import 'dart:convert';

import 'package:http/http.dart' as http;

import '../../config/api_config.dart';
import '../../models/question_source_preference.dart';
import '../../services/auth_service.dart';
import 'question_source_api_exception.dart';

/// HTTP client for per-user question source preferences.
class QuestionSourceRemoteStore {
  QuestionSourceRemoteStore({http.Client? client})
      : _client = client ?? http.Client();

  final http.Client _client;

  Future<List<QuestionSourcePreference>?> fetchPreferences() async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return null;
    }

    final http.Response response = await _client.get(
      Uri.parse('$apiBaseUrl/v1/me/question-sources'),
      headers: _authHeaders(token),
    );

    if (response.statusCode != 200) {
      throw QuestionSourceApiException(response.statusCode, response.body);
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final List<dynamic> sources =
        body['sources'] as List<dynamic>? ?? <dynamic>[];
    return sources
        .map(
          (dynamic entry) => QuestionSourcePreference.fromJson(
            entry as Map<String, dynamic>,
          ),
        )
        .toList();
  }

  Future<List<QuestionSourcePreference>> savePreferences(
    List<QuestionSourcePreference> sources,
  ) async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      throw StateError('Not signed in');
    }

    final http.Response response = await _client.put(
      Uri.parse('$apiBaseUrl/v1/me/question-sources'),
      headers: _authHeaders(token),
      body: jsonEncode(<String, dynamic>{
        'sources': sources
            .map((QuestionSourcePreference source) => source.toStorageJson())
            .toList(),
      }),
    );

    if (response.statusCode != 200) {
      throw QuestionSourceApiException(response.statusCode, response.body);
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final List<dynamic> saved =
        body['sources'] as List<dynamic>? ?? <dynamic>[];
    return saved
        .map(
          (dynamic entry) => QuestionSourcePreference.fromJson(
            entry as Map<String, dynamic>,
          ),
        )
        .toList();
  }

  Map<String, String> _authHeaders(String token) {
    return <String, String>{
      'Authorization': 'Bearer $token',
      'Content-Type': 'application/json',
      'Accept': 'application/json',
    };
  }
}