/**
 * Analytics Controller
 * API endpoints for analytics dashboard
 */

const { PageView, Session } = require('../models/Analytics.model');

/**
 * Get analytics overview
 */
async function getOverview(req, res) {
  try {
    const { period = '24h' } = req.query;

    // Calculate date range
    let startDate;
    const endDate = new Date();

    switch (period) {
      case '1h':
        startDate = new Date(Date.now() - 60 * 60 * 1000);
        break;
      case '24h':
        startDate = new Date(Date.now() - 24 * 60 * 60 * 1000);
        break;
      case '7d':
        startDate = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
        break;
      case '30d':
        startDate = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
        break;
      default:
        startDate = new Date(Date.now() - 24 * 60 * 60 * 1000);
    }

    // Get real-time visitors
    const realTimeVisitors = await Session.getRealTimeVisitors();

    // Get total page views
    const totalPageViews = await PageView.getPageViews(startDate, endDate);

    // Get unique visitors
    const uniqueVisitors = await PageView.getUniqueVisitors(startDate, endDate);

    // Get bounce rate
    const bounceRate = await Session.getBounceRate(startDate, endDate);

    // Get average session duration
    const avgDuration = await Session.getAverageDuration(startDate, endDate);

    // Get top pages
    const topPages = await PageView.getTopPages(startDate, endDate, 10);

    // Get top referrers
    const topReferrers = await PageView.getTopReferrers(startDate, endDate, 10);

    res.json({
      success: true,
      period,
      data: {
        realTimeVisitors,
        totalPageViews,
        uniqueVisitors,
        bounceRate: Math.round(bounceRate * 10) / 10,
        avgDuration,
        topPages,
        topReferrers
      }
    });
  } catch (error) {
    console.error('[Analytics] Overview error:', error);
    res.status(500).json({
      success: false,
      error: 'Failed to fetch analytics overview'
    });
  }
}

/**
 * Get hourly trend data
 */
async function getHourlyTrend(req, res) {
  try {
    const { hours = 24 } = req.query;

    const startDate = new Date(Date.now() - parseInt(hours, 10) * 60 * 60 * 1000);
    const endDate = new Date();

    const hourlyData = await PageView.getHourlyViews(startDate, endDate);

    res.json({
      success: true,
      data: hourlyData
    });
  } catch (error) {
    console.error('[Analytics] Hourly trend error:', error);
    res.status(500).json({
      success: false,
      error: 'Failed to fetch hourly trend'
    });
  }
}

/**
 * Get live visitors (for real-time dashboard)
 */
async function getLiveVisitors(req, res) {
  try {
    const fiveMinutesAgo = new Date(Date.now() - 5 * 60 * 1000);

    const activeSessions = await Session.find({
      isActive: true,
      endTime: { $gte: fiveMinutesAgo }
    }).select('entryPage exitPage pages startTime endTime language');

    const currentPages = await PageView.find({
      timestamp: { $gte: fiveMinutesAgo }
    })
      .sort({ timestamp: -1 })
      .limit(20)
      .select('path timestamp visitorId sessionId');

    res.json({
      success: true,
      data: {
        count: activeSessions.length,
        sessions: activeSessions,
        recentPages: currentPages
      }
    });
  } catch (error) {
    console.error('[Analytics] Live visitors error:', error);
    res.status(500).json({
      success: false,
      error: 'Failed to fetch live visitors'
    });
  }
}

/**
 * Get page-specific analytics
 */
async function getPageAnalytics(req, res) {
  try {
    const { path, period = '7d' } = req.query;

    if (!path) {
      return res.status(400).json({
        success: false,
        error: 'Page path required'
      });
    }

    // Calculate date range
    let startDate;
    const endDate = new Date();

    switch (period) {
      case '24h':
        startDate = new Date(Date.now() - 24 * 60 * 60 * 1000);
        break;
      case '7d':
        startDate = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
        break;
      case '30d':
        startDate = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
        break;
      default:
        startDate = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
    }

    const pageViews = await PageView.countDocuments({
      path,
      timestamp: { $gte: startDate, $lte: endDate }
    });

    const uniqueVisitors = await PageView.distinct('visitorId', {
      path,
      timestamp: { $gte: startDate, $lte: endDate }
    });

    const avgDuration = await PageView.aggregate([
      {
        $match: {
          path,
          timestamp: { $gte: startDate, $lte: endDate },
          duration: { $exists: true, $gt: 0 }
        }
      },
      {
        $group: {
          _id: null,
          avgDuration: { $avg: '$duration' }
        }
      }
    ]);

    res.json({
      success: true,
      path,
      period,
      data: {
        pageViews,
        uniqueVisitors: uniqueVisitors.length,
        avgDuration: avgDuration.length > 0 ? Math.round(avgDuration[0].avgDuration) : 0
      }
    });
  } catch (error) {
    console.error('[Analytics] Page analytics error:', error);
    res.status(500).json({
      success: false,
      error: 'Failed to fetch page analytics'
    });
  }
}

/**
 * Get UTM campaign performance
 */
async function getCampaignAnalytics(req, res) {
  try {
    const { period = '30d' } = req.query;

    let startDate;
    const endDate = new Date();

    switch (period) {
      case '7d':
        startDate = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
        break;
      case '30d':
        startDate = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
        break;
      case '90d':
        startDate = new Date(Date.now() - 90 * 24 * 60 * 60 * 1000);
        break;
      default:
        startDate = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
    }

    const campaigns = await PageView.aggregate([
      {
        $match: {
          timestamp: { $gte: startDate, $lte: endDate },
          utmCampaign: { $exists: true, $ne: null }
        }
      },
      {
        $group: {
          _id: {
            campaign: '$utmCampaign',
            source: '$utmSource',
            medium: '$utmMedium'
          },
          visits: { $sum: 1 },
          uniqueVisitors: { $addToSet: '$visitorId' }
        }
      },
      {
        $project: {
          campaign: '$_id.campaign',
          source: '$_id.source',
          medium: '$_id.medium',
          visits: 1,
          uniqueVisitors: { $size: '$uniqueVisitors' }
        }
      },
      {
        $sort: { visits: -1 }
      },
      {
        $limit: 20
      }
    ]);

    res.json({
      success: true,
      period,
      data: campaigns
    });
  } catch (error) {
    console.error('[Analytics] Campaign analytics error:', error);
    res.status(500).json({
      success: false,
      error: 'Failed to fetch campaign analytics'
    });
  }
}

module.exports = {
  getOverview,
  getHourlyTrend,
  getLiveVisitors,
  getPageAnalytics,
  getCampaignAnalytics
};