Achievements System

export interface UserStats {
  totalCardsViewed: number;
  unlockedAchievements: string[];
  categoryProgress: Record<string, number>;
  streak: number;
  logoClicks?: number;
  lastStudyTime?: number;
}

{
  id: 'streak_7',
  title: 'On Fire',
  description: 'Reach a 7-day study streak',
  icon: 'whatshot',
  condition: (stats) => stats.streak >= 7
}

function catSize(id: CategoryId): number {
  return getTermsByCategory(id).length;
}

{
  id: 'master_foundation',
  title: 'Foundation Setter',
  description: 'Master all terms in the Foundation category',
  icon: 'architecture',
  category: 'foundation',
  condition: (stats) => (stats.categoryProgress['foundation'] || 0) >= catSize('foundation')
}

export interface Achievement {
  id: string;
  title: string;
  description: string;
  icon: string;
  category?: CategoryId;
  isHidden?: boolean;
  condition: (stats: UserStats) => boolean;
}

// Check achievements after marking a term
const checkAchievements = useCallback(async (
  currentProgress: Progress,
  currentStreak: number,
  currentViews: number,
  currentClicks: number,
  currentUnlocked: string[]
) => {
  const stats = getCurrentStats(currentProgress, currentStreak, currentViews, currentClicks, currentUnlocked);
  const newUnlocked: string[] = [];
  
  ACHIEVEMENTS.forEach(achievement => {
    if (!currentUnlocked.includes(achievement.id)) {
      if (achievement.condition(stats)) {
        newUnlocked.push(achievement.id);
      }
    }
  });
  
  if (newUnlocked.length > 0) {
    // Save and notify user
  }
}, [getCurrentStats]);