pragma solidity 0.5.10;
pragma experimental "ABIEncoderV2";

import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";

import "../libs/LibOutcome.sol";
import "../interfaces/Interpreter.sol";


contract MultiAssetMultiPartyCoinTransferInterpreter is Interpreter {

  uint256 constant MAX_UINT256 = 2 ** 256 - 1;
  address constant CONVENTION_FOR_ETH_TOKEN_ADDRESS = address(0x0);

  struct MultiAssetMultiPartyCoinTransferInterpreterParams {
    uint256[] limit;
    address[] tokenAddresses;
  }

  // NOTE: This is useful for writing tests, but is bad practice
  // to have in the contract when deploying it. We do not want people
  // to send funds to this contract in any scenario.
  function () external payable { }

  function interpretOutcomeAndExecuteEffect(
    bytes calldata encodedOutcome,
    bytes calldata encodedParams
  )
    external
  {

    MultiAssetMultiPartyCoinTransferInterpreterParams memory params =
      abi.decode(
        encodedParams,
        (MultiAssetMultiPartyCoinTransferInterpreterParams)
      );

    LibOutcome.CoinTransfer[][] memory coinTransferListOfLists =
      abi.decode(
        encodedOutcome,
        (LibOutcome.CoinTransfer[][])
      );

    for (uint256 i = 0; i < coinTransferListOfLists.length; i++) {

      address tokenAddress = params.tokenAddresses[i];
      uint256 limitRemaining = params.limit[i];
      LibOutcome.CoinTransfer[] memory coinTransferList = coinTransferListOfLists[i];

      for (uint256 j = 0; j < coinTransferList.length; j++) {

        LibOutcome.CoinTransfer memory coinTransfer = coinTransferList[j];

        address payable to = address(uint160(coinTransfer.to));

        if (coinTransfer.amount > 0) {
          limitRemaining -= coinTransfer.amount;

          if (tokenAddress == CONVENTION_FOR_ETH_TOKEN_ADDRESS) {
            // note: send() is deliberately used instead of coinTransfer() here
            // so that a revert does not stop the rest of the sends
            to.send(coinTransfer.amount);
          } else {
            ERC20(tokenAddress).transfer(to, coinTransfer.amount);
          }
        }

      }

      // NOTE: If the limit is MAX_UINT256 it can bypass this check.
      // We do this for the FreeBalanceApp since its values change.
      if (params.limit[i] != MAX_UINT256)
        require(
          limitRemaining == 0,
          "Sum of total amounts received from outcome did not equate to limits."
        );

    }
  }
}