import express from "express";
import dotenv from "dotenv";
import cron from "node-cron";
import sgMail from "@sendgrid/mail"; // 1. Import SendGrid mail
import cors from "cors"; // 2. Import cors package
import connectDB from "./config/db.js";
import productRoutes from "./routes/productRoutes.js";
import userRoutes from "./routes/userRoutes.js";
import Product from "./models/productModel.js";

dotenv.config();
connectDB();
const app = express();

// 3. Use the cors middleware (cleaner than manual headers)
app.use(cors());

app.use(express.json());

app.get("/", (req, res) => {
  res.send("API is running...");
});

app.use("/api/products", productRoutes);
app.use("/api/users", userRoutes);

// Cron Job for Low Stock Alerts
cron.schedule("*/30 * * * * *", async () => {
  console.log("Running cron job: Checking for low-stock products...");
  try {
    const lowStockProducts = await Product.find({
      $expr: { $lte: ["$quantity", "$lowStockThreshold"] },
    });

    if (lowStockProducts.length > 0) {
      // --- Start of SendGrid Logic ---
      sgMail.setApiKey(process.env.SENDGRID_API_KEY);

      const productList = lowStockProducts
        .map(
          (p) =>
            `<li>${p.name} (SKU: ${p.sku}) - Quantity: ${p.quantity}, Threshold: ${p.lowStockThreshold}</li>`
        )
        .join("");

      const msg = {
        to: process.env.EMAIL_TO, // The recipient
        from: process.env.EMAIL_USER, // Your verified sender in SendGrid
        subject: "🔴 Low Stock Alert!",
        html: `
          <h3>The following products are running low on stock:</h3>
          <ul>
            ${productList}
          </ul>
          <p>Please restock them soon.</p>
        `,
      };

      try {
        await sgMail.send(msg);
        console.log("Low stock alert email sent successfully via SendGrid.");
      } catch (sendGridError) {
        console.error("Error sending email via SendGrid:", sendGridError);
      }
      // --- End of SendGrid Logic ---
    } else {
      console.log("No low-stock products found.");
    }
  } catch (error) {
    console.error("Error in cron job:", error);
  }
});

const PORT = process.env.PORT || 5000;

app.listen(
  PORT,
  "0.0.0.0", // Important for Docker networking
  console.log(`Server running in ${process.env.NODE_ENV} mode on port ${PORT}`)
);

////////////////////////////////////////////////////////////////////////////////

// import express from "express";
// import dotenv from "dotenv";
// import cron from "node-cron"; // 1. Import cron
// import nodemailer from "nodemailer"; // 2. Import nodemailer
// import connectDB from "./config/db.js";
// import productRoutes from "./routes/productRoutes.js";
// import userRoutes from "./routes/userRoutes.js";
// import Product from "./models/productModel.js"; // 3. Import Product Model

// dotenv.config();

// connectDB();

// const app = express();

// // CORS middleware for production
// app.use((req, res, next) => {
//   res.header("Access-Control-Allow-Origin", "*");
//   res.header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
//   res.header(
//     "Access-Control-Allow-Headers",
//     "Origin, X-Requested-With, Content-Type, Accept, Authorization"
//   );

//   if (req.method === "OPTIONS") {
//     res.sendStatus(200);
//   } else {
//     next();
//   }
// });

// // 1. Middleware to accept JSON data
// app.use(express.json());

// app.get("/", (req, res) => {
//   res.send("API is running...");
// });

// // 2. USE THE ROUTES
// app.use("/api/products", productRoutes);
// app.use("/api/users", userRoutes);

// // 3. Add the Cron Job for Low Stock Alerts '*/10 * * * * *'(10 sec) / "* * * * *"(1 min)
// cron.schedule("*/30 * * * *", async () => {
//   console.log("Running cron job: Checking for low-stock products...");
//   try {
//     const lowStockProducts = await Product.find({
//       $expr: { $lte: ["$quantity", "$lowStockThreshold"] },
//     });

//     if (lowStockProducts.length > 0) {
//       const transporter = nodemailer.createTransport({
//         service: "gmail",
//         auth: {
//           user: process.env.EMAIL_USER,
//           pass: process.env.EMAIL_PASS,
//         },
//       });

//       const productList = lowStockProducts
//         .map(
//           (p) =>
//             `<li>${p.name} (SKU: ${p.sku}) - Quantity: ${p.quantity}, Threshold: ${p.lowStockThreshold}</li>`
//         )
//         .join("");

//       const mailOptions = {
//         from: process.env.EMAIL_USER,
//         to: process.env.EMAIL_TO,
//         subject: "🔴 Low Stock Alert!",
//         html: `
//           <h3>The following products are running low on stock:</h3>
//           <ul>
//             ${productList}
//           </ul>
//           <p>Please restock them soon.</p>
//         `,
//       };

//       transporter.sendMail(mailOptions, (error, info) => {
//         if (error) {
//           console.error("Error sending email:", error);
//         } else {
//           console.log("Low stock alert email sent:", info.response);
//         }
//       });
//     } else {
//       console.log("No low-stock products found.");
//     }
//   } catch (error) {
//     console.error("Error in cron job:", error);
//   }
// });

// const PORT = process.env.PORT || 5000;

// app.listen(
//   PORT,
//   console.log(`Server running in ${process.env.NODE_ENV} mode on port ${PORT}`)
// );