// 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.Allocation;
using osu.Framework.Audio;
using osu.Framework.Audio.Sample;
using osu.Framework.Bindables;
using osu.Framework.Extensions.Color4Extensions;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Graphics.Shapes;
using osu.Framework.Screens;
using osu.Game.Audio;
using osu.Game.Beatmaps;
using osu.Game.Online.Rooms;
using osu.Game.Overlays;
using osu.Game.Overlays.Mods;
using osu.Game.Rulesets.Mods;
using osu.Game.Screens.OnlinePlay.Match.Components;

namespace osu.Game.Screens.OnlinePlay.Match
{
    [Cached(typeof(IPreviewTrackOwner))]
    public abstract class RoomSubScreen : OnlinePlaySubScreen, IPreviewTrackOwner
    {
        [Cached(typeof(IBindable<PlaylistItem>))]
        protected readonly Bindable<PlaylistItem> SelectedItem = new Bindable<PlaylistItem>();

        public override bool DisallowExternalBeatmapRulesetChanges => true;

        /// <summary>
        /// A container that provides controls for selection of user mods.
        /// This will be shown/hidden automatically when applicable.
        /// </summary>
        protected Drawable UserModsSection;

        private Sample sampleStart;

        /// <summary>
        /// Any mods applied by/to the local user.
        /// </summary>
        protected readonly Bindable<IReadOnlyList<Mod>> UserMods = new Bindable<IReadOnlyList<Mod>>(Array.Empty<Mod>());

        protected readonly IBindable<long?> RoomId = new Bindable<long?>();

        [Resolved]
        private MusicController music { get; set; }

        [Resolved]
        private BeatmapManager beatmapManager { get; set; }

        [Resolved(canBeNull: true)]
        protected OnlinePlayScreen ParentScreen { get; private set; }

        private IBindable<WeakReference<BeatmapSetInfo>> managerUpdated;

        [Cached]
        protected OnlinePlayBeatmapAvailabilityTracker BeatmapAvailabilityTracker { get; private set; }

        protected IBindable<BeatmapAvailability> BeatmapAvailability => BeatmapAvailabilityTracker.Availability;

        public readonly Room Room;
        private readonly bool allowEdit;

        private ModSelectOverlay userModsSelectOverlay;
        private RoomSettingsOverlay settingsOverlay;
        private Drawable mainContent;

        /// <summary>
        /// Creates a new <see cref="RoomSubScreen"/>.
        /// </summary>
        /// <param name="room">The <see cref="Room"/>.</param>
        /// <param name="allowEdit">Whether to allow editing room settings post-creation.</param>
        protected RoomSubScreen(Room room, bool allowEdit = true)
        {
            Room = room;
            this.allowEdit = allowEdit;

            Padding = new MarginPadding { Top = Header.HEIGHT };

            BeatmapAvailabilityTracker = new OnlinePlayBeatmapAvailabilityTracker
            {
                SelectedItem = { BindTarget = SelectedItem }
            };

            RoomId.BindTo(room.RoomID);
        }

        [BackgroundDependencyLoader]
        private void load(AudioManager audio)
        {
            sampleStart = audio.Samples.Get(@"SongSelect/confirm-selection");

            InternalChildren = new Drawable[]
            {
                BeatmapAvailabilityTracker,
                new GridContainer
                {
                    RelativeSizeAxes = Axes.Both,
                    RowDimensions = new[]
                    {
                        new Dimension(),
                        new Dimension(GridSizeMode.AutoSize)
                    },
                    Content = new[]
                    {
                        // Padded main content (drawable room + main content)
                        new Drawable[]
                        {
                            new Container
                            {
                                RelativeSizeAxes = Axes.Both,
                                Padding = new MarginPadding
                                {
                                    Horizontal = WaveOverlayContainer.WIDTH_PADDING,
                                    Bottom = 30
                                },
                                Children = new[]
                                {
                                    mainContent = new GridContainer
                                    {
                                        RelativeSizeAxes = Axes.Both,
                                        RowDimensions = new[]
                                        {
                                            new Dimension(GridSizeMode.AutoSize),
                                            new Dimension(GridSizeMode.Absolute, 10)
                                        },
                                        Content = new[]
                                        {
                                            new Drawable[]
                                            {
                                                new DrawableMatchRoom(Room, allowEdit)
                                                {
                                                    MatchingFilter = true,
                                                    OnEdit = () => settingsOverlay.Show()
                                                }
                                            },
                                            null,
                                            new Drawable[]
                                            {
                                                new Container
                                                {
                                                    RelativeSizeAxes = Axes.Both,
                                                    Children = new[]
                                                    {
                                                        new Container
                                                        {
                                                            RelativeSizeAxes = Axes.Both,
                                                            Masking = true,
                                                            CornerRadius = 10,
                                                            Child = new Box
                                                            {
                                                                RelativeSizeAxes = Axes.Both,
                                                                Colour = Color4Extensions.FromHex(@"3e3a44") // This is super temporary.
                                                            },
                                                        },
                                                        new Container
                                                        {
                                                            RelativeSizeAxes = Axes.Both,
                                                            Padding = new MarginPadding(10),
                                                            Child = CreateMainContent(),
                                                        },
                                                        new Container
                                                        {
                                                            Anchor = Anchor.BottomLeft,
                                                            Origin = Anchor.BottomLeft,
                                                            RelativeSizeAxes = Axes.X,
                                                            AutoSizeAxes = Axes.Y,
                                                            Child = userModsSelectOverlay = new UserModSelectOverlay
                                                            {
                                                                SelectedMods = { BindTarget = UserMods },
                                                                IsValidMod = _ => false
                                                            }
                                                        },
                                                    }
                                                }
                                            }
                                        }
                                    },
                                    new Container
                                    {
                                        RelativeSizeAxes = Axes.Both,
                                        // Resolves 1px masking errors between the settings overlay and the room panel.
                                        Padding = new MarginPadding(-1),
                                        Child = settingsOverlay = CreateRoomSettingsOverlay()
                                    }
                                },
                            },
                        },
                        // Footer
                        new[]
                        {
                            CreateFooter()
                        }
                    }
                }
            };
        }

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

            RoomId.BindValueChanged(id =>
            {
                if (id.NewValue == null)
                {
                    // A new room is being created.
                    // The main content should be hidden until the settings overlay is hidden, signaling the room is ready to be displayed.
                    mainContent.Hide();
                    settingsOverlay.Show();
                }
                else
                {
                    mainContent.Show();
                    settingsOverlay.Hide();
                }
            }, true);

            SelectedItem.BindValueChanged(_ => Scheduler.AddOnce(selectedItemChanged));

            managerUpdated = beatmapManager.ItemUpdated.GetBoundCopy();
            managerUpdated.BindValueChanged(beatmapUpdated);

            UserMods.BindValueChanged(_ => Scheduler.AddOnce(UpdateMods));
        }

        public override bool OnBackButton()
        {
            if (Room.RoomID.Value == null)
            {
                // room has not been created yet; exit immediately.
                return base.OnBackButton();
            }

            if (userModsSelectOverlay.State.Value == Visibility.Visible)
            {
                userModsSelectOverlay.Hide();
                return true;
            }

            if (settingsOverlay.State.Value == Visibility.Visible)
            {
                settingsOverlay.Hide();
                return true;
            }

            return base.OnBackButton();
        }

        protected void ShowUserModSelect() => userModsSelectOverlay.Show();

        public override void OnEntering(IScreen last)
        {
            base.OnEntering(last);
            beginHandlingTrack();
        }

        public override void OnSuspending(IScreen next)
        {
            endHandlingTrack();
            base.OnSuspending(next);
        }

        public override void OnResuming(IScreen last)
        {
            base.OnResuming(last);
            beginHandlingTrack();
            Scheduler.AddOnce(UpdateMods);
        }

        public override bool OnExiting(IScreen next)
        {
            RoomManager?.PartRoom();
            Mods.Value = Array.Empty<Mod>();

            endHandlingTrack();

            return base.OnExiting(next);
        }

        protected void StartPlay()
        {
            sampleStart?.Play();

            // fallback is to allow this class to operate when there is no parent OnlineScreen (testing purposes).
            var targetScreen = (Screen)ParentScreen ?? this;

            targetScreen.Push(CreateGameplayScreen());
        }

        /// <summary>
        /// Creates the gameplay screen to be entered.
        /// </summary>
        /// <returns>The screen to enter.</returns>
        protected abstract Screen CreateGameplayScreen();

        private void selectedItemChanged()
        {
            updateWorkingBeatmap();

            var selected = SelectedItem.Value;

            if (selected == null)
                return;

            // Remove any user mods that are no longer allowed.
            UserMods.Value = UserMods.Value
                                     .Where(m => selected.AllowedMods.Any(a => m.GetType() == a.GetType()))
                                     .ToList();

            UpdateMods();

            Ruleset.Value = selected.Ruleset.Value;

            if (!selected.AllowedMods.Any())
            {
                UserModsSection?.Hide();
                userModsSelectOverlay.Hide();
                userModsSelectOverlay.IsValidMod = _ => false;
            }
            else
            {
                UserModsSection?.Show();
                userModsSelectOverlay.IsValidMod = m => selected.AllowedMods.Any(a => a.GetType() == m.GetType());
            }
        }

        private void beatmapUpdated(ValueChangedEvent<WeakReference<BeatmapSetInfo>> weakSet) => Schedule(updateWorkingBeatmap);

        private void updateWorkingBeatmap()
        {
            var beatmap = SelectedItem.Value?.Beatmap.Value;

            // Retrieve the corresponding local beatmap, since we can't directly use the playlist's beatmap info
            var localBeatmap = beatmap == null ? null : beatmapManager.QueryBeatmap(b => b.OnlineBeatmapID == beatmap.OnlineBeatmapID);

            Beatmap.Value = beatmapManager.GetWorkingBeatmap(localBeatmap);
        }

        protected virtual void UpdateMods()
        {
            if (SelectedItem.Value == null)
                return;

            Mods.Value = UserMods.Value.Concat(SelectedItem.Value.RequiredMods).ToList();
        }

        private void beginHandlingTrack()
        {
            Beatmap.BindValueChanged(applyLoopingToTrack, true);
        }

        private void endHandlingTrack()
        {
            Beatmap.ValueChanged -= applyLoopingToTrack;
            cancelTrackLooping();
        }

        private void applyLoopingToTrack(ValueChangedEvent<WorkingBeatmap> _ = null)
        {
            if (!this.IsCurrentScreen())
                return;

            var track = Beatmap.Value?.Track;

            if (track != null)
            {
                Beatmap.Value.PrepareTrackForPreviewLooping();
                music?.EnsurePlayingSomething();
            }
        }

        private void cancelTrackLooping()
        {
            var track = Beatmap?.Value?.Track;

            if (track != null)
                track.Looping = false;
        }

        protected abstract Drawable CreateMainContent();

        protected abstract Drawable CreateFooter();

        protected abstract RoomSettingsOverlay CreateRoomSettingsOverlay();

        private class UserModSelectOverlay : LocalPlayerModSelectOverlay
        {
        }

        public class UserModSelectButton : PurpleTriangleButton
        {
        }
    }
}