pragma solidity 0.5.10;
pragma experimental "ABIEncoderV2";

import "../libs/LibStateChannelApp.sol";
import "./MChallengeRegistryCore.sol";


contract MixinCancelChallenge is
  LibStateChannelApp,
  MChallengeRegistryCore
{

  /// @notice Unanimously agree to cancel a challenge
  /// @param appIdentity an AppIdentity object pointing to the app being cancelled
  /// @param signatures Signatures by all participants of the currently latest challenged
  /// state; an indication of agreement of this state and valid to cancel a challenge
  /// @dev Note this function is only callable when the application has an open challenge
  function cancelChallenge(
    AppIdentity memory appIdentity,
    bytes[] memory signatures
  )
    // TODO: Uncomment when ABIEncoderV2 supports `external`
    //       ref: https://github.com/ethereum/solidity/issues/3199
    // external
    public
  {
    bytes32 identityHash = appIdentityToHash(appIdentity);

    AppChallenge storage challenge = appChallenges[identityHash];

    require(
      (
        challenge.status == ChallengeStatus.FINALIZES_AFTER_DEADLINE
      ) && challenge.finalizesAt >= block.number,
      "cancelChallenge called on app not in FINALIZES_AFTER_DEADLINE state"
    );

    bytes32 stateHash = computeAppChallengeHash(
      identityHash,
      challenge.appStateHash,
      challenge.versionNumber,
      appIdentity.defaultTimeout
    );

    require(
      verifySignatures(signatures, stateHash, appIdentity.participants),
      "Invalid signatures"
    );

    challenge.finalizesAt = 0;
    challenge.status = ChallengeStatus.NO_CHALLENGE;
    challenge.latestSubmitter = msg.sender;
  }
}