// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System;
using System.Collections.Generic;
using System.Linq;
using osu.Framework.Graphics;
using osu.Framework.Graphics.UserInterface;
using osu.Game.Graphics.UserInterface;
using osu.Game.Rulesets.Edit;
using osu.Game.Screens.Edit.Compose.Components;
using osu.Game.Screens.Play.HUD;
using osuTK;

namespace osu.Game.Skinning.Editor
{
    public class SkinSelectionHandler : SelectionHandler<ISkinnableComponent>
    {
        protected override void DeleteItems(IEnumerable<ISkinnableComponent> items)
        {
            foreach (var i in items)
                i.Hide();
        }

        protected override IEnumerable<MenuItem> GetContextMenuItemsForSelection(IEnumerable<SelectionBlueprint<ISkinnableComponent>> selection)
        {
            yield return new OsuMenuItem("Anchor")
            {
                Items = createAnchorItems().ToArray()
            };

            foreach (var item in base.GetContextMenuItemsForSelection(selection))
                yield return item;

            IEnumerable<AnchorMenuItem> createAnchorItems()
            {
                var displayableAnchors = new[]
                {
                    Anchor.TopLeft,
                    Anchor.TopCentre,
                    Anchor.TopRight,
                    Anchor.CentreLeft,
                    Anchor.Centre,
                    Anchor.CentreRight,
                    Anchor.BottomLeft,
                    Anchor.BottomCentre,
                    Anchor.BottomRight,
                };

                return displayableAnchors.Select(a =>
                {
                    var countExisting = selection.Count(b => ((Drawable)b.Item).Anchor == a);
                    var countTotal = selection.Count();

                    TernaryState state;

                    if (countExisting == countTotal)
                        state = TernaryState.True;
                    else if (countExisting > 0)
                        state = TernaryState.Indeterminate;
                    else
                        state = TernaryState.False;

                    return new AnchorMenuItem(a, selection, _ => applyAnchor(a))
                    {
                        State = { Value = state }
                    };
                });
            }
        }

        private void applyAnchor(Anchor anchor)
        {
            foreach (var item in SelectedItems)
                ((Drawable)item).Anchor = anchor;
        }

        protected override void OnSelectionChanged()
        {
            base.OnSelectionChanged();

            SelectionBox.CanRotate = true;
            SelectionBox.CanScaleX = true;
            SelectionBox.CanScaleY = true;
            SelectionBox.CanReverse = false;
        }

        public override bool HandleRotation(float angle)
        {
            foreach (var c in SelectedBlueprints)
                ((Drawable)c.Item).Rotation += angle;

            return base.HandleRotation(angle);
        }

        public override bool HandleScale(Vector2 scale, Anchor anchor)
        {
            adjustScaleFromAnchor(ref scale, anchor);

            foreach (var c in SelectedBlueprints)
                ((Drawable)c.Item).Scale += scale * 0.01f;

            return true;
        }

        public override bool HandleMovement(MoveSelectionEvent<ISkinnableComponent> moveEvent)
        {
            foreach (var c in SelectedBlueprints)
            {
                ((Drawable)c.Item).Position += moveEvent.InstantDelta;
            }

            return true;
        }

        private static void adjustScaleFromAnchor(ref Vector2 scale, Anchor reference)
        {
            // cancel out scale in axes we don't care about (based on which drag handle was used).
            if ((reference & Anchor.x1) > 0) scale.X = 0;
            if ((reference & Anchor.y1) > 0) scale.Y = 0;

            // reverse the scale direction if dragging from top or left.
            if ((reference & Anchor.x0) > 0) scale.X = -scale.X;
            if ((reference & Anchor.y0) > 0) scale.Y = -scale.Y;
        }

        public class AnchorMenuItem : TernaryStateMenuItem
        {
            public AnchorMenuItem(Anchor anchor, IEnumerable<SelectionBlueprint<ISkinnableComponent>> selection, Action<TernaryState> action)
                : base(anchor.ToString(), getNextState, MenuItemType.Standard, action)
            {
            }

            private void updateState(TernaryState obj)
            {
                throw new NotImplementedException();
            }

            private static TernaryState getNextState(TernaryState state) => TernaryState.True;
        }
    }
}