName,
        uint256 stake,
        address[] calldata workersToRegister,
        address relayer,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        torn.permit(relayer, address(this), stake, deadline, v, r, s);
        _register(relayer, ensName, stake, workersToRegister);
    }

    function _register(
        address relayer,
        string calldata ensName,
        uint256 stake,
        address[] calldata workersToRegister
    ) internal {
        bytes32 ensHash = bytes(ensName).namehash();
        address domainOwner = ens.owner(ensHash);
        address ensNameWrapper = 0xD4416b13d2b3a9aBae7AcD5D6C2BbDBE25686401;

        require(domainOwner != ensNameWrapper, "only unwrapped ens domains");
        require(relayer == domainOwner, "only ens domain owner");
        require(workers[relayer] == address(0), "cant register again");
        RelayerState storage metadata = relayers[relayer];

        require(metadata.ensHash == bytes32(0), "registered already");
        require(stake >= minStakeAmount, "!min_stake");

        torn.safeTransferFrom(relayer, address(staking), stake);
        emit StakeAddedToRelayer(relayer, stake);

        metadata.balance = stake;
        metadata.ensHash = ensHash;
        workers[relayer] = relayer;

        for (uint256 i = 0; i < workersToRegister.length; i++) {
            address worker = workersToRegister[i];
            _registerWorker(relayer, worker);
        }

        emit RelayerRegistered(ensHash, ensName, relayer, stake);
    }

    /**
     * @notice This function should allow relayers to register more workeres
     * @param relayer Relayer which should send message from any worker which is already registered
     * @param worker Address to register
     *
     */
    function registerWorker(address relayer, address worker) external onlyRelayer(msg.sender, relayer) {
        _registerWorker(relayer, worker);
    }

    function _registerWorker(address relayer, address worker) internal {
        require(workers[worker] == address(0), "can't steal an address");
        workers[worker] = relayer;
        emit WorkerRegistered(relayer, worker);
    }

    /**
     * @notice This function should allow anybody to unregister an address they own
     * @dev designed this way as to allow someone to unregister themselves in case a relayer misbehaves
     *      - this should be followed by an action like burning relayer stake
     *      - there was an option of allowing the sender to burn relayer stake in case of malicious behaviour, this feature was not included in the end
     *      - reverts if trying to unregister master, otherwise contract would break. in general, there should be no reason to unregister master at all
     *
     */
    function unregisterWorker(address worker) external {
        if (worker != msg.sender) require(workers[worker] == msg.sender, "only owner of worker");
        require(workers[worker] != worker, "cant unregister master");
        emit WorkerUnregistered(workers[worker], worker);
        workers[worker] = address(0);
    }

    /**
     * @notice This function should allow governance to unregister relayer
     * @param relayer Address of the relayer
     *
     */
    function unregisterRelayer(address relayer) external onlyGovernance {
        nullifyBalance(relayer);
        delete relayers[relayer];
        delete workers[relayer];
        emit RelayerUnregistered(relayer);
    }

    /**
     * @notice This function should allow anybody to stake to a relayer more TORN
     * @param relayer Relayer main address to stake to
     * @param stake Stake to be added to relayer
     *
     */
    function stakeToRelayer(address relayer, uint256 stake) external {
        _stakeToRelayer(msg.sender, relayer, stake);
    }

    /**
     * @dev stakeToRelayer function equivalent with permit-approval instead of regular approve.
     * @param staker address from that stake is paid
     *
     */
    function stakeToRelayerPermit(
        address relayer,
        uint256 stake,
        address staker,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        torn.permit(staker, address(this), stake, deadline, v, r, s);
        _stakeToRelayer(staker, relayer, stake);
    }

    function _stakeToRelayer(address staker, address relayer, uint256 stake) internal {
        require(workers[relayer] == relayer, "!registered");
        torn.safeTransferFrom(staker, address(staking), stake);
        relayers[relayer].balance = stake.add(relayers[relayer].balance);
        emit StakeAddedToRelayer(relayer, stake);
    }

    /**
     * @notice This function should burn some relayer stake on withdraw and notify staking of this
     * @dev IMPORTANT FUNCTION:
     *      - This should be only called by the tornado proxy
     *      - Should revert if relayer does not call proxy from valid worker
     *      - Should not overflow
     *      - Should underflow and revert (SafeMath) on not enough stake (balance)
     * @param sender worker to check sender == relayer
     * @param relayer address of relayer who's stake is being burned
     * @param pool instance to get fee for
     *
     */
    function burn(address sender, address relayer, ITornadoInstance pool) external onlyTornadoRouter {
        address masterAddress = workers[sender];
        if (masterAddress == address(0)) {
            require(workers[relayer] == address(0), "Only custom relayer");
            return;
        }

        require(masterAddress == relayer, "only relayer");
        uint256 toBurn = feeManager.instanceFeeWithUpdate(pool);
        relayers[relayer].balance = relayers[relayer].balance.sub(toBurn);
        staking.addBurnRewards(toBurn);
        emit StakeBurned(relayer, toBurn);
    }

    /**
     * @notice This function should allow governance to set the minimum stake amount
     * @param minAmount new minimum stake amount
     *
     */
    function setMinStakeAmount(uint256 minAmount) external onlyGovernance {
        minStakeAmount = minAmount;
        emit MinimumStakeAmount(minAmount);
    }

    /**
     * @notice This function should allow governance to set a new tornado proxy address
     * @param tornadoRouterAddress address of the new proxy
     *
     */
    function setTornadoRouter(address tornadoRouterAddress) external onlyGovernance {
        tornadoRouter = tornadoRouterAddress;
        emit RouterRegistered(tornadoRouterAddress);
    }

    /**
     * @notice This function should allow governance to nullify a relayers balance
     * @dev IMPORTANT FUNCTION:
     *      - Should nullify the balance
     *      - Adding nullified balance as rewards was refactored to allow for the flexibility of these funds (for gov to operate with them)
     * @param relayer address of relayer who's balance is to nullify
     *
     */
    function nullifyBalance(address relayer) public onlyGovernance {
        address masterAddress = workers[relayer];
        require(relayer == masterAddress, "must be master");
        relayers[masterAddress].balance = 0;
        emit RelayerBalanceNullified(relayer);
    }

    /**
     * @notice This function should check if a worker is associated with a relayer
     * @param toResolve address to check
     * @return true if is associated
     *
     */
    function isRelayer(address toResolve) external view returns (bool) {
        return workers[toResolve] != address(0);
    }

    /**
     * @notice This function should check if a worker is registered to the relayer stated
     * @param relayer relayer to check
     * @param toResolve address to check
     * @return true if registered
     *
     */
    function isRelayerRegistered(address relayer, address toResolve) external view returns (bool) {
        return workers[toResolve] == relayer;
    }

    /**
     * @notice This function should get a relayers ensHash
     * @param relayer address to fetch for
     * @return relayer's ensHash
     *
     */
    function getRelayerEnsHash(address relayer) external view returns (bytes32) {
        return relayers[workers[relayer]].ensHash;
    }

    /**
     * @notice This function should get a relayers balance
     * @param relayer relayer who's balance is to fetch
     * @return relayer's balance
     *
     */
    function getRelayerBalance(address relayer) external view returns (uint256) {
        return relayers[workers[relayer]].balance;
    }
}