// https://tornado.cash
/*
* d888888P                                           dP              a88888b.                   dP
*    88                                              88             d8'   `88                   88
*    88    .d8888b. 88d888b. 88d888b. .d8888b. .d888b88 .d8888b.    88        .d8888b. .d8888b. 88d888b.
*    88    88'  `88 88'  `88 88'  `88 88'  `88 88'  `88 88'  `88    88        88'  `88 Y8ooooo. 88'  `88
*    88    88.  .88 88       88    88 88.  .88 88.  .88 88.  .88 dP Y8.   .88 88.  .88       88 88    88
*    dP    `88888P' dP       dP    dP `88888P8 `88888P8 `88888P' 88  Y88888P' `88888P8 `88888P' dP    dP
* ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
*/

pragma solidity ^0.5.8;

library Hasher {
  function MiMCSponge(uint256 in_xL, uint256 in_xR) public pure returns (uint256 xL, uint256 xR);
}

contract MerkleTreeWithHistory {
  uint256 public constant FIELD_SIZE = 21888242871839275222246405745257275088548364400416034343698204186575808495617;
  uint256 public constant ZERO_VALUE = 21663839004416932945382355908790599225266501822907911457504978515578255421292; // = keccak256("tornado") % FIELD_SIZE

  uint32 public levels;

  // the following variables are made public for easier testing and debugging and
  // are not supposed to be accessed in regular code
  bytes32[] public filledSubtrees;
  bytes32[] public zeros;
  uint32 public currentRootIndex = 0;
  uint32 public nextIndex = 0;
  uint32 public constant ROOT_HISTORY_SIZE = 100;
  bytes32[ROOT_HISTORY_SIZE] public roots;

  constructor(uint32 _treeLevels) public {
    require(_treeLevels > 0, "_treeLevels should be greater than zero");
    require(_treeLevels < 32, "_treeLevels should be less than 32");
    levels = _treeLevels;

    bytes32 currentZero = bytes32(ZERO_VALUE);
    zeros.push(currentZero);
    filledSubtrees.push(currentZero);

    for (uint32 i = 1; i < levels; i++) {
      currentZero = hashLeftRight(currentZero, currentZero);
      zeros.push(currentZero);
      filledSubtrees.push(currentZero);
    }

    roots[0] = hashLeftRight(currentZero, currentZero);
  }

  /**
    @dev Hash 2 tree leaves, returns MiMC(_left, _right)
  */
  function hashLeftRight(bytes32 _left, bytes32 _right) public pure returns (bytes32) {
    require(uint256(_left) < FIELD_SIZE, "_left should be inside the field");
    require(uint256(_right) < FIELD_SIZE, "_right should be inside the field");
    uint256 R = uint256(_left);
    uint256 C = 0;
    (R, C) = Hasher.MiMCSponge(R, C);
    R = addmod(R, uint256(_right), FIELD_SIZE);
    (R, C) = Hasher.MiMCSponge(R, C);
    return bytes32(R);
  }

  function _insert(bytes32 _leaf) internal returns(uint32 index) {
    uint32 currentIndex = nextIndex;
    require(currentIndex != uint32(2)**levels, "Merkle tree is full. No more leafs can be added");
    nextIndex += 1;
    bytes32 currentLevelHash = _leaf;
    bytes32 left;
    bytes32 right;

    for (uint32 i = 0; i < levels; i++) {
      if (currentIndex % 2 == 0) {
        left = currentLevelHash;
        right = zeros[i];

        filledSubtrees[i] = currentLevelHash;
      } else {
        left = filledSubtrees[i];
        right = currentLevelHash;
      }

      currentLevelHash = hashLeftRight(left, right);

      currentIndex /= 2;
    }

    currentRootIndex = (currentRootIndex + 1) % ROOT_HISTORY_SIZE;
    roots[currentRootIndex] = currentLevelHash;
    return nextIndex - 1;
  }

  /**
    @dev Whether the root is present in the root history
  */
  function isKnownRoot(bytes32 _root) public view returns(bool) {
    if (_root == 0) {
      return false;
    }
    uint32 i = currentRootIndex;
    do {
      if (_root == roots[i]) {
        return true;
      }
      if (i == 0) {
        i = ROOT_HISTORY_SIZE;
      }
      i--;
    } while (i != currentRootIndex);
    return false;
  }

  /**
    @dev Returns the last root
  */
  function getLastRoot() public view returns(bytes32) {
    return roots[currentRootIndex];
  }
}

// File: @openzeppelin/contracts/utils/ReentrancyGuard.sol

pragma solidity ^0.5.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 */
contract ReentrancyGuard {
    // counter to allow mutex lock with only one SSTORE operation
    uint256 private _guardCounter;

    constructor () internal {
        // The counter starts at one to prevent changing it from zero to a non-zero
        // value, which is a more expensive operation.
        _guardCounter = 1;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _guardCounter += 1;
        uint256 localCounter = _guardCounter;
        _;
        require(localCounter == _guardCounter, "ReentrancyGuard: reentrant call");
    }
}

// File: contracts/Tornado.sol

// https://tornado.cash
/*
* d888888P                                           dP              a88888b.                   dP
*    88                                              88             d8'   `88                   88
*    88    .d8888b. 88d888b. 88d888b. .d8888b. .d888b88 .d8888b.    88        .d8888b. .d8888b. 88d888b.
*    88    88'  `88 88'  `88 88'  `88 88'  `88 88'  `88 88'  `88    88        88'  `88 Y8ooooo. 88'  `88
*    88    88.  .88 88       88    88 88.  .88 88.  .88 88.  .88 dP Y8.   .88 88.  .88       88 88    88
*    dP    `88888P' dP       dP    dP `88888P8 `88888P8 `88888P' 88  Y88888P' `88888P8 `88888P' dP    dP
* ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
*/

pragma solidity ^0.5.8;



contract IVerifier {
  function verifyProof(bytes memory _proof, uint256[6] memory _input) public returns(bool);
}

contract Tornado is MerkleTreeWithHistory, ReentrancyGuard {
  uint256 public denomination;
  mapping(bytes32 => bool) public nullifierHashes;
  // we store all commitments just to prevent accidental deposits with the same commitment
  mapping(bytes32 => bool) public commitments;
  IVerifier public verifier;

  // operator can update snark verification key
  // after the final trusted setup ceremony operator rights are supposed to be transferred to zero address
  address public operator;
  modifier onlyOperator {
    require(msg.sender == operator, "Only operator can call this function.");
    _;
  }

  event Deposit(bytes32 indexed commitment, uint32 leafIndex, uint256 timestamp);
  event Withdrawal(address to, bytes32 nullifierHash, address indexed relayer, uint256 fee);

  /**
    @dev The constructor
    @param _verifier the address of SNARK verifier for this contract
    @param _denomination transfer amount for each deposit
    @param _merkleTreeHeight the height of deposits' Merkle Tree
    @param _operator operator address (see operator comment above)
  */
  constructor(
    IVerifier _verifier,
    uint256 _denomination,
    uint32 _merkleTreeHeight,
    address _operator
  ) MerkleTreeWithHistory(_merkleTreeHeight) public {
    require(_denomination > 0, "denomination should be greater than 0");
    verifier = _verifier;
    operator = _operator;
    denomination = _denomination;
  }

  /**
    @dev Deposit funds into the contract. The caller must send (for ETH) or approve (for ERC20) value equal to or `denomination` of this instance.
    @param _commitment the note commitment, which is PedersenHash(nullifier + secret)
  */
  function deposit(bytes32 _commitment) external payable nonReentrant {
    require(!commitments[_commitment], "The commitment has been submitted");

    uint32 insertedIndex = _insert(_commitment);
    commitments[_commitment] = true;
    _processDeposit();

    emit Deposit(_commitment, insertedIndex, block.timestamp);
  }

  /** @dev this function is defined in a child contract */
  function _processDeposit() internal;

  /**
    @dev Withdraw a deposit from the contract. `proof` is a zkSNARK proof data, and input is an array of circuit public inputs
    `input` array consists of:
      - merkle root of all deposits in the contract
      - hash of unique deposit nullifier to prevent double spends
      - the recipient of funds
      - optional fee that goes to the transaction sender (usually a relay)
  */
  function withdraw(bytes calldata _proof, bytes32 _root, bytes32 _nullifierHash, address payable _recipient, address payable _relayer, uint256 _fee, uint256 _refund) external payable nonReentrant {
    require(_fee <= denomination, "Fee exceeds transfer value");
    require(!nullifierHashes[_nullifierHash], "The note has been already spent");
    require(isKnownRoot(_root), "Cannot find your merkle root"); // Make sure to use a recent one
    require(verifier.verifyProof(_proof, [uint256(_root), uint256(_nullifierHash), uint256(_recipient), uint256(_relayer), _fee, _refund]), "Invalid withdraw proof");

    nullifierHashes[_nullifierHash] = true;
    _processWithdraw(_recipient, _relayer, _fee, _refund);
    emit Withdrawal(_recipient, _nullifierHash, _relayer, _fee);
  }

  /** @dev this function is defined in a child contract */
  function _processWithdraw(address payable _recipient, address payable _relayer, uint256 _fee, uint256 _refund) internal;

  /** @dev whether a note is already spent */
  function isSpent(bytes32 _nullifierHash) public view returns(bool) {
    return nullifierHashes[_nullifierHash];
  }

  /** @dev whether an array of notes is already spent */
  function isSpentArray(bytes32[] calldata _nullifierHashes) external view returns(bool[] memory spent) {
    spent = new bool[](_nullifierHashes.length);
    for(uint i = 0; i < _nullifierHashes.length; i++) {
      if (isSpent(_nullifierHashes[i])) {
        spent[i] = true;
      }
    }
  }

  /**
    @dev allow operator to update SNARK verification keys. This is needed to update keys after the final trusted setup ceremony is held.
    After that operator rights are supposed to be transferred to zero address
  */
  function updateVerifier(address _newVerifier) external onlyOperator {
    verifier = IVerifier(_newVerifier);
  }

  /** @dev operator can change his address */
  function changeOperator(address _newOperator) external onlyOperator {
    operator = _newOperator;
  }
}

// File: contracts/ERC20Tornado.sol

// https://tornado.cash
/*
* d888888P                                           dP              a88888b.                   dP
*    88                                              88             d8'   `88                   88
*    88    .d8888b. 88d888b. 88d888b. .d8888b. .d888b88 .d8888b.    88        .d8888b. .d8888b. 88d888b.
*    88    88'  `88 88'  `88 88'  `88 88'  `88 88'  `88 88'  `88    88        88'  `88 Y8ooooo. 88'  `88
*    88    88.  .88 88       88    88 88.  .88 88.  .88 88.  .88 dP Y8.   .88 88.  .88       88 88    88
*    dP    `88888P' dP       dP    dP `88888P8 `88888P8 `88888P' 88  Y88888P' `88888P8 `88888P' dP    dP
* ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
*/

pragma solidity ^0.5.8;


contract TornadoCash_erc20 is Tornado {
  address public token;

  constructor(
    IVerifier _verifier,
    uint256 _denomination,
    uint32 _merkleTreeHeight,
    address _operator,
    address _token
  ) Tornado(_verifier, _denomination, _merkleTreeHeight, _operator) public {
    token = _token;
  }

  function _processDeposit() internal {
    require(msg.value == 0, "ETH value is supposed to be 0 for ERC20 instance");
    _safeErc20TransferFrom(msg.sender, address(this), denomination);
  }

  function _processWithdraw(address payable _recipient, address payable _relayer, uint256 _fee, uint256 _refund) internal {
    require(msg.value == _refund, "Incorrect refund amount received by the contract");

    _safeErc20Transfer(_recipient, denomination - _fee);
    if (_fee > 0) {
      _safeErc20Transfer(_relayer, _fee);
    }

    if (_refund > 0) {
      (bool success, ) = _recipient.call.value(_refund)("");
      if (!success) {
        // let's return _refund back to the relayer
        _relayer.transfer(_refund);
      }
    }
  }

  function _safeErc20TransferFrom(address _from, address _to, uint256 _amount) internal {
    (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd /* transferFrom */, _from, _to, _amount));
    require(success, "not enough allowed tokens");

    // if contract returns some data lets make sure that is `true` according to standard
    if (data.length > 0) {
      require(data.length == 32, "data length should be either 0 or 32 bytes");
      success = abi.decode(data, (bool));
      require(success, "not enough allowed tokens. Token returns false.");
    }
  }

  function _safeErc20Transfer(address _to, uint256 _amount) internal {
    (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb /* transfer */, _to, _amount));
    require(success, "not enough tokens");

    // if contract returns some data lets make sure that is `true` according to standard
    if (data.length > 0) {
      require(data.length == 32, "data length should be either 0 or 32 bytes");
      success = abi.decode(data, (bool));
      require(success, "not enough tokens. Token returns false.");
    }
  }
}

// https://tornado.cash Verifier.sol generated by trusted setup ceremony.
/*
* d888888P                                           dP              a88888b.                   dP
*    88                                              88             d8'   `88                   88
*    88    .d8888b. 88d888b. 88d888b. .d8888b. .d888b88 .d8888b.    88        .d8888b. .d8888b. 88d888b.
*    88    88'  `88 88'  `88 88'  `88 88'  `88 88'  `88 88'  `88    88        88'  `88 Y8ooooo. 88'  `88
*    88    88.  .88 88       88    88 88.  .88 88.  .88 88.  .88 dP Y8.   .88 88.  .88       88 88    88
*    dP    `88888P' dP       dP    dP `88888P8 `88888P8 `88888P' 88  Y88888P' `88888P8 `88888P' dP    dP
* ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
*/
// Copyright 2017 Christian Reitwiessner
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

// 2019 OKIMS

pragma solidity 0.5.17;

library Pairing {
    uint256 constant PRIME_Q = 21888242871839275222246405745257275088696311157297823662689037894645226208583;

    struct G1Point {
        uint256 X;
        uint256 Y;
    }

    // Encoding of field elements is: X[0] * z + X[1]
    struct G2Point {
        uint256[2] X;
        uint256[2] Y;
    }

    /*
     * @return The negation of p, i.e. p.plus(p.negate()) should be zero.
     */
    function negate(G1Point memory p) internal pure returns (G1Point memory) {
        // The prime q in the base field F_q for G1
        if (p.X == 0 && p.Y == 0) {
            return G1Point(0, 0);
        } else {
            return G1Point(p.X, PRIME_Q - (p.Y % PRIME_Q));
        }
    }

    /*
     * @return r the sum of two points of G1
     */
    function plus(
        G1Point memory p1,
        G1Point memory p2
    ) internal view returns (G1Point memory r) {
        uint256[4] memory input;
        input[0] = p1.X;
        input[1] = p1.Y;
        input[2] = p2.X;
        input[3] = p2.Y;
        bool success;

        // solium-disable-next-line security/no-inline-assembly
        assembly {
            success := staticcall(sub(gas(), 2000), 6, input, 0xc0, r, 0x60)
            // Use "invalid" to make gas estimation work
            switch success case 0 { invalid() }
        }

        require(success, "pairing-add-failed");
    }

    /*
     * @return r the product of a point on G1 and a scalar, i.e.
     *         p == p.scalar_mul(1) and p.plus(p) == p.scalar_mul(2) for all
     *         points p.
     */
    function scalar_mul(G1Point memory p, uint256 s) internal view returns (G1Point memory r) {
        uint256[3] memory input;
        input[0] = p.X;
        input[1] = p.Y;
        input[2] = s;
        bool success;
        // solium-disable-next-line security/no-inline-assembly
        assembly {
            success := staticcall(sub(gas(), 2000), 7, input, 0x80, r, 0x60)
            // Use "invalid" to make gas estimation work
            switch success case 0 { invalid() }
        }
        require(success, "pairing-mul-failed");
    }

    /* @return The result of computing the pairing check
     *         e(p1[0], p2[0]) *  .... * e(p1[n], p2[n]) == 1
     *         For example,
     *         pairing([P1(), P1().negate()], [P2(), P2()]) should return true.
     */
    function pairing(
        G1Point memory a1,
        G2Point memory a2,
        G1Point memory b1,
        G2Point memory b2,
        G1Point memory c1,
        G2Point memory c2,
        G1Point memory d1,
        G2Point memory d2
    ) internal view returns (bool) {
        G1Point[4] memory p1 = [a1, b1, c1, d1];
        G2Point[4] memory p2 = [a2, b2, c2, d2];

        uint256 inputSize = 24;
        uint256[] memory input = new uint256[](inputSize);

        for (uint256 i = 0; i < 4; i++) {
            uint256 j = i * 6;
            input[j + 0] = p1[i].X;
            input[j + 1] = p1[i].Y;
            input[j + 2] = p2[i].X[0];
            input[j + 3] = p2[i].X[1];
            input[j + 4] = p2[i].Y[0];
            input[j + 5] = p2[i].Y[1];
        }

        uint256[1] memory out;
        bool success;

        // solium-disable-next-line security/no-inline-assembly
        assembly {
            success := staticcall(sub(gas(), 2000), 8, add(input, 0x20), mul(inputSize, 0x20), out, 0x20)
            // Use "invalid" to make gas estimation work
            switch success case 0 { invalid() }
        }

        require(success, "pairing-opcode-failed");

        return out[0] != 0;
    }
}

contract Verifier {
    uint256 constant SNARK_SCALAR_FIELD = 21888242871839275222246405745257275088548364400416034343698204186575808495617;
    uint256 constant PRIME_Q = 21888242871839275222246405745257275088696311157297823662689037894645226208583;
    using Pairing for *;

    struct VerifyingKey {
        Pairing.G1Point alfa1;
        Pairing.G2Point beta2;
        Pairing.G2Point gamma2;
        Pairing.G2Point delta2;
        Pairing.G1Point[7] IC;
    }

    struct Proof {
        Pairing.G1Point A;
        Pairing.G2Point B;
        Pairing.G1Point C;
    }

    function verifyingKey() internal pure returns (VerifyingKey memory vk) {
        vk.alfa1 = Pairing.G1Point(uint256(20692898189092739278193869274495556617788530808486270118371701516666252877969), uint256(11713062878292653967971378194351968039596396853904572879488166084231740557279));
        vk.beta2 = Pairing.G2Point([uint256(12168528810181263706895252315640534818222943348193302139358377162645029937006), uint256(281120578337195720357474965979947690431622127986816839208576358024608803542)], [uint256(16129176515713072042442734839012966563817890688785805090011011570989315559913), uint256(9011703453772030375124466642203641636825223906145908770308724549646909480510)]);
        vk.gamma2 = Pairing.G2Point([uint256(11559732032986387107991004021392285783925812861821192530917403151452391805634), uint256(10857046999023057135944570762232829481370756359578518086990519993285655852781)], [uint256(4082367875863433681332203403145435568316851327593401208105741076214120093531), uint256(8495653923123431417604973247489272438418190587263600148770280649306958101930)]);
        vk.delta2 = Pairing.G2Point([uint256(21280594949518992153305586783242820682644996932183186320680800072133486887432), uint256(150879136433974552800030963899771162647715069685890547489132178314736470662)], [uint256(1081836006956609894549771334721413187913047383331561601606260283167615953295), uint256(11434086686358152335540554643130007307617078324975981257823476472104616196090)]);
        vk.IC[0] = Pairing.G1Point(uint256(16225148364316337376768119297456868908427925829817748684139175309620217098814), uint256(5167268689450204162046084442581051565997733233062478317813755636162413164690));
        vk.IC[1] = Pairing.G1Point(uint256(12882377842072682264979317445365303375159828272423495088911985689463022094260), uint256(19488215856665173565526758360510125932214252767275816329232454875804474844786));
        vk.IC[2] = Pairing.G1Point(uint256(13083492661683431044045992285476184182144099829507350352128615182516530014777), uint256(602051281796153692392523702676782023472744522032670801091617246498551238913));
        vk.IC[3] = Pairing.G1Point(uint256(9732465972180335629969421513785602934706096902316483580882842789662669212890), uint256(2776526698606888434074200384264824461688198384989521091253289776235602495678));
        vk.IC[4] = Pairing.G1Point(uint256(8586364274534577154894611080234048648883781955345622578531233113180532234842), uint256(21276134929883121123323359450658320820075698490666870487450985603988214349407));
        vk.IC[5] = Pairing.G1Point(uint256(4910628533171597675018724709631788948355422829499855033965018665300386637884), uint256(20532468890024084510431799098097081600480376127870299142189696620752500664302));
        vk.IC[6] = Pairing.G1Point(uint256(15335858102289947642505450692012116222827233918185150176888641903531542034017), uint256(5311597067667671581646709998171703828965875677637292315055030353779531404812));

    }

    /*
     * @returns Whether the proof is valid given the hardcoded verifying key
     *          above and the public inputs
     */
    function verifyProof(
        bytes memory proof,
        uint256[6] memory input
    ) public view returns (bool) {
        uint256[8] memory p = abi.decode(proof, (uint256[8]));

        // Make sure that each element in the proof is less than the prime q
        for (uint8 i = 0; i < p.length; i++) {
            require(p[i] < PRIME_Q, "verifier-proof-element-gte-prime-q");
        }

        Proof memory _proof;
        _proof.A = Pairing.G1Point(p[0], p[1]);
        _proof.B = Pairing.G2Point([p[2], p[3]], [p[4], p[5]]);
        _proof.C = Pairing.G1Point(p[6], p[7]);

        VerifyingKey memory vk = verifyingKey();

        // Compute the linear combination vk_x
        Pairing.G1Point memory vk_x = Pairing.G1Point(0, 0);
        vk_x = Pairing.plus(vk_x, vk.IC[0]);

        // Make sure that every input is less than the snark scalar field
        for (uint256 i = 0; i < input.length; i++) {
            require(input[i] < SNARK_SCALAR_FIELD, "verifier-gte-snark-scalar-field");
            vk_x = Pairing.plus(vk_x, Pairing.scalar_mul(vk.IC[i + 1], input[i]));
        }

        return Pairing.pairing(
            Pairing.negate(_proof.A),
            _proof.B,
            vk.alfa1,
            vk.beta2,
            vk_x,
            vk.gamma2,
            _proof.C,
            vk.delta2
        );
    }
}