/**
 * Analytics Model - Sovereign Analytics Tracking
 * Privacy-respecting, self-hosted analytics (no cookies, no external services)
 */

const mongoose = require('mongoose');

const PageViewSchema = new mongoose.Schema({
  // Page Information
  path: { type: String, required: true, index: true },
  title: { type: String },
  referrer: { type: String },

  // Visitor Information (privacy-respecting)
  visitorId: { type: String, required: true, index: true }, // Hashed IP + User Agent
  sessionId: { type: String, required: true }, // Session identifier (indexed via compound index below)

  // Request Details
  userAgent: { type: String },
  language: { type: String },
  country: { type: String }, // Optional: derived from IP if available

  // Timing
  timestamp: { type: Date, default: Date.now, index: true },
  duration: { type: Number }, // Time spent on page (if available)

  // Metadata
  isUnique: { type: Boolean, default: false }, // First visit of the day
  isBounce: { type: Boolean, default: false }, // Only page visited in session

  // UTM Parameters (marketing attribution)
  utmSource: { type: String },
  utmMedium: { type: String },
  utmCampaign: { type: String },
  utmContent: { type: String },
  utmTerm: { type: String }
}, {
  timestamps: true
});

// Indexes for performance
PageViewSchema.index({ timestamp: -1 });
PageViewSchema.index({ path: 1, timestamp: -1 });
PageViewSchema.index({ visitorId: 1, timestamp: -1 });
PageViewSchema.index({ sessionId: 1, timestamp: -1 });

// Session Schema
const SessionSchema = new mongoose.Schema({
  sessionId: { type: String, required: true, unique: true }, // unique already creates index
  visitorId: { type: String, required: true, index: true },

  startTime: { type: Date, default: Date.now },
  endTime: { type: Date },
  duration: { type: Number }, // Total session duration in seconds

  pageViews: { type: Number, default: 1 },
  pages: [{ type: String }], // Paths visited

  entryPage: { type: String },
  exitPage: { type: String },

  referrer: { type: String },
  utmSource: { type: String },
  utmMedium: { type: String },
  utmCampaign: { type: String },

  country: { type: String },
  language: { type: String },

  isActive: { type: Boolean, default: true } // Session still active
}, {
  timestamps: true
});

SessionSchema.index({ sessionId: 1 });
SessionSchema.index({ visitorId: 1, startTime: -1 });
SessionSchema.index({ startTime: -1 });

// Statics for analytics queries

/**
 * Get real-time visitor count (last 5 minutes)
 */
SessionSchema.statics.getRealTimeVisitors = async function() {
  const fiveMinutesAgo = new Date(Date.now() - 5 * 60 * 1000);
  return await this.countDocuments({
    isActive: true,
    endTime: { $gte: fiveMinutesAgo }
  });
};

/**
 * Get total page views for a date range
 */
PageViewSchema.statics.getPageViews = async function(startDate, endDate) {
  return await this.countDocuments({
    timestamp: { $gte: startDate, $lte: endDate }
  });
};

/**
 * Get unique visitors for a date range
 */
PageViewSchema.statics.getUniqueVisitors = async function(startDate, endDate) {
  const result = await this.distinct('visitorId', {
    timestamp: { $gte: startDate, $lte: endDate }
  });
  return result.length;
};

/**
 * Get top pages by views
 */
PageViewSchema.statics.getTopPages = async function(startDate, endDate, limit = 10) {
  return await this.aggregate([
    {
      $match: {
        timestamp: { $gte: startDate, $lte: endDate }
      }
    },
    {
      $group: {
        _id: '$path',
        views: { $sum: 1 },
        uniqueVisitors: { $addToSet: '$visitorId' }
      }
    },
    {
      $project: {
        path: '$_id',
        views: 1,
        uniqueVisitors: { $size: '$uniqueVisitors' }
      }
    },
    {
      $sort: { views: -1 }
    },
    {
      $limit: limit
    }
  ]);
};

/**
 * Get top referrers
 */
PageViewSchema.statics.getTopReferrers = async function(startDate, endDate, limit = 10) {
  return await this.aggregate([
    {
      $match: {
        timestamp: { $gte: startDate, $lte: endDate },
        referrer: { $exists: true, $ne: '' }
      }
    },
    {
      $group: {
        _id: '$referrer',
        visits: { $sum: 1 }
      }
    },
    {
      $project: {
        referrer: '$_id',
        visits: 1
      }
    },
    {
      $sort: { visits: -1 }
    },
    {
      $limit: limit
    }
  ]);
};

/**
 * Get hourly page views (for trend charts)
 */
PageViewSchema.statics.getHourlyViews = async function(startDate, endDate) {
  return await this.aggregate([
    {
      $match: {
        timestamp: { $gte: startDate, $lte: endDate }
      }
    },
    {
      $group: {
        _id: {
          year: { $year: '$timestamp' },
          month: { $month: '$timestamp' },
          day: { $dayOfMonth: '$timestamp' },
          hour: { $hour: '$timestamp' }
        },
        views: { $sum: 1 },
        uniqueVisitors: { $addToSet: '$visitorId' }
      }
    },
    {
      $project: {
        hour: '$_id',
        views: 1,
        uniqueVisitors: { $size: '$uniqueVisitors' }
      }
    },
    {
      $sort: { '_id.year': 1, '_id.month': 1, '_id.day': 1, '_id.hour': 1 }
    }
  ]);
};

/**
 * Get bounce rate
 */
SessionSchema.statics.getBounceRate = async function(startDate, endDate) {
  const totalSessions = await this.countDocuments({
    startTime: { $gte: startDate, $lte: endDate }
  });

  const bouncedSessions = await this.countDocuments({
    startTime: { $gte: startDate, $lte: endDate },
    pageViews: 1
  });

  return totalSessions > 0 ? (bouncedSessions / totalSessions) * 100 : 0;
};

/**
 * Get average session duration
 */
SessionSchema.statics.getAverageDuration = async function(startDate, endDate) {
  const result = await this.aggregate([
    {
      $match: {
        startTime: { $gte: startDate, $lte: endDate },
        duration: { $exists: true, $gt: 0 }
      }
    },
    {
      $group: {
        _id: null,
        avgDuration: { $avg: '$duration' }
      }
    }
  ]);

  return result.length > 0 ? Math.round(result[0].avgDuration) : 0;
};

const PageView = mongoose.model('PageView', PageViewSchema);
const Session = mongoose.model('Session', SessionSchema);

module.exports = { PageView, Session };