northwind-rest-api/backend/business-logic/products-logic.js

Local REST API Exposing 'Northwind Traders' Database.

const dal = require("../data-access-layer/dal");
const imageHelper = require("../helpers/image-helper");

async function getAllProducts() {
    const products = await dal.getAllProducts();
    return products;
};

async function getOneProduct(id) {
    const products = await dal.getAllProducts();
    const product = products.find(p => p.id === id);
    return product;
};

async function addProduct(product, image) {
    const products = await dal.getAllProducts();
    const maxId = products.reduce((maxId, p) => p.id > maxId ? p.id : maxId, 0);
    product.id = maxId + 1;
    const fileName = await imageHelper.saveProductImage(image);
    product.imageUrl = fileName ? "http://localhost:3030/api/products/images/" + fileName : null;
    products.push(product);
    await dal.saveAllProducts(products);
    return product;
};

async function updateProduct(newProduct, image) {
    const products = await dal.getAllProducts();
    const existingProduct = products.find(p => p.id === newProduct.id);
    if (!existingProduct) return null;
    for (const prop in newProduct) {
        if (newProduct[prop] !== undefined) {
            existingProduct[prop] = newProduct[prop];
        }
    }
    const currentFileName = existingProduct.imageUrl ? existingProduct.imageUrl.substring(existingProduct.imageUrl.lastIndexOf("/") + 1) : null;
    const newFileName = await imageHelper.updateProductImage(currentFileName, image);
    if (newFileName) {
        existingProduct.imageUrl = "http://localhost:3030/api/products/images/" + newFileName;
    }
    await dal.saveAllProducts(products);
    return existingProduct;
};

async function deleteProduct(id) {
    const products = await dal.getAllProducts();
    const index = products.findIndex(p => p.id === id);
    if (index === -1) return;
    const existingProduct = products[index];
    const currentFileName = existingProduct.imageUrl ? existingProduct.imageUrl.substring(existingProduct.imageUrl.lastIndexOf("/") + 1) : null;
    await imageHelper.deleteProductImage(currentFileName)
    products.splice(index, 1);
    await dal.saveAllProducts(products);
};

async function getTopProducts() {
    const products = await dal.getAllProducts();
    const now = new Date();
    const base1 = now.getDate();
    const base2 = base1 + 1;
    const base3 = base1 + 2;
    const knuthMultiplicativeHashConstant = 2654435761;
    const index1 = (base1 * knuthMultiplicativeHashConstant) % products.length;
    const index2 = (base2 * knuthMultiplicativeHashConstant) % products.length;
    const index3 = (base3 * knuthMultiplicativeHashConstant) % products.length;
    const product1 = products[index1];
    const product2 = products[index2];
    const product3 = products[index3];
    const topProducts = [product1, product2, product3];
    return topProducts;
};

async function getOutOfStockProducts() {
    const products = await dal.getAllProducts();
    const outOfStock = products.filter(p => p.stock === 0);
    return outOfStock;
};

module.exports = {
    getAllProducts,
    getOneProduct,
    addProduct,
    updateProduct,
    deleteProduct,
    getTopProducts,
    getOutOfStockProducts
};