// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE

using System.Collections.Generic;
using System.Linq;
using osu.Framework.Allocation;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Graphics.Primitives;
using osu.Framework.Input.Events;
using osu.Framework.Input.States;
using osu.Game.Rulesets.Edit;
using osu.Game.Rulesets.Edit.Tools;
using osu.Game.Rulesets.Objects.Drawables;

namespace osu.Game.Screens.Edit.Compose.Components
{
    public class BlueprintContainer : CompositeDrawable
    {
        private SelectionBlueprintContainer selectionBlueprints;

        private Container<PlacementBlueprint> placementBlueprintContainer;
        private PlacementBlueprint currentPlacement;

        private SelectionBox selectionBox;

        private IEnumerable<SelectionBlueprint> selections => selectionBlueprints.Children.Where(c => c.IsAlive);

        [Resolved]
        private HitObjectComposer composer { get; set; }

        public BlueprintContainer()
        {
            RelativeSizeAxes = Axes.Both;
        }

        [BackgroundDependencyLoader]
        private void load()
        {
            selectionBox = composer.CreateSelectionBox();
            selectionBox.DeselectAll = deselectAll;

            var dragBox = new DragBox(select);
            dragBox.DragEnd += () => selectionBox.UpdateVisibility();

            InternalChildren = new[]
            {
                dragBox,
                selectionBox,
                selectionBlueprints = new SelectionBlueprintContainer { RelativeSizeAxes = Axes.Both },
                placementBlueprintContainer = new Container<PlacementBlueprint> { RelativeSizeAxes = Axes.Both },
                dragBox.CreateProxy()
            };

            foreach (var obj in composer.HitObjects)
                AddBlueprintFor(obj);
        }

        private HitObjectCompositionTool currentTool;

        /// <summary>
        /// The current placement tool.
        /// </summary>
        public HitObjectCompositionTool CurrentTool
        {
            get => currentTool;
            set
            {
                if (currentTool == value)
                    return;
                currentTool = value;

                refreshTool();
            }
        }

        /// <summary>
        /// Adds a blueprint for a <see cref="DrawableHitObject"/> which adds movement support.
        /// </summary>
        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to create a blueprint for.</param>
        public void AddBlueprintFor(DrawableHitObject hitObject)
        {
            refreshTool();

            var blueprint = composer.CreateBlueprintFor(hitObject);
            if (blueprint == null)
                return;

            blueprint.Selected += onBlueprintSelected;
            blueprint.Deselected += onBlueprintDeselected;
            blueprint.SelectionRequested += onSelectionRequested;
            blueprint.DragRequested += onDragRequested;

            selectionBlueprints.Add(blueprint);
        }

        /// <summary>
        /// Removes a blueprint for a <see cref="DrawableHitObject"/>.
        /// </summary>
        /// <param name="hitObject">The <see cref="DrawableHitObject"/> for which to remove the blueprint.</param>
        public void RemoveBlueprintFor(DrawableHitObject hitObject)
        {
            var blueprint = selectionBlueprints.Single(m => m.HitObject == hitObject);
            if (blueprint == null)
                return;

            blueprint.Deselect();

            blueprint.Selected -= onBlueprintSelected;
            blueprint.Deselected -= onBlueprintDeselected;
            blueprint.SelectionRequested -= onSelectionRequested;
            blueprint.DragRequested -= onDragRequested;

            selectionBlueprints.Remove(blueprint);
        }

        protected override bool OnClick(ClickEvent e)
        {
            deselectAll();
            return true;
        }

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

            if (currentPlacement != null)
            {
                if (composer.CursorInPlacementArea)
                    currentPlacement.State = PlacementState.Shown;
                else if (currentPlacement?.PlacementBegun == false)
                    currentPlacement.State = PlacementState.Hidden;
            }
        }

        /// <summary>
        /// Refreshes the current placement tool.
        /// </summary>
        private void refreshTool()
        {
            placementBlueprintContainer.Clear();
            currentPlacement = null;

            var blueprint = CurrentTool?.CreatePlacementBlueprint();
            if (blueprint != null)
                placementBlueprintContainer.Child = currentPlacement = blueprint;
        }

        /// <summary>
        /// Select all masks in a given rectangle selection area.
        /// </summary>
        /// <param name="rect">The rectangle to perform a selection on in screen-space coordinates.</param>
        private void select(RectangleF rect)
        {
            foreach (var blueprint in selections.ToList())
            {
                if (blueprint.IsPresent && rect.Contains(blueprint.SelectionPoint))
                    blueprint.Select();
                else
                    blueprint.Deselect();
            }
        }

        /// <summary>
        /// Deselects all selected <see cref="SelectionBlueprint"/>s.
        /// </summary>
        private void deselectAll() => selections.ToList().ForEach(m => m.Deselect());

        private void onBlueprintSelected(SelectionBlueprint blueprint)
        {
            selectionBox.HandleSelected(blueprint);
            selectionBlueprints.ChangeChildDepth(blueprint, 1);
        }

        private void onBlueprintDeselected(SelectionBlueprint blueprint)
        {
            selectionBox.HandleDeselected(blueprint);
            selectionBlueprints.ChangeChildDepth(blueprint, 0);
        }

        private void onSelectionRequested(SelectionBlueprint blueprint, InputState state) => selectionBox.HandleSelectionRequested(blueprint, state);

        private void onDragRequested(DragEvent dragEvent) => selectionBox.HandleDrag(dragEvent);

        private class SelectionBlueprintContainer : Container<SelectionBlueprint>
        {
            protected override int Compare(Drawable x, Drawable y)
            {
                if (!(x is SelectionBlueprint xBlueprint) || !(y is SelectionBlueprint yBlueprint))
                    return base.Compare(x, y);
                return Compare(xBlueprint, yBlueprint);
            }

            public int Compare(SelectionBlueprint x, SelectionBlueprint y)
            {
                // dpeth is used to denote selected status (we always want selected blueprints to handle input first).
                int d = x.Depth.CompareTo(y.Depth);
                if (d != 0)
                    return d;

                // Put earlier hitobjects towards the end of the list, so they handle input first
                int i = y.HitObject.HitObject.StartTime.CompareTo(x.HitObject.HitObject.StartTime);
                return i == 0 ? CompareReverseChildID(x, y) : i;
            }
        }
    }
}