using OpenTK.Mathematics;

namespace VoxelEngine.Rendering;

public sealed class Camera
{
    private static readonly Vector3 WorldUp = Vector3.UnitY;

    public Vector3 Position { get; private set; }
    public float Yaw { get; private set; } = -90f;   // degrees; -90 looks down -Z
    public float Pitch { get; private set; } = 0f;    // degrees
    public float Fov { get; set; } = 60f;             // degrees
    public float AspectRatio { get; set; }

    public Vector3 Front { get; private set; } = -Vector3.UnitZ;
    public Vector3 Right { get; private set; } = Vector3.UnitX;
    public Vector3 Up { get; private set; } = Vector3.UnitY;

    public Camera(Vector3 position, float aspectRatio)
    {
        Position = position;
        AspectRatio = aspectRatio;
        UpdateVectors();
    }

    public void Move(Vector3 delta) => Position += delta;

    public void AddRotation(float yawDelta, float pitchDelta)
    {
        Yaw += yawDelta;
        Pitch = MathHelper.Clamp(Pitch + pitchDelta, -89f, 89f);
        UpdateVectors();
    }

    public Matrix4 GetViewMatrix() => Matrix4.LookAt(Position, Position + Front, Up);

    public Matrix4 GetProjectionMatrix() =>
        Matrix4.CreatePerspectiveFieldOfView(
            MathHelper.DegreesToRadians(Fov), AspectRatio, 0.1f, 100f);

    private void UpdateVectors()
    {
        float yaw = MathHelper.DegreesToRadians(Yaw);
        float pitch = MathHelper.DegreesToRadians(Pitch);

        Front = Vector3.Normalize(new Vector3(
            MathF.Cos(yaw) * MathF.Cos(pitch),
            MathF.Sin(pitch),
            MathF.Sin(yaw) * MathF.Cos(pitch)));

        Right = Vector3.Normalize(Vector3.Cross(Front, WorldUp));
        Up = Vector3.Normalize(Vector3.Cross(Right, Front));
    }
}