using UnityEngine;
using System.Collections;

public enum ScanType {
    ROTATING,
    RANDOM
}

public class TurretController : MonoBehaviour {

    public float rotateSpeed = 20;
    public float lookDistance = 3;
    public float FOV = 90;
    public ScanType ScanMode;
    float delayTime = 2;
    float elapsedTime = 0;

    Vector3 target = Vector3.forward;
    GameObject player;

    void Start () {
        player = GameObject.FindGameObjectWithTag("Player");
    }

    void Update ()
    {
        if( CanSeePlayer() && IsWithinFOV() )
            CenterOnPlayer();
        else
            ScanForPlayer();
    }

    void ScanForPlayer()
    {
        switch( ScanMode )
        {
        case ScanType.ROTATING:
            RotatingScan();
            break;

        case ScanType.RANDOM:
            RandomScan();
            break;

        default:
            RotatingScan();
            break;
        }
    }

    void RotatingScan()
    {
        Debug.DrawRay( transform.position, transform.forward * lookDistance, Color.green );
        transform.Rotate( Vector3.up * rotateSpeed * Time.deltaTime );
    }

    void RandomScan()
    {
        elapsedTime += Time.deltaTime;

        if( elapsedTime > delayTime ) {
            elapsedTime = 0;

            float x = Random.Range( -10, 10);
            float y = Random.Range( -10, 10 );

            this.target = new Vector3( x, 0, y );

            Debug.Log( string.Format("Getting new scan location, {0} {1}", x, y) );
        }

        CenterOnTarget( this.target );
    }

    private bool IsWithinFOV()
    {
        Vector3 playerLookAtVector = player.transform.position - transform.position;
        float angleBetween = Vector3.Angle( transform.forward, playerLookAtVector );

        var distance = Vector3.Distance( transform.position, player.transform.position );

        return (angleBetween < FOV && distance < lookDistance);
    }

    private void CenterOnPlayer()
    {
        Debug.DrawRay( transform.position, transform.forward * lookDistance, Color.red );

        var rotate = Quaternion.LookRotation( player.transform.position - transform.position );
        transform.rotation = Quaternion.Slerp( transform.rotation, rotate, 5 * Time.deltaTime );
    }

    private void CenterOnTarget( Vector3 target )
    {
        Debug.DrawRay( transform.position, transform.forward * lookDistance, Color.red );

        var rotate = Quaternion.LookRotation( target - transform.position );
        transform.rotation = Quaternion.Slerp( transform.rotation, rotate, 5 * Time.deltaTime );
    }

    private bool CanSeePlayer()
    {
        Vector3 playerLookAtVector = player.transform.position - transform.position;
        RaycastHit hit = new RaycastHit();

        if( Physics.Raycast( transform.position, playerLookAtVector, out hit, lookDistance ) )
            return hit.collider.gameObject.tag == "Player";

        return false;
    }
}