import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:ikar/frontend/screens/chats/chat/view/anchored_message_list.dart';

void main() {
  testWidgets(
    'a distant message can become the center without walking the list',
    (tester) async {
      final controller = ScrollController();
      final anchor = ValueNotifier<int?>(null);
      final keys = <int, GlobalKey>{};
      addTearDown(controller.dispose);
      addTearDown(anchor.dispose);

      await tester.pumpWidget(
        MaterialApp(
          home: Scaffold(
            body: SizedBox(
              height: 300,
              child: ValueListenableBuilder<int?>(
                valueListenable: anchor,
                builder: (context, index, _) => AnchoredMessageList(
                  controller: controller,
                  cacheExtent: 300,
                  padding: EdgeInsets.zero,
                  epoch: 0,
                  itemCount: 500,
                  anchorIndex: index,
                  itemBuilder: (context, i) => KeyedSubtree(
                    key: keys.putIfAbsent(i, GlobalKey.new),
                    child: SizedBox(
                      key: ValueKey('message-$i'),
                      height: 60,
                      child: Text('message $i'),
                    ),
                  ),
                  bottomSpacer: const SizedBox.shrink(),
                  loadingOlder: false,
                  loadingIndicator: const SizedBox(height: 30),
                ),
              ),
            ),
          ),
        ),
      );
      expect(find.byKey(const ValueKey('message-499')), findsOneWidget);
      expect(find.byKey(const ValueKey('message-20')), findsNothing);

      anchor.value = 20;
      controller.jumpTo(
        AnchoredMessageList.anchoredPixels(
          alignment: 0.3,
          viewport: controller.position.viewportDimension,
          anchorHeight: 0,
        ),
      );
      await tester.pump();

      expect(find.byKey(const ValueKey('message-20')), findsOneWidget);
      expect(
        find.byKey(const ValueKey('message-20')).hitTestable(),
        findsOneWidget,
      );
      expect(controller.position.pixels.isFinite, isTrue);
      expect(controller.position.minScrollExtent, lessThan(0));
      expect(
        AnchoredMessageList.distanceFromBottom(controller.position),
        greaterThan(120),
      );
      controller.jumpTo(controller.position.minScrollExtent);
      await tester.pump();
      expect(
        AnchoredMessageList.distanceFromBottom(controller.position),
        lessThanOrEqualTo(120),
      );
      anchor.value = null;
      await tester.pump();
      controller.jumpTo(controller.position.minScrollExtent);
      await tester.pump();
      expect(
        find.byKey(const ValueKey('message-499')).hitTestable(),
        findsOneWidget,
      );
      expect(tester.takeException(), isNull);
    },
  );

  testWidgets('older loading indicator remains on the history edge', (
    tester,
  ) async {
    final controller = ScrollController();
    addTearDown(controller.dispose);
    await tester.pumpWidget(
      MaterialApp(
        home: Scaffold(
          body: SizedBox(
            height: 300,
            child: AnchoredMessageList(
              controller: controller,
              cacheExtent: 300,
              padding: EdgeInsets.zero,
              epoch: 0,
              itemCount: 3,
              anchorIndex: 1,
              itemBuilder: (context, i) =>
                  SizedBox(height: 60, child: Text('message $i')),
              bottomSpacer: const SizedBox.shrink(),
              loadingOlder: true,
              loadingIndicator: const Text('loading older'),
            ),
          ),
        ),
      ),
    );
    expect(find.text('loading older'), findsOneWidget);
    expect(tester.takeException(), isNull);
  });
}