// 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.Collections.Generic;
using System.Linq;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Graphics;
using osu.Framework.Input;
using osu.Framework.Input.Events;
using osu.Framework.Input.StateChanges;
using osu.Game.Configuration;

namespace osu.Game.Rulesets.Osu.UI
{
    public partial class OsuTouchInputMapper : Drawable
    {
        /// <summary>
        /// All the active <see cref="TouchSource"/>s and the <see cref="OsuAction"/> that it triggered (if any).
        /// Ordered from oldest to newest touch chronologically.
        /// </summary>
        private readonly List<TrackedTouch> trackedTouches = new List<TrackedTouch>();

        private readonly OsuInputManager osuInputManager;

        private Bindable<bool> mouseDisabled = null!;

        public OsuTouchInputMapper(OsuInputManager inputManager)
        {
            osuInputManager = inputManager;
        }

        [BackgroundDependencyLoader]
        private void load(OsuConfigManager config)
        {
            mouseDisabled = config.GetBindable<bool>(OsuSetting.MouseDisableButtons);
        }

        protected override void OnTouchMove(TouchMoveEvent e)
        {
            base.OnTouchMove(e);
            handleTouchMovement(e);
        }

        protected override bool OnTouchDown(TouchDownEvent e)
        {
            OsuAction action = trackedTouches.Any(t => t.Action == OsuAction.LeftButton)
                ? OsuAction.RightButton
                : OsuAction.LeftButton;

            // Ignore any taps which trigger an action which is already handled. But track them for potential positional input in the future.
            bool shouldResultInAction = !mouseDisabled.Value && trackedTouches.All(t => t.Action != action);

            trackedTouches.Add(new TrackedTouch(e.Touch.Source, shouldResultInAction ? action : null));

            // Important to update position before triggering the pressed action.
            handleTouchMovement(e);

            if (shouldResultInAction)
                osuInputManager.KeyBindingContainer.TriggerPressed(action);

            return true;
        }

        private void handleTouchMovement(TouchEvent touchEvent)
        {
            // Movement should only be tracked for the most recent touch.
            if (touchEvent.Touch.Source != trackedTouches.Last().Source)
                return;

            new MousePositionAbsoluteInput { Position = touchEvent.ScreenSpaceTouch.Position }.Apply(osuInputManager.CurrentState, osuInputManager);
        }

        protected override void OnTouchUp(TouchUpEvent e)
        {
            var tracked = trackedTouches.Single(t => t.Source == e.Touch.Source);

            if (tracked.Action is OsuAction action)
                osuInputManager.KeyBindingContainer.TriggerReleased(action);

            trackedTouches.Remove(tracked);

            base.OnTouchUp(e);
        }

        private class TrackedTouch
        {
            public readonly TouchSource Source;

            public readonly OsuAction? Action;

            public TrackedTouch(TouchSource source, OsuAction? action)
            {
                Source = source;
                Action = action;
            }
        }
    }
}