C.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.17;

import "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";

contract C {
    struct MerkleRoot {
        bytes32 data;
        bytes32 signatures;
    }
    
    event AppendNewMerkleRoots(uint64 indexed batchIndex, bytes32 dataMerkleRoot, bytes32 sigMerkleRoot);
    
    mapping(uint64 => MerkleRoot) public rootHistory;
    
    function update(uint64 batchIndex, bytes32 dataMerkleRoot, bytes32 sigMerkleRoot) public {
        MerkleRoot memory new_value = MerkleRoot({
            data: dataMerkleRoot,
            signatures: sigMerkleRoot
        });
        
        MerkleRoot storage old_value = rootHistory[batchIndex];
        
        if((old_value.data != bytes32(0)) || (old_value.signatures != bytes32(0))) {
            revert("Cannot override an existed MerkleRoot slot");
        }
        else {
            rootHistory[batchIndex] = new_value;
        }
        
        emit AppendNewMerkleRoots(batchIndex, dataMerkleRoot, sigMerkleRoot);
    }
    
    function verifyData(bytes32[] calldata proof, uint64 batchIndex, bytes32 leafData) public view returns (bool) {
        MerkleRoot storage merkleRoots = rootHistory[batchIndex];
        
        if((merkleRoots.data == bytes32(0)) && (merkleRoots.signatures == bytes32(0))) {
            return false; // There is no Merkle root at the given `batchIndex`.
        }
        else {
            bytes32 leaf = keccak256(bytes.concat(keccak256(abi.encode(batchIndex, leafData))));
            bytes32 root = merkleRoots.data;
            
            return MerkleProof.verifyCalldata(
                proof, 
                root, 
                leaf
            );
        }
    }
    
    function verifySig(bytes32[] calldata proof, uint64 batchIndex, bytes32 leafSig) public view returns (bool) {
        MerkleRoot storage merkleRoots = rootHistory[batchIndex];
        
        if((merkleRoots.data == bytes32(0)) && (merkleRoots.signatures == bytes32(0))) {
            return false; // There is no Merkle root at the given `batchIndex`.
        }
        else {
            bytes32 leaf = keccak256(bytes.concat(keccak256(abi.encode(batchIndex, leafSig))));
            bytes32 root = merkleRoots.signatures;
            
            return MerkleProof.verifyCalldata(
                proof, 
                root, 
                leaf
            );
        }
    }
}