// 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.Diagnostics;
using System.Linq;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Extensions.ObjectExtensions;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Logging;
using osu.Framework.Screens;
using osu.Framework.Threading;
using osu.Game.Beatmaps;
using osu.Game.Configuration;
using osu.Game.Graphics.Cursor;
using osu.Game.Online;
using osu.Game.Online.API;
using osu.Game.Online.API.Requests.Responses;
using osu.Game.Online.Multiplayer;
using osu.Game.Online.Rooms;
using osu.Game.Overlays;
using osu.Game.Overlays.Dialog;
using osu.Game.Rulesets;
using osu.Game.Rulesets.Mods;
using osu.Game.Screens.OnlinePlay.Components;
using osu.Game.Screens.OnlinePlay.Match;
using osu.Game.Screens.OnlinePlay.Match.Components;
using osu.Game.Screens.OnlinePlay.Multiplayer.Match;
using osu.Game.Screens.OnlinePlay.Multiplayer.Match.Playlist;
using osu.Game.Screens.OnlinePlay.Multiplayer.Participants;
using osu.Game.Screens.OnlinePlay.Multiplayer.Spectate;
using osu.Game.Screens.Play.HUD;
using osu.Game.Users;
using osuTK;
using ParticipantsList = osu.Game.Screens.OnlinePlay.Multiplayer.Participants.ParticipantsList;

namespace osu.Game.Screens.OnlinePlay.Multiplayer
{
    [Cached]
    public partial class MultiplayerMatchSubScreen : RoomSubScreen, IHandlePresentBeatmap
    {
        public override string Title { get; }

        public override string ShortTitle => "room";

        [Resolved]
        private MultiplayerClient client { get; set; } = null!;

        [Resolved(canBeNull: true)]
        private OsuGame? game { get; set; }

        private AddItemButton addItemButton = null!;

        public MultiplayerMatchSubScreen(Room room)
            : base(room)
        {
            Title = room.RoomID == null ? "New room" : room.Name;
            Activity.Value = new UserActivity.InLobby(room);
        }

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

            BeatmapAvailability.BindValueChanged(updateBeatmapAvailability, true);
            UserMods.BindValueChanged(onUserModsChanged);

            client.LoadRequested += onLoadRequested;
            client.RoomUpdated += onRoomUpdated;

            if (!client.IsConnected.Value)
                handleRoomLost();
        }

        protected override bool IsConnected => base.IsConnected && client.IsConnected.Value;

        protected override Drawable CreateMainContent() => new Container
        {
            RelativeSizeAxes = Axes.Both,
            Padding = new MarginPadding { Horizontal = 5, Vertical = 10 },
            Child = new OsuContextMenuContainer
            {
                RelativeSizeAxes = Axes.Both,
                Child = new GridContainer
                {
                    RelativeSizeAxes = Axes.Both,
                    ColumnDimensions = new[]
                    {
                        new Dimension(),
                        new Dimension(GridSizeMode.Absolute, 10),
                        new Dimension(),
                        new Dimension(GridSizeMode.Absolute, 10),
                        new Dimension(),
                    },
                    Content = new[]
                    {
                        new Drawable?[]
                        {
                            new GridContainer
                            {
                                RelativeSizeAxes = Axes.Both,
                                RowDimensions = new[]
                                {
                                    new Dimension(GridSizeMode.AutoSize)
                                },
                                Content = new[]
                                {
                                    new Drawable[] { new ParticipantsListHeader() },
                                    new Drawable[]
                                    {
                                        new ParticipantsList
                                        {
                                            RelativeSizeAxes = Axes.Both
                                        },
                                    }
                                }
                            },
                            null,
                            new GridContainer
                            {
                                RelativeSizeAxes = Axes.Both,
                                Content = new[]
                                {
                                    new Drawable[] { new OverlinedHeader("Beatmap") },
                                    new Drawable[]
                                    {
                                        addItemButton = new AddItemButton
                                        {
                                            RelativeSizeAxes = Axes.X,
                                            Height = 40,
                                            Text = "Add item",
                                            Action = () => OpenSongSelection()
                                        },
                                    },
                                    null,
                                    new Drawable[]
                                    {
                                        new MultiplayerPlaylist(Room)
                                        {
                                            RelativeSizeAxes = Axes.Both,
                                            RequestEdit = OpenSongSelection,
                                            SelectedItem = SelectedItem
                                        }
                                    },
                                    new[]
                                    {
                                        UserModsSection = new FillFlowContainer
                                        {
                                            RelativeSizeAxes = Axes.X,
                                            AutoSizeAxes = Axes.Y,
                                            Margin = new MarginPadding { Top = 10 },
                                            Alpha = 0,
                                            Children = new Drawable[]
                                            {
                                                new OverlinedHeader("Extra mods"),
                                                new FillFlowContainer
                                                {
                                                    AutoSizeAxes = Axes.Both,
                                                    Direction = FillDirection.Horizontal,
                                                    Spacing = new Vector2(10, 0),
                                                    Children = new Drawable[]
                                                    {
                                                        new UserModSelectButton
                                                        {
                                                            Anchor = Anchor.CentreLeft,
                                                            Origin = Anchor.CentreLeft,
                                                            Width = 90,
                                                            Text = "Select",
                                                            Action = ShowUserModSelect,
                                                        },
                                                        new ModDisplay
                                                        {
                                                            Anchor = Anchor.CentreLeft,
                                                            Origin = Anchor.CentreLeft,
                                                            Current = UserMods,
                                                            Scale = new Vector2(0.8f),
                                                        },
                                                    }
                                                },
                                            }
                                        }
                                    },
                                    new[]
                                    {
                                        UserStyleSection = new FillFlowContainer
                                        {
                                            RelativeSizeAxes = Axes.X,
                                            AutoSizeAxes = Axes.Y,
                                            Margin = new MarginPadding { Top = 10 },
                                            Alpha = 0,
                                            Children = new Drawable[]
                                            {
                                                new OverlinedHeader("Difficulty"),
                                                UserStyleDisplayContainer = new Container<DrawableRoomPlaylistItem>
                                                {
                                                    RelativeSizeAxes = Axes.X,
                                                    AutoSizeAxes = Axes.Y
                                                }
                                            }
                                        },
                                    },
                                },
                                RowDimensions = new[]
                                {
                                    new Dimension(GridSizeMode.AutoSize),
                                    new Dimension(GridSizeMode.AutoSize),
                                    new Dimension(GridSizeMode.Absolute, 5),
                                    new Dimension(),
                                    new Dimension(GridSizeMode.AutoSize),
                                }
                            },
                            null,
                            new GridContainer
                            {
                                RelativeSizeAxes = Axes.Both,
                                Content = new[]
                                {
                                    new Drawable[] { new OverlinedHeader("Chat") },
                                    new Drawable[] { new MatchChatDisplay(Room) { RelativeSizeAxes = Axes.Both } }
                                },
                                RowDimensions = new[]
                                {
                                    new Dimension(GridSizeMode.AutoSize),
                                    new Dimension(),
                                }
                            },
                        }
                    }
                }
            }
        };

        /// <summary>
        /// Opens the song selection screen to add or edit an item.
        /// </summary>
        /// <param name="itemToEdit">An optional playlist item to edit. If null, a new item will be added instead.</param>
        internal void OpenSongSelection(PlaylistItem? itemToEdit = null)
        {
            if (!this.IsCurrentScreen())
                return;

            this.Push(new MultiplayerMatchSongSelect(Room, itemToEdit));
        }

        protected override void OpenStyleSelection()
        {
            if (!this.IsCurrentScreen() || SelectedItem.Value is not PlaylistItem item)
                return;

            this.Push(new MultiplayerMatchFreestyleSelect(Room, item));
        }

        protected override Drawable CreateFooter() => new MultiplayerMatchFooter
        {
            SelectedItem = SelectedItem
        };

        protected override RoomSettingsOverlay CreateRoomSettingsOverlay(Room room) => new MultiplayerMatchSettingsOverlay(room)
        {
            SelectedItem = SelectedItem
        };

        protected override APIMod[] GetGameplayMods()
        {
            // Using the room's reported status makes the server authoritative.
            return client.LocalUser?.Mods != null ? client.LocalUser.Mods.Concat(SelectedItem.Value!.RequiredMods).ToArray() : base.GetGameplayMods();
        }

        protected override RulesetInfo GetGameplayRuleset()
        {
            // Using the room's reported status makes the server authoritative.
            return client.LocalUser?.RulesetId != null ? Rulesets.GetRuleset(client.LocalUser.RulesetId.Value)! : base.GetGameplayRuleset();
        }

        protected override IBeatmapInfo GetGameplayBeatmap()
        {
            // Using the room's reported status makes the server authoritative.
            return client.LocalUser?.BeatmapId != null ? new APIBeatmap { OnlineID = client.LocalUser.BeatmapId.Value } : base.GetGameplayBeatmap();
        }

        [Resolved(canBeNull: true)]
        private IDialogOverlay? dialogOverlay { get; set; }

        private bool exitConfirmed;

        public override bool OnExiting(ScreenExitEvent e)
        {
            // room has not been created yet or we're offline; exit immediately.
            if (client.Room == null || !IsConnected)
                return base.OnExiting(e);

            if (!exitConfirmed && dialogOverlay != null)
            {
                if (dialogOverlay.CurrentDialog is ConfirmDialog confirmDialog)
                    confirmDialog.PerformOkAction();
                else
                {
                    dialogOverlay.Push(new ConfirmDialog("Are you sure you want to leave this multiplayer match?", () =>
                    {
                        exitConfirmed = true;
                        if (this.IsCurrentScreen())
                            this.Exit();
                    }));
                }

                return true;
            }

            return base.OnExiting(e);
        }

        private ModSettingChangeTracker? modSettingChangeTracker;
        private ScheduledDelegate? debouncedModSettingsUpdate;

        private void onUserModsChanged(ValueChangedEvent<IReadOnlyList<Mod>> mods)
        {
            modSettingChangeTracker?.Dispose();

            if (client.Room == null)
                return;

            client.ChangeUserMods(mods.NewValue).FireAndForget();

            modSettingChangeTracker = new ModSettingChangeTracker(mods.NewValue);
            modSettingChangeTracker.SettingChanged += onModSettingsChanged;
        }

        private void onModSettingsChanged(Mod mod)
        {
            // Debounce changes to mod settings so as to not thrash the network.
            debouncedModSettingsUpdate?.Cancel();
            debouncedModSettingsUpdate = Scheduler.AddDelayed(() =>
            {
                if (client.Room == null)
                    return;

                client.ChangeUserMods(UserMods.Value).FireAndForget();
            }, 500);
        }

        private void updateBeatmapAvailability(ValueChangedEvent<BeatmapAvailability> availability)
        {
            if (client.Room == null)
                return;

            client.ChangeBeatmapAvailability(availability.NewValue).FireAndForget();

            switch (availability.NewValue.State)
            {
                case DownloadState.LocallyAvailable:
                    if (client.LocalUser?.State == MultiplayerUserState.Spectating
                        && (client.Room?.State == MultiplayerRoomState.WaitingForLoad || client.Room?.State == MultiplayerRoomState.Playing))
                    {
                        onLoadRequested();
                    }

                    break;

                case DownloadState.Unknown:
                    // Don't do anything rash in an unknown state.
                    break;

                default:
                    // while this flow is handled server-side, this covers the edge case of the local user being in a ready state and then deleting the current beatmap.
                    if (client.LocalUser?.State == MultiplayerUserState.Ready)
                        client.ChangeState(MultiplayerUserState.Idle);
                    break;
            }
        }

        private void onRoomUpdated()
        {
            // may happen if the client is kicked or otherwise removed from the room.
            if (client.Room == null)
            {
                handleRoomLost();
                return;
            }

            SelectedItem.Value = Room.Playlist.SingleOrDefault(i => i.ID == client.Room.Settings.PlaylistItemId);

            addItemButton.Alpha = localUserCanAddItem ? 1 : 0;

            Activity.Value = new UserActivity.InLobby(Room);
        }

        private bool localUserCanAddItem => client.IsHost || Room.QueueMode != QueueMode.HostOnly;

        private void handleRoomLost() => Schedule(() =>
        {
            Logger.Log($"{this} exiting due to loss of room or connection");

            if (this.IsCurrentScreen())
                this.Exit();
            else
                ValidForResume = false;
        });

        private void onLoadRequested()
        {
            // In the case of spectating, IMultiplayerClient.LoadRequested can be fired while the game is still spectating a previous session.
            // For now, we want to game to switch to the new game so need to request exiting from the play screen.
            if (!ParentScreen.IsCurrentScreen())
            {
                ParentScreen.MakeCurrent();

                Schedule(onLoadRequested);
                return;
            }

            // The beatmap is queried asynchronously when the selected item changes.
            // This is an issue with MultiSpectatorScreen which is effectively in an always "ready" state and receives LoadRequested() callbacks
            // even when it is not truly ready (i.e. the beatmap hasn't been selected by the client yet). For the time being, a simple fix to this is to ignore the callback.
            // Note that spectator will be entered automatically when the client is capable of doing so via beatmap availability callbacks (see: updateBeatmapAvailability()).
            if (client.LocalUser?.State == MultiplayerUserState.Spectating && (SelectedItem.Value == null || Beatmap.IsDefault))
                return;

            if (BeatmapAvailability.Value.State != DownloadState.LocallyAvailable)
                return;

            StartPlay();
        }

        protected override Screen CreateGameplayScreen(PlaylistItem selectedItem)
        {
            Debug.Assert(client.LocalUser != null);
            Debug.Assert(client.Room != null);

            int[] userIds = client.CurrentMatchPlayingUserIds.ToArray();
            MultiplayerRoomUser[] users = userIds.Select(id => client.Room.Users.First(u => u.UserID == id)).ToArray();

            switch (client.LocalUser.State)
            {
                case MultiplayerUserState.Spectating:
                    return new MultiSpectatorScreen(Room, users.Take(PlayerGrid.MAX_PLAYERS).ToArray());

                default:
                    return new MultiplayerPlayerLoader(() => new MultiplayerPlayer(Room, selectedItem, users));
            }
        }

        public void PresentBeatmap(WorkingBeatmap beatmap, RulesetInfo ruleset)
        {
            if (!this.IsCurrentScreen())
                return;

            if (!localUserCanAddItem)
                return;

            // If there's only one playlist item and we are the host, assume we want to change it. Else add a new one.
            PlaylistItem? itemToEdit = client.IsHost && Room.Playlist.Count == 1 ? Room.Playlist.Single() : null;

            OpenSongSelection(itemToEdit);

            // Re-run PresentBeatmap now that we've pushed a song select that can handle it.
            game?.PresentBeatmap(beatmap.BeatmapSetInfo, b => b.ID == beatmap.BeatmapInfo.ID);
        }

        protected override void Dispose(bool isDisposing)
        {
            base.Dispose(isDisposing);

            if (client.IsNotNull())
            {
                client.RoomUpdated -= onRoomUpdated;
                client.LoadRequested -= onLoadRequested;
            }

            modSettingChangeTracker?.Dispose();
        }

        public partial class AddItemButton : PurpleRoundedButton
        {
        }
    }
}