import 'package:easy_localization/easy_localization.dart';
import 'package:flutter_mimir/flutter_mimir.dart';
import 'package:search_engine/database.dart';
import 'package:flutter/foundation.dart';

typedef ProgressCallback = void Function(String message, double progress);

class MimirService {
  static final MimirService _instance = MimirService._internal();
  factory MimirService() => _instance;
  MimirService._internal();

  late MimirIndex _index;
  bool _isInitialized = false;

  Future<void> initialize() async {
    if (_isInitialized) return;

    final instance = await Mimir.defaultInstance;
    _index = instance.getIndex('messages');
    _isInitialized = true;
  }

  Future<int> getDocumentCount() async {
    if (!_isInitialized) await initialize();
    final stats = await _index.getAllDocuments();
    return stats.length;
  }

  Future<List<Map<String, dynamic>>> getAllDocuments() async {
    if (!_isInitialized) await initialize();
    return await _index.getAllDocuments();
  }

  Future<void> addDocument(
      String id, String languagesCode, String content) async {
    if (!_isInitialized) await initialize();

    await _index.addDocument({
      'id': id,
      'languages_code': languagesCode,
      'content': content,
    });
  }

  Future<void> addDocuments(List<Map<String, String>> documents) async {
    if (!_isInitialized) await initialize();

    await _index.addDocuments(documents);
  }

  Future<Map<String, dynamic>> search(String query, String languagesCode,
      {int limit = 1000, int offset = 0}) async {
    if (!_isInitialized) await initialize();

    // Execute the search without pagination to get ALL matching results
    final allResults = await _index.search(
      query: query,
      filter: Mimir.where('languages_code', isEqualTo: languagesCode),
    );

    if (kDebugMode && allResults.isNotEmpty) {
      print('🔍 Mimir encontró ${allResults.length} resultados totales');
    }

    // Apply pagination AFTER getting all results
    final start = offset;
    final end = offset + limit;
    final paginatedResults = allResults.sublist(
      start.clamp(0, allResults.length),
      end.clamp(0, allResults.length),
    );

    // Transform results to include both id and content snippet
    final transformedResults = paginatedResults.map((doc) {
      final String content = doc['content'] as String;
      // Extract a snippet of content and position information
      final Map<String, dynamic> snippetInfo =
          _extractSnippetWithPosition(content, query);

      return {
        'id': doc['id'] as String,
        'content': snippetInfo['snippet'] as String,
        'position': snippetInfo['position'].toString(),
        'length': snippetInfo['length'].toString(),
      };
    }).toList();

    // Return both the paginated results and the total count
    return {
      'results': transformedResults,
      'total': allResults.length,
      'allResultIds': allResults.map((doc) => doc['id'] as String).toList(),
    };
  }

  // Helper method to extract a relevant snippet from content with position information
  Map<String, dynamic> _extractSnippetWithPosition(
      String content, String query) {
    // Clean HTML tags and entities first
    String cleanContent = _cleanHtmlContent(content);

    // Default values
    int snippetPosition = 0;
    int matchLength = 0;

    // If content is short enough, return it all
    if (cleanContent.length <= 300) {
      return {
        'snippet': cleanContent,
        'position': 0,
        'length': cleanContent.length
      };
    }

    // Try to find the query in the content
    final lowerContent = cleanContent.toLowerCase();
    final lowerQuery = query.toLowerCase();
    final int position = lowerContent.indexOf(lowerQuery);

    if (position != -1) {
      // Found the query, extract a snippet around it
      final int start = (position - 100).clamp(0, cleanContent.length);
      final int end =
          (position + query.length + 100).clamp(0, cleanContent.length);

      String snippet = cleanContent.substring(start, end);

      // Add ellipsis if needed
      if (start > 0) snippet = '...$snippet';
      if (end < cleanContent.length) snippet = '$snippet...';

      // Calculate relative position in the snippet
      snippetPosition = position - start;
      if (start > 0) snippetPosition += 3; // Adjust for ellipsis
      matchLength = query.length;

      return {
        'snippet': snippet,
        'position': snippetPosition,
        'length': matchLength
      };
    } else {
      // Query not found directly, try with individual words
      final List<String> queryWords =
          query.split(' ').where((word) => word.trim().length > 2).toList();

      for (final word in queryWords) {
        final int wordPos = lowerContent.indexOf(word.toLowerCase());
        if (wordPos != -1) {
          final int start = (wordPos - 100).clamp(0, cleanContent.length);
          final int end =
              (wordPos + word.length + 100).clamp(0, cleanContent.length);

          String snippet = cleanContent.substring(start, end);

          if (start > 0) snippet = '...$snippet';
          if (end < cleanContent.length) snippet = '$snippet...';

          // Calculate relative position in the snippet
          snippetPosition = wordPos - start;
          if (start > 0) snippetPosition += 3; // Adjust for ellipsis
          matchLength = word.length;

          return {
            'snippet': snippet,
            'position': snippetPosition,
            'length': matchLength
          };
        }
      }

      // No match found, return the beginning of the content
      return {
        'snippet': '${cleanContent.substring(0, 300)}...',
        'position': 0,
        'length': 0
      };
    }
  }

  // Helper method to extract a snippet without position information (legacy)
  String _extractSnippet(String content, String query) {
    return _extractSnippetWithPosition(content, query)['snippet'] as String;
  }

  // Helper method to clean HTML content using regex
  String _cleanHtmlContent(String html) {
    if (html.isEmpty) return '';

    // Step 1: Remove HTML tags
    String result = html.replaceAll(RegExp(r'<[^>]*>'), ' ');

    // Step 2: Replace common HTML entities
    final Map<String, String> htmlEntities = {
      '&nbsp;': ' ',
      '&amp;': '&',
      '&lt;': '<',
      '&gt;': '>',
      '&quot;': '"',
      '&apos;': "'",
      '&cent;': '¢',
      '&pound;': '£',
      '&yen;': '¥',
      '&euro;': '€',
      '&copy;': '©',
      '&reg;': '®',
      '&aacute;': 'á',
      '&eacute;': 'é',
      '&iacute;': 'í',
      '&oacute;': 'ó',
      '&uacute;': 'ú',
      '&ntilde;': 'ñ',
      '&Aacute;': 'Á',
      '&Eacute;': 'É',
      '&Iacute;': 'Í',
      '&Oacute;': 'Ó',
      '&Uacute;': 'Ú',
      '&Ntilde;': 'Ñ',
    };

    // Replace known HTML entities
    htmlEntities.forEach((entity, replacement) {
      result = result.replaceAll(entity, replacement);
    });

    // Step 3: Replace numeric HTML entities (like &#123;)
    result = result.replaceAllMapped(RegExp(r'&#(\d+);'), (match) {
      try {
        final int charCode = int.parse(match.group(1)!);
        return String.fromCharCode(charCode);
      } catch (e) {
        return '';
      }
    });

    // Step 4: Replace any remaining entities with a generic pattern
    result = result.replaceAll(RegExp(r'&[a-zA-Z0-9]+;'), '');

    // Step 5: Normalize whitespace (replace multiple spaces with a single space)
    result = result.replaceAll(RegExp(r'\s+'), ' ').trim();

    return result;
  }

  Future<void> deleteDocument(String id) async {
    if (!_isInitialized) await initialize();

    await _index.deleteDocument(id);
  }

  Future<void> clearIndex() async {
    if (!_isInitialized) await initialize();

    await _index.deleteAllDocuments();
  }

  Future<void> syncWithDatabase({ProgressCallback? onProgress}) async {
    if (!_isInitialized) await initialize();

    final database = AppDatabase();
    try {
      // Get all documents from Mimir
      final mimirDocuments = await getAllDocuments();
      final mimirCount = mimirDocuments.length;

      // Create a set of document IDs that are already in Mimir
      final mimirIds =
          Set<String>.from(mimirDocuments.map((doc) => doc['id'] as String));

      // Get all messages from database
      final messages = await database.getAllMessages();
      final dbCount = messages.length;

      if (kDebugMode) {
        print('📊 Documentos en Mimir: $mimirCount');
        print('📊 Documentos en Base de Datos: $dbCount');
      }

      // Find documents that need to be added (in DB but not in Mimir)
      final documentsToAdd = messages.where((draft) {
        return !mimirIds.contains(draft.id) &&
            draft.body != null &&
            draft.body!.isNotEmpty;
      }).toList();

      if (documentsToAdd.isNotEmpty) {
        if (kDebugMode) {
          print('🔄 Documentos a agregar a Mimir: ${documentsToAdd.length}');
        }

        onProgress?.call('updating_search_index'.tr(), 0.0);

        // Prepare documents for Mimir
        final documents = documentsToAdd.map((draft) {
          return {
            'id': draft.id,
            'languages_code': draft.languagesCode,
            'content': draft.body!,
          };
        }).toList();

        if (kDebugMode) {
          print('📝 Documentos válidos para indexar: ${documents.length}');
        }

        // Add documents to Mimir in batches
        const batchSize = 50;
        var indexedCount = 0;
        for (var i = 0; i < documents.length; i += batchSize) {
          final end = (i + batchSize < documents.length)
              ? i + batchSize
              : documents.length;
          final batch = documents.sublist(i, end);
          await addDocuments(batch);
          indexedCount += batch.length;

          // Update progress
          final progress = indexedCount / documents.length;
          onProgress?.call('updating_search_index'.tr(), progress);

          if (kDebugMode) {
            print(
                '✓ Progreso de indexación: $indexedCount/${documents.length}');
          }
        }

        if (kDebugMode) {
          final finalCount = await getDocumentCount();
          print('✅ Indexación completada. Documentos en Mimir: $finalCount');
        }

        onProgress?.call('search_index_updated'.tr(), 1.0);
      } else {
        if (kDebugMode) {
          print('✅ Mimir y Base de Datos están sincronizados');
        }
      }
    } finally {
      database.close();
    }
  }
}