import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:dio/dio.dart';
import 'package:geolocator/geolocator.dart';
import '../../models/document_model.dart';
import '../../core/location/location_service.dart';
import '../../core/network/api_client.dart';
import '../../config/app_config.dart';

enum PendingDocumentStatus { uploading, processing, success, error }

class PendingDocument {
  final String id;
  final String imagePath;
  final PendingDocumentStatus status;
  final DocumentModel? document;
  final double? latitude;
  final double? longitude;
  final String? errorMessage;
  final DateTime createdAt;

  PendingDocument({
    required this.id,
    required this.imagePath,
    this.status = PendingDocumentStatus.uploading,
    this.document,
    this.latitude,
    this.longitude,
    this.errorMessage,
    DateTime? createdAt,
  }) : createdAt = createdAt ?? DateTime.now();

  PendingDocument copyWith({
    PendingDocumentStatus? status,
    DocumentModel? document,
    double? latitude,
    double? longitude,
    String? errorMessage,
  }) {
    return PendingDocument(
      id: id,
      imagePath: imagePath,
      status: status ?? this.status,
      document: document ?? this.document,
      latitude: latitude ?? this.latitude,
      longitude: longitude ?? this.longitude,
      errorMessage: errorMessage,
      createdAt: createdAt,
    );
  }
}

class PendingDocumentsNotifier extends StateNotifier<List<PendingDocument>> {
  PendingDocumentsNotifier() : super([]);

  void addDocument(String imagePath, {double? latitude, double? longitude}) {
    final id = DateTime.now().millisecondsSinceEpoch.toString();
    final newDoc = PendingDocument(
      id: id, 
      imagePath: imagePath,
      latitude: latitude,
      longitude: longitude,
    );
    state = [newDoc, ...state];
    
    _uploadAndProcess(id, imagePath, latitude: latitude, longitude: longitude);
  }

  Future<Position?> _determinePosition() async {
    return await LocationService.determinePosition();
  }

  Future<void> _uploadAndProcess(String id, String imagePath, {double? latitude, double? longitude}) async {
    double? lat = latitude;
    double? lng = longitude;
    
    if (lat == null || lng == null) {
      try {
        final position = await _determinePosition();
        if (position != null) {
          lat = position.latitude;
          lng = position.longitude;
          if (mounted) {
            state = [
              for (final item in state)
                if (item.id == id)
                  item.copyWith(latitude: lat, longitude: lng)
                else
                  item
            ];
          }
        }
      } catch (_) {
        // Gracefully continue without location tags if fetch fails
      }
    }

    try {
      // API call to upload and process
      final apiClient = ApiClient();
      final formData = FormData.fromMap({
        'image': await MultipartFile.fromFile(
          imagePath,
          filename: imagePath.split(RegExp(r'[/\\]')).last,
        ),
        if (lat != null) 'latitude': lat.toString(),
        if (lng != null) 'longitude': lng.toString(),
      });

      final response = await apiClient.client.post(
        AppConfig.uploadDocumentEndpoint,
        data: formData,
      );

      final doc = DocumentModel.fromJson(response.data['data']);
      
      if (!mounted) return;
      state = [
        for (final item in state)
          if (item.id == id)
            item.copyWith(status: PendingDocumentStatus.processing, document: doc)
          else
            item
      ];

      // Poll until the document is parsed on the server
      bool isParsed = false;
      DocumentModel? parsedDoc;
      int retries = 0;
      const maxRetries = 60; // 2 minutes max polling (60 retries * 2s)

      while (!isParsed && retries < maxRetries && mounted) {
        await Future.delayed(const Duration(seconds: 2));
        if (!mounted) return;

        try {
          final getRes = await apiClient.client.get(AppConfig.fetchDocumentsEndpoint);
          if (getRes.statusCode == 200 && getRes.data['data'] is List) {
            final list = (getRes.data['data'] as List)
                .map((e) => DocumentModel.fromJson(Map<String, dynamic>.from(e)))
                .toList();
            
            final found = list.firstWhere(
              (element) => element.id == doc.id,
              orElse: () => doc,
            );

            if (found != doc) {
              isParsed = true;
              parsedDoc = found;
            }
          }
        } catch (_) {
          // Ignore network glitch during polling
        }
        retries++;
      }

      if (!mounted) return;

      if (isParsed && parsedDoc != null) {
        state = [
          for (final item in state)
            if (item.id == id)
              item.copyWith(status: PendingDocumentStatus.success, document: parsedDoc)
            else
              item
        ];
      } else {
        state = [
          for (final item in state)
            if (item.id == id)
              item.copyWith(
                status: PendingDocumentStatus.error,
                errorMessage: 'Gagal mengekstrak data dari dokumen (Timeout).',
              )
            else
              item
        ];
      }
    } catch (e) {
      if (!mounted) return;
      state = [
        for (final item in state)
          if (item.id == id)
            item.copyWith(status: PendingDocumentStatus.error, errorMessage: e.toString())
          else
            item
      ];
    }
  }
  
  void removeDocument(String id) {
    state = state.where((item) => item.id != id).toList();
  }
  
  void retryUpload(String id) {
    final doc = state.firstWhere((item) => item.id == id);
    final lat = doc.latitude;
    final lng = doc.longitude;
    state = [
      for (final item in state)
        if (item.id == id)
          item.copyWith(
            status: PendingDocumentStatus.uploading, 
            errorMessage: null,
          )
        else
          item
    ];
    _uploadAndProcess(id, doc.imagePath, latitude: lat, longitude: lng);
  }
}

final pendingDocumentsProvider = StateNotifierProvider<PendingDocumentsNotifier, List<PendingDocument>>((ref) {
  return PendingDocumentsNotifier();
});