enum LearningGoal { dailyLife, travel, workStarter }

enum PlacementLevel { beginner, someBasics, simpleConversation }

enum AppTab { home, learn, dialogue, review, progress }

enum LessonStep {
  preview,
  listening,
  speaking,
  reading,
  writing,
  dialogue,
  independent,
  complete,
}

enum MasteryStatus { newItem, recognize, recall, use, master, needsReview }

enum EvidenceKind {
  exposure,
  assisted,
  independentSuccess,
  languageError,
  pending,
}

class AttemptEvidence {
  const AttemptEvidence({
    required this.id,
    required this.itemId,
    required this.taskId,
    required this.skill,
    required this.inputMode,
    required this.outcome,
    required this.createdAt,
    this.rawAnswer,
    this.recordingPath,
    this.assisted = false,
    this.variantIndex = 0,
    this.originalTranscript,
    this.transcriptConfirmed = false,
    this.transcriptEdited = false,
  });

  final String id;
  final String itemId;
  final String taskId;
  final String skill;
  final String inputMode;
  final EvidenceKind outcome;
  final DateTime createdAt;
  final String? rawAnswer;

  /// Local-only file reference. It is absent unless the learner opted to keep
  /// recordings; no path or audio is sent to an AI provider.
  final String? recordingPath;
  final bool assisted;
  final int variantIndex;

  /// The device STT result before the learner edits it. This local-only field
  /// distinguishes confirmed spoken input from a subsequent typed rewrite.
  final String? originalTranscript;
  final bool transcriptConfirmed;
  final bool transcriptEdited;
}

enum AiProviderType { mock, gemini, openAi, compatible }

enum AssessmentSkill { listening, speaking, reading, writing }

enum ContentStatus { draft, validated, approved, rejected }

enum ContentSource { builtInOriginal, aiGenerated, importedReference }

/// A validated, bounded suggestion from an AI conversation provider.
/// The client still owns task completion and mastery decisions.
class DialogueAiResponse {
  const DialogueAiResponse({
    required this.reply,
    this.slots = const {},
    this.evidence = const [],
    this.suggestsComplete = false,
    this.translation,
    this.feedback,
  });

  final String reply;
  final String? translation;
  final Map<String, String> slots;
  final List<String> evidence;
  final bool suggestsComplete;
  final String? feedback;
}

/// A bounded suggestion only. It never changes completion, mastery, or a
/// stage result; those decisions remain on-device and evidence-based.
class WritingAiFeedback {
  const WritingAiFeedback({
    required this.verdict,
    required this.feedback,
    required this.suggestion,
    required this.missing,
  });

  /// `accepted`, `rewrite`, or `uncertain`.
  final String verdict;
  final String feedback;
  final String? suggestion;
  final List<String> missing;
}

class AssessmentRecord {
  const AssessmentRecord({
    required this.packId,
    required this.completedAt,
    required this.results,
    this.pendingSkills = const {},
  });

  final String packId;
  final DateTime completedAt;
  final Map<AssessmentSkill, bool> results;
  final Set<AssessmentSkill> pendingSkills;

  bool get passed =>
      AssessmentSkill.values.every((skill) => results[skill] == true);

  List<AssessmentSkill> get failedSkills => AssessmentSkill.values
      .where(
        (skill) => results[skill] != true && !pendingSkills.contains(skill),
      )
      .toList();
}

class AssessmentDraft {
  const AssessmentDraft({
    required this.packId,
    required this.taskIndex,
    required this.results,
  });
  final String packId;
  final int taskIndex;
  final Map<String, bool> results;
}

class DialogueDraft {
  const DialogueDraft({
    required this.lessonId,
    required this.stage,
    required this.turns,
    required this.usedHelp,
  });
  final String lessonId;
  final int stage;
  final List<DialogueTurn> turns;
  final bool usedHelp;
}

class LessonSummary {
  const LessonSummary({
    required this.number,
    required this.title,
    required this.outcome,
    this.isComplete = false,
    this.isCurrent = false,
  });

  final int number;
  final String title;
  final String outcome;
  final bool isComplete;
  final bool isCurrent;
}

class VocabularyItem {
  const VocabularyItem({
    required this.id,
    required this.word,
    required this.meaning,
    required this.example,
    required this.exampleMeaning,
    this.ipa,
  });

  final String id;
  final String word;
  final String meaning;
  final String example;
  final String exampleMeaning;
  final String? ipa;
}

/// A non-core explanation returned by a configured text provider for a word
/// or phrase that is not present in the reviewed course lexicon.  These
/// entries deliberately never participate in review scheduling or mastery.
class TemporaryLexiconEntry {
  const TemporaryLexiconEntry({
    required this.query,
    required this.definition,
    required this.provider,
    required this.model,
    required this.createdAt,
  });

  final String query;
  final String definition;
  final String provider;
  final String model;
  final DateTime createdAt;
}

/// Represents an extracted key phrase or vocabulary item within a sentence.
class PhraseBreakdownItem {
  const PhraseBreakdownItem({
    required this.phrase,
    required this.meaning,
    this.ipa,
    this.usageNote,
  });

  final String phrase;
  final String meaning;
  final String? ipa;
  final String? usageNote;

  Map<String, dynamic> toJson() => {
    'phrase': phrase,
    'meaning': meaning,
    if (ipa != null) 'ipa': ipa,
    if (usageNote != null) 'usageNote': usageNote,
  };

  factory PhraseBreakdownItem.fromJson(Map<String, dynamic> json) =>
      PhraseBreakdownItem(
        phrase: json['phrase'] as String? ?? '',
        meaning: json['meaning'] as String? ?? '',
        ipa: json['ipa'] as String?,
        usageNote: json['usageNote'] as String?,
      );
}

/// Structured multi-dimensional analysis for a sentence or phrase, including
/// translation, sentence pattern, grammar note, pronunciation tips, and extracted phrases.
class SentenceAnalysisResult {
  const SentenceAnalysisResult({
    required this.originalText,
    required this.translation,
    this.sentencePattern,
    this.grammarNote,
    this.pronunciationTips,
    this.phrases = const [],
    this.provider = 'unknown',
    this.model = '',
    required this.createdAt,
  });

  final String originalText;
  final String translation;
  final String? sentencePattern;
  final String? grammarNote;
  final String? pronunciationTips;
  final List<PhraseBreakdownItem> phrases;
  final String provider;
  final String model;
  final DateTime createdAt;

  Map<String, dynamic> toJson() => {
    'originalText': originalText,
    'translation': translation,
    if (sentencePattern != null) 'sentencePattern': sentencePattern,
    if (grammarNote != null) 'grammarNote': grammarNote,
    if (pronunciationTips != null) 'pronunciationTips': pronunciationTips,
    'phrases': phrases.map((p) => p.toJson()).toList(),
    'provider': provider,
    'model': model,
    'createdAt': createdAt.toIso8601String(),
  };

  factory SentenceAnalysisResult.fromJson(Map<String, dynamic> json) =>
      SentenceAnalysisResult(
        originalText: json['originalText'] as String? ?? '',
        translation: json['translation'] as String? ?? '',
        sentencePattern: json['sentencePattern'] as String?,
        grammarNote: json['grammarNote'] as String?,
        pronunciationTips: json['pronunciationTips'] as String?,
        phrases: (json['phrases'] as List<dynamic>? ?? const [])
            .whereType<Map<String, dynamic>>()
            .map(PhraseBreakdownItem.fromJson)
            .toList(),
        provider: json['provider'] as String? ?? 'unknown',
        model: json['model'] as String? ?? '',
        createdAt: json['createdAt'] != null
            ? DateTime.tryParse(json['createdAt'] as String) ?? DateTime.now()
            : DateTime.now(),
      );
}

class ReviewItem {
  const ReviewItem({
    required this.id,
    required this.target,
    required this.prompt,
    required this.hint,
    required this.dueAt,
    required this.skill,
    this.attempts = 0,
    this.successfulReviews = 0,
    this.variantIndex = 0,
    this.lastProgressedAt,
    this.isAiGenerated = false,
  });

  final String id;
  final String target;
  final String prompt;
  final String hint;
  final DateTime dueAt;
  final String skill;
  final int attempts;
  final int successfulReviews;
  final int variantIndex;
  final DateTime? lastProgressedAt;
  final bool isAiGenerated;

  ReviewItem copyWith({
    DateTime? dueAt,
    int? attempts,
    int? successfulReviews,
    int? variantIndex,
    String? prompt,
    String? hint,
    String? skill,
    DateTime? lastProgressedAt,
    bool? isAiGenerated,
  }) => ReviewItem(
    id: id,
    target: target,
    prompt: prompt ?? this.prompt,
    hint: hint ?? this.hint,
    dueAt: dueAt ?? this.dueAt,
    skill: skill ?? this.skill,
    attempts: attempts ?? this.attempts,
    successfulReviews: successfulReviews ?? this.successfulReviews,
    variantIndex: variantIndex ?? this.variantIndex,
    lastProgressedAt: lastProgressedAt ?? this.lastProgressedAt,
    isAiGenerated: isAiGenerated ?? this.isAiGenerated,
  );
}

class MasteryItem {
  const MasteryItem({
    required this.id,
    required this.label,
    required this.status,
    required this.evidence,
    this.needsReview = false,
    this.checkpoint = 0,
    this.firstTaughtAt,
  });

  final String id;
  final String label;
  final MasteryStatus status;
  final List<EvidenceKind> evidence;
  final bool needsReview;
  final int checkpoint;
  final DateTime? firstTaughtAt;

  MasteryItem copyWith({
    MasteryStatus? status,
    List<EvidenceKind>? evidence,
    bool? needsReview,
    int? checkpoint,
    DateTime? firstTaughtAt,
  }) => MasteryItem(
    id: id,
    label: label,
    status: status ?? this.status,
    evidence: evidence ?? this.evidence,
    needsReview: needsReview ?? this.needsReview,
    checkpoint: checkpoint ?? this.checkpoint,
    firstTaughtAt: firstTaughtAt ?? this.firstTaughtAt,
  );
}

class DialogueTurn {
  const DialogueTurn({
    required this.text,
    required this.isLearner,
    this.translation,
  });

  final String text;
  final bool isLearner;
  final String? translation;

  DialogueTurn copyWith({
    String? text,
    bool? isLearner,
    String? translation,
  }) {
    return DialogueTurn(
      text: text ?? this.text,
      isLearner: isLearner ?? this.isLearner,
      translation: translation ?? this.translation,
    );
  }
}

/// Ephemeral presentation data for a completed controlled dialogue. The
/// related recap review is separately persisted in AppState.
class DialogueSummaryData {
  const DialogueSummaryData({
    required this.completedTasks,
    required this.personalSentence,
    required this.usedHelp,
    this.improvement,
  });

  final List<String> completedTasks;
  final String personalSentence;
  final bool usedHelp;

  /// One improvement point collected during the dialogue and shown only at the
  /// end, per "对话中不逐句打断" in the conversation spec.
  final String? improvement;
}