src/controllers/productController.js

// src/controllers/productController.js
const Product = require('../models/Product');
const sendTelegramAlert = require('../utils/telegram');

// @desc    Fetch all products (with search & category filter)
// @route   GET /api/products
// @access  Public
const getProducts = async (req, res) => {
  try {
    const keyword = req.query.keyword
      ? {
          name: {
            $regex: req.query.keyword,
            $options: 'i', // Case insensitive
          },
        }
      : {};

    // Filter by category if provided
    const categoryFilter = req.query.category ? { category: req.query.category } : {};

    const products = await Product.find({ ...keyword, ...categoryFilter });
    res.json(products);
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
};

// @desc    Fetch single product
// @route   GET /api/products/:id
// @access  Public
const getProductById = async (req, res) => {
  try {
    const product = await Product.findById(req.params.id);
    if (product) {
      res.json(product);
    } else {
      res.status(404).json({ message: 'Product not found' });
    }
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
};

// @desc    Create a product
// @route   POST /api/products
// @access  Private/Admin
const createProduct = async (req, res) => {
  const { name, price, originalPrice, description, image, category, stock } = req.body;

  try {
    const product = new Product({
      name,
      price,
      originalPrice,
      description,
      image,
      category,
      stock,
    });

    const createdProduct = await product.save();
    res.status(201).json(createdProduct);
  } catch (error) {
    res.status(400).json({ message: error.message });
  }
};

// @desc    Update a product
// @route   PUT /api/products/:id
// @access  Private/Admin
const updateProduct = async (req, res) => {
  const { name, price, originalPrice, description, image, category, stock, isActive } = req.body;

  try {
    const product = await Product.findById(req.params.id);

    if (product) {
      product.name = name || product.name;
      product.price = price || product.price;
      product.originalPrice = originalPrice !== undefined ? originalPrice : product.originalPrice; 
      product.description = description || product.description;
      product.image = image || product.image;
      product.category = category || product.category;
      product.stock = stock !== undefined ? stock : product.stock;
      product.isActive = isActive !== undefined ? isActive : product.isActive;
      
      // 🔥 Stock Low Alert
      if (product.stock < 5) {
        sendTelegramAlert(`⚠️ <b>Low Stock Alert</b>\nProduct: <b>${product.name}</b> is down to ${product.stock} units!`);
      }

      const updatedProduct = await product.save();
      res.json(updatedProduct);
    } else {
      res.status(404).json({ message: 'Product not found' });
    }
  } catch (error) {
    res.status(400).json({ message: error.message });
  }
};

// @desc    Delete a product
// @route   DELETE /api/products/:id
// @access  Private/Admin
const deleteProduct = async (req, res) => {
  try {
    const product = await Product.findById(req.params.id);

    if (product) {
      await product.deleteOne();
      res.json({ message: 'Product removed' });
    } else {
      res.status(404).json({ message: 'Product not found' });
    }
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
};

module.exports = {
  getProducts,
  getProductById,
  createProduct,
  updateProduct,
  deleteProduct,
};