Supply chain system: Refactor

supplyChain.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract SupplyChain {
    address public owner;
    uint public productCount;

    struct Product {
        uint id;
        string name;
        string description;
        address manufacturer;
        address[] supplyChainHistory;
    }

    mapping(uint => Product) public products;

    modifier onlyOwner() {
        require(msg.sender == owner, "Only the owner can perform this action");
        _;
    }

    constructor() {
        owner = msg.sender;
    }

    function addProduct(string memory _name, string memory _description) external onlyOwner {
        productCount++; // very gas intensive, pass product id as parameter
        products[productCount] = Product(productCount, _name, _description, msg.sender, new address[](0));
    }

    // function getProduct(uint _productId) external view returns (
    //     uint id,
    //     string memory name,
    //     string memory description,
    //     address manufacturer,
    //     address[] memory supplyChainHistory
    // ) {
    //     require(_productId > 0 && _productId <= productCount, "Invalid product ID");
    //     Product memory product = products[_productId];
    //     return (
    //         product.id,
    //         product.name,
    //         product.description,
    //         product.manufacturer,
    //         product.supplyChainHistory
    //     );
    // }

    /// @notice Function returns struct Product; this is the simplest way to do this. 
    /// Solidity also generates a public function automatically to return the products mapping for you because the mapping is public
    function products_(uint product_id) external  view returns (Product memory) {
        Product memory product = products[product_id];
        return product;
    }

    function addToSupplyChain(uint _productId) external {
        require(_productId > 0 && _productId <= productCount, "Invalid product ID");
        Product storage product = products[_productId];
        require(msg.sender == product.manufacturer, "Only the manufacturer can add to the supply chain");

        // Add the current user to the supply chain history
        product.supplyChainHistory.push(msg.sender);
    }
}