// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;
pragma experimental ABIEncoderV2;

import "../v1/Governance.sol";
import "../v3-relayer-registry/GovernanceStakingUpgrade.sol";

contract GovernancePatchUpgrade is GovernanceStakingUpgrade {
  mapping(uint256 => bytes32) public proposalCodehashes;

  event CodehashDifferent(address target, bytes32 oldHash, bytes32 newHash);

  // The stakingRewardsAddress sets the immutable to the new staking contract
  constructor(
    address stakingRewardsAddress,
    address gasCompLogic,
    address userVaultAddress
  ) public GovernanceStakingUpgrade(stakingRewardsAddress, gasCompLogic, userVaultAddress) {}

  // This should guarantee that the proposal extcodehashes are good
  function execute(uint256 proposalId) public payable virtual override(Governance) {
    require(msg.sender != address(this), "pseudo-external function");

    Proposal storage proposal = proposals[proposalId];

    address target = proposal.target;

    bytes32 proposalCodehash;

    assembly {
      proposalCodehash := extcodehash(target)
    }

    if (proposalCodehash == proposalCodehashes[proposalId]) {
      super.execute(proposalId);
    } else {
      // Note that this is the easiest way to block further execution
      proposal.executed = true;

      // Let the event signify it was broken
      emit CodehashDifferent(target, proposalCodehashes[proposalId], proposalCodehash);
    }
  }

  // This should store the proposal extcodehash
  function _propose(
    address proposer,
    address target,
    string memory description
  ) internal virtual override(Governance) returns (uint256 proposalId) {
    // Implies all former predicates were valid
    proposalId = super._propose(proposer, target, description);

    bytes32 proposalCodehash;

    assembly {
      proposalCodehash := extcodehash(target)
    }

    proposalCodehashes[proposalId] = proposalCodehash;
  }
}