using Sandbox;
using System;

namespace VeloX;


[GameResource( "Wheel Friction", "tire", "Wheel Friction", Category = "VeloX", Icon = "radio_button_checked" )]
public class TirePreset : GameResource
{

	[Property] public Pacejka Pacejka { get; set; }

	public float RollResistanceLin { get; set; } = 1E-3f;
	public float RollResistanceQuad { get; set; } = 1E-6f;

	public float GetRollingResistance( float velocity, float resistance_factor )
	{   // surface influence on rolling resistance
		float resistance = resistance_factor * RollResistanceLin;

		// heat due to tire deformation increases rolling resistance
		// approximate by quadratic function
		resistance += velocity * velocity * RollResistanceQuad;

		return resistance;
	}

	public static void ComputeSlip( float lon_velocity, float lat_velocity, float rot_velocity, float wheel_radius, out float slip_ratio, out float slip_angle )
	{
		var abs_lon = Math.Max( MathF.Abs( lon_velocity ), 1e-3f );

		slip_ratio = lon_velocity - rot_velocity * wheel_radius;

		if ( abs_lon >= 0.005f )
			slip_ratio /= abs_lon;
		else
			slip_ratio *= abs_lon;

		if ( abs_lon >= 0.5f )
			slip_angle = MathF.Atan2( -lat_velocity, abs_lon ).RadianToDegree() / 50f;
		else
			slip_angle = -lat_velocity * (0.01f / Time.Delta);

		slip_ratio = Math.Clamp( slip_ratio, -1, 1 );
		slip_angle = Math.Clamp( slip_angle, -1, 1 );

	}

	/// approximate asin(x) = x + x^3/6 for +-18 deg range
	public static float ComputeCamberAngle( float sin_camber )
	{
		float sc = Math.Clamp( sin_camber, -0.3f, 0.3f );
		return ((1 / 6.0f) * (sc * sc) + 1) * sc;
	}

	public static float ComputeCamberVelocity( float sa, float vx )
	{
		float tansa = (1 / 3.0f * (sa * sa) + 1) * sa;
		return tansa * vx;
	}
}