const Visit = require('../models/visitModel');

// Track a visit
exports.trackVisit = async (req, res) => {
  try {
    const { sessionId, page, userId } = req.body;

    if (!sessionId) {
      return res.status(400).json({
        status: 'fail',
        message: 'Session ID is required',
      });
    }

    // Get IP address from request
    const xForwardedFor = req.headers['x-forwarded-for'];
    const ipAddress =
      (xForwardedFor ? xForwardedFor.split(',')[0] : null) ||
      req.connection.remoteAddress ||
      req.socket.remoteAddress ||
      req.ip;

    // Get user agent
    const userAgent = req.headers['user-agent'] || '';

    // Grouping priority:
    // 1. If we have a userId, we find the ONE global record for this user
    // 2. If no userId (guest), we find a recent record for this sessionId
    const today = new Date();
    today.setHours(0, 0, 0, 0);

    const query = { createdAt: { $gte: today } };
    if (userId) {
      query.user = userId;
    } else {
      query.sessionId = sessionId;
    }

    let visit = await Visit.findOne(query).populate('user', 'name email');

    if (visit) {
      // Grouping: Increment count and update last active time
      visit.count += 1;
      visit.lastVisitedAt = new Date();
      // Update user ID if it was null before (guest just logged in)
      if (!visit.user && userId) {
        visit.user = userId;
      }
      // Update IP and User Agent to latest
      visit.ipAddress = ipAddress;
      visit.userAgent = userAgent;
      visit.page = page || '/';
      await visit.save();
    } else {
      // Create new visit document
      visit = await Visit.create({
        user: userId || null,
        ipAddress,
        userAgent,
        page: page || '/',
        sessionId,
        count: 1,
        lastVisitedAt: new Date(),
      });
      // Populate if it was a user
      if (userId) {
        await visit.populate('user', 'name email');
      }
    }

    res.status(200).json({
      status: 'success',
      data: { visit },
    });
  } catch (err) {
    res.status(500).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Get visit statistics
exports.getVisitStats = async (req, res) => {
  try {
    const now = new Date();

    // Today's start
    const todayStart = new Date(
      now.getFullYear(),
      now.getMonth(),
      now.getDate(),
    );

    // Current month boundaries
    const currentMonthStart = new Date(now.getFullYear(), now.getMonth(), 1);
    const currentMonthEnd = new Date(
      now.getFullYear(),
      now.getMonth() + 1,
      0,
      23,
      59,
      59,
    );

    // Previous month boundaries
    const previousMonthStart = new Date(
      now.getFullYear(),
      now.getMonth() - 1,
      1,
    );
    const previousMonthEnd = new Date(
      now.getFullYear(),
      now.getMonth(),
      0,
      23,
      59,
      59,
    );

    // Helper for summing counts and counting documents
    const getStats = async (filter = {}) => {
      const uniqueVisits = await Visit.countDocuments(filter);
      const totalResult = await Visit.aggregate([
        { $match: filter },
        { $group: { _id: null, total: { $sum: '$count' } } },
      ]);
      const totalVisits = totalResult.length > 0 ? totalResult[0].total : 0;
      return { uniqueVisits, totalVisits };
    };

    // Get all time stats
    const allTime = await getStats();

    // Get today's stats
    const today = await getStats({ createdAt: { $gte: todayStart } });

    // Get monthly stats for growth calculation
    const currentMonth = await getStats({
      createdAt: { $gte: currentMonthStart, $lte: currentMonthEnd },
    });
    const previousMonth = await getStats({
      createdAt: { $gte: previousMonthStart, $lte: previousMonthEnd },
    });

    // Calculate monthly growth percentage based on TOTAL visits
    let monthlyGrowth = 0;
    if (previousMonth.totalVisits > 0) {
      monthlyGrowth =
        ((currentMonth.totalVisits - previousMonth.totalVisits) /
          previousMonth.totalVisits) *
        100;
    } else if (currentMonth.totalVisits > 0) {
      monthlyGrowth = 100;
    }

    res.status(200).json({
      status: 'success',
      data: {
        totalVisits: allTime.totalVisits,
        uniqueVisits: allTime.uniqueVisits,
        todayVisits: today.totalVisits,
        todayUnique: today.uniqueVisits,
        currentMonthVisits: currentMonth.totalVisits,
        previousMonthVisits: previousMonth.totalVisits,
        monthlyGrowth: parseFloat(monthlyGrowth.toFixed(1)),
      },
    });
  } catch (err) {
    res.status(500).json({
      status: 'fail',
      message: err.message,
    });
  }
};

// Get all visits (admin only)
exports.getAllVisits = async (req, res) => {
  try {
    const { page = 1, limit = 50, startDate, endDate } = req.query;

    // Build filter
    const filter = {};
    if (startDate || endDate) {
      filter.createdAt = {};
      if (startDate) filter.createdAt.$gte = new Date(startDate);
      if (endDate) filter.createdAt.$lte = new Date(endDate);
    }

    const visits = await Visit.find(filter)
      .populate('user', 'name email')
      .sort({ createdAt: -1 })
      .limit(limit * 1)
      .skip((page - 1) * limit);

    const count = await Visit.countDocuments(filter);

    res.status(200).json({
      status: 'success',
      results: visits.length,
      totalPages: Math.ceil(count / limit),
      currentPage: page,
      data: { visits },
    });
  } catch (err) {
    res.status(500).json({
      status: 'fail',
      message: err.message,
    });
  }
};