global using Sys = Cosmos.Kernel.System;
using System.Diagnostics;
using System.Drawing;
using System.Runtime;
using System.Runtime.InteropServices;
using Cosmos.Build.API.Attributes;
using Cosmos.Kernel.Core;
using Cosmos.Kernel.System.Graphics;
using RemSox.Processing;
using RemSox.Processing.IPC;
using RemSox.UI.GUI.CLI;
using RemSox.UI.GUI.CLI.Commands;
using RemSox.UI.GUI.Rendering;
using RemSox.UI.GUI.Windows;

namespace RemSox;

/// <summary>
/// Main kernel class - inherits from Cosmos.Kernel.System.Kernel.
/// </summary>
public class Kernel : Sys.Kernel
{
    private static Window? activeDragWindow = null;

    private static Point lastPointerPosition = Point.Empty;

    private static bool wasLeftButtonDown = false;

    private static int mousePollCounter = 0;

    protected override void BeforeRun()
    {
        Console.WriteLine("Cosmos booted successfully!");
        Console.WriteLine("Type a command to get it executed.");

        WindowManager.AddRenderSource(new CanvasRenderSource());

        CommandManager.RegisterCommands(new ICommand[]
        {
            new HelpCommand(),
            new ClearCommand(),
            new HaltCommand(),
            new SpawnTestProcessCommand(),
            new ListProcessesCommand(),
            new StopProcessCommand()
        });

        Sys.Mouse.MouseManager.Initialize();
        Sys.Keyboard.KeyboardManager.Initialize();

        ProcessManager.SpawnProcess<TestProcess>();

        Console.WriteLine(CosmosFeatures.MouseEnabled);
        Console.WriteLine(CosmosFeatures.KeyboardEnabled);
        Console.WriteLine($"Canvas size: {FullScreenCanvas.GetFullScreenCanvas().Mode.Width}x{FullScreenCanvas.GetFullScreenCanvas().Mode.Height}");
    }

    protected override void Run()
    {
        WindowInputTick();
        return;

        Console.Write("> ");

        string? input = Console.ReadLine();

        if (string.IsNullOrEmpty(input))
        {
            return;
        }

        if (CommandManager.TryExecute(input))
        {
            return;
        }

        Console.WriteLine($"\"{input}\" is not a command");
    }

    private static void WindowInputTick()
    {
        mousePollCounter++;
        Sys.Mouse.MouseManager.Poll();

        Point pointerPosition = new(Sys.Mouse.MouseManager.X, Sys.Mouse.MouseManager.Y);
        bool leftButtonDown = Sys.Mouse.MouseManager.LeftButton;

        if (leftButtonDown && !wasLeftButtonDown)
        {
            activeDragWindow = TryBeginDrag(pointerPosition);
        }
        else if (leftButtonDown && activeDragWindow is not null)
        {
            activeDragWindow.DragTo(pointerPosition);
        }
        else if (!leftButtonDown && activeDragWindow is not null)
        {
            activeDragWindow.EndDrag();
            activeDragWindow = null;
        }

        wasLeftButtonDown = leftButtonDown;

        // Render all canvases and cursor every tick, or if changed
        Canvas canvas = FullScreenCanvas.GetFullScreenCanvas();
        CanvasRenderSource.CompositeAndDisplay(canvas, pointerPosition);

        lastPointerPosition = pointerPosition;
    }

    private static Window? TryBeginDrag(Point pointerPosition)
    {
        foreach (Processing.Process process in ProcessManager.GetAllProcesses())
        {
            List<Window> windows = WindowManager.GetWindowsForProcess(process);

            for (int index = windows.Count - 1; index >= 0; index--)
            {
                Window window = windows[index];

                if (window.TryBeginDrag(pointerPosition))
                {
                    return window;
                }
            }
        }

        return null;
    }
}

public class TestProcess() : Processing.Process("Test Process")
{
    internal override void Run()
    {
        Window window = WindowManager.CreateWindow(this, "Test Window", Point.Empty, new Size(200, 150));
        window.AutoFlush = true;

        var circle = window.CreateUIElement<UI.GUI.UIEelements.Shapes.Circle>(rect =>
        {
            rect.Position = new Point(10, 10);
            rect.Radius = 50;
            rect.Color = Color.Red;
        });

        circle.Radius = 40;

        SendMessageToAllProcesses(new TestMessage { SenderProcessId = Id });

        while (!StopRequested)
        {
            Thread.Sleep(1000);
        }
    }

    internal override void HandleInterProcessMessage(Message message)
    {
        if (message is TestMessage testMessage && message.SenderProcessId != Id)
        {
            Console.WriteLine($"Received message in {Name} (ID: {Id}): {testMessage.MessageText}");
        }
    }
}

internal class TestMessage : Message
{
    public string MessageText { get; set; } = "Hello from TestMessage!";
}

public static unsafe partial class StartupCodeHelpers
{
    [RuntimeExport("fmod")]
    public static double fmod(double x, double y)
    {
        if (Math.Abs(y) < double.Epsilon)
            return double.NaN;

        double q = Math.Truncate(x / y);
        return x - q * y;
    }
}