Best Practices

function multiWriteToDiscSignature( 
    uint256[] memory tokenIds, 
    uint256[] memory songSelections, 
    bytes memory signature
) public {
    require(
        tokenIds.length == songSelections.length,
        "tokenIds and songSelections arrays must have the same length"
    );

    //Constructing the signed hash for signer address recovery
    bytes32 messageHash = keccak256(abi.encodePacked(tokenIds, songSelections));  

    bytes32 ethSignedHash = keccak256(  
        abi.encodePacked("\x19Ethereum Signed Message:\n32", messageHash)  
    );  

    address signer = recoverSigner(ethSignedHash, signature);  

    for (uint256 i = 0; i < tokenIds.length; i++) {
        uint256 tokenId = tokenIds[i];
        uint256 songChoiceId = songSelections[i];

        // Check if CdMemory is not written before allowing an update
        CdMemory storage cd = readCdMemory[tokenId];
        require(
            ownerOf(tokenId) == signer,
            "Only the owner can set CdMemory"
        );
        require(
            songChoiceId >= 1 && songChoiceId <= 5,
            "Invalid song choice ID"
        );
        require(!cd.written, "One or more tokens are already written.");

        // Update CdMemory and mark it as written
        cd.writerAddress = signer;
        cd.songChoiceId = songChoiceId;
        cd.written = true;

        writeCount += 1;

        emit CdMemorySet(tokenId, signer, songChoiceId);
    }
}

//Helper function to determine signer address based on the signed hash and the signature

function recoverSigner( 
    bytes32 ethSignedHash, 
    bytes memory signature
) public pure returns (address) { 
    // Extract the r, s, and v values from the signature
    (bytes32 r, bytes32 s, uint8 v) = splitSignature(signature); 

    // Recover and return the signer address
    return ecrecover(ethSignedHash, v, r, s); 
}

//Helper Function to split signature into RSV values
function splitSignature( 
    bytes memory signature
) public pure returns (bytes32 r, bytes32 s, uint8 v) { 
    require(signature.length == 65, "Invalid signature length"); 

    assembly { 
        // Slice the r, s, and v components from the signature
        r := mload(add(signature, 32)) 
        s := mload(add(signature, 64)) 
        v := byte(0, mload(add(signature, 96))) 
    } 
}