using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

using Engine.Core;

namespace Engine.Integration.MonoGame;

public class MonoGameCamera2D : Behaviour, ICamera2D, IFirstFrameUpdate, ILastFrameUpdate, IPreDraw
{
    public Event<MonoGameCamera2D> OnViewMatrixChanged { get; } = new();
    public Event<MonoGameCamera2D> OnProjectionMatrixChanged { get; } = new();
    public Event<MonoGameCamera2D> OnViewportChanged { get; } = new();
    public Event<MonoGameCamera2D> OnZoomChanged { get; } = new();

    public GraphicsDeviceManager Graphics { get; private set; } = null!;
    public ITransform2D Transform { get; private set; } = null!;

    public Matrix4x4 ProjectionMatrix
    {
        get;
        private set
        {
            if (field == value)
                return;

            field = value;
            OnProjectionMatrixChanged.Invoke(this);
        }
    } = Matrix4x4.Identity;

    public Matrix4x4 ViewMatrix
    {
        get;
        private set
        {
            if (field == value)
                return;

            field = value;
            OnViewMatrixChanged.Invoke(this);
        }
    } = Matrix4x4.Identity;

    public Viewport Viewport
    {
        get;
        set
        {
            if (field.Equals(value))
                return;

            field = value;
            OnViewportChanged.Invoke(this);
        }
    } = default;

    public float Zoom
    {
        get;
        set
        {
            float newValue = Math.Max(0.1f, value);

            if (field == newValue)
                return;

            field = newValue;
            OnZoomChanged.Invoke(this);
        }
    } = 1f;

    // TODO This causes delay since OnPreDraw calls assuming this is called in in Update 
    public Vector2D ScreenToWorldPosition(Vector2D screenPosition)
    {
        float x = 2f * screenPosition.X / Viewport.Width - 1f;
        float y = 1f - 2f * screenPosition.Y / Viewport.Height;
        Vector4D normalizedCoordinates = new(x, y, 0f, 1f);

        Matrix4x4 invertedViewProjectionMatrix = (ProjectionMatrix * ViewMatrix).Inverse;

        Vector4D worldPosition = invertedViewProjectionMatrix * normalizedCoordinates;

        if (worldPosition.W != 0f)
            worldPosition /= worldPosition.W;

        return new(worldPosition.X, worldPosition.Y);
    }

    public Vector2D WorldToScreenPosition(Vector2D worldPosition)
    {
        Vector4D worldPosition4D = new(worldPosition.X, worldPosition.Y, 0f, 1f);

        Matrix4x4 viewProjection = ProjectionMatrix * ViewMatrix;
        Vector4D clip = viewProjection * worldPosition4D;

        if (clip.W != 0f)
            clip /= clip.W;

        float screenX = (clip.X + 1f) * .5f * Viewport.Width;
        float screenY = (1f - clip.Y) * .5f * Viewport.Height;

        return new(screenX, screenY);
    }

    public void LastActiveFrame() => Transform = null!;
    public void FirstActiveFrame()
    {
        Graphics = BehaviourController.UniverseObject.Universe.FindRequiredBehaviour<MonoGameWindowContainer>().Window.Graphics;
        Viewport = Graphics.GraphicsDevice.Viewport;
        Transform = BehaviourController.GetRequiredBehaviour<ITransform2D>();
    }

    public void PreDraw()
    {
        ProjectionMatrix = Matrix4x4.CreateOrthographicViewCentered(Viewport.Width, Viewport.Height);
        ViewMatrix =
            Matrix4x4.CreateTranslation(new Vector3D(-Transform.Position.X, -Transform.Position.Y, 0f))
                .ApplyRotationZ(Transform.Rotation * Math.DegreeToRadian)
                .ApplyScale(Transform.Scale.X.Max(Transform.Scale.Y))
                .ApplyScale(Zoom);
    }
}