// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE

using System;
using System.Linq;
using osu.Framework.Allocation;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Input;
using osu.Framework.Timing;
using osu.Game.Graphics;
using OpenTK.Graphics;
using OpenTK.Input;

namespace osu.Game.Screens.Play
{
    /// <summary>
    /// A container which handles pausing children, displaying a pause overlay with choices etc.
    /// This alleviates a lot of the intricate pause logic from being in <see cref="Player"/>
    /// </summary>
    public class PauseContainer : Container
    {
        public bool IsPaused { get; private set; }

        public bool AllowExit => IsPaused && pauseOverlay.Alpha == 1;

        public Func<bool> CheckCanPause;

        private const double pause_cooldown = 1000;
        private double lastPauseActionTime;

        private readonly PauseOverlay pauseOverlay;

        private readonly Container content;

        protected override Container<Drawable> Content => content;

        public int Retries { set { pauseOverlay.Retries = value; } }

        public bool CanPause => (CheckCanPause?.Invoke() ?? true) && Time.Current >= lastPauseActionTime + pause_cooldown;

        public Action OnRetry;
        public Action OnQuit;

        public Action OnResume;
        public Action OnPause;

        public IAdjustableClock AudioClock;
        public FramedClock FramedClock;

        public PauseContainer()
        {
            RelativeSizeAxes = Axes.Both;

            AddInternal(content = new Container { RelativeSizeAxes = Axes.Both });

            AddInternal(pauseOverlay = new PauseOverlay
            {
                OnResume = delegate
                {
                    Delay(400);
                    Schedule(Resume);
                },
                OnRetry = () => OnRetry(),
                OnQuit = () => OnQuit(),
            });
        }

        public void Pause(bool force = false)
        {
            if (!CanPause && !force) return;

            if (IsPaused) return;

            // stop the decoupled clock (stops the audio eventually)
            AudioClock.Stop();

            // stop processing updatess on the offset clock (instantly freezes time for all our components)
            FramedClock.ProcessSourceClockFrames = false;

            IsPaused = true;

            // we need to do a final check after all of our children have processed up to the paused clock time.
            // this is to cover cases where, for instance, the player fails in the current processing frame.
            Schedule(() =>
            {
                if (!CanPause) return;

                lastPauseActionTime = Time.Current;

                OnPause?.Invoke();
                pauseOverlay.Show();
            });
        }

        public void Resume()
        {
            if (!IsPaused) return;

            IsPaused = false;
            FramedClock.ProcessSourceClockFrames = true;

            lastPauseActionTime = Time.Current;

            OnResume?.Invoke();

            pauseOverlay.Hide();
            AudioClock.Start();
        }

        private OsuGameBase game;

        [BackgroundDependencyLoader]
        private void load(OsuGameBase game)
        {
            this.game = game;
        }

        protected override void Update()
        {
            // eagerly pause when we lose window focus (if we are locally playing).
            if (!game.IsActive && CanPause)
                Pause();

            base.Update();
        }

        public class PauseOverlay : MenuOverlay
        {
            public Action OnResume;

            public override string Header => "paused";
            public override string Description => "you're not going to do what i think you're going to do, are ya?";

            protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
            {
                if (!args.Repeat && args.Key == Key.Escape)
                {
                    Buttons.Children.First().TriggerClick();
                    return true;
                }

                return base.OnKeyDown(state, args);
            }

            [BackgroundDependencyLoader]
            private void load(OsuColour colours)
            {
                AddButton("Continue", colours.Green, OnResume);
                AddButton("Retry", colours.YellowDark, OnRetry);
                AddButton("Quit", new Color4(170, 27, 39, 255), OnQuit);
            }
        }
    }
}