#nullable enable

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
using Cysharp.Threading.Tasks;
using Godot;
using ShrinkEventBus;
using ShrinkDataSaver;
using ShrinkApp;
using ShrinkNetwork;
using ShrinkSDK.Runtime;

namespace ShrinkSDK.Godot;

public partial class ShrinkGodotHost : Node, IShrinkMainThreadDispatcher,
    IShrinkLogger, IShrinkClock, IShrinkPathProvider, IShrinkScreenshotProvider,
    IShrinkApplicationLifecycle
{
    private readonly ConcurrentQueue<Action> _dispatchQueue = new();
    private readonly Dictionary<ShrinkNetworkService, ShrinkNetworkDispatchQueue> _networkServices = new();
    private int _mainThreadId;
    private bool _networkPumpRunning;
    private ShrinkAppRuntime? _appRuntime;

    public event Action? Paused;
    public event Action? Resumed;
    public event Action? Exiting;

    [Export] public int DispatchBudgetPerFrame { get; set; } = 256;
    [Export] public int NetworkDispatchBudgetPerFrame { get; set; } = 256;

    public bool IsMainThread => Thread.CurrentThread.ManagedThreadId == _mainThreadId;
    public DateTimeOffset UtcNow => DateTimeOffset.UtcNow;
    public double UnscaledTimeSeconds => Time.GetTicksMsec() / 1000d;
    public string PersistentDataPath => ProjectSettings.GlobalizePath("user://");
    public string TemporaryDataPath => OS.GetCacheDir();

    public override void _Ready()
    {
        _mainThreadId = Thread.CurrentThread.ManagedThreadId;
        ShrinkRuntimeServices.Configure(this, this, this, this, this, this);
        ShrinkEventBusRuntime.ConfigureMainThreadDispatcher(this);
        ShrinkDataSaverPlatform.Configure(this, this, this, this);
        SetProcess(true);
    }

    public override void _Process(double delta)
    {
        var budget = Math.Max(1, DispatchBudgetPerFrame);
        while (budget-- > 0 && _dispatchQueue.TryDequeue(out var action))
            action();
        PumpNetworkAsync().Forget();
    }

    public override void _Notification(int what)
    {
        switch ((long)what)
        {
            case NotificationApplicationPaused:
            case NotificationApplicationFocusOut:
                Paused?.Invoke();
                break;
            case NotificationApplicationResumed:
            case NotificationApplicationFocusIn:
                Resumed?.Invoke();
                break;
            case NotificationWMCloseRequest:
            case NotificationPredelete:
                Exiting?.Invoke();
                break;
        }
    }

    public async UniTask<ShrinkAppRuntime> StartAppAsync(ShrinkAppSettings? settings = null, ShrinkAppServices? services = null)
    {
        if (_appRuntime?.IsRunning == true) return _appRuntime;
        _appRuntime = new ShrinkAppRuntime(this, settings, services);
        await _appRuntime.StartAsync();
        return _appRuntime;
    }

    public async UniTask ShutdownAppAsync()
    {
        if (_appRuntime == null) return;
        await _appRuntime.ShutdownAsync();
        _appRuntime = null;
    }

    public bool TryPost(Action action)
    {
        if (action == null) throw new ArgumentNullException(nameof(action));
        _dispatchQueue.Enqueue(action);
        return true;
    }

    public void AddNetworkService(ShrinkNetworkService service)
    {
        if (service == null) throw new ArgumentNullException(nameof(service));
        if (_networkServices.ContainsKey(service)) return;
        var queue = new ShrinkNetworkDispatchQueue(Math.Max(1, NetworkDispatchBudgetPerFrame * 4));
        service.DispatchScheduler = queue;
        _networkServices.Add(service, queue);
    }

    public bool RemoveNetworkService(ShrinkNetworkService service)
    {
        if (!_networkServices.Remove(service, out var queue)) return false;
        service.DispatchScheduler = ShrinkNetworkDispatchSchedulers.Inline;
        queue.Dispose();
        return true;
    }

    public static ShrinkCodeGenWovenAttribute RequireWoven(Assembly assembly)
    {
        if (assembly == null) throw new ArgumentNullException(nameof(assembly));
        return assembly.GetCustomAttribute<ShrinkCodeGenWovenAttribute>() ??
               throw new InvalidOperationException(
                   $"Assembly '{assembly.GetName().Name}' was not woven by ShrinkSDK.CodeGen. Ensure the package is installed and ShrinkCodeGenEnabled is not false.");
    }

    public void Log(ShrinkLogLevel level, string message, Exception? exception = null)
    {
        var text = exception == null ? message : $"{message}{System.Environment.NewLine}{exception}";
        if (level >= ShrinkLogLevel.Error) GD.PushError(text);
        else if (level >= ShrinkLogLevel.Warning) GD.PushWarning(text);
        else GD.Print(text);
    }

    public ValueTask<byte[]> CapturePngAsync(CancellationToken cancellationToken = default)
    {
        cancellationToken.ThrowIfCancellationRequested();
        var image = GetViewport().GetTexture().GetImage();
        return ValueTask.FromResult(image.SavePngToBuffer());
    }

    private async UniTaskVoid PumpNetworkAsync()
    {
        if (_networkPumpRunning) return;
        _networkPumpRunning = true;
        try
        {
            foreach (var queue in _networkServices.Values)
                await queue.PumpAsync(Math.Max(1, NetworkDispatchBudgetPerFrame));
        }
        finally
        {
            _networkPumpRunning = false;
        }
    }
}