using System.Numerics;

namespace DaggerFramework.Rendering
{
    /// <summary>
    /// An abstract class representing the graphics renderer.
    /// </summary>
    public abstract class Renderer
    {
        // INIT
        /// <summary>
        /// Creates the renderer window and initializes internal resources.
        /// </summary>
        /// <param name="windowSettings">Settings for the rendering window.</param>
        /// <param name="renderSettings">Rendering settings.</param>
        public abstract void CreateAndInitialize(WindowSettings windowSettings, RendererSettings renderSettings);
        /// <summary>
        /// Initializes internal resources. Should be called before other methods.
        /// </summary>
        /// <param name="settings">Rendering settings.</param>
        public abstract void Initialize(RendererSettings settings);

        // UTIL
        /// <summary>
        /// Indicates if the renderer will render the next frame.
        /// </summary>
        public abstract bool ShouldRun { get; }
        /// <summary>
        /// Target frames per second for rendering.
        /// </summary>
        public abstract int TargetFps { get; set; }
        public abstract bool VSync { get; set; }
        public double FrameTime => GetFrameTime();

        // WINDOW
        /// <summary>
        /// The size of the render window.
        /// </summary>
        public abstract Vector2 WindowSize { get; }

        public abstract string WindowTitle { get; set; }

        /// <summary>
        /// Active monitor's size.
        /// </summary>
        public abstract Vector2 MonitorSize { get; }

        /// <summary>
        /// Creates a window.
        /// </summary>
        /// <param name="windowSettings">Window settings to use to create the window.</param>
        public abstract void CreateWindow(WindowSettings windowSettings);
        protected abstract void SetWindowTitle(string title);
        protected abstract void SetWindowVSync(bool value);
        protected abstract void SetTargetFps(int fps);
        protected abstract double GetFrameTime();
        protected abstract int GetMonitorWidth(int monitorId);
        protected abstract int GetMonitorHeight(int monitorId);
        protected abstract int GetCurrentMonitor();
        protected abstract bool WindowShouldClose();
        public abstract void Shutdown();

        // DRAWING
        /// <summary>
        /// Prepares the renderer for drawing the next frame.
        /// </summary>
        public abstract void BeginFrame();
        /// <summary>
        /// Ends rendering of the frame.
        /// </summary>
        public abstract void EndFrame();

        public abstract void BeginCamera2d(Vector2 offset, Vector2 target, float rotation, float zoom);
        public abstract void EndCamera2d();

        /// <summary>
        /// Clears the render canvas and sets a background color.
        /// </summary>
        /// <param name="color">Background color.</param>
        public abstract void ClearBackground(Color color);

        /// <summary>
        /// Loads the texture onto the GPU for later use in DrawTexture or other Texture related methods.
        /// </summary>
        /// <param name="texture">Texture to load.</param>
        /// <returns>A texture handler on the GPU.</returns>
        public abstract int LoadTexture(Texture2d texture);

        /// <summary>
        /// Sets transforms for the next draw operation.
        /// </summary>
        /// <param name="position">Global transform position.</param>
        /// <param name="offset">Local offset point around which shapes will rotate.</param> 
        /// <param name="rotation">Rotation.</param>
        public abstract void SetTransform(Vector2 position, Vector2 offset, float rotation = 0.0f);
        /// <summary>
        /// Sets the transform for the next draw operation.
        /// </summary>
        /// <param name="transform">Transform matrix.</param>
        public abstract void SetTransform(Matrix4x4 transform);
        /// <summary>
        /// Draws a filled circle.
        /// </summary>
        /// <param name="radius">Radius of a circle.</param>
        /// <param name="color">Fill color.</param>
        public abstract void DrawCircle(float radius, Color color);
        /// <summary>
        /// Draws a filled rectangle.
        /// </summary>
        /// <param name="size">Rectangle size.</param>
        /// <param name="color">Fill color.</param>
        public abstract void DrawRectangle(Vector2 size, Color color);
        /// <summary>
        /// Draws a debug text with a default font.
        /// </summary>
        /// <param name="position"></param>
        /// <param name="text"></param>
        /// <param name="fontSize"></param>
        /// <param name="color"></param>
        public abstract void DrawDebugText(string text, int fontSize, Color color);
        /// <summary>
        /// Draws text using a signed distance field font atlas.
        /// </summary>
        /// <param name="text">Text to draw.</param>
        /// <param name="fontSize">Size of the font.</param>
        /// <param name="color">Color of the text.</param>
        public abstract void DrawSdfText(string text, int fontSize, Color color);

        public abstract void DrawText(Font font, string text, Color color);

        /// <summary>
        /// Draws the texture.
        /// </summary>
        /// <param name="id">Texture handle.</param>
        /// <param name="tint">Texture tint.</param>
        public abstract void DrawTexture(int id, Color tint);
    }

    public enum Msaa
    {
        None,
        Msaa2x,
        Msaa4x,
        Msaa8x
    }
    public struct RendererSettings
    {
        public Msaa Msaa;
        public bool UseVSync;
        public bool Fullscreen;
        public int TargetFps = 60;

        public RendererSettings() { }

        public static RendererSettings Default => new RendererSettings()
        {
            UseVSync = true,
            TargetFps = 60
        };
    }

    public struct WindowSettings
    {
        public string Title;
        public Vector2 Size = new Vector2(640, 480);
        public bool Resizable { get; set; }

        public WindowSettings(string title, Vector2 size)
        {
            Title = title;
            Size = size;
        }
    }
}