using UnityEngine;
using System.Collections;

public class CarController : MonoBehaviour {
    public WheelCollider Wheel_FL;
    public WheelCollider Wheel_FR;
    public WheelCollider Wheel_RL;
    public WheelCollider Wheel_RR;

    public float[] GearRatio;
    public int CurrentGear;

    public float EngineTorque = 600.0f;

    public float MaxEngineRPM = 3000.0f;
    public float MinEngineRPM = 1000.0f;

    public float SteerAngle = 10f;

    public Transform COM;

    public float Speed;

    public float maxSpeed = 150f;

    public AudioSource skidAudio;

    private float EngineRPM = 0.0f;

    private float motorInput;

    void Start () {
        rigidbody.centerOfMass = new Vector3(COM.localPosition.x * transform.localScale.x, COM.localPosition.y * transform.localScale.y, COM.localPosition.z * transform.localScale.z);
    }

    void Update () {
        Speed = rigidbody.velocity.magnitude * 3.6f;
        //rigidbody.drag = rigidbody.velocity.magnitude / 100;
        EngineRPM = (Wheel_FL.rpm + Wheel_FR.rpm)/2 * GearRatio[CurrentGear];

        ShiftGears();

        //Input For MotorInput.
        motorInput = Input.GetAxis("Vertical");

        //Audio
        audio.pitch = Mathf.Abs(EngineRPM / MaxEngineRPM)/3 + .3f;
        if (audio.pitch > 2.0f) {
            audio.pitch = 2.0f;
        }

        //Steering
        Wheel_FL.steerAngle = (SteerAngle - 15*(Speed/maxSpeed)) * Input.GetAxis("Horizontal");
        Wheel_FR.steerAngle = Wheel_FL.steerAngle;

        if(Speed > maxSpeed){
            Wheel_RL.motorTorque = 0;
            Wheel_RR.motorTorque = 0;
        }else{
            Wheel_RL.motorTorque = EngineTorque / GearRatio[CurrentGear] * Input.GetAxis("Vertical") * ((maxSpeed - Speed)/maxSpeed);
            Wheel_RR.motorTorque = Wheel_RL.motorTorque;
        }

        //Input.
        if(motorInput <= 0){
            Wheel_RL.brakeTorque = 30;
            Wheel_RR.brakeTorque = 30;
        }else if (motorInput >= 0){
            Wheel_RL.brakeTorque = 0;
            Wheel_RR.brakeTorque = 0;
        }

        //SkidAudio.
        WheelHit CorrespondingGroundHit = new WheelHit();
        Wheel_RR.GetGroundHit(out CorrespondingGroundHit );
        if(Mathf.Abs(CorrespondingGroundHit.sidewaysSlip) > 10) {
            skidAudio.enabled = true;
        }else{
            skidAudio.enabled = false;
        }

        //HandBrake
        if(Input.GetButtonDown("Jump")){
            Wheel_FL.brakeTorque = 1000;
            Wheel_FR.brakeTorque = 1000;
        }
        if(Input.GetButtonUp("Jump")){
            Wheel_FL.brakeTorque = 0;
            Wheel_FR.brakeTorque = 0;
        }

        //Flip
        if(Input.GetKeyDown(KeyCode.R))
            FlipCar();
    }

    void ShiftGears() {

        if (EngineRPM >= MaxEngineRPM) {
            int AppropriateGear = CurrentGear;

            for (int i = 0; i < GearRatio.Length; i ++) {
                if(Wheel_FL.rpm * GearRatio[i] < MaxEngineRPM) {
                    AppropriateGear = i;
                    break;
                }
            }
            CurrentGear = AppropriateGear;
        }

        if(EngineRPM <= MinEngineRPM) {
            int AppropriateGear = CurrentGear;
            for ( int j = GearRatio.Length-1; j >= 0; j -- ) {
                if ( Wheel_FL.rpm * GearRatio[j] > MinEngineRPM ) {
                    AppropriateGear = j;
                    break;
                }
            }
            CurrentGear = AppropriateGear;
        }
    }

    void FlipCar()
    {
        transform.eulerAngles = new Vector3(transform.eulerAngles.x, transform.eulerAngles.y, transform.eulerAngles.z+180);
    }
}