// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/rendering.dart';

class TestFlowDelegate extends FlowDelegate {
  TestFlowDelegate({this.startOffset}) : super(repaint: startOffset);

  final Animation<double> startOffset;

  @override
  BoxConstraints getConstraintsForChild(int i, BoxConstraints constraints) {
    return constraints.loosen();
  }

  @override
  void paintChildren(FlowPaintingContext context) {
    double dy = startOffset.value;
    for (int i = 0; i < context.childCount; ++i) {
      context.paintChild(i, transform: Matrix4.translationValues(0.0, dy, 0.0));
      dy += 0.75 * context.getChildSize(i).height;
    }
  }

  @override
  bool shouldRepaint(TestFlowDelegate oldDelegate) => startOffset == oldDelegate.startOffset;
}

class OpacityFlowDelegate extends FlowDelegate {
  OpacityFlowDelegate(this.opacity);

  double opacity;

  @override
  void paintChildren(FlowPaintingContext context) {
    for (int i = 0; i < context.childCount; ++i) {
      context.paintChild(i, opacity: opacity);
    }
  }

  @override
  bool shouldRepaint(OpacityFlowDelegate oldDelegate) => opacity != oldDelegate.opacity;
}

void main() {
  testWidgets('Flow control test', (WidgetTester tester) async {
    final AnimationController startOffset = AnimationController.unbounded(
      vsync: tester,
    );
    final List<int> log = <int>[];

    Widget buildBox(int i) {
      return GestureDetector(
        onTap: () {
          log.add(i);
        },
        child: Container(
          width: 100.0,
          height: 100.0,
          color: const Color(0xFF0000FF),
          child: Text('$i', textDirection: TextDirection.ltr)
        )
      );
    }

    await tester.pumpWidget(
      Flow(
        delegate: TestFlowDelegate(startOffset: startOffset),
        children: <Widget>[
          buildBox(0),
          buildBox(1),
          buildBox(2),
          buildBox(3),
          buildBox(4),
          buildBox(5),
          buildBox(6),
        ]
      )
    );

    await tester.tap(find.text('0'));
    expect(log, equals(<int>[0]));
    await tester.tap(find.text('1'));
    expect(log, equals(<int>[0, 1]));
    await tester.tap(find.text('2'));
    expect(log, equals(<int>[0, 1, 2]));

    log.clear();
    await tester.tapAt(const Offset(20.0, 90.0));
    expect(log, equals(<int>[1]));

    startOffset.value = 50.0;
    await tester.pump();

    log.clear();
    await tester.tapAt(const Offset(20.0, 90.0));
    expect(log, equals(<int>[0]));
  });

  testWidgets('Flow opacity layer', (WidgetTester tester) async {
    const double opacity = 0.2;
    await tester.pumpWidget(
      Flow(
        delegate: OpacityFlowDelegate(opacity),
        children: <Widget>[
          Container(width: 100.0, height: 100.0),
        ]
      )
    );
    ContainerLayer layer = RendererBinding.instance.renderView.debugLayer;
    while (layer != null && !(layer is OpacityLayer))
      layer = layer.firstChild;
    expect(layer, isInstanceOf<OpacityLayer>());
    final OpacityLayer opacityLayer = layer;
    expect(opacityLayer.alpha, equals(opacity * 255));
    expect(layer.firstChild, isInstanceOf<TransformLayer>());
  });
}
