import 'dart:convert';

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:image_picker/image_picker.dart';

import '../../core/api/api_client.dart';
import '../../core/auth/auth_provider.dart';

// ---------------------------------------------------------------------------
// Models
// ---------------------------------------------------------------------------

class RecognizedItem {
  final String name;
  double quantity;
  String unit;
  final String category;
  final double confidence;
  final String? mappingId;
  final int storageDays;

  RecognizedItem({
    required this.name,
    required this.quantity,
    required this.unit,
    required this.category,
    required this.confidence,
    this.mappingId,
    required this.storageDays,
  });

  factory RecognizedItem.fromJson(Map<String, dynamic> json) {
    return RecognizedItem(
      name: json['name'] as String? ?? '',
      quantity: (json['quantity'] as num?)?.toDouble() ?? 1.0,
      unit: json['unit'] as String? ?? 'шт',
      category: json['category'] as String? ?? 'other',
      confidence: (json['confidence'] as num?)?.toDouble() ?? 0.0,
      mappingId: json['mapping_id'] as String?,
      storageDays: json['storage_days'] as int? ?? 7,
    );
  }
}

class UnrecognizedItem {
  final String rawText;
  final double? price;

  const UnrecognizedItem({required this.rawText, this.price});

  factory UnrecognizedItem.fromJson(Map<String, dynamic> json) {
    return UnrecognizedItem(
      rawText: json['raw_text'] as String? ?? '',
      price: (json['price'] as num?)?.toDouble(),
    );
  }
}

class ReceiptResult {
  final List<RecognizedItem> items;
  final List<UnrecognizedItem> unrecognized;

  const ReceiptResult({required this.items, required this.unrecognized});
}

/// A single dish recognition candidate with estimated nutrition for the portion in the photo.
class DishCandidate {
  final String? dishId;
  final String dishName;
  final int weightGrams;
  final double calories;
  final double proteinG;
  final double fatG;
  final double carbsG;
  final double confidence;

  const DishCandidate({
    this.dishId,
    required this.dishName,
    required this.weightGrams,
    required this.calories,
    required this.proteinG,
    required this.fatG,
    required this.carbsG,
    required this.confidence,
  });

  factory DishCandidate.fromJson(Map<String, dynamic> json) {
    return DishCandidate(
      dishId: json['dish_id'] as String?,
      dishName: json['dish_name'] as String? ?? '',
      weightGrams: json['weight_grams'] as int? ?? 0,
      calories: (json['calories'] as num?)?.toDouble() ?? 0,
      proteinG: (json['protein_g'] as num?)?.toDouble() ?? 0,
      fatG: (json['fat_g'] as num?)?.toDouble() ?? 0,
      carbsG: (json['carbs_g'] as num?)?.toDouble() ?? 0,
      confidence: (json['confidence'] as num?)?.toDouble() ?? 0,
    );
  }
}

/// Result of dish recognition: ordered list of candidates (best match first).
class DishResult {
  final List<DishCandidate> candidates;

  const DishResult({required this.candidates});

  /// The best matching candidate.
  DishCandidate get best => candidates.first;

  // Convenience getters delegating to the best candidate.
  String get dishName    => best.dishName;
  int    get weightGrams => best.weightGrams;
  double get calories    => best.calories;
  double get proteinG    => best.proteinG;
  double get fatG        => best.fatG;
  double get carbsG      => best.carbsG;
  double get confidence  => best.confidence;

  factory DishResult.fromJson(Map<String, dynamic> json) {
    // New format: {"candidates": [...]}
    if (json['candidates'] is List) {
      final candidatesList = (json['candidates'] as List<dynamic>)
          .map((element) => DishCandidate.fromJson(element as Map<String, dynamic>))
          .toList();
      return DishResult(candidates: candidatesList);
    }

    // Legacy flat format: {"dish_name": "...", "calories": ..., ...}
    if (json['dish_name'] != null) {
      return DishResult(candidates: [DishCandidate.fromJson(json)]);
    }

    return const DishResult(candidates: []);
  }
}

// ---------------------------------------------------------------------------
// Service
// ---------------------------------------------------------------------------

class RecognitionService {
  const RecognitionService(this._client);

  final ApiClient _client;

  /// Recognizes food items from a receipt photo.
  Future<ReceiptResult> recognizeReceipt(XFile image) async {
    final payload = await _buildImagePayload(image);
    final data = await _client.post('/ai/recognize-receipt', data: payload);
    return ReceiptResult(
      items: (data['items'] as List<dynamic>? ?? [])
          .map((e) => RecognizedItem.fromJson(e as Map<String, dynamic>))
          .toList(),
      unrecognized: (data['unrecognized'] as List<dynamic>? ?? [])
          .map((e) => UnrecognizedItem.fromJson(e as Map<String, dynamic>))
          .toList(),
    );
  }

  /// Recognizes food items from 1–3 product photos.
  Future<List<RecognizedItem>> recognizeProducts(List<XFile> images) async {
    final imageList = await Future.wait(images.map(_buildImagePayload));
    final data = await _client.post(
      '/ai/recognize-products',
      data: {'images': imageList},
    );
    return (data['items'] as List<dynamic>? ?? [])
        .map((e) => RecognizedItem.fromJson(e as Map<String, dynamic>))
        .toList();
  }

  /// Recognizes a dish and estimates its nutritional content.
  Future<DishResult> recognizeDish(XFile image) async {
    final payload = await _buildImagePayload(image);
    final data = await _client.post('/ai/recognize-dish', data: payload);
    return DishResult.fromJson(data);
  }

  Future<Map<String, String>> _buildImagePayload(XFile image) async {
    final bytes = await image.readAsBytes();
    final base64Data = base64Encode(bytes);
    // XFile.mimeType may be null on some platforms; fall back to path extension.
    final mimeType = image.mimeType ??
        (image.path.toLowerCase().endsWith('.png') ? 'image/png' : 'image/jpeg');
    return {'image_base64': base64Data, 'mime_type': mimeType};
  }
}

final recognitionServiceProvider = Provider<RecognitionService>((ref) {
  return RecognitionService(ref.read(apiClientProvider));
});