import '../models/user_progress.dart';
import '../models/achievement_config.dart';

/// Service for managing achievements
class AchievementService {
  /// Check for newly unlocked achievements asynchronously
  /// Returns list of newly unlocked achievement IDs
  Future<List<String>> checkAchievementsAsync(UserProgress progress) async {
    List<String> newlyUnlocked = [];

    for (var achievement in AchievementConfig.all) {
      // Skip if already unlocked
      if (progress.unlockedAchievements.containsKey(achievement.id)) {
        continue;
      }

      // Check if requirement is met
      bool unlocked = false;
      switch (achievement.type) {
        case AchievementType.sessionCount:
          unlocked = progress.totalSessions >= achievement.requiredValue;
          break;
        case AchievementType.distractionCount:
          unlocked = progress.totalDistractions >= achievement.requiredValue;
          break;
        case AchievementType.totalMinutes:
          unlocked = progress.totalFocusMinutes >= achievement.requiredValue;
          break;
        case AchievementType.consecutiveDays:
          unlocked = progress.consecutiveCheckIns >= achievement.requiredValue;
          break;
      }

      if (unlocked) {
        // Mark as unlocked with timestamp
        progress.unlockedAchievements[achievement.id] = DateTime.now();

        // Award bonus points
        progress.totalPoints += achievement.bonusPoints;
        progress.currentPoints += achievement.bonusPoints;

        newlyUnlocked.add(achievement.id);
      }
    }

    return newlyUnlocked;
  }

  /// Get progress towards a specific achievement (0.0 - 1.0)
  double getAchievementProgress(
    UserProgress progress,
    AchievementConfig achievement,
  ) {
    int currentValue = 0;

    switch (achievement.type) {
      case AchievementType.sessionCount:
        currentValue = progress.totalSessions;
        break;
      case AchievementType.distractionCount:
        currentValue = progress.totalDistractions;
        break;
      case AchievementType.totalMinutes:
        currentValue = progress.totalFocusMinutes;
        break;
      case AchievementType.consecutiveDays:
        currentValue = progress.consecutiveCheckIns;
        break;
    }

    return (currentValue / achievement.requiredValue).clamp(0.0, 1.0);
  }

  /// Get current value for achievement type
  int getAchievementCurrentValue(
    UserProgress progress,
    AchievementConfig achievement,
  ) {
    switch (achievement.type) {
      case AchievementType.sessionCount:
        return progress.totalSessions;
      case AchievementType.distractionCount:
        return progress.totalDistractions;
      case AchievementType.totalMinutes:
        return progress.totalFocusMinutes;
      case AchievementType.consecutiveDays:
        return progress.consecutiveCheckIns;
    }
  }

  /// Get all achievements with their current progress
  Map<AchievementConfig, double> getAllAchievementsWithProgress(
    UserProgress progress,
  ) {
    final result = <AchievementConfig, double>{};
    for (var achievement in AchievementConfig.all) {
      result[achievement] = getAchievementProgress(progress, achievement);
    }
    return result;
  }

  /// Get newly unlocked achievements since last check
  /// This can be used to show notifications for achievements unlocked in background
  List<String> getNewlyUnlockedAchievements(
    UserProgress progress,
    Set<String> previouslyUnlocked,
  ) {
    final currentlyUnlocked = progress.unlockedAchievements.keys.toSet();
    return currentlyUnlocked.difference(previouslyUnlocked).toList();
  }
}