import 'dart:convert';
import 'dart:developer';
import 'package:http/http.dart' as http;
import 'package:hive/hive.dart';
import 'package:lat_lng_to_timezone/lat_lng_to_timezone.dart' as tzmap;
import '../utils/preferences_helper.dart';
import 'package:flutter/material.dart';
import '../screens/meteo_models.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';
import 'dart:async';

class WeatherService {
  static const String _boxName = 'weatherMasterCache';

  Future<Box> _openBox() async {
    if (!Hive.isBoxOpen(_boxName)) {
      return await Hive.openBox(_boxName);
    }
    return Hive.box(_boxName);
  }

  Future<Map<String, dynamic>?> fetchWeather(double lat, double lon,
      {String? locationName,
      BuildContext? context,
      bool isOnlyView = false,
      bool isBackground = false}) async {
    final timezone = tzmap.latLngToTimezoneString(lat, lon);
    final key = locationName ?? 'loc_${lat}_${lon}';
    final box = await _openBox();

    final selectedModel =
        PreferencesHelper.getString("selectedWeatherModel") ?? "best_match";

    final uri = Uri.parse('https://api.open-meteo.com/v1/forecast')
        .replace(queryParameters: {
      'latitude': lat.toString(),
      'longitude': lon.toString(),
      'current':
          'temperature_2m,is_day,apparent_temperature,pressure_msl,relative_humidity_2m,precipitation,weather_code,cloud_cover,wind_speed_10m,wind_direction_10m,wind_gusts_10m',
      'hourly':
          'wind_speed_10m,wind_direction_10m,relative_humidity_2m,pressure_msl,cloud_cover,temperature_2m,dew_point_2m,apparent_temperature,precipitation_probability,precipitation,weather_code,visibility,uv_index',
      'daily':
          'weather_code,temperature_2m_max,temperature_2m_min,sunrise,sunset,daylight_duration,uv_index_max,precipitation_sum,precipitation_probability_max,precipitation_hours,wind_speed_10m_max,wind_gusts_10m_max',
      'timezone': timezone,
      'forecast_days': '7',
      'models': selectedModel
    });
    final airQualityUri =
        Uri.parse('https://air-quality-api.open-meteo.com/v1/air-quality')
            .replace(queryParameters: {
      'latitude': lat.toString(),
      'longitude': lon.toString(),
      'current':
          'us_aqi,european_aqi,pm10,pm2_5,carbon_monoxide,nitrogen_dioxide,sulphur_dioxide,ozone,alder_pollen,birch_pollen,grass_pollen,mugwort_pollen,olive_pollen,ragweed_pollen',
      'timezone': timezone,
      'forecast_hours': '1',
    });

    Uri? astronomyUri;
    if (isBackground == false) {
      astronomyUri = Uri.parse(
          'https://api.weatherapi.com/v1/astronomy.json?key=${dotenv.env['API_KEY_WEATHERAPI'].toString()}&q=$lat,$lon');
    }

    // Prepare list of HTTP requests
    try {
      final requests = <Future<http.Response>>[
        http.get(uri).timeout(const Duration(seconds: 15)),
        http.get(airQualityUri).timeout(const Duration(seconds: 15)),
        if (astronomyUri != null)
          http.get(astronomyUri).timeout(const Duration(seconds: 15)),
      ];

      final responses = await Future.wait(requests);

      for (var response in responses) {
        if (response.statusCode < 200 || response.statusCode >= 300) {
          throw Exception(
              'HTTP request failed with status: ${response.statusCode}');
        }
      }

      if (astronomyUri != null) log("Astronomy response: ${responses[2].body}");
      // Parse responses
      final weatherData =
          json.decode(responses[0].body) as Map<String, dynamic>;
      final airQualityData =
          json.decode(responses[1].body) as Map<String, dynamic>;
      final astronomyData = astronomyUri != null
          ? json.decode(responses[2].body) as Map<String, dynamic>
          : {};
      // Check if we need fallback data for missing fields
      Map<String, dynamic> finalWeatherData = weatherData;
      if (selectedModel != "best_match" && _hasIncompleteData(weatherData)) {
        finalWeatherData = await _fetchWithFallback(
            lat, lon, timezone, weatherData, selectedModel);
      }

      finalWeatherData['current'] =
          sanitizeCurrent(finalWeatherData['current']);
      finalWeatherData['hourly'] = sanitizeHourly(finalWeatherData['hourly']);
      finalWeatherData['daily'] = sanitizeDaily(finalWeatherData['daily']);

      if (finalWeatherData['error'] == true ||
          airQualityData['error'] == true ||
          astronomyData['error'] == true) {
        final reason = finalWeatherData['reason'] ??
            airQualityData['reason'] ??
            astronomyData['reason'] ??
            'Unknown error';
        if (context != null) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              duration: Duration(seconds: 10),
              content: Text("$reason. Please change your model"),
              action: SnackBarAction(
                label: 'Change model',
                onPressed: () {
                  Navigator.of(context).push(
                    MaterialPageRoute(builder: (_) => const MeteoModelsPage()),
                  );
                },
              ),
            ),
          );
        }

        return null;
      }

      final combinedDataForView = {
        ...finalWeatherData,
        'air_quality': airQualityData,
        'astronomy': astronomyData,
      };

      final nowForView = DateTime.now().toIso8601String();

      if (isOnlyView) {
        log("Only viewing data for $key. Not saving to cache.");
        return {
          'data': combinedDataForView,
          'last_updated': nowForView,
          'from_cache': false,
        };
      }

      final existingJson = box.get(key);
      if (existingJson != null) {
        final cachedMap = json.decode(existingJson);
        final cachedData = cachedMap['data'];
        final lastUpdated = cachedMap['last_updated'];

        if (json.encode(cachedData['current']) ==
                json.encode(finalWeatherData['current']) &&
            json.encode(cachedData['air_quality'] ?? {}) ==
                json.encode(airQualityData) &&
            json.encode(cachedData['astronomy'] ?? {}) ==
                json.encode(astronomyData)) {
          log("Hive: No update needed for $key");
          return {
            'data': cachedData,
            'last_updated': lastUpdated,
            'from_cache': true,
          };
        }
      }

      final now = DateTime.now().toIso8601String();
      final combinedData = {
        ...finalWeatherData,
        'air_quality': airQualityData,
        'astronomy': astronomyData,
      };

      final wrappedData = {
        'data': combinedData,
        'last_updated': now,
      };

      await box.put(key, json.encode(wrappedData));
      log("Hive: Updated cache for $key at $now");

      return {
        'data': combinedData,
        'last_updated': now,
        'from_cache': false,
      };
    } on TimeoutException catch (_) {
      throw Exception("Request timed out after 15 seconds");
    } catch (e) {
      throw Exception('WeatherService.fetchWeather failed: $e');
    }
  }

  /// Check if weather data has missing or incomplete fields
  bool _hasIncompleteData(Map<String, dynamic> weatherData) {
    // Check current data completeness
    final current = weatherData['current'] as Map<String, dynamic>?;
    if (current == null) return true;

    // All fields requested in the API call that should be available
    final allCurrentFields = [
      'temperature_2m',
      'is_day',
      'apparent_temperature',
      'pressure_msl',
      'relative_humidity_2m',
      'precipitation',
      'weather_code',
      'cloud_cover',
      'wind_speed_10m',
      'wind_direction_10m',
      'wind_gusts_10m'
    ];

    // Check for missing current fields
    int missingCurrentFields = 0;
    for (final field in allCurrentFields) {
      if (current[field] == null) {
        missingCurrentFields++;
      }
    }

    // Check hourly data completeness
    final hourly = weatherData['hourly'] as Map<String, dynamic>?;
    if (hourly == null) return true;

    final allHourlyFields = [
      'wind_speed_10m',
      'wind_direction_10m',
      'relative_humidity_2m',
      'pressure_msl',
      'cloud_cover',
      'temperature_2m',
      'dew_point_2m',
      'apparent_temperature',
      'precipitation_probability',
      'precipitation',
      'weather_code',
      'visibility',
      'uv_index'
    ];

    // Check for missing hourly fields
    int missingHourlyFields = 0;
    for (final field in allHourlyFields) {
      final data = hourly[field] as List?;
      if (data == null || data.isEmpty || !data.any((value) => value != null)) {
        missingHourlyFields++;
      }
    }

    // Check daily data completeness
    final daily = weatherData['daily'] as Map<String, dynamic>?;
    if (daily == null) return true;

    final allDailyFields = [
      'weather_code',
      'temperature_2m_max',
      'temperature_2m_min',
      'sunrise',
      'sunset',
      'daylight_duration',
      'uv_index_max',
      'precipitation_sum',
      'precipitation_probability_max',
      'precipitation_hours',
      'wind_speed_10m_max',
      'wind_gusts_10m_max'
    ];

    // Check for missing daily fields
    int missingDailyFields = 0;
    for (final field in allDailyFields) {
      final data = daily[field] as List?;
      if (data == null || data.isEmpty || !data.any((value) => value != null)) {
        missingDailyFields++;
      }
    }

    // Trigger fallback if any fields are missing
    final totalMissing =
        missingCurrentFields + missingHourlyFields + missingDailyFields;
    return totalMissing > 0;
  }

  /// Fetch weather data with fallback to best_match for missing fields
  Future<Map<String, dynamic>> _fetchWithFallback(
      double lat,
      double lon,
      String timezone,
      Map<String, dynamic> primaryData,
      String selectedModel) async {
    try {
      // Fetch fallback data using best_match
      final fallbackUri = Uri.parse('https://api.open-meteo.com/v1/forecast')
          .replace(queryParameters: {
        'latitude': lat.toString(),
        'longitude': lon.toString(),
        'current':
            'temperature_2m,is_day,apparent_temperature,pressure_msl,relative_humidity_2m,precipitation,weather_code,cloud_cover,wind_speed_10m,wind_direction_10m,wind_gusts_10m',
        'hourly':
            'wind_speed_10m,wind_direction_10m,relative_humidity_2m,pressure_msl,cloud_cover,temperature_2m,dew_point_2m,apparent_temperature,precipitation_probability,precipitation,weather_code,visibility,uv_index',
        'daily':
            'weather_code,temperature_2m_max,temperature_2m_min,sunrise,sunset,daylight_duration,uv_index_max,precipitation_sum,precipitation_probability_max,precipitation_hours,wind_speed_10m_max,wind_gusts_10m_max',
        'timezone': timezone,
        'forecast_days': '7',
        'models': 'best_match'
      });

      final fallbackResponse = await http.get(fallbackUri);
      final fallbackData =
          json.decode(fallbackResponse.body) as Map<String, dynamic>;

      if (fallbackData['error'] == true) {
        return primaryData;
      }

      // Merge data: primary model takes precedence, fallback fills gaps
      return _mergeWeatherData(primaryData, fallbackData);
    } catch (e) {
      return primaryData;
    }
  }

  /// Merge primary weather data with fallback data, prioritizing primary data
  Map<String, dynamic> _mergeWeatherData(
      Map<String, dynamic> primary, Map<String, dynamic> fallback) {
    final merged = Map<String, dynamic>.from(primary);

    // Merge current data
    merged['current'] = _mergeSection(
        primary['current'] as Map<String, dynamic>?,
        fallback['current'] as Map<String, dynamic>?);

    // Merge hourly data
    merged['hourly'] = _mergeSection(primary['hourly'] as Map<String, dynamic>?,
        fallback['hourly'] as Map<String, dynamic>?);

    // Merge daily data
    merged['daily'] = _mergeSection(primary['daily'] as Map<String, dynamic>?,
        fallback['daily'] as Map<String, dynamic>?);

    // Keep other fields from primary, fallback if missing
    for (final key in fallback.keys) {
      if (!merged.containsKey(key) || merged[key] == null) {
        merged[key] = fallback[key];
      }
    }

    return merged;
  }

  /// Merge a specific section (current/hourly/daily) with fallback data
  Map<String, dynamic> _mergeSection(
      Map<String, dynamic>? primary, Map<String, dynamic>? fallback) {
    if (primary == null && fallback == null) return {};
    if (primary == null) return Map<String, dynamic>.from(fallback!);
    if (fallback == null) return Map<String, dynamic>.from(primary);

    final merged = Map<String, dynamic>.from(primary);

    for (final key in fallback.keys) {
      if (!merged.containsKey(key) || merged[key] == null) {
        merged[key] = fallback[key];
      } else if (merged[key] is List) {
        // For array fields, merge element by element, filling null values from fallback
        final primaryList = merged[key] as List;
        final fallbackList = fallback[key] as List;

        // Create a new list with the same length as primary, filling nulls from fallback
        final mergedList = <dynamic>[];
        final maxLength = primaryList.length > fallbackList.length
            ? primaryList.length
            : fallbackList.length;

        for (int i = 0; i < maxLength; i++) {
          final primaryValue = i < primaryList.length ? primaryList[i] : null;
          final fallbackValue =
              i < fallbackList.length ? fallbackList[i] : null;

          // Use primary value if not null, otherwise use fallback
          mergedList.add(primaryValue ?? fallbackValue);
        }

        merged[key] = mergedList;
      }
    }

    return merged;
  }

  T nullSafeValue<T extends num>(dynamic value) {
    if (value == null) {
      if (T == int) return 0000 as T;
      if (T == double) return 0.0000001 as T;
      return 0 as T;
    }

    if (value is T) return value;

    if (value is num) {
      if (T == int) return value.toInt() as T;
      if (T == double) return value.toDouble() as T;
    }

    return T == int ? 0 as T : 0.0000001 as T;
  }

  Map<String, dynamic> sanitizeCurrent(Map? current) {
    current ??= {};
    return {
      'temperature_2m': nullSafeValue<double>(current['temperature_2m']),
      'apparent_temperature':
          nullSafeValue<double>(current['apparent_temperature']),
      'pressure_msl': nullSafeValue<double>(current['pressure_msl']),
      'relative_humidity_2m': nullSafeValue(current['relative_humidity_2m']),
      'precipitation': nullSafeValue<double>(current['precipitation']),
      'weather_code': nullSafeValue<int>(current['weather_code']),
      'cloud_cover': nullSafeValue<int>(current['cloud_cover']),
      'wind_speed_10m': nullSafeValue<double>(current['wind_speed_10m']),
      'wind_direction_10m': nullSafeValue<int>(current['wind_direction_10m']),
      'wind_gusts_10m': nullSafeValue<double>(current['wind_gusts_10m']),
      'is_day': nullSafeValue<int>(current['is_day']),
    };
  }

  Map<String, dynamic> sanitizeHourly(Map? hourly) {
    hourly ??= {};
    return {
      'time': (hourly['time'] as List?) ?? [],
      'wind_speed_10m': (hourly['wind_speed_10m'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'wind_direction_10m': (hourly['wind_direction_10m'] as List?)
              ?.map((v) => nullSafeValue<int>(v))
              .toList() ??
          [],
      'relative_humidity_2m': (hourly['relative_humidity_2m'] as List?)
              ?.map((v) => nullSafeValue<int>(v))
              .toList() ??
          [],
      'pressure_msl': (hourly['pressure_msl'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'cloud_cover': (hourly['cloud_cover'] as List?)
              ?.map((v) => nullSafeValue<int>(v))
              .toList() ??
          [],
      'temperature_2m': (hourly['temperature_2m'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'dew_point_2m': (hourly['dew_point_2m'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'apparent_temperature': (hourly['apparent_temperature'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'precipitation_probability':
          (hourly['precipitation_probability'] as List?)
                  ?.map((v) => nullSafeValue<int>(v))
                  .toList() ??
              [],
      'precipitation': (hourly['precipitation'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'weather_code': (hourly['weather_code'] as List?)
              ?.map((v) => nullSafeValue<int>(v))
              .toList() ??
          [],
      'visibility': (hourly['visibility'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'uv_index': (hourly['uv_index'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
    };
  }

  Map<String, dynamic> sanitizeDaily(Map? daily) {
    daily ??= {};
    return {
      'time': (daily['time'] as List?) ?? [],
      'weather_code': (daily['weather_code'] as List?)
              ?.map((v) => nullSafeValue<int>(v))
              .toList() ??
          [],
      'temperature_2m_max': (daily['temperature_2m_max'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'temperature_2m_min': (daily['temperature_2m_min'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'sunrise': (daily['sunrise'] as List?) ?? [],
      'sunset': (daily['sunset'] as List?) ?? [],
      'daylight_duration': (daily['daylight_duration'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'uv_index_max': (daily['uv_index_max'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'precipitation_sum': (daily['precipitation_sum'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'precipitation_probability_max':
          (daily['precipitation_probability_max'] as List?)
                  ?.map((v) => nullSafeValue<int>(v))
                  .toList() ??
              [],
      'precipitation_hours': (daily['precipitation_hours'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'wind_speed_10m_max': (daily['wind_speed_10m_max'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
      'wind_gusts_10m_max': (daily['wind_gusts_10m_max'] as List?)
              ?.map((v) => nullSafeValue<double>(v))
              .toList() ??
          [],
    };
  }
}