import 'models.dart';

/// Combines strict local matching with an advisory semantic AI result.
///
/// Progress is deliberately permissive: a strict local match can continue if
/// AI is unavailable or disagrees. Mastery evidence is conservative: a free
/// scene produces independent evidence only when local and AI agree and the
/// learner received no answer-level help.
DialogueTurnDecision resolveDialogueTurnDecision({
  required LocalDialogueVerdict local,
  required DialogueAiIntervention? ai,
  required bool aiWasAttempted,
  required bool isFreeScene,
  required DialogueSupportLevel supportLevel,
}) {
  if (local == LocalDialogueVerdict.rejected) {
    return const DialogueTurnDecision(
      canAdvance: false,
      evidenceOutcome: EvidenceKind.languageError,
      validationSource: DialogueValidationSource.local,
      supportLevel: DialogueSupportLevel.none,
      feedback: '请输入一个有效的英文回答。',
    );
  }

  final aiAccepted =
      ai?.accepted == true &&
      ai?.goalSatisfied == true &&
      ai?.verdict == DialogueAiVerdict.accepted;
  final assisted = switch (supportLevel) {
    DialogueSupportLevel.hint ||
    DialogueSupportLevel.translation ||
    DialogueSupportLevel.correction ||
    DialogueSupportLevel.skipped => true,
    _ => false,
  };

  if (local == LocalDialogueVerdict.accepted && aiAccepted) {
    return DialogueTurnDecision(
      canAdvance: true,
      evidenceOutcome: !isFreeScene
          ? (assisted ? EvidenceKind.assisted : EvidenceKind.pending)
          : (assisted
                ? EvidenceKind.assisted
                : EvidenceKind.independentSuccess),
      validationSource: DialogueValidationSource.localAndAi,
      supportLevel: supportLevel,
      feedback: ai?.explanation,
    );
  }

  if (aiAccepted) {
    return DialogueTurnDecision(
      canAdvance: true,
      evidenceOutcome: assisted ? EvidenceKind.assisted : EvidenceKind.pending,
      validationSource: DialogueValidationSource.ai,
      supportLevel: supportLevel == DialogueSupportLevel.none
          ? DialogueSupportLevel.validationOnly
          : supportLevel,
      feedback: ai?.explanation,
    );
  }

  if (local == LocalDialogueVerdict.accepted) {
    final aiExplicitlyRejected =
        ai?.verdict == DialogueAiVerdict.correctable ||
        ai?.verdict == DialogueAiVerdict.offTopic;
    if (aiExplicitlyRejected) {
      return DialogueTurnDecision(
        canAdvance: false,
        evidenceOutcome: assisted
            ? EvidenceKind.assisted
            : EvidenceKind.pending,
        validationSource: DialogueValidationSource.disagreement,
        supportLevel: supportLevel,
        feedback: ai?.explanation,
        suggestion: ai?.suggestion,
      );
    }
    final source = aiWasAttempted
        ? (ai == null
              ? DialogueValidationSource.unavailable
              : DialogueValidationSource.disagreement)
        : DialogueValidationSource.local;
    return DialogueTurnDecision(
      canAdvance: true,
      evidenceOutcome: assisted
          ? EvidenceKind.assisted
          : aiWasAttempted
          ? EvidenceKind.pending
          : isFreeScene
          ? EvidenceKind.independentSuccess
          : EvidenceKind.pending,
      validationSource: source,
      supportLevel: supportLevel,
      feedback: ai?.explanation,
    );
  }

  return DialogueTurnDecision(
    canAdvance: false,
    evidenceOutcome: assisted ? EvidenceKind.assisted : EvidenceKind.pending,
    validationSource: aiWasAttempted
        ? (ai == null
              ? DialogueValidationSource.unavailable
              : DialogueValidationSource.localAndAi)
        : DialogueValidationSource.local,
    supportLevel: supportLevel,
    feedback: ai?.explanation ?? '暂时无法确认这句是否完成本轮任务，请换一种说法。',
    suggestion: ai?.suggestion,
  );
}