// 📦 Full backend code for your Price Tracker project

const express = require("express");
const axios = require("axios");
const cheerio = require("cheerio");
const mongoose = require("mongoose");
const cors = require("cors");

const app = express();
app.use(cors());
app.use(express.json());

// ⚙️ Connect to MongoDB Atlas
mongoose.connect("mongodb+srv://<username>:<password>@cluster.mongodb.net/price-tracker", {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

// 🧠 Mongoose Schemas
const Product = mongoose.model("Product", new mongoose.Schema({
  url: String,
  title: String,
  site: String,
  createdAt: { type: Date, default: Date.now }
}));

const Price = mongoose.model("Price", new mongoose.Schema({
  productId: mongoose.Schema.Types.ObjectId,
  price: Number,
  date: { type: Date, default: Date.now }
}));

// 🔍 Amazon Scraper Function
async function scrapeAmazon(url) {
  const { data } = await axios.get(url, {
    headers: { "User-Agent": "Mozilla/5.0" }
  });
  const $ = cheerio.load(data);
  const title = $("#productTitle").text().trim();
  const priceStr = $("#priceblock_ourprice").text() || $("#priceblock_dealprice").text();
  const price = parseFloat(priceStr.replace(/[₹,]/g, ""));
  return { title, price, site: "Amazon" };
}

// 🛒 Track Product Route
app.post("/track-product", async (req, res) => {
  const { url } = req.body;
  if (!url) return res.json({ success: false, message: "No URL provided" });

  try {
    const { title, price, site } = await scrapeAmazon(url);

    if (!price || !title) {
      return res.json({ success: false, message: "Failed to fetch price/title" });
    }

    let product = await Product.findOne({ url });
    if (!product) {
      product = await Product.create({ url, title, site });
    }

    await Price.create({ productId: product._id, price });

    res.json({
      success: true,
      title,
      price,
      site,
      productId: product._id
    });
  } catch (err) {
    console.error("Scraping error:", err.message);
    res.json({ success: false, message: "Error during scraping" });
  }
});

// 🪙 Gold Price Route (Optional Static Demo)
app.get("/gold-price", async (req, res) => {
  try {
    // You can replace this with a real API like Metals-API
    const fakePrice = 5995; // INR per gram (example)
    res.json({ success: true, price: fakePrice, source: "Static Demo" });
  } catch (err) {
    res.json({ success: false, message: "Failed to fetch gold price" });
  }
});

// 🚀 Start Server
app.listen(3000, () => {
  console.log("Server running on http://localhost:3000");
});