Engine-Template/Platforms/Desktop/Engine.Integration.SDL3/SdlWindow.cs

using System;

using Engine.Core;

using SDL3;

namespace Engine.Integration.SDL3;

public class Sdl3Window : Behaviour, IWindow, IUpdate, IDisposable, IEnterUniverse, IExitUniverse
{
    public Event<IWindow, IWindow.StateChangedArguments> OnStateChanged { get; } = new();
    public Event<IWindow, IWindow.FocusStateChangedArguments> OnFocusStateChanged { get; } = new();
    public Event<IWindow, IWindow.ModeChangedArguments> OnModeChanged { get; } = new();
    public Event<IWindow, IWindow.ShowStateChangedArguments> OnShowStateChanged { get; } = new();
    public Event<IWindow, IWindow.ResizeModeChangedArguments> OnResizeModeChanged { get; } = new();

    public Event<IWindow, IWindow.TitleChangedArguments> OnTitleChanged { get; } = new();
    public Event<IWindow, IWindow.TargetFpsChangedArguments> OnTargetFpsChanged { get; } = new();
    public Event<IWindow, IWindow.SizeChangedArguments> OnSizeChanged { get; } = new();
    public Event<IWindow, IWindow.BackgroundColorChangedArguments> OnBackgroundColorChanged { get; } = new();

    private IntPtr window = IntPtr.Zero;
    private IntPtr renderer = IntPtr.Zero;

    private ulong nextRenderTick = 0;
    private ulong renderInterval = (ulong)(1f / 60f * 1000f);

    public uint TargetFps
    {
        get => field;
        set
        {
            if (value == field)
                return;

            uint previousTargetFps = field;
            field = value;
            renderInterval = value == 0 ? 0 : (ulong)(1f / value * 1000f);
            OnTargetFpsChanged.Invoke(this, new(previousTargetFps));
        }
    } = 0;

    public WindowState State
    {
        get => field;
        set
        {
            if (value == field)
                return;

            switch (value)
            {
                case WindowState.Open: OpenWindow(); break;
                case WindowState.Closed: default: CloseWindow(); break;
            }

            WindowState previousState = field;
            field = value;
            OnStateChanged.Invoke(this, new(previousState));
        }
    } = WindowState.Open;

    public WindowFocusState FocusState
    {
        get => field;
        private set
        {
            if (value == field)
                return;

            WindowFocusState previousFocusState = field;
            field = value;
            OnFocusStateChanged.Invoke(this, new(previousFocusState));
        }
    } = WindowFocusState.Unfocused;

    public WindowMode Mode
    {
        get => field;
        set
        {
            if (value == field)
                return;

            if (value is WindowMode.Windowed or WindowMode.BorderlessWindowed)
            {
                SDL.SetWindowFullscreen(window, false);
                SDL.SyncWindow(window);
            }

            if (window != IntPtr.Zero)
                switch (value)
                {
                    case WindowMode.Windowed: SDL.SetWindowBordered(window, true); break;
                    case WindowMode.BorderlessWindowed: SDL.SetWindowBordered(window, false); break;
                    case WindowMode.BorderlessFullscreen: SDL.SetWindowFullscreen(window, true); break;
                    case WindowMode.Fullscreen: SDL.SetWindowFullscreen(window, true); break;
                }

            SDL.SyncWindow(window);

            WindowMode previousMode = field;
            field = value;
            OnModeChanged.Invoke(this, new(previousMode));
        }
    } = WindowMode.Fullscreen;

    public WindowShowState ShowState
    {
        get => field;
        set
        {
            if (value == field)
                return;

            if (window != IntPtr.Zero)
                switch (value)
                {
                    case WindowShowState.Normal: SDL.RestoreWindow(window); break;
                    case WindowShowState.Minimized: SDL.MinimizeWindow(window); break;
                    case WindowShowState.Maximized: SDL.MaximizeWindow(window); break;
                }

            WindowShowState previousShowState = field;
            field = value;
            OnShowStateChanged.Invoke(this, new(previousShowState));
        }
    } = WindowShowState.Normal;

    public WindowResizeMode ResizeMode
    {
        get => field;
        set
        {
            if (value == field)
                return;

            if (window != IntPtr.Zero)
                switch (value)
                {
                    case WindowResizeMode.Fixed:
                        SDL.SetWindowResizable(window, false);
                        break;
                    case WindowResizeMode.Resizable:
                    case WindowResizeMode.AspectLocked:
                        SDL.SetWindowResizable(window, true);
                        break;
                }

            WindowResizeMode previousResizeMode = field;
            field = value;
            OnResizeModeChanged.Invoke(this, new(previousResizeMode));
        }
    } = WindowResizeMode.Fixed;

    public ColorRGB BackgroundColor
    {
        get => field;
        set
        {
            if (value == field)
                return;

            ColorRGB previousBackgroundColor = field;
            field = value;
            OnBackgroundColorChanged.Invoke(this, new(previousBackgroundColor));
        }
    } = new ColorRGB(35, 20, 35);

    public string Title
    {
        get => field;
        set
        {
            if (value == field)
                return;

            string previousTitle = field;
            field = value;
            OnTitleChanged.Invoke(this, new(previousTitle));
        }
    } = nameof(Sdl3Window);

    public Vector2DInt Size
    {
        get => field;
        set
        {
            if (value == field)
                return;

            if (value.Max(Vector2DInt.One) == Vector2DInt.One)
                throw new Exception($"Window size can not be smaller than 1x1");

            Vector2DInt previousSize = field;
            field = value;
            OnSizeChanged.Invoke(this, new(previousSize));
        }
    } = Vector2DInt.Zero;

    public void Update()
    {
        while (SDL.PollEvent(out SDL.Event e))
            ProcessInternalEvents((SDL.EventType)e.Type);

        ulong currentTick = SDL.GetTicks();

        if (currentTick >= nextRenderTick)
        {
            nextRenderTick = currentTick + renderInterval;

            SDL.SetRenderDrawColor(renderer, BackgroundColor.R, BackgroundColor.G, BackgroundColor.B, 255);
            SDL.RenderClear(renderer);

            // TODO Render

            SDL.RenderPresent(renderer);
        }
    }

    public void ExitUniverse(IUniverse universe) => CloseWindow();
    public void EnterUniverse(IUniverse universe)
    {
        if (State == WindowState.Open)
            OpenWindow();
    }

    private void OpenWindow()
    {
        if (!UniverseObject.IsInUniverse)
            throw new Exception($"{UniverseObject.Name} is not in a universe. The window can not be opened.");

        SDL.WindowFlags windowFlags = 0;
        switch (Mode)
        {
            case WindowMode.Windowed: break;
            case WindowMode.Fullscreen: windowFlags |= SDL.WindowFlags.Fullscreen; break;
            case WindowMode.BorderlessWindowed: windowFlags |= SDL.WindowFlags.Borderless; break;
            case WindowMode.BorderlessFullscreen: windowFlags |= SDL.WindowFlags.Fullscreen | SDL.WindowFlags.Borderless; break;
        }

        if (!SDL.Init(SDL.InitFlags.Video))
            throw new Exception($"SDL_Init failed: {SDL.GetError()}");

        if (!SDL.CreateWindowAndRenderer(Title, Size.X, Size.Y, windowFlags, out window, out renderer))
            throw new Exception($"SDL_CreateWindowAndRenderer failed: {SDL.GetError()}");
    }

    private void CloseWindow()
    {
        if (renderer != IntPtr.Zero) SDL.DestroyRenderer(renderer);
        if (window != IntPtr.Zero) SDL.DestroyWindow(window);

        renderer = IntPtr.Zero;
        window = IntPtr.Zero;
    }

    private void ProcessInternalEvents(SDL.EventType eventType)
    {
        switch (eventType)
        {
            case SDL.EventType.WindowRestored: ShowState = WindowShowState.Normal; break;
            case SDL.EventType.WindowMaximized: ShowState = WindowShowState.Maximized; break;
            case SDL.EventType.WindowMinimized: ShowState = WindowShowState.Minimized; break;

            case SDL.EventType.WindowFocusGained: FocusState = WindowFocusState.Focused; break;
            case SDL.EventType.WindowFocusLost: FocusState = WindowFocusState.Unfocused; break;

            case SDL.EventType.Quit:
                State = WindowState.Closed;
                BehaviourController.RemoveBehaviour(this);
                break;
        }
    }

    public void Dispose()
    {
        CloseWindow();

        // SDL.Quit(); // TODO This possibly prevents multi window

        GC.SuppressFinalize(this);
    }
}