zkVoting.sol

// https://gist.github.com/Turupawn/6a4391fb54d09aae7a091ad2478c1f62#file-zkvoting-sol

//SPDX-License-Identifier: MIT
pragma solidity >=0.8.19;

contract zkVoting is UltraVerifier {

    struct Proposal {
        string description;
        uint deadline;
        uint forVotes;
        uint againstVotes;
    }

    bytes32 merkleRoot;
    uint proposalCount;
    mapping (uint proposalId => Proposal) public proposals;
    mapping(bytes32 hash => bool isNullified) nullifiers;

    constructor(bytes32 _merkleRoot) {
        merkleRoot = _merkleRoot;
    }

    function propose(string memory description, uint deadline) public {
        proposals[proposalCount] = Proposal(description, deadline, 0, 0);
        proposalCount += 1;
    }

    function castVote(bytes calldata proof, uint proposalId, uint vote, bytes32 nullifierHash) public {
        require(!nullifier[proof], "Proof has been already submitted");
        require(block.timestamp < proposals[proposalId].deadline, "Voting period is over.");
        nullifier[proof] = true;

        bytes32[] memory publicInputs = new bytes32[](4);
        publicInputs[0] = bytes32(merkleRoot);
        publicInputs[1] = bytes32(proposalId);
        publicInputs[2] = bytes32(vote);
        publicInputs[3] = bytes32(nullifierHash);
        require(verify(proof, publicInputs), "Invalid proof");

        if(vote == 1)
            proposals[proposalId].forVotes += 1;
        else if (vote == 2)
            proposals[proposalId].againstVotes += 1;
    }
}