import 'dart:convert';

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

import '../../config/api_config.dart';
import '../../services/auth_service.dart';

class SpellingWordsApiException implements Exception {
  SpellingWordsApiException(this.statusCode, this.body);

  final int statusCode;
  final String body;

  @override
  String toString() => 'SpellingWordsApiException($statusCode): $body';
}

/// HTTP client for the shared spelling word catalog.
class SpellingWordsRemoteStore {
  SpellingWordsRemoteStore({http.Client? client})
      : _client = client ?? http.Client();

  final http.Client _client;

  static const String _basePath = '/v1/me/spelling-words';

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

    final http.Response response = await _client.get(
      Uri.parse('$apiBaseUrl$_basePath'),
      headers: _authHeaders(token),
    );
    if (response.statusCode != 200) {
      throw SpellingWordsApiException(response.statusCode, response.body);
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final List<dynamic> words = body['words'] as List<dynamic>? ?? <dynamic>[];
    return words.map((dynamic w) => w as String).toList(growable: false);
  }

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

    final http.Response response = await _client.post(
      Uri.parse('$apiBaseUrl$_basePath'),
      headers: _authHeaders(token),
      body: jsonEncode(<String, dynamic>{'word': word}),
    );
    if (response.statusCode != 201) {
      throw SpellingWordsApiException(response.statusCode, response.body);
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final List<dynamic> words = body['words'] as List<dynamic>? ?? <dynamic>[];
    return words.map((dynamic w) => w as String).toList(growable: false);
  }

  Future<({int added, int skipped})> importText(String text) async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      throw StateError('Not signed in');
    }

    final http.Response response = await _client.post(
      Uri.parse('$apiBaseUrl$_basePath/import'),
      headers: <String, String>{
        ..._authHeaders(token),
        'Content-Type': 'text/plain; charset=utf-8',
      },
      body: text,
    );
    if (response.statusCode != 200) {
      throw SpellingWordsApiException(response.statusCode, response.body);
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    return (
      added: (body['added'] as num?)?.toInt() ?? 0,
      skipped: (body['skipped'] as num?)?.toInt() ?? 0,
    );
  }

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

    final http.Response response = await _client.get(
      Uri.parse('$apiBaseUrl$_basePath/export'),
      headers: <String, String>{
        'Authorization': 'Bearer $token',
        'Accept': 'text/plain',
      },
    );
    if (response.statusCode != 200) {
      throw SpellingWordsApiException(response.statusCode, response.body);
    }
    return response.body;
  }

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