//server.js

require("dotenv").config();
const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const cors = require("cors");
const nodemailer = require("nodemailer");
const multer = require("multer");
const path = require("path");
const moment = require("moment");

const app = express();
app.use(cors());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use("/uploads", express.static("uploads"));

// Multer setup for file uploads
const storage = multer.diskStorage({
  destination: "uploads/",
  filename: (req, file, cb) => {
    cb(null, Date.now() + path.extname(file.originalname));
  },
});
const upload = multer({ storage });

// MongoDB connection
mongoose
  .connect(process.env.MONGODB_URI, { useNewUrlParser: true, useUnifiedTopology: true })
  .then(() => console.log("Connected to MongoDB"))
  .catch((err) => console.error("MongoDB Connection Error:", err));

// Meeting Schema
const meetingSchema = new mongoose.Schema({
  program: String,
  department: String,
  subject: String,
  body: String,
  agenda: [String],
  date: String,
  startTime: String,
  endTime: String,
  recipients: [String],
  attachments: [{ filename: String, path: String }],
});
const Meeting = mongoose.model("Meeting", meetingSchema);

// API to send email
app.post("/api/send-email", upload.array("attachments"), async (req, res) => {
  try {
    const { program, department, subject, body, agenda, date, startTime, endTime, recipients } = req.body;
    const files = req.files;

    if (!program || !department || !subject || !body || !date || !startTime || !endTime || !recipients) {
      return res.status(400).json({ error: "All fields are required!" });
    }

    // Check for meeting conflicts
    const conflict = await Meeting.findOne({
      date,
      startTime: { $lt: endTime },
      endTime: { $gt: startTime },
    });

    if (conflict) {
      // Return the details of the conflicting meeting
      const conflictDetails = {
        department: conflict.department,
        date: conflict.date,
        startTime: conflict.startTime,
        endTime: conflict.endTime,
        recipients: conflict.recipients,
        subject: conflict.subject,
      };

      return res.status(409).json({ 
        error: "Meeting conflict detected! Please choose a different time.",
        conflictDetails 
      });
    }

    // Format date and time properly
    const formattedDate = moment(date, "YYYY-MM-DD").format("dddd, MMMM Do YYYY");
    const formattedStartTime = moment(startTime, "HH:mm").format("hh:mm A");
    const formattedEndTime = moment(endTime, "HH:mm").format("hh:mm A");

    // Format Google Calendar event link
    const formattedStart = moment(`${date} ${startTime}`, "YYYY-MM-DD HH:mm").utc().format("YYYYMMDDTHHmmss[Z]");
    const formattedEnd = moment(`${date} ${endTime}`, "YYYY-MM-DD HH:mm").utc().format("YYYYMMDDTHHmmss[Z]");
    const zoomLink = "https://us05web.zoom.us/j/2655616202?pwd=S3d6RjVPNnhmQ3AzTlZsRC9GYmNHQT09";
    const calendarLink = `https://calendar.google.com/calendar/render?action=TEMPLATE&text=${encodeURIComponent(
      subject
    )}&details=${encodeURIComponent(`${body}\nJoin Zoom Meeting: ${zoomLink}`)}&dates=${formattedStart}/${formattedEnd}`;

    // Format agenda into pointwise list
    const formattedAgenda = agenda
      ? agenda.map((item, index) => `<li>${index + 1}. ${item}</li>`).join("")
      : "<li>No agenda provided</li>";

    // Store meeting in DB
    const newMeeting = new Meeting({
      program,
      department,
      subject,
      body,
      agenda,
      date,
      startTime,
      endTime,
      recipients,
      attachments: files.map((file) => ({ filename: file.filename, path: file.path })),
    });
    await newMeeting.save();

    // Email transporter
    const transporter = nodemailer.createTransport({
      service: "gmail",
      auth: {
        user: process.env.EMAIL,
        pass: process.env.EMAIL_PASSWORD,
      },
    });

    // Email options
    const mailOptions = {
      from: process.env.EMAIL,
      to: recipients,
      subject,
      html: `
        <p><strong>Respected Board Members,</strong></p>
        <p><strong>Greetings from Somaiya Vidyavihar University !!</strong></p>
        <p><strong>We are glad to invite you to the Board of Studies meeting: </strong></p>
        <p>${body}</p>
        <p><strong>Program:</strong> ${program}</p>
        <p><strong>Department:</strong> ${department}</p>
        <p><strong>Date:</strong> ${formattedDate}</p>
        <p><strong>Time:</strong> ${formattedStartTime} - ${formattedEndTime}</p>
        <p><strong>Zoom Meeting Details:</strong></p>
        <p><strong>Meeting ID: </strong>265 561 6202</p>
        <p><strong>Meeting Password: </strong>123456</p>
        <p><strong>Zoom Meeting Link: </strong><a href="https://us05web.zoom.us/j/2655616202?pwd=S3d6RjVPNnhmQ3AzTlZsRC9GYmNHQT09" target="_blank">Join the Meeting</a></p>
        <p><strong>Agenda:</strong></p>
        <ul>${formattedAgenda}</ul>
        <p><a href="${calendarLink}">📅 Click here to add this event to Google Calendar</a></p>
      `,
      attachments: files.map((file) => ({
        filename: file.filename,
        path: file.path,
      })),
    };

    // Send email
    await transporter.sendMail(mailOptions);
    res.status(200).json({ message: "Email sent successfully!", calendarLink });
  } catch (error) {
    console.error("Error sending email:", error);
    res.status(500).json({ error: "Error sending email" });
  }
});

// Start server
const PORT = process.env.PORT || 5000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));