using UnityEngine;

[RequireComponent(typeof (Rigidbody))]

public class RigidbodyPlayer : MonoBehaviour {

    public float speed = 10.0f;
    public float gravity = 10.0f;
    public float maxVelocityChange = 10.0f;
    public bool canJump = true;
    public float jumpHeight = 2.0f;
    private bool grounded = false;

    Rigidbody phisicBody;



    void Awake()
    {
        phisicBody = GetComponent<Rigidbody>();

        phisicBody.freezeRotation = true;
        phisicBody.useGravity = false;
    }

    void FixedUpdate()
    {
        if (grounded)
        {
            // Calculate how fast we should be moving
            Vector3 targetVelocity = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
            targetVelocity = transform.TransformDirection(targetVelocity);
            targetVelocity *= speed;

            // Apply a force that attempts to reach our target velocity
            Vector3 velocity = phisicBody.velocity;
            Vector3 velocityChange = (targetVelocity - velocity);
            velocityChange.x = Mathf.Clamp(velocityChange.x, -maxVelocityChange, maxVelocityChange);
            velocityChange.z = Mathf.Clamp(velocityChange.z, -maxVelocityChange, maxVelocityChange);
            velocityChange.y = 0;
            phisicBody.AddForce(velocityChange, ForceMode.VelocityChange);

            // Jump
            if (canJump && Input.GetButton("Jump"))
            {
                phisicBody.velocity = new Vector3(velocity.x, CalculateJumpVerticalSpeed(), velocity.z);
            }
        }

        // We apply gravity manually for more tuning control
        phisicBody.AddForce(new Vector3(0, -gravity * phisicBody.mass, 0));

        grounded = false;
    }

    void OnCollisionStay()
    {
        grounded = true;
    }

    float CalculateJumpVerticalSpeed()
    {
        // From the jump height and gravity we deduce the upwards speed
        // for the character to reach at the apex.
        return Mathf.Sqrt(2 * jumpHeight * gravity);
    }
}