import 'dart:async';
import 'dart:typed_data';

import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:social_app/core/chat/agent_stage.dart';
import 'package:social_app/core/chat/ag_ui_event.dart';
import 'package:social_app/core/chat/ag_ui_service.dart';
import 'package:social_app/core/chat/chat_api.dart';
import 'package:social_app/core/chat/chat_list_item.dart';
import 'package:social_app/core/l10n/l10n.dart';
import 'package:social_app/features/chat/presentation/bloc/chat_bloc.dart';

class _NoopChatApi implements ChatApi {
  @override
  Future<void> cancelRun({required String threadId, required String runId}) {
    throw UnimplementedError();
  }

  @override
  Future<Map<String, dynamic>> createRun(Map<String, dynamic> runInput) {
    throw UnimplementedError();
  }

  @override
  Future<Map<String, dynamic>> fetchHistory({
    String? threadId,
    DateTime? beforeDate,
  }) {
    throw UnimplementedError();
  }

  @override
  Future<Uint8List> fetchAttachmentPreview(String previewPath) {
    throw UnimplementedError();
  }

  @override
  Future<Stream<String>> streamRunEvents(
    String threadId, {
    required String runId,
    String? lastEventId,
  }) {
    throw UnimplementedError();
  }

  @override
  Future<String> transcribeAudio(String filePath) {
    throw UnimplementedError();
  }

  @override
  Future<Map<String, dynamic>> uploadAttachment({
    required String threadId,
    required String filename,
    required String mimeType,
    required Uint8List bytes,
  }) {
    throw UnimplementedError();
  }
}

class _FakeAgUiService extends AgUiService {
  _FakeAgUiService() : super(chatApi: _NoopChatApi(), onEvent: (_) {});

  Future<SendMessageResult> Function(
    String content,
    List<AttachmentUploadInput>? attachments,
  )?
  sendMessageHandler;

  Future<HistorySnapshot> Function({DateTime? beforeDate, bool forceRefresh})?
  loadHistoryHandler;

  int loadHistoryCalls = 0;
  final List<String?> setUserContextCalls = <String?>[];

  void emitEventForTest(AgUiEvent event) {
    onEvent(event);
  }

  @override
  Future<SendMessageResult> sendMessage(
    String content, {
    List<AttachmentUploadInput>? attachments,
  }) async {
    final handler = sendMessageHandler;
    if (handler == null) {
      throw UnimplementedError();
    }
    return handler(content, attachments);
  }

  @override
  Future<HistorySnapshot> loadHistory({
    DateTime? beforeDate,
    bool forceRefresh = false,
  }) async {
    loadHistoryCalls += 1;
    final handler = loadHistoryHandler;
    if (handler == null) {
      throw UnimplementedError();
    }
    return handler(beforeDate: beforeDate, forceRefresh: forceRefresh);
  }

  @override
  Future<void> setUserContext(String? userId) async {
    setUserContextCalls.add(userId);
  }
}

HistorySnapshot _snapshot(
  List<HistoryMessage> messages, {
  bool hasMore = false,
}) {
  return HistorySnapshot(
    scope: 'history_day',
    threadId: 'thread-1',
    day: '2026-03-30',
    hasMore: hasMore,
    messages: messages,
  );
}

HistoryMessage _historyMessage({
  required String id,
  required int seq,
  required String role,
  required String content,
  required DateTime timestamp,
}) {
  return HistoryMessage(
    id: id,
    seq: seq,
    role: role,
    content: content,
    timestamp: timestamp,
  );
}

void main() {
  setUp(() {
    L10n.setLocale(const Locale('zh'));
  });

  test(
    'loadHistory ignores stale result after switchUser epoch change',
    () async {
      final service = _FakeAgUiService();
      final completer = Completer<HistorySnapshot>();
      var loadCall = 0;
      service.loadHistoryHandler =
          ({DateTime? beforeDate, bool forceRefresh = false}) {
            loadCall += 1;
            if (loadCall == 1) {
              return completer.future;
            }
            return Future<HistorySnapshot>.value(_snapshot(const []));
          };

      final bloc = ChatBloc(
        service: service,
        chatApi: _NoopChatApi(),
        recoveryPollInterval: const Duration(milliseconds: 1),
        recoveryTimeout: const Duration(milliseconds: 80),
      );

      final pendingLoad = bloc.loadHistory();
      await bloc.switchUser('user-b');
      completer.complete(
        _snapshot([
          _historyMessage(
            id: 'old-1',
            seq: 1,
            role: 'assistant',
            content: 'old session data',
            timestamp: DateTime.now(),
          ),
        ]),
      );
      await pendingLoad;

      expect(bloc.state.items, isEmpty);
      expect(bloc.state.isLoadingHistory, isFalse);
    },
  );

  test('switchUser loads history after resetting state', () async {
    final service = _FakeAgUiService();
    service.loadHistoryHandler =
        ({DateTime? beforeDate, bool forceRefresh = false}) async {
          final now = DateTime.now();
          return _snapshot([
            _historyMessage(
              id: 'history-1',
              seq: 1,
              role: 'assistant',
              content: 'welcome back',
              timestamp: now,
            ),
          ]);
        };

    final bloc = ChatBloc(service: service, chatApi: _NoopChatApi());
    await bloc.switchUser('user-a');

    expect(service.setUserContextCalls, ['user-a']);
    expect(service.loadHistoryCalls, 1);
    expect(bloc.state.items, hasLength(1));
    expect(
      bloc.state.items.single,
      isA<TextMessageItem>().having(
        (item) => item.content,
        'content',
        'welcome back',
      ),
    );
  });

  test('switchUser keeps flow when history load fails', () async {
    final service = _FakeAgUiService();
    service.loadHistoryHandler =
        ({DateTime? beforeDate, bool forceRefresh = false}) {
          throw StateError('history unavailable');
        };

    final bloc = ChatBloc(service: service, chatApi: _NoopChatApi());
    await bloc.switchUser('user-a');

    expect(service.setUserContextCalls, ['user-a']);
    expect(service.loadHistoryCalls, 1);
    expect(bloc.state.error, contains('history unavailable'));
  });

  test(
    'tool calendar_write success triggers calendar refresh callback',
    () async {
      final service = _FakeAgUiService();
      var refreshCalls = 0;
      final bloc = ChatBloc(
        service: service,
        chatApi: _NoopChatApi(),
        onCalendarMutated: () async {
          refreshCalls += 1;
        },
      );

      service.emitEventForTest(
        ToolCallResultEvent(
          messageId: 'msg-1',
          toolCallId: 'call-1',
          toolName: 'calendar_write',
          resultSummary: 'ok',
          status: 'success',
        ),
      );
      await Future<void>.delayed(Duration.zero);

      expect(refreshCalls, 1);
      expect(bloc.state.isLoading, isFalse);
    },
  );

  test(
    'sendMessage recovers from premature SSE close with polled history',
    () async {
      final service = _FakeAgUiService();
      service.sendMessageHandler = (content, attachments) async {
        throw StateError('SSE closed before terminal event for run');
      };

      var loadAttempt = 0;
      service.loadHistoryHandler =
          ({DateTime? beforeDate, bool forceRefresh = false}) async {
            loadAttempt += 1;
            final now = DateTime.now();
            if (loadAttempt == 1) {
              return _snapshot([
                _historyMessage(
                  id: 'db-user-1',
                  seq: 1,
                  role: 'user',
                  content: 'hello',
                  timestamp: now,
                ),
              ]);
            }
            return _snapshot([
              _historyMessage(
                id: 'db-user-1',
                seq: 1,
                role: 'user',
                content: 'hello',
                timestamp: now,
              ),
              _historyMessage(
                id: 'db-assistant-1',
                seq: 2,
                role: 'assistant',
                content: 'world',
                timestamp: now.add(const Duration(seconds: 1)),
              ),
            ]);
          };

      final bloc = ChatBloc(
        service: service,
        chatApi: _NoopChatApi(),
        recoveryPollInterval: const Duration(milliseconds: 1),
        recoveryTimeout: const Duration(milliseconds: 50),
      );
      await bloc.sendMessage('hello');

      final userMessages = bloc.state.items
          .whereType<TextMessageItem>()
          .where((item) => item.sender == MessageSender.user)
          .toList();
      expect(userMessages.length, 1);
      expect(userMessages.first.id, 'db-user-1');
      expect(
        bloc.state.items.any(
          (item) =>
              item is TextMessageItem &&
              item.sender == MessageSender.ai &&
              item.content == 'world',
        ),
        isTrue,
      );
      expect(bloc.state.error, isNull);
      expect(service.loadHistoryCalls, 2);
    },
  );

  test('sendMessage reports error after recovery attempts exhausted', () async {
    final service = _FakeAgUiService();
    service.sendMessageHandler = (content, attachments) async {
      throw StateError('SSE closed before terminal event for run');
    };
    service.loadHistoryHandler =
        ({DateTime? beforeDate, bool forceRefresh = false}) async {
          final now = DateTime.now();
          return _snapshot([
            _historyMessage(
              id: 'db-user-1',
              seq: 1,
              role: 'user',
              content: 'hello',
              timestamp: now,
            ),
          ]);
        };

    final bloc = ChatBloc(
      service: service,
      chatApi: _NoopChatApi(),
      recoveryPollInterval: const Duration(milliseconds: 1),
      recoveryTimeout: const Duration(milliseconds: 15),
    );
    await bloc.sendMessage('hello');

    expect(bloc.state.error, L10n.current.chatSseInterruptedRetry);
    expect(service.loadHistoryCalls, greaterThanOrEqualTo(1));
  });

  test(
    'tracks hasSeenStep to distinguish requesting vs processing stage',
    () async {
      final service = _FakeAgUiService();
      final bloc = ChatBloc(service: service, chatApi: _NoopChatApi());

      service.emitEventForTest(
        RunStartedEvent(threadId: 'thread-1', runId: 'run-1'),
      );
      expect(bloc.state.isWaitingFirstToken, isTrue);
      expect(bloc.state.hasSeenStep, isFalse);
      expect(bloc.state.currentStage, isNull);

      service.emitEventForTest(StepStartedEvent(stepName: 'router'));
      expect(bloc.state.hasSeenStep, isTrue);
      expect(bloc.state.currentStage, AgentStage.routing);

      service.emitEventForTest(StepFinishedEvent(stepName: 'router'));
      expect(bloc.state.hasSeenStep, isTrue);
      expect(bloc.state.currentStage, isNull);
    },
  );
}