import 'dart:async';

import 'package:flutter_test/flutter_test.dart';
import 'package:halkyon_ui/halkyon_ui.dart';
import 'package:material_ui/material_ui.dart';

import '../support/test_app.dart';

void main() {
  late StreamController<List<String>> items;

  setUp(() => items = StreamController());
  tearDown(() => items.close());

  /// Opens the screen of the item [id] over a first screen.
  Future<void> open(
    WidgetTester tester,
    String id, {
    ({String label, VoidCallback onPressed})? wayBack,
  }) async {
    await tester.pumpWidget(
      testApp(
        Builder(
          builder: (context) => TextButton(
            onPressed: () => Navigator.of(context).push(
              MaterialPageRoute<void>(
                builder: (context) => FoundById<String>(
                  id: id,
                  items: () => items.stream,
                  idOf: (item) => item,
                  builder: (item, items) =>
                      Scaffold(body: Text('Item $item of ${items.length}')),
                  wayBack: wayBack,
                ),
              ),
            ),
            child: const Text('Open'),
          ),
        ),
      ),
    );
    await tester.tap(find.text('Open'));
    // Through the opening transition; the spinner never settles.
    await tester.pump();
    await tester.pump(const Duration(seconds: 1));
  }

  testWidgets('shows a spinner until the list arrives, then the item', (
    tester,
  ) async {
    await open(tester, 'a');
    expect(find.byType(AppLoadingIndicator), findsOneWidget);

    items.add(['a', 'b']);
    await tester.pump();

    expect(find.text('Item a of 2'), findsOneWidget);
    expect(find.byType(AppLoadingIndicator), findsNothing);
  });

  testWidgets('says that an item missing from the list no longer exists', (
    tester,
  ) async {
    await open(tester, 'c');

    items.add(['a', 'b']);
    await tester.pump();

    expect(find.textContaining('no longer exists'), findsOneWidget);
  });

  testWidgets('leads the way back from there, as the app says', (
    tester,
  ) async {
    var ledBack = 0;
    await open(
      tester,
      'c',
      wayBack: (label: 'To the library', onPressed: () => ledBack++),
    );
    items.add(['a']);
    await tester.pump();

    await tester.tap(find.text('To the library'));

    expect(ledBack, 1);
  });

  testWidgets('says so once the item goes while its screen is open', (
    tester,
  ) async {
    await open(tester, 'a');
    items.add(['a']);
    await tester.pump();

    // Deleted on another device, say.
    items.add([]);
    await tester.pump();

    expect(find.text('Item a of 1'), findsNothing);
    expect(find.textContaining('no longer exists'), findsOneWidget);
  });

  testWidgets('a screen that closes as its item goes keeps showing the item '
      'on its way out', (tester) async {
    await open(tester, 'a');
    items.add(['a']);
    await tester.pump();

    // As when the screen deleted its item and closes.
    Navigator.of(tester.element(find.text('Item a of 1'))).pop();
    items.add([]);
    await tester.pump();
    await tester.pump(const Duration(milliseconds: 100));

    expect(find.text('Item a of 1'), findsOneWidget);
    expect(find.textContaining('no longer exists'), findsNothing);
    await tester.pumpAndSettle();
    expect(find.text('Open'), findsOneWidget);
  });
}