// User Analytics and Tracking System for प्रिथ्वी Guardian AI
interface UserSession {
  sessionId: string;
  startTime: Date;
  endTime?: Date;
  pageViews: string[];
  actionsPerformed: string[];
  modulesUsed: string[];
  calculationsCount: number;
  reportsGenerated: number;
  timeSpent: number; // in minutes
}

interface UserAnalytics {
  totalSessions: number;
  totalUsers: number;
  averageSessionTime: number;
  mostUsedModules: Record<string, number>;
  dailyActiveUsers: Record<string, number>;
  featureUsage: Record<string, number>;
  retentionRate: number;
}

class UserTrackingSystem {
  private currentSession: UserSession | null = null;
  private sessionKey = 'prithvi_user_session';
  private analyticsKey = 'prithvi_analytics';
  private userIdKey = 'prithvi_user_id';

  constructor() {
    this.initializeTracking();
  }

  private initializeTracking() {
    // Generate unique user ID if not exists
    if (!localStorage.getItem(this.userIdKey)) {
      const userId = 'user_' + Date.now() + '_' + Math.random().toString(36).substr(2, 9);
      localStorage.setItem(this.userIdKey, userId);
    }

    // Start new session
    this.startSession();

    // Track page visibility changes
    document.addEventListener('visibilitychange', () => {
      if (document.hidden) {
        this.pauseSession();
      } else {
        this.resumeSession();
      }
    });

    // Track before page unload
    window.addEventListener('beforeunload', () => {
      this.endSession();
    });
  }

  startSession() {
    const sessionId = 'session_' + Date.now() + '_' + Math.random().toString(36).substr(2, 9);
    
    this.currentSession = {
      sessionId,
      startTime: new Date(),
      pageViews: [window.location.pathname],
      actionsPerformed: [],
      modulesUsed: [],
      calculationsCount: 0,
      reportsGenerated: 0,
      timeSpent: 0
    };

    localStorage.setItem(this.sessionKey, JSON.stringify(this.currentSession));
    this.updateAnalytics('sessionStart');
  }

  trackPageView(path: string) {
    if (!this.currentSession) return;
    
    this.currentSession.pageViews.push(path);
    this.updateSession();
    this.updateAnalytics('pageView', { path });
  }

  trackAction(action: string, details?: any) {
    if (!this.currentSession) return;
    
    const actionLog = {
      action,
      timestamp: new Date(),
      details
    };
    
    this.currentSession.actionsPerformed.push(JSON.stringify(actionLog));
    this.updateSession();
    this.updateAnalytics('action', { action });
  }

  trackModuleUsage(module: string) {
    if (!this.currentSession) return;
    
    if (!this.currentSession.modulesUsed.includes(module)) {
      this.currentSession.modulesUsed.push(module);
    }
    this.updateSession();
    this.updateAnalytics('moduleUsage', { module });
  }

  trackCalculation(module: string, type: string) {
    if (!this.currentSession) return;
    
    this.currentSession.calculationsCount++;
    this.trackAction('calculation', { module, type });
    this.trackModuleUsage(module);
    this.updateSession();
  }

  trackReportGeneration(title: string) {
    if (!this.currentSession) return;
    
    this.currentSession.reportsGenerated++;
    this.trackAction('reportGenerated', { title });
    this.updateSession();
  }

  private updateSession() {
    if (!this.currentSession) return;
    
    const now = new Date();
    this.currentSession.timeSpent = Math.round((now.getTime() - this.currentSession.startTime.getTime()) / 60000);
    localStorage.setItem(this.sessionKey, JSON.stringify(this.currentSession));
  }

  private pauseSession() {
    this.updateSession();
  }

  private resumeSession() {
    // Session continues, just update time
    this.updateSession();
  }

  endSession() {
    if (!this.currentSession) return;
    
    this.currentSession.endTime = new Date();
    this.updateSession();
    
    // Save to permanent storage
    this.saveSessionToHistory();
    this.updateAnalytics('sessionEnd');
    
    this.currentSession = null;
    localStorage.removeItem(this.sessionKey);
  }

  private saveSessionToHistory() {
    if (!this.currentSession) return;
    
    const historyKey = 'prithvi_session_history';
    const history = JSON.parse(localStorage.getItem(historyKey) || '[]');
    history.push(this.currentSession);
    
    // Keep only last 100 sessions
    if (history.length > 100) {
      history.splice(0, history.length - 100);
    }
    
    localStorage.setItem(historyKey, JSON.stringify(history));
  }

  private updateAnalytics(eventType: string, data?: any) {
    const analytics = this.getAnalytics();
    const today = new Date().toISOString().split('T')[0];
    
    switch (eventType) {
      case 'sessionStart':
        analytics.totalSessions++;
        analytics.dailyActiveUsers[today] = (analytics.dailyActiveUsers[today] || 0) + 1;
        break;
      case 'moduleUsage':
        analytics.mostUsedModules[data.module] = (analytics.mostUsedModules[data.module] || 0) + 1;
        break;
      case 'action':
        analytics.featureUsage[data.action] = (analytics.featureUsage[data.action] || 0) + 1;
        break;
    }
    
    localStorage.setItem(this.analyticsKey, JSON.stringify(analytics));
  }

  getAnalytics(): UserAnalytics {
    const defaultAnalytics: UserAnalytics = {
      totalSessions: 0,
      totalUsers: 1,
      averageSessionTime: 0,
      mostUsedModules: {},
      dailyActiveUsers: {},
      featureUsage: {},
      retentionRate: 100
    };
    
    const stored = localStorage.getItem(this.analyticsKey);
    return stored ? { ...defaultAnalytics, ...JSON.parse(stored) } : defaultAnalytics;
  }

  getCurrentSession(): UserSession | null {
    return this.currentSession;
  }

  getSessionHistory(): UserSession[] {
    const historyKey = 'prithvi_session_history';
    return JSON.parse(localStorage.getItem(historyKey) || '[]');
  }

  getUserId(): string {
    return localStorage.getItem(this.userIdKey) || 'anonymous';
  }

  exportAnalyticsData(): string {
    const data = {
      userId: this.getUserId(),
      analytics: this.getAnalytics(),
      sessionHistory: this.getSessionHistory(),
      currentSession: this.currentSession,
      exportDate: new Date().toISOString()
    };
    
    return JSON.stringify(data, null, 2);
  }

  clearAnalyticsData() {
    localStorage.removeItem(this.analyticsKey);
    localStorage.removeItem('prithvi_session_history');
    localStorage.removeItem(this.sessionKey);
    // Don't clear user ID to maintain identity
  }
}

// Create global instance
export const userTracking = new UserTrackingSystem();

// Export for use in components
export { UserTrackingSystem };
export type { UserSession, UserAnalytics };