using Amphora;
using Annulus;
using Azimuth;
using Clave;
using System;
using System.Collections.Generic;
using Prism;

namespace Glass.Testbed.TestCases.Rendering
{
    /// <summary>
    /// A guided tour whose spotlight the user can move or dismiss, so it needs a Setup to put itself back.
    /// </summary>
    public class SpotlightTestCase : TestCase
    {
        /// <summary>
        /// Sits below whatever it is a child of, which under a Spotlight is the highlighted control.
        /// </summary>
        private class CoachMark : Panel
        {
            public Vector Offset { get; set; }

            public override void Update(Duration elapsed, UpdateState state)
            {
                base.Update(elapsed, state);

                Bounds = Rect.FromPositionAndSize(
                    new Vector(0, state.ParentCanvasRect.Height) + Offset, Bounds.Size);
            }
        }

        private static readonly Vector ButtonSize = MeasuredButtonSize();

        private static Vector MeasuredButtonSize()
        {
            return UiPacksheetMaterials.Button.SolveBoundsFor(
                Widgets.ButtonLabel("Build: 0"), Constraints.TightWidth(190, Scalar.PositiveInfinity));
        }

        private readonly List<Button> targets = new List<Button>();
        private readonly Spotlight spotlight;
        private readonly Label coachLabel;
        private int step;

        public SpotlightTestCase()
        {
            spotlight = new Spotlight(new SolidColorMaterial
            {
                Color = Color.FromArgb(170, 0, 0, 0),
            })
            {
                DebugName = "spotlight",
            };

            coachLabel = new Label(Widgets.ButtonLabelStyle, "Click");
        }

        /// <summary>
        /// Re-parenting is the whole move: nothing else tells the spotlight where its new target sits.
        /// </summary>
        private void MoveSpotlightTo(int target)
        {
            targets[step].CanvasChildren.Remove(spotlight);
            step = target;
            targets[step].CanvasChildren.Add(spotlight);
            coachLabel.Text = $"Click {targets[step].DebugName}";
        }

        private void BuildTargets()
        {
            Rect buttonRow = ContentAggregator.NewRow(ButtonSize.Y);

            foreach (string name in new[] { "Build", "Attack", "Harvest" })
            {
                string buttonName = name;
                int clicks = 0;
                var label = new Label(Widgets.ButtonLabelStyle, $"{buttonName}: 0");

                Button target = label.FillParent(new Button(ButtonBehavior.Default)
                {
                    DebugName = buttonName,
                    ButtonMaterial = UiPacksheetMaterials.Button,
                    Bounds = buttonRow.NewCol(ButtonSize.X, margin: Gutter),
                });

                target.OnActivate += delegate (ButtonBase _, in KeyboardSnapshot __, KeyboardManager ___)
                {
                    ++clicks;
                    label.Text = $"{buttonName}: {clicks}";
                };

                Add(target);
                targets.Add(target);
            }
        }

        private static Button BuildCoachButton(string debugName, string text, Vector labelSize)
        {
            Button button = new Label(Widgets.ButtonLabelStyle, text, Constraints.Tight(labelSize))
                .WrapIn(UiPacksheetMaterials.Button, ButtonBehavior.Default);
            button.DebugName = debugName;
            return button;
        }

        private void BuildCoachMark()
        {
            Scalar coachTextHeight = coachLabel.PreferredSize(Constraints.Unbounded).Y;

            // Both buttons share the wider label's size so the row stays visually even.
            Vector labelSize = Vector.Max(
                Widgets.ButtonLabel("Next").PreferredSize(Constraints.Unbounded),
                Widgets.ButtonLabel("Done").PreferredSize(Constraints.Unbounded));

            Button next = BuildCoachButton("next step", "Next", labelSize);
            Button done = BuildCoachButton("done", "Done", labelSize);
            Vector buttonSize = next.Bounds.Size;

            // Laid out before the mark exists, so the mark can be sized to what it ends up holding rather than to a
            // guess that has to stay in step with it.  The button row sets the width, and the label centres across it.
            var content = new RectAggregator(
                Rect.FromPositionAndSize(Vector.Zero, new Vector(2 * buttonSize.X + Gutter, 0)),
                new Vector(0, Gutter));

            coachLabel.Bounds = content.NewRow(coachTextHeight);
            Rect coachButtonRow = content.NewRow(buttonSize.Y);

            next.Bounds = coachButtonRow.NewCol(buttonSize.X, margin: Gutter);
            done.Bounds = coachButtonRow.NewCol(buttonSize.X);

            var coachMark = new CoachMark
            {
                DebugName = "coach mark",
                Material = UiPacksheetMaterials.YellowPanel,
                Bounds = Rect.FromPositionAndSize(
                    Vector.Zero, UiPacksheetMaterials.YellowPanel.BoundsSizeFor(content.Rect.Size)),
                Offset = new Vector(0, Gutter),
            };
            spotlight.CanvasChildren.Add(coachMark);

            coachMark.CanvasChildren.Add(coachLabel);
            coachMark.CanvasChildren.Add(next);
            coachMark.CanvasChildren.Add(done);

            next.OnActivate += delegate (ButtonBase _, in KeyboardSnapshot __, KeyboardManager ___)
            {
                MoveSpotlightTo((step + 1) % targets.Count);
            };

            done.OnActivate += delegate (ButtonBase _, in KeyboardSnapshot __, KeyboardManager ___)
            {
                targets[step].CanvasChildren.Remove(spotlight);
            };
        }

        protected override void Populate()
        {
            AddCaption("Everything dims but the highlighted button, which still takes its clicks");
            AddCaption("Modal means the menu bar is blocked too — Done releases it");

            BuildTargets();
            BuildCoachMark();
        }

        /// <summary>
        /// Cases are built once, so a tour the user left part way through or dismissed restarts here.
        /// </summary>
        protected override void Setup()
        {
            MoveSpotlightTo(0);
        }
    }
}