import 'deck_config.dart';
import 'question.dart';
import 'attempt_history_entry.dart';
import 'incomplete_attempt.dart';

/// A practice deck containing questions and configuration.
class Deck {
  /// Unique identifier for this deck.
  final String id;

  /// Title of the deck.
  final String title;

  /// Description of the deck.
  final String description;

  /// List of questions in this deck.
  final List<Question> questions;

  /// Configuration for this deck.
  final DeckConfig config;

  /// Current global attempt index (incremented with each attempt).
  final int currentAttemptIndex;

  /// History of completed attempts.
  final List<AttemptHistoryEntry> attemptHistory;

  /// Incomplete attempt that can be resumed.
  final IncompleteAttempt? incompleteAttempt;

  const Deck({
    required this.id,
    required this.title,
    required this.description,
    required this.questions,
    required this.config,
    this.currentAttemptIndex = 0,
    this.attemptHistory = const [],
    this.incompleteAttempt,
  });

  /// Creates a copy of this deck with the given fields replaced.
  Deck copyWith({
    String? id,
    String? title,
    String? description,
    List<Question>? questions,
    DeckConfig? config,
    int? currentAttemptIndex,
    List<AttemptHistoryEntry>? attemptHistory,
    IncompleteAttempt? incompleteAttempt,
    bool clearIncompleteAttempt = false,
  }) {
    return Deck(
      id: id ?? this.id,
      title: title ?? this.title,
      description: description ?? this.description,
      questions: questions ?? this.questions,
      config: config ?? this.config,
      currentAttemptIndex: currentAttemptIndex ?? this.currentAttemptIndex,
      attemptHistory: attemptHistory ?? this.attemptHistory,
      incompleteAttempt: clearIncompleteAttempt ? null : (incompleteAttempt ?? this.incompleteAttempt),
    );
  }

  /// Total number of questions in the deck.
  int get numberOfQuestions => questions.length;

  /// Number of questions marked as known.
  int get knownCount => questions.where((q) => q.isKnown).length;

  /// Number of questions the user has flagged.
  int get flaggedCount => questions.where((q) => q.isFlagged).length;

  /// Questions that the user has flagged.
  List<Question> get flaggedQuestions => questions.where((q) => q.isFlagged).toList();

  /// Practice percentage: (known / total) * 100
  double get practicePercentage {
    if (questions.isEmpty) return 0.0;
    return (knownCount / questions.length) * 100.0;
  }

  /// Progress percentage including partial credit: each question contributes
  /// 1.0 if known, otherwise (consecutiveCorrect / requiredConsecutiveCorrect)
  /// capped at 1.0. Averaged over all questions * 100.
  double get progressPercentage {
    if (questions.isEmpty) return 0.0;
    final required = config.requiredConsecutiveCorrect;
    final sum = questions.fold<double>(0.0, (sum, q) {
      if (q.isKnown) return sum + 1.0;
      final partial = (q.consecutiveCorrect / required).clamp(0.0, 1.0);
      return sum + partial;
    });
    return (sum / questions.length) * 100.0;
  }

  /// Number of completed attempts.
  int get attemptCount => attemptHistory.length;

  /// Average percentage correct across all attempts.
  double get averagePercentageCorrect {
    if (attemptHistory.isEmpty) return 0.0;
    final sum = attemptHistory.fold<double>(
      0.0,
      (sum, entry) => sum + entry.percentageCorrect,
    );
    return sum / attemptHistory.length;
  }

  /// Total time spent on all attempts in milliseconds.
  int get totalTimeSpent {
    return attemptHistory.fold<int>(
      0,
      (sum, entry) => sum + entry.timeSpent,
    );
  }

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is Deck &&
          runtimeType == other.runtimeType &&
          id == other.id &&
          title == other.title &&
          description == other.description &&
          questions.toString() == other.questions.toString() &&
          config == other.config &&
          currentAttemptIndex == other.currentAttemptIndex &&
          attemptHistory.toString() == other.attemptHistory.toString() &&
          incompleteAttempt == other.incompleteAttempt;

  @override
  int get hashCode =>
      id.hashCode ^
      title.hashCode ^
      description.hashCode ^
      questions.hashCode ^
      config.hashCode ^
      currentAttemptIndex.hashCode ^
      attemptHistory.hashCode ^
      (incompleteAttempt?.hashCode ?? 0);
}