tornado-instances/contracts/InstanceProposalFactory.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.7.6;
pragma abicoder v2;

import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
import { Address } from "@openzeppelin/contracts/utils/Address.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { IERC20Permit } from "@openzeppelin/contracts/drafts/IERC20Permit.sol";
import { IUniswapV3Factory } from "@uniswap/v3-core/contracts/interfaces/IUniswapV3Factory.sol";
import { IUniswapV3PoolState } from "@uniswap/v3-core/contracts/interfaces/pool/IUniswapV3PoolState.sol";
import { InstanceAdditionProposal } from "./InstanceAdditionProposal.sol";

/**
 * @notice Contract which creates instance addition proposals.
 * @dev In this version, no initializable is needed, and it was also a kind of bad initializable
 * in the first place, because the variables which were set, do not have to be pseudo-immutable.
 *
 * Also in this version, there is no "creationFee", this was a bad idea in the first place by
 * whoever implemented it, because anyone would just be able to fork this code in 1 hour as
 * I did, and redeploy a free version.
 */
contract InstanceProposalFactory {
  using SafeMath for uint256;
  using Address for address;

  address public immutable weth;
  address public immutable governance;
  address public immutable instanceFactory;
  address public immutable instanceRegistry;
  IUniswapV3Factory public immutable UniswapV3Factory;

  uint16 public minObservationCardinality;

  event NewMinimumObservationCardinalitySet(uint256 newMinObservationCardinality);
  event NewGovernanceProposalCreated(address indexed proposal);

  /**
   * @dev Throws if called by any account other than the Governance.
   */
  modifier onlyGovernance() {
    require(governance == msg.sender, "IF: caller is not the Governance");
    _;
  }

  /**
   * @notice Contract constructor.
   * @param _governance The TC governance address.
   * @param _instanceFactory The factory address with which created proposals will use to deploy an instance.
   * @param _instanceRegistry The registry address with which created proposals will use to register an instance.
   * @param _UniswapV3Factory The UNIV3 Factory address with which we check TWAP cardinality.
   * @param _wethAddress The address of the Wrapped Ether contract.
   * @param _minObservationCardinality The minimum TWAP cardinality for a pool which we will accept.
   */
  constructor(
    address _governance,
    address _instanceFactory,
    address _instanceRegistry,
    address _UniswapV3Factory,
    address _wethAddress,
    uint16 _minObservationCardinality
  ) {
    governance = _governance;
    instanceFactory = _instanceFactory;
    instanceRegistry = _instanceRegistry;
    UniswapV3Factory = IUniswapV3Factory(_UniswapV3Factory);
    minObservationCardinality = _minObservationCardinality;
    weth = _wethAddress;
  }

  /**
   * @notice Create an instance addition proposal contract.
   * @dev Note that here, Uniswap is being used as an anti-shitcoin oracle. Also, specifically in this version the upper limit on the protocol fee is 3%, I do not consider it very beneficial for anyone to have it above this number.
   * The statement of the function: "I have some tokens for which there exist good uniswap pools, for which I would like to create [total number denominations] instances, of denominations which may be divided by a common exponent characteristic for each token's denomination group, and with a protocol fee which is reasonable (under 3%)."
   * @param _tokenAddresses ERC20 token addresses to add to the proposal.
   * @param _uniswapPoolSwappingFees Swapping fees for each token which are used to determine whether the observation cardinality of the Uniswap Pool is large enough. `3000` means 0.3% fee Uniswap pool.
   * @param _denomBase10DivExponents These are the exponents of the (10**exp) divisor which is used to assure that the denomination may be represented as a number below 2^40 - 1.
   * @param _denominations The denominations for each token. These will be stored as smallDenom = denomination / (10 ^ exponent)
   * @param _protocolFees List of protocol fees for each new instance. `100` means that instance withdrawal fee is 1% of denomination.
   * @param _totalNumberDenominations This is the total number of denominations, the sum of the lengths of subarrays of denominations.
   */
  function createProposalContract(
    address[] calldata _tokenAddresses,
    uint24[] calldata _uniswapPoolSwappingFees,
    uint16[] calldata _denomBase10DivExponents,
    uint256[][] calldata _denominations,
    uint16[][] calldata _protocolFees,
    uint256 _totalNumberDenominations
  ) external returns (address) {
    InstanceAdditionProposal.InstanceAdditionData[] memory toAdd = new InstanceAdditionProposal.InstanceAdditionData[](
      _totalNumberDenominations
    );

    uint256 toAddSize = 0;

    require(0 < _tokenAddresses.length, "No tokens specified");

    // 1️⃣ Each token must be ether, or a contract with a uniswap pool of a minimum cardinality.

    for (uint256 t = 0; t < _tokenAddresses.length; t++) {
      address token = _tokenAddresses[t];

      // 2️⃣ The swapping fees must have an element at t.
      //    We do not care if there is more swapping fees than tokens

      uint24 swappingFee = _uniswapPoolSwappingFees[t];

      // 3️⃣ If not eth the token is a contract, the swapping fee must give a good pool, the cardinality must be good.

      if (token != address(0)) {
        require(token.isContract(), "Token must be a contract if not addr(0)");

        address poolAddress = UniswapV3Factory.getPool(token, weth, swappingFee);

        require(poolAddress != address(0), "A Uniswap V3 pool does not exist for this token.");

        (, , , , uint16 observationCardinalityNext, , ) = IUniswapV3PoolState(poolAddress).slot0();

        require(minObservationCardinality <= observationCardinalityNext, "Uniswap Pool observation cardinality is low.");
      }

      // 4️⃣ Denominations, div exponent and protocol fees must have an element at t(oken). The exponent must be good.

      uint256[] memory denominations = _denominations[t];

      uint16 exponent = _denomBase10DivExponents[t];

      require(0 < exponent, "Exponent is 0.");

      uint16[] memory protocolFees = _protocolFees[t];

      // 5️⃣ The denominations element must never have 0 length.

      uint256 numDenoms = denominations.length;

      require(0 < numDenoms, "There is no denominations for some token");

      // 6️⃣ All denominations divided by the exponent must not be 0, and there must be a reasonable protocol fee for each.

      for (uint256 d = 0; d < numDenoms; d++) {
        // 7️⃣ protocolFee must have an element at d and be appropriate.
        // We do not care if there is more fees than denominations

        uint16 protocolFee = protocolFees[d];

        require(protocolFee <= 300, "Protocol fee is more than 3%!");

        // 8️⃣ The denomination must not be 0 post division.

        uint40 smallDenomination = uint40(denominations[d].div(10 ** exponent));

        require(0 < smallDenomination, "When divided, denom is 0");

        // 9️⃣ If all of the above are fine, add the packed struct to the memory array.

        toAdd[toAddSize] = InstanceAdditionProposal.InstanceAdditionData({
          tokenAddress: token,
          smallDenomination: smallDenomination,
          base10Exponent: exponent,
          uniPoolSwappingFee: swappingFee,
          protocolFee: protocolFee
        });

        toAddSize++;
      }
    }

    // 🔟 The number of elements added must be _totalNumberDenominations.

    require(toAddSize == _totalNumberDenominations, "Wrong total number of denominations.");

    // 1️⃣1️⃣ Finish and return.

    address proposal = address(new InstanceAdditionProposal(instanceFactory, instanceRegistry, toAdd));

    emit NewGovernanceProposalCreated(proposal);

    return proposal;
  }

  function setMinObservationCardinality(uint16 _newMinObservationCardinality) external onlyGovernance {
    minObservationCardinality = _newMinObservationCardinality;
    emit NewMinimumObservationCardinalitySet(_newMinObservationCardinality);
  }
}