using System.Threading;
using Cysharp.Threading.Tasks;
using R3;
using RebootKit.Engine.Foundation;
using RebootKit.Engine.Main;
using RebootKit.Engine.Services.Simulation;

namespace RebootKit.Engine.Services.GameMode {
    public class GameModesService : IService {
        static readonly Logger s_logger = new(nameof(GameModesService));

        [Inject] DIContext m_DIContext;

        GameModeAsset m_GameModeAsset;

        readonly CancellationTokenSource m_DestroyCancellationTokenSource = new();
        DisposableBag m_ActiveGameModeDisposableBag;
        readonly ReactiveProperty<IGameMode> m_ActiveGameMode = new(null);
        
        public ReadOnlyReactiveProperty<IGameMode> ActiveGameMode => m_ActiveGameMode;

        public void Dispose() {
            m_DestroyCancellationTokenSource.Cancel();
            m_DestroyCancellationTokenSource.Dispose();
            m_ActiveGameModeDisposableBag.Dispose();
        }

        public void Start(GameModeAsset asset, WorldConfig worldConfig) {
            if (m_ActiveGameMode.Value != null) {
                s_logger.Warning("Game is already running");
                return;
            }

            Stop();

            m_ActiveGameModeDisposableBag = new DisposableBag();
            m_ActiveGameMode.Value = asset.Create(m_DIContext);
            m_ActiveGameModeDisposableBag.Add(m_ActiveGameMode);
            
            InitializeGameModeAsync(worldConfig, CancellationToken.None).Forget();
        }

        async UniTask InitializeGameModeAsync(WorldConfig worldConfig, CancellationToken cancellationToken) {
            await m_ActiveGameMode.Value.OnInit(m_DestroyCancellationTokenSource.Token);

            await RR.World.LoadAsync(worldConfig, cancellationToken);
            m_ActiveGameMode.Value.OnStart();
            Observable.EveryUpdate().Subscribe(_ => { m_ActiveGameMode.Value?.OnTick(); }).AddTo(ref m_ActiveGameModeDisposableBag);
        }

        public void Stop() {
            if (m_ActiveGameMode.Value == null) {
                return;
            }

            m_ActiveGameMode.Value.OnStop();
            m_ActiveGameMode.Value = null;

            m_ActiveGameModeDisposableBag.Dispose();
        }
    }
}