// User Progress Tracking System
class UserProgressTracker {
  constructor() {
    // Define learning levels
    this.levels = {
      'A1': { 
        minPoints: 0, 
        badge: '🌱 Beginner',
        description: 'Starting your English journey!'
      },
      'A2': { 
        minPoints: 500, 
        badge: '🌿 Elementary',
        description: 'Basic communication skills'
      },
      'B1': { 
        minPoints: 1000, 
        badge: '🌳 Intermediate',
        description: 'Confident in most situations'
      },
      'B2': { 
        minPoints: 1500, 
        badge: '🌲 Advanced',
        description: 'Advanced language skills'
      }
    };

    // Initialize or load user progress
    this.initializeProgress();
  }

  // Initialize progress from local storage
  initializeProgress() {
    const savedProgress = localStorage.getItem('englishLearningProgress');
    
    if (savedProgress) {
      this.userData = JSON.parse(savedProgress);
    } else {
      this.userData = {
        totalPoints: 0,
        currentLevel: 'A1',
        completedExercises: []
      };
    }
  }

  // Add points for completed exercise
  addExercisePoints(exerciseId, points = 5) {
    // Prevent duplicate exercise counting
    if (this.userData.completedExercises.includes(exerciseId)) {
      console.log('Exercise already completed');
      return false;
    }

    // Add points
    this.userData.totalPoints += points;
    this.userData.completedExercises.push(exerciseId);

    // Update level
    this.updateCurrentLevel();

    // Save progress
    this.saveProgress();

    // Show achievement
    this.showAchievement(points);

    return true;
  }

  // Determine current level based on points
  updateCurrentLevel() {
    for (let levelKey in this.levels) {
      if (this.userData.totalPoints >= this.levels[levelKey].minPoints) {
        this.userData.currentLevel = levelKey;
      }
    }
  }

  // Save progress to local storage
  saveProgress() {
    localStorage.setItem('englishLearningProgress', JSON.stringify(this.userData));
  }

  // Get current progress details
  getProgress