using UnityEngine;
using System.Collections;

public class RaycastWheelSimple : MonoBehaviour {

    // Simple Vehicle Raycast wheel

    public Transform graphic;

    public float mass = 1.0f;
    public float radius = 1.0f;
    public float maxSuspension = 0.2f;
    public float spring = 100.0f;
    public float damper = 0.0f;

    public float wheelAngle = 0f;

    private float circumference;

    private float contactPatchArea;
    private Rigidbody parent;
    private bool grounded = false;

    public bool IsGrounded
    {
        get
        {
            return grounded;
        }
    }

    void  Awake ()
    {
        circumference = (radius * 2) * Mathf.PI;
        parent = transform.root.GetComponent<Rigidbody>();
    }

    void  FixedUpdate ()
    {
        GetGround();
    }

    void  GetGround (){
        grounded = false;
        Vector3 downwards = transform.TransformDirection (-Vector3.up);
        RaycastHit hit;

        // down = local downwards direction
        Vector3 down = transform.TransformDirection(Vector3.down);

        if (Physics.Raycast(transform.position, downwards, out hit, radius + maxSuspension)) {

            grounded = true;
            // the velocity at point of contact
            Vector3 velocityAtTouch = parent.GetPointVelocity(hit.point);

            // calculate spring compression
            // difference in positions divided by total suspension range
            float compression = hit.distance / (maxSuspension + radius);
            compression = -compression + 1;

            // final force
            Vector3 force = -downwards * compression * spring;
            // velocity at point of contact transformed into local space

            Vector3 t = transform.InverseTransformDirection(velocityAtTouch);

            // local x and z directions = 0
            t.z = t.x = 0;

            // back to world space * -damping
            Vector3 damping = transform.TransformDirection(t) * -damper;
            Vector3 finalForce = force + damping;

            // VERY simple turning - force rigidbody in direction of wheel
            t = parent.transform.InverseTransformDirection(velocityAtTouch);
            t.y = 0;
            t.z = 0;

            t = transform.TransformDirection(t);

            parent.AddForceAtPosition(finalForce + (t), hit.point);

            if (graphic) graphic.position = transform.position + (down * (hit.distance - radius));

        }
        else
        {
            if (graphic) graphic.position = transform.position + (down * maxSuspension);
        }

        float speed = parent.velocity.magnitude;

        if (graphic)
        {
            //graphic.transform.localEulerAngles = new Vector3 (graphic.transform.localEulerAngles.x, wheelAngle, graphic.transform.localEulerAngles.z);
            //graphic.transform.Rotate (360 * (speed / circumference) * Time.fixedDeltaTime, 0, 0);
        }
    }

    void  OnDrawGizmosSelected ()
    {
        Gizmos.color = new Color(0,1,0,1);
        Vector3 direction = transform.TransformDirection (-Vector3.up) * (this.radius);
        Gizmos.DrawRay(transform.position,direction);

        Gizmos.color = new Color(0,0,1,1);
        direction = transform.TransformDirection (-Vector3.up) * (this.maxSuspension);
        Gizmos.DrawRay(new Vector3(transform.position.x,transform.position.y - radius,transform.position.z),direction);
    }
}