import 'dart:convert';
import 'dart:math';

import 'package:injectable/injectable.dart';
import 'package:drift_postgres/drift_postgres.dart';
import 'package:mnemo_cards_backend/database/database.dart';
import 'package:mnemo_cards_backend/packs/card_image_storage.dart';
import 'package:mnemo_cards_backend/packs/voice_storage.dart';
import 'package:mnemo_cards_backend/storage/minio_config.dart';
import 'package:mnemo_cards_backend/storage/minio_service.dart';
import 'package:mnemo_cards_common_backend/mnemo_cards_common_backend.dart';
import 'package:mnemo_cards_backend/tests/generators/models/creation_test_data.dart';
import 'package:mnemo_cards_common/mnemo_cards_common.dart';
import 'package:drift/drift.dart' as drift;

import 'generators/pack_test_generator.dart';

@lazySingleton
class TestManager {
  final AppDatabase _db;
  final MinioService _minioService;

  TestManager(this._db, this._minioService);

  static final _uuidRegex = RegExp(
    r'^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$',
    caseSensitive: false,
  );

  bool _isUuid(String value) => _uuidRegex.hasMatch(value.trim());

  bool _isBase64OrDataUrlImage(String value) =>
      CardImageStorage.tryParseBase64Image(value) != null;

  String? _extractCardIdFromApiImageUrl(String value) {
    final v = value.trim();
    if (!CardImageStorage.isApiImageUrl(v)) return null;
    final match =
        RegExp(r'/cards/([^/]+)/image(?:Back)?$').firstMatch(v)?.group(1);
    if (match == null) return null;
    return _isUuid(match) ? match : null;
  }

  Future<void> _tryLinkCardToPack({
    required String packId,
    required String cardId,
  }) async {
    try {
      final card = await _db.packDao.getCardById(cardId);
      if (card == null) return;
      await _db.packDao.addCardToPack(packId: packId, cardId: cardId);
    } catch (_) {
      // Best-effort only.
    }
  }

  Future<String?> _convertBase64ToCard(String base64Image, String? packId) async {
    try {
      final companion = GameCardsCompanion.insert(
        original: 'test_image',
        translation: 'test_image',
        image: '',
        mnemo: const drift.Value('test_image'),
      );

      final cardId = await _db.packDao.createCard(companion);
      if (packId != null) {
        await _tryLinkCardToPack(packId: packId, cardId: cardId);
      }

      final stored = await CardImageStorage.persistFromBase64(
        cardId: cardId,
        imageValue: base64Image,
        preferredFileName: null,
        isBack: false,
      );
      if (stored == null) return null;

      final created = await _db.packDao.getCardById(cardId);
      if (created == null) return null;

      await _db.packDao.updateCard(
        created.copyWith(
          image: stored.fileName,
          updatedAt: PgDateTime(DateTime.now()),
        ),
      );

      return cardId;
    } catch (_) {
      return null;
    }
  }

  Future<String?> _normalizeImageValueForDb(
    String? value, {
    required String? packId,
  }) async {
    if (value == null) return null;
    final v = value.trim();
    if (v.isEmpty) return null;

    // Remote URL: keep as is
    if (CardImageStorage.isRemoteUrl(v)) return v;

    // If it's already a valid UUID (object ID in MinIO), keep it
    if (_isUuid(v)) {
      return v;
    }

    // API URL: extract cardId if it's a valid UUID
    final fromApi = _extractCardIdFromApiImageUrl(v);
    if (fromApi != null && _isUuid(fromApi)) {
      return fromApi; // Return as object ID
    }

    // Base64/data-url: upload to MinIO and return object ID
    if (_isBase64OrDataUrlImage(v)) {
      final parsed = CardImageStorage.tryParseBase64Image(v);
      if (parsed != null) {
        try {
          final objectId = await _minioService.uploadFile(
            bucket: MinioConfig.cardImagesBucket,
            bytes: parsed.bytes,
            contentType: parsed.contentType,
          );
          return objectId;
        } catch (e) {
          print('Error uploading test image to MinIO: $e');
          // Fallback: try old method for backward compatibility
          return _convertBase64ToCard(v, packId);
        }
      }
    }

    // Legacy: old filename format or other - keep as is for backward compatibility
    return v;
  }

  /// Converts image value to presigned URL for display
  Future<String?> _imageValueToApiUrl(
    String? value, {
    required String? packId,
  }) async {
    if (value == null) return null;
    final v = value.trim();
    if (v.isEmpty) return null;

    // Already a URL: return as is
    if (CardImageStorage.isRemoteUrl(v) || CardImageStorage.isApiImageUrl(v)) {
      return v;
    }

    // If it's a valid UUID (object ID in MinIO), generate presigned URL
    if (_isUuid(v)) {
      final presignedUrl = await _minioService.getPresignedUrl(
        bucket: MinioConfig.cardImagesBucket,
        objectId: v,
      );
      return presignedUrl;
    }

    // Legacy: try to extract cardId from API URL
    final cardId = _extractCardIdFromApiImageUrl(v);
    if (cardId != null && packId != null) {
      // If cardId is UUID, generate presigned URL
      if (_isUuid(cardId)) {
        final presignedUrl = await _minioService.getPresignedUrl(
          bucket: MinioConfig.cardImagesBucket,
          objectId: cardId,
        );
        return presignedUrl;
      }
      // Old format: use API endpoint
      return '/api/v2/packs/$packId/cards/$cardId/image';
    }

    // Don't leak base64 through user API.
    if (_isBase64OrDataUrlImage(v)) return null;
    return v;
  }

  /// Converts an audio value to a presigned URL if it's a UUID (objectId in MinIO),
  /// or returns it as-is if it's already a remote URL.
  ///
  /// Similar to _imageValueToApiUrl but for audio files stored in voice-audio bucket.
  Future<String?> _audioValueToApiUrl(String? value) async {
    if (value == null) return null;
    final v = value.trim();
    if (v.isEmpty) return null;

    // Already a remote URL: return as is
    if (VoiceStorage.isRemoteUrl(v)) {
      return v;
    }

    // If it's a valid UUID (object ID in MinIO), generate presigned URL
    if (_isUuid(v)) {
      final presignedUrl = await _minioService.getPresignedUrl(
        bucket: MinioConfig.voiceAudioBucket,
        objectId: v,
      );
      return presignedUrl;
    }

    // Legacy formats (base64, filenames) - don't leak through API
    // Return null to indicate invalid/unsupported format
    if (VoiceStorage.tryParseBase64Audio(v) != null) return null;
    
    // For other formats (like legacy filenames), return null
    // They should be migrated to UUID format
    return null;
  }

  Future<TestStatisticsDto?> _testStatisticsDto(
      String userId, String testId) async {
    final statistics = await _db.testDao.getTestStatistics(userId, testId);
    if (statistics == null) return null;

    // Convert TestStatistic to TestStatisticsDto
    // metadata is stored as JSON string with 'attempts' key
    final metadataMap = statistics.metadata.isNotEmpty
        ? (json.decode(statistics.metadata) as Map<String, dynamic>? ?? {})
        : <String, dynamic>{};
    final attempts = (metadataMap['attempts'] as List<dynamic>?) ?? [];
    
    // Get words from the last attempt, or empty list if no attempts
    final lastAttempt = attempts.isNotEmpty 
        ? attempts.last as Map<String, dynamic>?
        : null;
    final wordsJson = (lastAttempt?['words'] as List<dynamic>?) ?? [];
    
    // Convert words JSON to WordStatisticsDto
    final words = wordsJson
        .map((w) => WordStatisticsDto.fromJson(w as Map<String, dynamic>))
        .toList();
    
    return TestStatisticsDto(
      testId: statistics.testId,
      words: AllWordsStatisticsDto(words: words),
      attempts: attempts.length,
      sessionToken: lastAttempt?['sessionToken'] as String?,
    );
  }

  Future<TestDto?> fetchTest(String id, UserModel user) async {
    final testId = id;

    final test = await _db.testDao.getTestById(testId);
    if (test == null) return null;

    // Get packId for the test to convert image IDs to URLs
    final packId = await _db.testDao.getPackIdForTest(testId);

    final questions = await _db.testDao.getTestQuestions(testId);
    final statistics = await _testStatisticsDto(user.id!, testId);

    // Convert Test to TestDto
    final questionsList = <AbstractTestQuestion>[];
    for (final q in questions) {
      // Build question JSON from separate fields
      final questionJson = <String, dynamic>{
        'questionType': q.questionType,
        'id': q.id,
        'word': q.word,
        'answer': q.answer,
      };

      // Parse options (JSON array of buttons / matrix cards)
      List<dynamic> buttons = [];
      try {
        buttons = json.decode(q.options) as List<dynamic>;
      } catch (_) {
        buttons = [];
      }
      questionJson['buttons'] = buttons;

      // Parse uiData (image, text, audio, template, matrixSize, ...)
      Map<String, dynamic> uiData = {};
      try {
        uiData = json.decode(q.uiData) as Map<String, dynamic>;
      } catch (_) {
        uiData = {};
      }

      var mutated = false;

      if (uiData['image'] != null) {
        final raw = uiData['image']?.toString();
        final normalized =
            await _normalizeImageValueForDb(raw, packId: packId);
        if ((raw ?? '').trim() != (normalized ?? '').trim()) {
          mutated = true;
        }
        if (normalized == null) {
          uiData.remove('image');
        } else {
          // Keep image as objectId, add imageUrl as presigned URL
          uiData['image'] = normalized;
          final imageUrl = await _imageValueToApiUrl(
            normalized,
            packId: packId,
          );
          if (imageUrl != null) {
            uiData['imageUrl'] = imageUrl;
          }
        }
      } else {
        // If image was removed, also remove imageUrl
        uiData.remove('imageUrl');
      }

      // Normalize button images too (so response is always URLs, never base64).
      // Keep image as objectId, add imageUrl as presigned URL
      final normalizedButtons = <dynamic>[];
      for (final b in buttons) {
        if (b is Map) {
          final buttonMap = Map<String, dynamic>.from(
            b.map((k, v) => MapEntry(k.toString(), v)),
          );
          if (buttonMap['image'] != null) {
            final raw = buttonMap['image']?.toString();
            final normalized =
                await _normalizeImageValueForDb(raw, packId: packId);
            if ((raw ?? '').trim() != (normalized ?? '').trim()) {
              mutated = true;
            }
            if (normalized == null) {
              buttonMap.remove('image');
              buttonMap.remove('imageUrl');
            } else {
              // Keep image as objectId, add imageUrl as presigned URL
              buttonMap['image'] = normalized;
              final imageUrl = await _imageValueToApiUrl(
                normalized,
                packId: packId,
              );
              if (imageUrl != null) {
                buttonMap['imageUrl'] = imageUrl;
              }
            }
          }
          normalizedButtons.add(buttonMap);
        } else {
          normalizedButtons.add(b);
        }
      }
      questionJson['buttons'] = normalizedButtons;

      if (mutated) {
        await _db.testDao.updateTestQuestion(
          q.copyWith(
            options: jsonEncode(normalizedButtons),
            uiData: jsonEncode(uiData),
            updatedAt: PgDateTime(DateTime.now()),
          ),
        );
      }

      // Convert audio to presigned URL if it's a UUID (objectId in MinIO)
      // Note: image and imageUrl were already set above during normalization
      final uiDataForResponse = Map<String, dynamic>.from(uiData);
      if (uiDataForResponse['audio'] != null) {
        final audioUrl = await _audioValueToApiUrl(
          uiDataForResponse['audio']?.toString(),
        );
        if (audioUrl != null) {
          uiDataForResponse['audio'] = audioUrl;
        } else {
          // If conversion failed (e.g., base64 or invalid format), remove audio
          uiDataForResponse.remove('audio');
        }
      }

      // Buttons already have image (objectId) and imageUrl (presigned URL)
      // from normalization above, no need to convert again
      questionJson['buttons'] = normalizedButtons;
      questionJson.addAll(uiDataForResponse);

      // Matrix question: allow storing only config (matrixSize) and generate
      // actual matrix cards from pack pool on-the-fly if buttons are missing.
      if (q.questionType == TestQuestionType.matrix.name) {
        final matrixSizeRaw = questionJson['matrixSize'];
        final matrixSize = switch (matrixSizeRaw) {
          int v => v,
          num v => v.toInt(),
          String v => int.tryParse(v) ?? 3,
          _ => 3,
        };
        questionJson['matrixSize'] = matrixSize;

        final currentButtons = (questionJson['buttons'] as List<dynamic>?) ?? [];
        if (currentButtons.isEmpty && packId != null) {
          final pool = await _db.packDao.getPackCards(packId);
          final maxSize = sqrt(pool.length).floor().clamp(1, 4);
          final resolvedSize = matrixSize.clamp(1, maxSize);
          final total = resolvedSize * resolvedSize;

          final rng = Random(
            (testId.hashCode ^ q.id.hashCode ^ resolvedSize) & 0x7fffffff,
          );

          final shuffled = pool.toList()..shuffle(rng);
          final selected = shuffled.take(total).toList();

          final generatedButtons = selected
              .map(
                (c) => <String, dynamic>{
                  'id': c.id,
                  // store image as objectId (MinIO) or filename
                  'image': c.image,
                  'original': c.original,
                  'translation': c.translation,
                },
              )
              .toList();

          questionJson['buttons'] = generatedButtons;

          if (selected.isNotEmpty) {
            final target = selected[rng.nextInt(selected.length)];
            questionJson['word'] = target.original;
            questionJson['answer'] = target.id;
          }

          questionJson['matrixSize'] = resolvedSize;
        } else if ((questionJson['answer'] as String?)?.isEmpty != false) {
          // If matrix cards exist but answer is missing, derive initial target
          // from the first card.
          final first = currentButtons.firstOrNull;
          if (first is Map<String, dynamic>) {
            final id = first['id']?.toString();
            final original = first['original']?.toString();
            if (id != null && id.isNotEmpty) {
              questionJson['answer'] = id;
            }
            if (original != null && original.isNotEmpty) {
              questionJson['word'] = original;
            }
          }
        }
      }

      // Convert button images to URLs (works for both TestButtonDto and matrix cards)
      // Add imageUrl while keeping image (objectId) for admin
      // All images now use the same cardImagesBucket
      final updatedButtons = await Future.wait(
        (questionJson['buttons'] as List<dynamic>? ?? []).map((button) async {
          if (button is Map<String, dynamic> && button['image'] != null) {
            final buttonMap = Map<String, dynamic>.from(button);
            final imageValue = buttonMap['image']?.toString();
            
            // Convert image to presigned URL
            final imageUrl = await _imageValueToApiUrl(
              imageValue,
              packId: packId,
            );
            
            if (imageUrl != null) {
              buttonMap['imageUrl'] = imageUrl;
            }
            return buttonMap;
          }
          return button;
        }),
      );
      questionJson['buttons'] = updatedButtons;

      questionsList.add(AbstractTestQuestion.fromJson(questionJson));
    }

    final normalizedCover =
        await _normalizeImageValueForDb(test.cover, packId: packId);
    final coverUrl = await _imageValueToApiUrl(
      normalizedCover,
      packId: packId,
    );

    return TestDto(
      id: testId.toString(),
      name: test.name,
      color: test.color,
      cover: normalizedCover, // Object ID (for admin)
      coverUrl: coverUrl, // Presigned URL (for display)
      version: test.version ?? '1.0',
      time: test.time,
      timeSubtitle: test.timeSubtitle,
      questions: questionsList,
      statistics: statistics,
    );
  }

  Future<List<TestDto>> availableTests(UserModel userModel) async {
    final tests = await _db.testDao.getAllTests();

    final testDtos = <TestDto>[];
    for (final test in tests) {
      final questions = await _db.testDao.getTestQuestions(test.id);
      final statistics = await _testStatisticsDto(userModel.id!, test.id);

      final questionsList = questions.map((q) {
        // Build question JSON from separate fields
        final questionJson = <String, dynamic>{
          'questionType': q.questionType,
          'id': q.id,
          'word': q.word,
        };
        
        // Parse options (JSON array of buttons)
        try {
          final options = json.decode(q.options) as List<dynamic>;
          questionJson['buttons'] = options;
        } catch (e) {
          questionJson['buttons'] = [];
        }
        
        // Add answer
        questionJson['answer'] = q.answer;
        
        // Parse uiData (image, text, audio, template)
        try {
          final uiData = json.decode(q.uiData) as Map<String, dynamic>;
          questionJson.addAll(uiData);
        } catch (e) {
          // If uiData is empty or invalid, ignore
        }
        
        return AbstractTestQuestion.fromJson(questionJson);
      }).toList();

      testDtos.add(TestDto(
        id: test.id.toString(),
        name: test.name,
        color: test.color,
        cover: test.cover,
        version: test.version ?? '1.0',
        time: test.time,
        timeSubtitle: test.timeSubtitle,
        questions: questionsList,
        statistics: statistics,
      ));
    }

    return testDtos;
  }

  Future<List<TestDto>> fetchPackTests(
    UserModel user,
    CardPackModel model,
  ) async {
    final packId = model.id;
    if (packId == null) return [];

    final tests = await _db.testDao.getTestsByPackId(packId);

    final testDtos = <TestDto>[];
    for (final test in tests) {
      final questions = await _db.testDao.getTestQuestions(test.id);
      final statistics = await _testStatisticsDto(user.id!, test.id);

      final questionsList = await Future.wait(
        questions.map((q) async {
          // Build question JSON from separate fields
          final questionJson = <String, dynamic>{
            'questionType': q.questionType,
            'id': q.id,
            'word': q.word,
          };
          
          // Parse options (JSON array of buttons)
          List<dynamic> buttons = [];
          try {
            buttons = json.decode(q.options) as List<dynamic>;
          } catch (e) {
            buttons = [];
          }
          
          // Convert button images to URLs (works for both TestButtonDto and matrix cards)
          // Add imageUrl while keeping image (objectId) for admin
          final updatedButtons = await Future.wait(
            buttons.map((button) async {
              if (button is Map<String, dynamic> && button['image'] != null) {
                final buttonMap = Map<String, dynamic>.from(button);
                final imageValue = buttonMap['image']?.toString();
                
                // Convert image to presigned URL
                final imageUrl = await _imageValueToApiUrl(
                  imageValue,
                  packId: packId,
                );
                
                if (imageUrl != null) {
                  buttonMap['imageUrl'] = imageUrl;
                }
                return buttonMap;
              }
              return button;
            }),
          );
          
          questionJson['buttons'] = updatedButtons;
          
          // Add answer
          questionJson['answer'] = q.answer;
          
          // Parse uiData (image, text, audio, template)
          try {
            final uiData = json.decode(q.uiData) as Map<String, dynamic>;
            // Convert question image to URL
            if (uiData['image'] != null) {
              final imageValue = uiData['image']?.toString();
              final imageUrl = await _imageValueToApiUrl(
                imageValue,
                packId: packId,
              );
              if (imageUrl != null) {
                uiData['imageUrl'] = imageUrl;
              }
            }
            questionJson.addAll(uiData);
          } catch (e) {
            // If uiData is empty or invalid, ignore
          }
          
          return AbstractTestQuestion.fromJson(questionJson);
        }),
      );

      final normalizedCover =
          await _normalizeImageValueForDb(test.cover, packId: packId);
      final coverUrl = await _imageValueToApiUrl(
        normalizedCover,
        packId: packId,
      );

      testDtos.add(TestDto(
        id: test.id.toString(),
        name: test.name,
        color: test.color,
        cover: normalizedCover, // Object ID (for admin)
        coverUrl: coverUrl, // Presigned URL (for display)
        version: test.version ?? '1.0',
        time: test.time,
        timeSubtitle: test.timeSubtitle,
        questions: questionsList,
        statistics: statistics,
      ));
    }

    return testDtos;
  }

  Future<void> refreshCustomCreationTestsData() async {
    // Load custom creation test data from database
    // For now, keep it simple
  }

  Future<void> updateGeneratedTests(CardPackModel model) async {
    final packId = model.id;
    if (packId == null) return;

    // Get pack data from database
    final pack = await _db.packDao.getPackById(packId);
    if (pack == null) return;

    // Get all cards for the pack
    final cards = await _db.packDao.getPackCards(packId);
    if (cards.isEmpty) return;

    // Delete old generated tests for this pack
    final existingTests = await _db.testDao.getTestsByPackId(packId);
    final oldGeneratedTests = existingTests
        .where((test) => test.version == 'generated')
        .toList();
    for (final oldTest in oldGeneratedTests) {
      await _db.testDao.softDeleteTest(oldTest.id);
    }

    // Create creation test data
    final testDataItems = cards.map((card) {
      return TestDataItem(
        id: card.id.toString(),
        original: card.original,
        translation: card.translation,
        image: card.image,
        audio: card.original, // Use original as audio
      );
    }).toList();

    final creationTestData = CreationTestData(
      items: testDataItems,
      title: pack.title,
      color: pack.color,
      packId: packId.toString(),
    );

    // Generate test using PackTestGenerator
    final generator = PackTestGenerator(creationTestData);
    final testDto = await generator.generate(
      name: '${pack.title} Test',
      ratios: {
        TestQuestionType.simple: 0.6,
        TestQuestionType.input_buttons: 0.2,
        TestQuestionType.matrix: 0.2,
      },
      multiply: 1.0,
    );

    // Save test to database and link it to the pack in one transaction.
    await addTest(
      testDto,
      packId: packId,
    );
  }

  Future<String> addTest(
    TestDto testDto, {
    String? packId,
  }) async {
    String? createdTestId;
    await _db.transaction(() async {
      // Create test
      final testCompanion = TestsCompanion.insert(
        name: testDto.name,
        color: drift.Value(testDto.color),
        cover: drift.Value(testDto.cover),
        version: drift.Value(testDto.version),
        time: drift.Value(testDto.time),
        timeSubtitle: drift.Value(testDto.timeSubtitle),
      );

      createdTestId = await _db.testDao.createTest(testCompanion);
      final testId = createdTestId!;

      if (packId != null) {
        await _db.testDao.linkTestToPack(testId, packId);
      }

      // Create questions
      int orderIndex = 0;
      for (final question in testDto.questions) {
        final questionJson = question.toJson();
        
        // Extract key fields
        final word = questionJson['word'] as String? ?? '';
        final answer = questionJson['answer'] as String? ?? '';
        final buttons = questionJson['buttons'] as List<dynamic>? ?? [];
        
        // UI data (image, text, audio, template)
        final uiData = <String, dynamic>{};
        if (questionJson['image'] != null) uiData['image'] = questionJson['image'];
        if (questionJson['text'] != null) uiData['text'] = questionJson['text'];
        if (questionJson['audio'] != null) uiData['audio'] = questionJson['audio'];
        if (questionJson['template'] != null) uiData['template'] = questionJson['template'];
        if (questionJson['matrixSize'] != null) uiData['matrixSize'] = questionJson['matrixSize'];
        
        final questionCompanion = TestQuestionsCompanion.insert(
          testId: testId,
          orderIndex: drift.Value(orderIndex++),
          questionType: question.questionType.name,
          word: word,
          answer: answer,
          options: drift.Value(json.encode(buttons)),
          uiData: drift.Value(json.encode(uiData)),
        );

        await _db.testDao.createTestQuestion(questionCompanion);
      }
    });
    return createdTestId!;
  }
}