using Annulus;
using Azimuth;
using System;

namespace Glass.Testbed
{
    /// <summary>
    /// ScrollViews sized from their own items by BoundsSizeFor: capped and scrolling on one axis or both, fitting
    /// so the bar hides but its strip stays, and with the bars on different edges.  Clicking an item scrolls it
    /// fully into view, and the mouse wheel scrolls the view under the pointer.
    /// </summary>
    public class ScrollViewTestCase : TestCase
    {
        public ScrollViewTestCase(string name) : base(name) { }

        private ScrollView BuildView(bool scrollsHorizontally, bool scrollsVertically, Anchor horizontalAnchor,
            Anchor verticalAnchor, int columns, int rows, Vector maximumSize)
        {
            var view = NewChild<ScrollView>($"{columns}x{rows} scroll view");
            view.ScrollsHorizontally = scrollsHorizontally;
            view.ScrollsVertically = scrollsVertically;
            view.HorizontalScrollBarAnchor = horizontalAnchor;
            view.VerticalScrollBarAnchor = verticalAnchor;
            view.ScrollViewMaterial = new ScrollViewMaterial
            {
                Background = Material.Invisible,
                Canvas = UiPacksheetMaterials.GreenFlatPanel,
                HorizontalScrollBar = UiPacksheetMaterials.HorizontalScrollBar,
                VerticalScrollBar = UiPacksheetMaterials.VerticalScrollBar,
            };

            Vector labelSize = Widgets.ButtonLabel("00, 00").PreferredSize(Constraints.Unbounded);
            Vector itemSize = UiPacksheetMaterials.YellowButton.BoundsSizeFor(labelSize);
            RectDivider grid = RectAggregator.NewGrid(
                Vector.Zero, itemSize, rows, columns, margin: new Vector(Margin, Margin));

            for (int row = 0; row < rows; ++row)
            {
                for (int column = 0; column < columns; ++column)
                {
                    Button item = Widgets.ButtonLabel($"{row}, {column}")
                        .BuildControl(Constraints.Tight(labelSize))
                        .WrapIn(UiPacksheetMaterials.YellowButton);

                    item.Bounds = grid[row, column];
                    item.OnClick += (in MouseState _, MouseButtonFlags __) => view.ScrollIntoView(item.Bounds);
                    view.CanvasChildren.Add(item);
                }
            }

            Vector contentSize = grid.Bounds.Size;
            Vector boundsSize = view.ScrollViewMaterial.BoundsSizeFor(contentSize, view.ScrollAxes);
            view.Bounds = Rect.FromPositionAndSize(Vector.Zero, Vector.Min(boundsSize, maximumSize));
            view.ContentSize = contentSize;
            return view;
        }

        private void PlaceInRow(ScrollView[] views)
        {
            Scalar rowHeight = 0;

            foreach (ScrollView view in views)
            {
                rowHeight = Math.Max(rowHeight, view.Bounds.Height);
            }

            Rect row = ContentAggregator.NewRow(rowHeight);

            foreach (ScrollView view in views)
            {
                Rect slot = row.NewCol(view.Bounds.Width, margin: Margin);
                view.Bounds = view.Bounds.WithPosition(slot.TopLeft);
            }
        }

        protected override void Populate()
        {
            Scalar uncapped = Scalar.PositiveInfinity;

            AddCaption("Items go straight onto each view's CanvasChildren; click one to scroll it fully into view");
            AddCaption("The mouse wheel scrolls the view under the pointer; a horizontal-only view scrolls sideways");
            AddCaption("Left to right: vertical only and capped; vertical only and short enough to fit, so the bar");
            AddCaption("hides but its strip stays; both axes with bars bottom right; both axes with bars top left");

            PlaceInRow(new[]
            {
                BuildView(scrollsHorizontally: false, scrollsVertically: true, Anchor.Bottom, Anchor.Right,
                    columns: 1, rows: 16, new Vector(uncapped, 190)),
                BuildView(scrollsHorizontally: false, scrollsVertically: true, Anchor.Bottom, Anchor.Right,
                    columns: 1, rows: 3, new Vector(uncapped, 190)),
                BuildView(scrollsHorizontally: true, scrollsVertically: true, Anchor.Bottom, Anchor.Right,
                    columns: 6, rows: 12, new Vector(300, 190)),
                BuildView(scrollsHorizontally: true, scrollsVertically: true, Anchor.Top, Anchor.Left,
                    columns: 5, rows: 8, new Vector(240, 160)),
            });

            AddCaption("Horizontal only, bar along the top");

            PlaceInRow(new[]
            {
                BuildView(scrollsHorizontally: true, scrollsVertically: false, Anchor.Top, Anchor.Right,
                    columns: 12, rows: 1, new Vector(300, uncapped)),
            });
        }
    }
}