// File: contracts/ZodiacPolygonRootTunnel.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.7.3;

import "./lib/FxBaseRootTunnel.sol";
import "./TunnelEnd.sol";

contract ZodiacPolygonRootTunnel is FxBaseRootTunnel, TunnelEnd {
  constructor(address _checkpointManager, address _fxRoot)
    FxBaseRootTunnel(_checkpointManager, _fxRoot)
  {}

  /// @dev Requests message relay to Child network
  /// @param target executor address on Child network
  /// @param data calldata passed to the executor on Child network
  /// @param gas gas limit used on Child Network for executing - 0xfffffff for unbound
  function sendMessage(
    address target,
    bytes memory data,
    uint256 gas
  ) public {
    bytes memory message = encodeIntoTunnel(target, data, gas);
    _sendMessageToChild(message);
  }

  function _processMessageFromChild(bytes memory message) internal override {
    (
      bytes32 sourceChainId,
      address sourceChainSender,
      address target,
      bytes memory data,
      uint256 gas
    ) = decodeFromTunnel(message);
    forwardToTarget(sourceChainId, sourceChainSender, target, data, gas);
  }
}

// File: contracts/lib/FxBaseRootTunnel.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.7.3;

import "./RLPReader.sol";
import "./Merkle.sol";
import "./MerklePatriciaProof.sol";

interface IFxStateSender {
  function sendMessageToChild(address _receiver, bytes calldata _data) external;
}

contract ICheckpointManager {
  struct HeaderBlock {
    bytes32 root;
    uint256 start;
    uint256 end;
    uint256 createdAt;
    address proposer;
  }

  /**
   * @notice mapping of checkpoint header numbers to block details
   * @dev These checkpoints are submited by plasma contracts
   */
  mapping(uint256 => HeaderBlock) public headerBlocks;
}

abstract contract FxBaseRootTunnel {
  using RLPReader for bytes;
  using RLPReader for RLPReader.RLPItem;
  using Merkle for bytes32;

  // keccak256(MessageSent(bytes))
  bytes32 public constant SEND_MESSAGE_EVENT_SIG =
    0x8c5261668696ce22758910d05bab8f186d6eb247ceac2af2e82c7dc17669b036;

  // state sender contract
  IFxStateSender public fxRoot;
  // root chain manager
  ICheckpointManager public checkpointManager;
  // child tunnel contract which receives and sends messages
  address public fxChildTunnel;

  // storage to avoid duplicate exits
  mapping(bytes32 => bool) public processedExits;

  constructor(address _checkpointManager, address _fxRoot) {
    checkpointManager = ICheckpointManager(_checkpointManager);
    fxRoot = IFxStateSender(_fxRoot);
  }

  // set fxChildTunnel if not set already
  function setFxChildTunnel(address _fxChildTunnel) public {
    require(
      fxChildTunnel == address(0x0),
      "FxBaseRootTunnel: CHILD_TUNNEL_ALREADY_SET"
    );
    fxChildTunnel = _fxChildTunnel;
  }

  /**
   * @notice Send bytes message to Child Tunnel
   * @param message bytes message that will be sent to Child Tunnel
   * some message examples -
   *   abi.encode(tokenId);
   *   abi.encode(tokenId, tokenMetadata);
   *   abi.encode(messageType, messageData);
   */
  function _sendMessageToChild(bytes memory message) internal {
    fxRoot.sendMessageToChild(fxChildTunnel, message);
  }

  function _validateAndExtractMessage(bytes memory inputData)
    internal
    returns (bytes memory)
  {
    RLPReader.RLPItem[] memory inputDataRLPList = inputData
      .toRlpItem()
      .toList();

    // checking if exit has already been processed
    // unique exit is identified using hash of (blockNumber, branchMask, receiptLogIndex)
    bytes32 exitHash = keccak256(
      abi.encodePacked(
        inputDataRLPList[2].toUint(), // blockNumber
        // first 2 nibbles are dropped while generating nibble array
        // this allows branch masks that are valid but bypass exitHash check (changing first 2 nibbles only)
        // so converting to nibble array and then hashing it
        MerklePatriciaProof._getNibbleArray(inputDataRLPList[8].toBytes()), // branchMask
        inputDataRLPList[9].toUint() // receiptLogIndex
      )
    );
    require(
      processedExits[exitHash] == false,
      "FxRootTunnel: EXIT_ALREADY_PROCESSED"
    );
    processedExits[exitHash] = true;

    RLPReader.RLPItem[] memory receiptRLPList = inputDataRLPList[6]
      .toBytes()
      .toRlpItem()
      .toList();
    RLPReader.RLPItem memory logRLP = receiptRLPList[3].toList()[
      inputDataRLPList[9].toUint() // receiptLogIndex
    ];

    RLPReader.RLPItem[] memory logRLPList = logRLP.toList();

    // check child tunnel
    require(
      fxChildTunnel == RLPReader.toAddress(logRLPList[0]),
      "FxRootTunnel: INVALID_FX_CHILD_TUNNEL"
    );

    // verify receipt inclusion
    require(
      MerklePatriciaProof.verify(
        inputDataRLPList[6].toBytes(), // receipt
        inputDataRLPList[8].toBytes(), // branchMask
        inputDataRLPList[7].toBytes(), // receiptProof
        bytes32(inputDataRLPList[5].toUint()) // receiptRoot
      ),
      "FxRootTunnel: INVALID_RECEIPT_PROOF"
    );

    // verify checkpoint inclusion
    _checkBlockMembershipInCheckpoint(
      inputDataRLPList[2].toUint(), // blockNumber
      inputDataRLPList[3].toUint(), // blockTime
      bytes32(inputDataRLPList[4].toUint()), // txRoot
      bytes32(inputDataRLPList[5].toUint()), // receiptRoot
      inputDataRLPList[0].toUint(), // headerNumber
      inputDataRLPList[1].toBytes() // blockProof
    );

    RLPReader.RLPItem[] memory logTopicRLPList = logRLPList[1].toList(); // topics

    require(
      bytes32(logTopicRLPList[0].toUint()) == SEND_MESSAGE_EVENT_SIG, // topic0 is event sig
      "FxRootTunnel: INVALID_SIGNATURE"
    );

    // received message data
    bytes memory receivedData = logRLPList[2].toBytes();
    bytes memory message = abi.decode(receivedData, (bytes)); // event decodes params again, so decoding bytes to get message
    return message;
  }

  function _checkBlockMembershipInCheckpoint(
    uint256 blockNumber,
    uint256 blockTime,
    bytes32 txRoot,
    bytes32 receiptRoot,
    uint256 headerNumber,
    bytes memory blockProof
  ) private view returns (uint256) {
    (
      bytes32 headerRoot,
      uint256 startBlock,
      ,
      uint256 createdAt,

    ) = checkpointManager.headerBlocks(headerNumber);

    require(
      keccak256(abi.encodePacked(blockNumber, blockTime, txRoot, receiptRoot))
        .checkMembership(blockNumber - startBlock, headerRoot, blockProof),
      "FxRootTunnel: INVALID_HEADER"
    );
    return createdAt;
  }

  /**
   * @notice receive message from  L2 to L1, validated by proof
   * @dev This function verifies if the transaction actually happened on child chain
   *
   * @param inputData RLP encoded data of the reference tx containing following list of fields
   *  0 - headerNumber - Checkpoint header block number containing the reference tx
   *  1 - blockProof - Proof that the block header (in the child chain) is a leaf in the submitted merkle root
   *  2 - blockNumber - Block number containing the reference tx on child chain
   *  3 - blockTime - Reference tx block time
   *  4 - txRoot - Transactions root of block
   *  5 - receiptRoot - Receipts root of block
   *  6 - receipt - Receipt of the reference transaction
   *  7 - receiptProof - Merkle proof of the reference receipt
   *  8 - branchMask - 32 bits denoting the path of receipt in merkle tree
   *  9 - receiptLogIndex - Log Index to read from the receipt
   */
  function receiveMessage(bytes memory inputData) public virtual {
    bytes memory message = _validateAndExtractMessage(inputData);
    _processMessageFromChild(message);
  }

  /**
   * @notice Process message received from Child Tunnel
   * @dev function needs to be implemented to handle message as per requirement
   * This is called by onStateReceive function.
   * Since it is called via a system call, any event will not be emitted during its execution.
   * @param message bytes message that was sent from Child Tunnel
   */
  function _processMessageFromChild(bytes memory message) internal virtual;
}

// File: contracts/TunnelEnd.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.7.3;

/// @title TunnelEnd - A contract that contains base/common functionality for ZodiacPolygonTunnel pairs
/// @author Cristóvão Honorato - <cristovao.honorato@gnosis.pm>
contract TunnelEnd {
  bytes32 private latestSourceChainId;
  address private latestSourceChainSender;

  /// @dev Provides the end executor contract with the id of the network where the call originated
  function messageSourceChainId() public view returns (bytes32) {
    return latestSourceChainId;
  }

  /// @dev Provides the end executor contract with the address that triggered the call
  function messageSender() public view returns (address) {
    return latestSourceChainSender;
  }

  /// @dev Encodes a message to be delivered to FxRoot/FxChild
  /// @param target executor address on the other side
  /// @param data calldata passed to the executor on the other side
  /// @param gas gas limit used on the other side for executing
  function encodeIntoTunnel(
    address target,
    bytes memory data,
    uint256 gas
  ) internal view returns (bytes memory) {
    return abi.encode(getChainId(), msg.sender, target, data, gas);
  }

  /// @dev Decodes a message delivered by FxRoot/FxChild
  /// @param message encoded payload describing executor and parameters. Includes also original sender and origin network id
  function decodeFromTunnel(bytes memory message)
    internal
    pure
    returns (
      bytes32,
      address,
      address,
      bytes memory,
      uint256
    )
  {
    (
      bytes32 sourceChainId,
      address sourceChainSender,
      address target,
      bytes memory data,
      uint256 gas
    ) = abi.decode(message, (bytes32, address, address, bytes, uint256));

    return (sourceChainId, sourceChainSender, target, data, gas);
  }

  /// @dev Triggers the process of sending a message to the opposite network
  /// @param sourceChainId id of the network where the call was initiated
  /// @param sourceChainSender address that initiated the call
  /// @param target executor address on the other side
  /// @param data calldata passed to the executor on the other side
  /// @param gas gas limit used on the other side for executing
  function forwardToTarget(
    bytes32 sourceChainId,
    address sourceChainSender,
    address target,
    bytes memory data,
    uint256 gas
  ) internal {
    require(gas == 0xffffffff || (gasleft() * 63) / 64 > gas);

    latestSourceChainId = sourceChainId;
    latestSourceChainSender = sourceChainSender;
    (bool success, ) = target.call{gas: gas}(data);
    latestSourceChainSender = address(0);
    latestSourceChainId = bytes32("0x");
    require(success, "ForwardToTarget failed");
  }

  function getChainId() private pure returns (bytes32) {
    uint256 id;
    assembly {
      id := chainid()
    }
    return bytes32(id);
  }
}

// File: contracts/lib/RLPReader.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.7.3;

library RLPReader {
  uint8 constant STRING_SHORT_START = 0x80;
  uint8 constant STRING_LONG_START = 0xb8;
  uint8 constant LIST_SHORT_START = 0xc0;
  uint8 constant LIST_LONG_START = 0xf8;
  uint8 constant WORD_SIZE = 32;

  struct RLPItem {
    uint256 len;
    uint256 memPtr;
  }

  /*
   * @param item RLP encoded bytes
   */
  function toRlpItem(bytes memory item) internal pure returns (RLPItem memory) {
    require(item.length > 0, "RLPReader: INVALID_BYTES_LENGTH");
    uint256 memPtr;
    assembly {
      memPtr := add(item, 0x20)
    }

    return RLPItem(item.length, memPtr);
  }

  /*
   * @param item RLP encoded list in bytes
   */
  function toList(RLPItem memory item)
    internal
    pure
    returns (RLPItem[] memory)
  {
    require(isList(item), "RLPReader: ITEM_NOT_LIST");

    uint256 items = numItems(item);
    RLPItem[] memory result = new RLPItem[](items);
    uint256 listLength = _itemLength(item.memPtr);
    require(listLength == item.len, "RLPReader: LIST_DECODED_LENGTH_MISMATCH");

    uint256 memPtr = item.memPtr + _payloadOffset(item.memPtr);
    uint256 dataLen;
    for (uint256 i = 0; i < items; i++) {
      dataLen = _itemLength(memPtr);
      result[i] = RLPItem(dataLen, memPtr);
      memPtr = memPtr + dataLen;
    }

    return result;
  }

  // @return indicator whether encoded payload is a list. negate this function call for isData.
  function isList(RLPItem memory item) internal pure returns (bool) {
    uint8 byte0;
    uint256 memPtr = item.memPtr;
    assembly {
      byte0 := byte(0, mload(memPtr))
    }

    if (byte0 < LIST_SHORT_START) return false;
    return true;
  }

  /** RLPItem conversions into data types **/

  // @returns raw rlp encoding in bytes
  function toRlpBytes(RLPItem memory item)
    internal
    pure
    returns (bytes memory)
  {
    bytes memory result = new bytes(item.len);

    uint256 ptr;
    assembly {
      ptr := add(0x20, result)
    }

    copy(item.memPtr, ptr, item.len);
    return result;
  }

  function toAddress(RLPItem memory item) internal pure returns (address) {
    require(!isList(item), "RLPReader: DECODING_LIST_AS_ADDRESS");
    // 1 byte for the length prefix
    require(item.len == 21, "RLPReader: INVALID_ADDRESS_LENGTH");

    return address(toUint(item));
  }

  function toUint(RLPItem memory item) internal pure returns (uint256) {
    require(!isList(item), "RLPReader: DECODING_LIST_AS_UINT");
    require(item.len <= 33, "RLPReader: INVALID_UINT_LENGTH");

    uint256 itemLength = _itemLength(item.memPtr);
    require(itemLength == item.len, "RLPReader: UINT_DECODED_LENGTH_MISMATCH");

    uint256 offset = _payloadOffset(item.memPtr);
    uint256 len = item.len - offset;
    uint256 result;
    uint256 memPtr = item.memPtr + offset;
    assembly {
      result := mload(memPtr)

      // shfit to the correct location if neccesary
      if lt(len, 32) {
        result := div(result, exp(256, sub(32, len)))
      }
    }

    return result;
  }

  // enforces 32 byte length
  function toUintStrict(RLPItem memory item) internal pure returns (uint256) {
    uint256 itemLength = _itemLength(item.memPtr);
    require(
      itemLength == item.len,
      "RLPReader: UINT_STRICT_DECODED_LENGTH_MISMATCH"
    );
    // one byte prefix
    require(item.len == 33, "RLPReader: INVALID_UINT_STRICT_LENGTH");

    uint256 result;
    uint256 memPtr = item.memPtr + 1;
    assembly {
      result := mload(memPtr)
    }

    return result;
  }

  function toBytes(RLPItem memory item) internal pure returns (bytes memory) {
    uint256 listLength = _itemLength(item.memPtr);
    require(listLength == item.len, "RLPReader: BYTES_DECODED_LENGTH_MISMATCH");
    uint256 offset = _payloadOffset(item.memPtr);

    uint256 len = item.len - offset; // data length
    bytes memory result = new bytes(len);

    uint256 destPtr;
    assembly {
      destPtr := add(0x20, result)
    }

    copy(item.memPtr + offset, destPtr, len);
    return result;
  }

  /*
   * Private Helpers
   */

  // @return number of payload items inside an encoded list.
  function numItems(RLPItem memory item) private pure returns (uint256) {
    // add `isList` check if `item` is expected to be passsed without a check from calling function
    // require(isList(item), "RLPReader: NUM_ITEMS_NOT_LIST");

    uint256 count = 0;
    uint256 currPtr = item.memPtr + _payloadOffset(item.memPtr);
    uint256 endPtr = item.memPtr + item.len;
    while (currPtr < endPtr) {
      currPtr = currPtr + _itemLength(currPtr); // skip over an item
      require(
        currPtr <= endPtr,
        "RLPReader: NUM_ITEMS_DECODED_LENGTH_MISMATCH"
      );
      count++;
    }

    return count;
  }

  // @return entire rlp item byte length
  function _itemLength(uint256 memPtr) private pure returns (uint256) {
    uint256 itemLen;
    uint256 byte0;
    assembly {
      byte0 := byte(0, mload(memPtr))
    }

    if (byte0 < STRING_SHORT_START) itemLen = 1;
    else if (byte0 < STRING_LONG_START)
      itemLen = byte0 - STRING_SHORT_START + 1;
    else if (byte0 < LIST_SHORT_START) {
      assembly {
        let byteLen := sub(byte0, 0xb7) // # of bytes the actual length is
        memPtr := add(memPtr, 1) // skip over the first byte

        /* 32 byte word size */
        let dataLen := div(mload(memPtr), exp(256, sub(32, byteLen))) // right shifting to get the len
        itemLen := add(dataLen, add(byteLen, 1))
      }
    } else if (byte0 < LIST_LONG_START) {
      itemLen = byte0 - LIST_SHORT_START + 1;
    } else {
      assembly {
        let byteLen := sub(byte0, 0xf7)
        memPtr := add(memPtr, 1)

        let dataLen := div(mload(memPtr), exp(256, sub(32, byteLen))) // right shifting to the correct length
        itemLen := add(dataLen, add(byteLen, 1))
      }
    }

    return itemLen;
  }

  // @return number of bytes until the data
  function _payloadOffset(uint256 memPtr) private pure returns (uint256) {
    uint256 byte0;
    assembly {
      byte0 := byte(0, mload(memPtr))
    }

    if (byte0 < STRING_SHORT_START) return 0;
    else if (
      byte0 < STRING_LONG_START ||
      (byte0 >= LIST_SHORT_START && byte0 < LIST_LONG_START)
    ) return 1;
    else if (byte0 < LIST_SHORT_START)
      // being explicit
      return byte0 - (STRING_LONG_START - 1) + 1;
    else return byte0 - (LIST_LONG_START - 1) + 1;
  }

  /*
   * @param src Pointer to source
   * @param dest Pointer to destination
   * @param len Amount of memory to copy from the source
   */
  function copy(
    uint256 src,
    uint256 dest,
    uint256 len
  ) private pure {
    if (len == 0) return;

    // copy as many word sizes as possible
    for (; len >= WORD_SIZE; len -= WORD_SIZE) {
      assembly {
        mstore(dest, mload(src))
      }

      src += WORD_SIZE;
      dest += WORD_SIZE;
    }

    // left over bytes. Mask is used to remove unwanted bytes from the word
    uint256 mask = 256**(WORD_SIZE - len) - 1;
    assembly {
      let srcpart := and(mload(src), not(mask)) // zero out src
      let destpart := and(mload(dest), mask) // retrieve the bytes
      mstore(dest, or(destpart, srcpart))
    }
  }
}

// File: contracts/lib/Merkle.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.7.3;

library Merkle {
  function checkMembership(
    bytes32 leaf,
    uint256 index,
    bytes32 rootHash,
    bytes memory proof
  ) internal pure returns (bool) {
    require(proof.length % 32 == 0, "Invalid proof length");
    uint256 proofHeight = proof.length / 32;
    // Proof of size n means, height of the tree is n+1.
    // In a tree of height n+1, max #leafs possible is 2 ^ n
    require(index < 2**proofHeight, "Leaf index is too big");

    bytes32 proofElement;
    bytes32 computedHash = leaf;
    for (uint256 i = 32; i <= proof.length; i += 32) {
      assembly {
        proofElement := mload(add(proof, i))
      }

      if (index % 2 == 0) {
        computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
      } else {
        computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
      }

      index = index / 2;
    }
    return computedHash == rootHash;
  }
}

// File: contracts/lib/MerklePatriciaProof.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.7.3;

import "./RLPReader.sol";

library MerklePatriciaProof {
  /*
   * @dev Verifies a merkle patricia proof.
   * @param value The terminating value in the trie.
   * @param encodedPath The path in the trie leading to value.
   * @param rlpParentNodes The rlp encoded stack of nodes.
   * @param root The root hash of the trie.
   * @return The boolean validity of the proof.
   */
  function verify(
    bytes memory value,
    bytes memory encodedPath,
    bytes memory rlpParentNodes,
    bytes32 root
  ) internal pure returns (bool) {
    RLPReader.RLPItem memory item = RLPReader.toRlpItem(rlpParentNodes);
    RLPReader.RLPItem[] memory parentNodes = RLPReader.toList(item);

    bytes memory currentNode;
    RLPReader.RLPItem[] memory currentNodeList;

    bytes32 nodeKey = root;
    uint256 pathPtr = 0;

    bytes memory path = _getNibbleArray(encodedPath);
    if (path.length == 0) {
      return false;
    }

    for (uint256 i = 0; i < parentNodes.length; i++) {
      if (pathPtr > path.length) {
        return false;
      }

      currentNode = RLPReader.toRlpBytes(parentNodes[i]);
      if (nodeKey != keccak256(currentNode)) {
        return false;
      }
      currentNodeList = RLPReader.toList(parentNodes[i]);

      if (currentNodeList.length == 17) {
        if (pathPtr == path.length) {
          if (
            keccak256(RLPReader.toBytes(currentNodeList[16])) ==
            keccak256(value)
          ) {
            return true;
          } else {
            return false;
          }
        }

        uint8 nextPathNibble = uint8(path[pathPtr]);
        if (nextPathNibble > 16) {
          return false;
        }
        nodeKey = bytes32(
          RLPReader.toUintStrict(currentNodeList[nextPathNibble])
        );
        pathPtr += 1;
      } else if (currentNodeList.length == 2) {
        uint256 traversed = _nibblesToTraverse(
          RLPReader.toBytes(currentNodeList[0]),
          path,
          pathPtr
        );
        if (pathPtr + traversed == path.length) {
          //leaf node
          if (
            keccak256(RLPReader.toBytes(currentNodeList[1])) == keccak256(value)
          ) {
            return true;
          } else {
            return false;
          }
        }

        //extension node
        if (traversed == 0) {
          return false;
        }

        pathPtr += traversed;
        nodeKey = bytes32(RLPReader.toUintStrict(currentNodeList[1]));
      } else {
        return false;
      }
    }
  }

  function _nibblesToTraverse(
    bytes memory encodedPartialPath,
    bytes memory path,
    uint256 pathPtr
  ) private pure returns (uint256) {
    uint256 len = 0;
    // encodedPartialPath has elements that are each two hex characters (1 byte), but partialPath
    // and slicedPath have elements that are each one hex character (1 nibble)
    bytes memory partialPath = _getNibbleArray(encodedPartialPath);
    bytes memory slicedPath = new bytes(partialPath.length);

    // pathPtr counts nibbles in path
    // partialPath.length is a number of nibbles
    for (uint256 i = pathPtr; i < pathPtr + partialPath.length; i++) {
      bytes1 pathNibble = path[i];
      slicedPath[i - pathPtr] = pathNibble;
    }

    if (keccak256(partialPath) == keccak256(slicedPath)) {
      len = partialPath.length;
    } else {
      len = 0;
    }
    return len;
  }

  // bytes b must be hp encoded
  function _getNibbleArray(bytes memory b)
    internal
    pure
    returns (bytes memory)
  {
    bytes memory nibbles = "";
    if (b.length > 0) {
      uint8 offset;
      uint8 hpNibble = uint8(_getNthNibbleOfBytes(0, b));
      if (hpNibble == 1 || hpNibble == 3) {
        nibbles = new bytes(b.length * 2 - 1);
        bytes1 oddNibble = _getNthNibbleOfBytes(1, b);
        nibbles[0] = oddNibble;
        offset = 1;
      } else {
        nibbles = new bytes(b.length * 2 - 2);
        offset = 0;
      }

      for (uint256 i = offset; i < nibbles.length; i++) {
        nibbles[i] = _getNthNibbleOfBytes(i - offset + 2, b);
      }
    }
    return nibbles;
  }

  function _getNthNibbleOfBytes(uint256 n, bytes memory str)
    private
    pure
    returns (bytes1)
  {
    return
      bytes1(n % 2 == 0 ? uint8(str[n / 2]) / 0x10 : uint8(str[n / 2]) % 0x10);
  }
}