import 'dart:async';

import 'package:flutter_test/flutter_test.dart';
import 'package:kooltap/models/bar_tab.dart';
import 'package:kooltap/models/tab_item.dart';
import 'package:kooltap/services/bar_tab_service.dart';
import 'package:kooltap/services/product_service.dart';
import 'package:kooltap/viewmodels/bar_screen_view_model.dart';
import 'package:mocktail/mocktail.dart';

class MockBarTabService extends Mock implements BarTabService {}

BarTab _tab(String id) {
  return BarTab(
    id: id,
    customerName: id,
    openedAt: DateTime(2026),
    items: const [],
  );
}

void main() {
  late MockBarTabService barTabService;
  late StreamController<List<BarTab>> openTabs;
  late BarScreenViewModel viewModel;

  setUp(() {
    barTabService = MockBarTabService();
    openTabs = StreamController<List<BarTab>>.broadcast();
    when(
      () => barTabService.watchOpenTabs(),
    ).thenAnswer((_) => openTabs.stream);

    viewModel = BarScreenViewModel(barTabService: barTabService);
  });

  tearDown(() async {
    viewModel.dispose();
    await openTabs.close();
  });

  test('shows tabs from the stream and selects the first one', () async {
    viewModel.ensureLoaded();
    expect(viewModel.isLoading, true);

    openTabs.add([_tab('a'), _tab('b')]);
    await pumpEventQueue();

    expect(viewModel.isLoading, false);
    expect(viewModel.tabs.map((tab) => tab.id), ['a', 'b']);
    expect(viewModel.selectedTabId, 'a');
  });

  test('keeps the selection while that tab still exists', () async {
    viewModel.ensureLoaded();
    openTabs.add([_tab('a'), _tab('b')]);
    await pumpEventQueue();
    viewModel.selectTab('b');

    openTabs.add([_tab('c'), _tab('b')]);
    await pumpEventQueue();

    expect(viewModel.selectedTabId, 'b');
  });

  test(
    'falls back to the first tab when the selected one disappears',
    () async {
      viewModel.ensureLoaded();
      openTabs.add([_tab('a'), _tab('b')]);
      await pumpEventQueue();
      viewModel.selectTab('b');

      openTabs.add([_tab('a')]);
      await pumpEventQueue();

      expect(viewModel.selectedTabId, 'a');
    },
  );

  test('exposes a load error when the stream fails', () async {
    viewModel.ensureLoaded();
    openTabs.addError(StateError('database closed'));
    await pumpEventQueue();

    expect(viewModel.loadError, isNotNull);
    expect(viewModel.isLoading, false);
  });

  test('propagates an insufficient-stock error from the transaction', () async {
    const item = TabItem(
      id: 'item-1',
      tabId: 'tab-1',
      productId: 'prod-1',
      productName: 'Chips',
      quantity: 20,
      unitPriceInCents: 150,
    );

    when(
      () => barTabService.adjustTabItemQuantity(tabItemId: 'item-1', delta: 1),
    ).thenAnswer((_) async => throw const InsufficientStockException());

    await expectLater(
      viewModel.changeItemQuantity(item, 1),
      throwsA(isA<InsufficientStockException>()),
    );

    expect(viewModel.loadError, isNull);
  });

  test('selects a newly created tab', () async {
    when(
      () => barTabService.createTab(customerName: 'New'),
    ).thenAnswer((_) async => _tab('new'));

    await viewModel.createTab('New');

    expect(viewModel.selectedTabId, 'new');
  });

  test(
    'rethrows failed actions without turning them into a load error',
    () async {
      when(
        () => barTabService.deleteTab('tab-1'),
      ).thenAnswer((_) async => throw StateError('boom'));

      await expectLater(viewModel.deleteTab('tab-1'), throwsStateError);

      expect(viewModel.loadError, isNull);
    },
  );
}