// Copyright (c) The Avalonia Project. All rights reserved.
// Licensed under the MIT license. See licence.md file in the project root for full license information.

using Avalonia.Controls;
using Avalonia.UnitTests;
using System;
using Xunit;
using System.Collections.Generic;

namespace Avalonia.Layout.UnitTests
{
    public class LayoutManagerTests
    {
        [Fact]
        public void Measures_And_Arranges_InvalidateMeasured_Control()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                var control = new LayoutTestControl();
                var root = new LayoutTestRoot { Child = control };

                target.ExecuteInitialLayoutPass(root);
                control.Measured = control.Arranged = false;

                control.InvalidateMeasure();
                target.ExecuteLayoutPass();

                Assert.True(control.Measured);
                Assert.True(control.Arranged);
            }
        }

        [Fact]
        public void Arranges_InvalidateArranged_Control()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                var control = new LayoutTestControl();
                var root = new LayoutTestRoot { Child = control };

                target.ExecuteInitialLayoutPass(root);
                control.Measured = control.Arranged = false;

                control.InvalidateArrange();
                target.ExecuteLayoutPass();

                Assert.False(control.Measured);
                Assert.True(control.Arranged);
            }
        }

        [Fact]
        public void Measures_Parent_Of_Newly_Added_Control()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                var control = new LayoutTestControl();
                var root = new LayoutTestRoot();

                target.ExecuteInitialLayoutPass(root);
                root.Child = control;
                root.Measured = root.Arranged = false;

                target.ExecuteLayoutPass();

                Assert.True(root.Measured);
                Assert.True(root.Arranged);
                Assert.True(control.Measured);
                Assert.True(control.Arranged);
            }
        }

        [Fact]
        public void Measures_In_Correct_Order()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                LayoutTestControl control1;
                LayoutTestControl control2;
                var root = new LayoutTestRoot
                {
                    Child = control1 = new LayoutTestControl
                    {
                        Child = control2 = new LayoutTestControl(),
                    }
                };


                var order = new List<ILayoutable>();
                Size MeasureOverride(ILayoutable control, Size size)
                {
                    order.Add(control);
                    return new Size(10, 10);
                }

                root.DoMeasureOverride = MeasureOverride;
                control1.DoMeasureOverride = MeasureOverride;
                control2.DoMeasureOverride = MeasureOverride;
                target.ExecuteInitialLayoutPass(root);

                control2.InvalidateMeasure();
                control1.InvalidateMeasure();
                root.InvalidateMeasure();

                order.Clear();
                target.ExecuteLayoutPass();

                Assert.Equal(new ILayoutable[] { root, control1, control2 }, order);
            }
        }

        [Fact]
        public void Measures_Root_And_Grandparent_In_Correct_Order()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                LayoutTestControl control1;
                LayoutTestControl control2;
                var root = new LayoutTestRoot
                {
                    Child = control1 = new LayoutTestControl
                    {
                        Child = control2 = new LayoutTestControl(),
                    }
                };


                var order = new List<ILayoutable>();
                Size MeasureOverride(ILayoutable control, Size size)
                {
                    order.Add(control);
                    return new Size(10, 10);
                }

                root.DoMeasureOverride = MeasureOverride;
                control1.DoMeasureOverride = MeasureOverride;
                control2.DoMeasureOverride = MeasureOverride;
                target.ExecuteInitialLayoutPass(root);

                control2.InvalidateMeasure();
                root.InvalidateMeasure();

                order.Clear();
                target.ExecuteLayoutPass();

                Assert.Equal(new ILayoutable[] { root, control2 }, order);
            }
        }

        [Fact]
        public void Doesnt_Measure_Non_Invalidated_Root()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                var control = new LayoutTestControl();
                var root = new LayoutTestRoot { Child = control };

                target.ExecuteInitialLayoutPass(root);
                root.Measured = root.Arranged = false;
                control.Measured = control.Arranged = false;

                control.InvalidateMeasure();
                target.ExecuteLayoutPass();

                Assert.False(root.Measured);
                Assert.False(root.Arranged);
                Assert.True(control.Measured);
                Assert.True(control.Arranged);
            }
        }

        [Fact]
        public void Doesnt_Measure_Removed_Control()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                var control = new LayoutTestControl();
                var root = new LayoutTestRoot { Child = control };

                target.ExecuteInitialLayoutPass(root);
                control.Measured = control.Arranged = false;

                control.InvalidateMeasure();
                root.Child = null;
                target.ExecuteLayoutPass();

                Assert.False(control.Measured);
                Assert.False(control.Arranged);
            }
        }

        [Fact]
        public void Measures_Root_With_Infinity()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                var root = new LayoutTestRoot();
                var availableSize = default(Size);

                // Should not measure with this size.
                root.MaxClientSize = new Size(123, 456);

                root.DoMeasureOverride = (_, s) =>
                {
                    availableSize = s;
                    return new Size(100, 100);
                };

                target.ExecuteInitialLayoutPass(root);

                Assert.Equal(Size.Infinity, availableSize);
            }
        }

        [Fact]
        public void Arranges_Root_With_DesiredSize()
        {
            var target = new LayoutManager();
 
            using (Start(target))
            {
                var root = new LayoutTestRoot
                {
                    Width = 100,
                    Height = 100,
                };
 
                var arrangeSize = default(Size);
 
                root.DoArrangeOverride = (_, s) =>
                {
                    arrangeSize = s;
                    return s;
                };
 
                target.ExecuteInitialLayoutPass(root);
                Assert.Equal(new Size(100, 100), arrangeSize);
 
                root.Width = 120;
 
                target.ExecuteLayoutPass();
                Assert.Equal(new Size(120, 100), arrangeSize);
            }
        }

        [Fact]
        public void Invalidating_Child_Remeasures_Parent()
        {
            var target = new LayoutManager();

            using (Start(target))
            {
                AvaloniaLocator.CurrentMutable.Bind<ILayoutManager>().ToConstant(target);

                Border border;
                StackPanel panel;

                var root = new LayoutTestRoot
                {
                    Child = panel = new StackPanel
                    {
                        Children =
                        {
                            (border = new Border())
                        }
                    }
                };

                target.ExecuteInitialLayoutPass(root);
                Assert.Equal(new Size(0, 0), root.DesiredSize);

                border.Width = 100;
                border.Height = 100;

                target.ExecuteLayoutPass();
                Assert.Equal(new Size(100, 100), panel.DesiredSize);
            }                
        }

        private IDisposable Start(LayoutManager layoutManager)
        {
            var result = AvaloniaLocator.EnterScope();
            AvaloniaLocator.CurrentMutable.Bind<ILayoutManager>().ToConstant(layoutManager);
            return result;
        }
    }
}