import 'dart:async';

import 'package:flutter_test/flutter_test.dart';
import 'package:flutter_app/core/network/api_repository.dart';
import 'package:flutter_app/features/chat/presentation/cubit/chat_cubit.dart';
import 'package:flutter_app/features/chat/presentation/cubit/chat_state.dart';

class _VersionTestApi extends ApiRepository {
  _VersionTestApi() : super(baseUrl: 'http://127.0.0.1:8000');

  final responses = <List<String>>[
    ['الجواب الأول'],
    ['الجواب الثاني'],
  ];
  SavedConversation? lastSaved;

  @override
  Future<String> getModelName() async => 'gemma4:e2b';

  @override
  Future<List<String>> getAvailableModels() async => ['gemma4:e2b'];

  @override
  Future<List<SavedConversation>> listConversations() async => [];

  @override
  Future<void> saveConversation(SavedConversation conversation) async {
    lastSaved = conversation;
  }

  @override
  Stream<String> completeStream(List<ChatMessage> messages, {String? model}) =>
      Stream<String>.fromIterable(responses.removeAt(0));
}

class _CancellableTestApi extends _VersionTestApi {
  final controller = StreamController<String>();
  var cancelled = false;
  final storedConversation = SavedConversation(
    id: 'conversation',
    title: 'سؤال قديم',
    updatedAt: DateTime.utc(2026),
    messages: const [
      ChatMessage('سؤال قديم', fromUser: true),
      ChatMessage(
        'إجابة محفوظة',
        fromUser: false,
        answerVersions: ['إجابة محفوظة'],
      ),
    ],
  );

  @override
  Future<SavedConversation> getConversation(String id) async =>
      storedConversation;

  @override
  Stream<String> completeStream(List<ChatMessage> messages, {String? model}) =>
      controller.stream;

  @override
  void cancelActiveRequest() {
    cancelled = true;
    controller.close();
  }
}

void main() {
  test('regeneration keeps prior answers and selection is persisted', () async {
    final api = _VersionTestApi();
    final cubit = ChatCubit(api);
    await Future<void>.delayed(Duration.zero);

    await cubit.send('ما معنى API؟');
    expect(cubit.state.messages.last.answerVersions, ['الجواب الأول']);
    expect(cubit.state.modelStatus, ModelConnectionStatus.connected);
    expect(cubit.state.requestStatus, RequestStatus.completed);
    expect(cubit.state.lastResponseDuration, isNotNull);

    await cubit.regenerateLastAnswer();
    expect(cubit.state.messages.last.text, 'الجواب الثاني');
    expect(cubit.state.messages.last.answerVersions, [
      'الجواب الأول',
      'الجواب الثاني',
    ]);
    expect(cubit.state.messages.last.selectedVersion, 1);

    await cubit.selectAnswerVersion(1, 0);
    expect(cubit.state.messages.last.text, 'الجواب الأول');
    expect(cubit.state.messages.last.selectedVersion, 0);
    expect(api.lastSaved?.messages.last.answerVersions, [
      'الجواب الأول',
      'الجواب الثاني',
    ]);
    expect(api.lastSaved?.messages.last.selectedVersion, 0);

    await cubit.close();
  });

  test(
    'cancelling generation preserves partial text and records duration',
    () async {
      final api = _CancellableTestApi();
      final cubit = ChatCubit(api);
      await Future<void>.delayed(Duration.zero);

      final send = cubit.send('اكتب فقرة قصيرة');
      await Future<void>.delayed(const Duration(milliseconds: 20));
      api.controller.add('بداية الإجابة');
      await Future<void>.delayed(Duration.zero);
      await cubit.cancelGeneration();
      await send;

      expect(api.cancelled, isTrue);
      expect(cubit.state.isSending, isFalse);
      expect(cubit.state.requestStatus, RequestStatus.cancelled);
      expect(cubit.state.messages.last.text, 'بداية الإجابة');
      expect(cubit.state.lastResponseDuration, isNotNull);
      expect(api.lastSaved?.messages.last.text, 'بداية الإجابة');

      await cubit.close();
      await api.controller.close();
    },
  );

  test(
    'cancelling regeneration before its first token keeps saved answer',
    () async {
      final api = _CancellableTestApi();
      final cubit = ChatCubit(api);
      await Future<void>.delayed(Duration.zero);
      await cubit.openConversation(api.storedConversation);

      final regeneration = cubit.regenerateLastAnswer();
      await Future<void>.delayed(const Duration(milliseconds: 20));
      await cubit.cancelGeneration();
      await regeneration;

      expect(cubit.state.messages.last.text, 'إجابة محفوظة');
      expect(api.lastSaved?.messages.last.text, 'إجابة محفوظة');
      expect(cubit.state.requestStatus, RequestStatus.cancelled);

      await cubit.close();
      await api.controller.close();
    },
  );
}