// 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.Linq;
using System.Threading.Tasks;
using osu.Framework.Allocation;
using osu.Framework.Configuration;
using osu.Framework.Logging;
using osu.Game.Beatmaps;
using osu.Game.Online;
using osu.Game.Online.API;
using osu.Game.Online.API.Requests;
using osu.Game.Online.Multiplayer;
using osu.Game.Rulesets;
using osu.Game.Screens.Multi.Lounge.Components;

namespace osu.Game.Screens.Multi
{
    public class RoomManager : PollingComponent, IRoomManager
    {
        public event Action RoomsUpdated;

        private readonly BindableList<Room> rooms = new BindableList<Room>();
        public IBindableList<Room> Rooms => rooms;

        private Room joinedRoom;

        [Resolved]
        private Bindable<FilterCriteria> currentFilter { get; set; }

        [Resolved]
        private APIAccess api { get; set; }

        [Resolved]
        private RulesetStore rulesets { get; set; }

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

        [BackgroundDependencyLoader]
        private void load()
        {
            currentFilter.BindValueChanged(_ =>
            {
                if (IsLoaded)
                    PollImmediately();
            });
        }

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

        public void CreateRoom(Room room, Action<Room> onSuccess = null, Action<string> onError = null)
        {
            room.Host.Value = api.LocalUser;

            var req = new CreateRoomRequest(room);

            req.Success += result =>
            {
                joinedRoom = room;

                update(room, result);
                addRoom(room);

                RoomsUpdated?.Invoke();
                onSuccess?.Invoke(room);
            };

            req.Failure += exception =>
            {
                if (req.Result != null)
                    onError?.Invoke(req.Result.Error);
                else
                    Logger.Log($"Failed to create the room: {exception}", level: LogLevel.Important);
            };

            api.Queue(req);
        }

        private JoinRoomRequest currentJoinRoomRequest;

        public void JoinRoom(Room room, Action<Room> onSuccess = null, Action<string> onError = null)
        {
            currentJoinRoomRequest?.Cancel();
            currentJoinRoomRequest = null;

            currentJoinRoomRequest = new JoinRoomRequest(room, api.LocalUser.Value);
            currentJoinRoomRequest.Success += () =>
            {
                joinedRoom = room;
                onSuccess?.Invoke(room);
            };

            currentJoinRoomRequest.Failure += exception =>
            {
                Logger.Log($"Failed to join room: {exception}", level: LogLevel.Important);
                onError?.Invoke(exception.ToString());
            };

            api.Queue(currentJoinRoomRequest);
        }

        public void PartRoom()
        {
            if (joinedRoom == null)
                return;

            api.Queue(new PartRoomRequest(joinedRoom, api.LocalUser.Value));
            joinedRoom = null;
        }

        private GetRoomsRequest pollReq;

        protected override Task Poll()
        {
            if (!api.IsLoggedIn)
                return base.Poll();

            var tcs = new TaskCompletionSource<bool>();

            pollReq?.Cancel();
            pollReq = new GetRoomsRequest(currentFilter.Value.PrimaryFilter);

            pollReq.Success += result =>
            {
                // Remove past matches
                foreach (var r in rooms.ToList())
                {
                    if (result.All(e => e.RoomID.Value != r.RoomID.Value))
                        rooms.Remove(r);
                }

                for (int i = 0; i < result.Count; i++)
                {
                    var r = result[i];
                    r.Position.Value = i;

                    update(r, r);
                    addRoom(r);
                }

                RoomsUpdated?.Invoke();
                tcs.SetResult(true);
            };

            pollReq.Failure += _ => tcs.SetResult(false);

            api.Queue(pollReq);

            return tcs.Task;
        }

        /// <summary>
        /// Updates a local <see cref="Room"/> with a remote copy.
        /// </summary>
        /// <param name="local">The local <see cref="Room"/> to update.</param>
        /// <param name="remote">The remote <see cref="Room"/> to update with.</param>
        private void update(Room local, Room remote)
        {
            foreach (var pi in remote.Playlist)
                pi.MapObjects(beatmaps, rulesets);

            local.CopyFrom(remote);
        }

        /// <summary>
        /// Adds a <see cref="Room"/> to the list of available rooms.
        /// </summary>
        /// <param name="room">The <see cref="Room"/> to add.<</param>
        private void addRoom(Room room)
        {
            var existing = rooms.FirstOrDefault(e => e.RoomID.Value == room.RoomID.Value);
            if (existing == null)
                rooms.Add(room);
            else
                existing.CopyFrom(room);
        }
    }
}