LaserTracking

/*
  Copyright 2019 John Wheeler<tmoneygames2019@gmail.com>
  From Class: 2D Galaxy Space Shooter - gamedevhq.com
*/
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class LaserTracking : MonoBehaviour
{

    // Variables
    private Transform[] _enemies;
    [SerializeField]
    private Transform _enemy;
    [SerializeField]
    private bool _isEnemyAquired = false;
    [SerializeField]
    private bool _isBeingTargeted = false;
    [SerializeField]
    private float _speed = 5.0f;
    [SerializeField]
    private float _angleChangeSpeed = 15f;
    private Rigidbody2D _rigidbody;
    private AudioSource _audioSource;

    // Start is called before the first frame update
    void Start()
    {

        // checks to make sure that the enemy is initialized correctly or gives error message
        if(_enemy == null)
        {
            Debug.LogError("The Enemy is NULL!");
        }

        // cache the rigidbody component on the LaserTracking missle
        _rigidbody = GetComponent<Rigidbody2D>();

        // checks to make sure that the rigidbody initialized correctly or gives error message
        if(_rigidbody == null)
        {
            Debug.LogError("The Rigidbody2D is NULL!");
        }

        // cache the _audioSource component on the LaserTracking Missle
        _audioSource = GetComponent<AudioSource>();

        // checks to make sure that the AudioSource is initialized correctly or gives error message
        if(_audioSource == null)
        {
            Debug.LogError("The AudioSource of the Tracking Laser is NULL!");
        }
    }

    // Update is called once per frame
    void Update()
    {
        // sets the travel and speed of the rigidbody component on the tracking laser
        _rigidbody.velocity = transform.up * _speed * Time.deltaTime;
    }

    // a method that will find and track enemies with the tracking laser
    public void FindAndTrackEnemies(Transform[] enemies)
    {
        // checks to see if any targets were found
        if(_isEnemyAquired == false)
        {

            // checks to make sure the _enemy is not null
            if(_enemy != null)
            {
                // if _enemy is not equal to null it turns the _isEnemyAquired to true
                _isEnemyAquired = true;
            }
            // else the enemy has to be tracked
            else
            {
                // if _enemy is not null
                if(_enemy != null)
                {
                    // starts the targeting of the _enemy by the tracking laser
                    Vector3 direction = (_enemy.position - transform.position);

                    // sets the direction to normal
                    direction.Normalize();

                    // sets the initial angle direction variable
                    float angle = Vector3.Angle(Vector3.up, direction);

                    // sets the cross direction variable
                    float cross = Vector3.Cross(transform.up, direction).z;

                    // sets the _rigidbody tracking velocity for the tracking laser
                    _rigidbody.angularVelocity = angle * cross * _angleChangeSpeed;
                }
                // else the enemy isn't being tracked
                else
                {
                    // the _enemy is not being tracked
                    _isEnemyAquired = false;
                }
            }
        }
    }

    // a method that will get the closest spawning enemies to track and destroy
    public void FindClosestTarget(Transform enemy, Transform[] _enemies)
    {
        // a local variable that sets the minimum distance from the player
        float minDist = Mathf.Infinity;

        // a local transform for the closest enemy
        Transform closestEnemy = null;

        // sets the current position to spawn
        Vector3 posToSpawn = transform.position;

        // a foreach loop that will go through and find enemies to track
        foreach( var _enemy in _enemies)
        {

            // checks if the enemy from the enemycontainer is being targeted
            if (_enemy.gameObject.name != "EnemyContainer" && enemy.gameObject.GetComponent<Enemy>()._isBeingTargeted == false)
            {
                // sets a local float variable for the enemy distance to spawn
                float distance = Vector3.Distance(enemy.transform.position, posToSpawn);

                //  checks if the distance is less than the minimum distance
                if(distance < minDist)
                {
                    // sets the closest enemy to the enemy transform
                    closestEnemy = enemy.transform;

                    // sets the minimum distance variable to the distance variable
                    minDist = distance;
                }
            }
        }

        // a check to make sure that the closest enemy is not null
        if(closestEnemy != null)
        {
            closestEnemy.transform.GetComponent<Enemy>()._isBeingTargeted = true;
        }
    }

    // a method that checks for collision with the enemy and then destroys itself
    public void OnTriggerEnter2D(Collider2D other)
    {
        // checks the tag of the other to see if it's the enemy
        if(other.tag == "Enemy")
        {
            // destroys the audio source component as soon as collison occurs
            Destroy(_audioSource.gameObject);

            // destroys the laser tracking missle
            Destroy(this.gameObject);
        }
    }
}