using UnityEngine;
using System.Collections;

public class EnemyShip : MonoBehaviour 
{
	public static float ROTATION_SPEED = 0.75f; // degrees

	public enum ShipType {SMALL_SHIP, BIG_SHIP};
	public ShipType shipType;
	public float life = 1000;
	public float topSpeed = 100.0f;
	public int maxShoots = 5;
	public float fireRate = 0.5f;
	public float reloadTime = 5.0f;
	public float shootRange = 2000.0f;

	public Vector3[] weaponMountPoints;
	public Transform laserShotPrefab;
	public AudioClip soundEffectFire;

	private static float BIG_ENEMY_MIN_RANGE = 10000.0f;
	private static float BIG_ENEMY_MAX_RANGE = 20000.0f;

	private static float SMALL_ENEMY_INITIAL_RANGE = 20000.0f;
	private static float SMALL_ENEMY_START_RANGE = 3500.0f;

	private static float WARP_SPEED = 10000.0f;
	private static float EVADE_DISTANCE = 400.0f;

	private static float WEAPON_AIM = 2.5f; // degrees

	private float timeToShot = 0;
	private int availableShoots = 0;

	private bool isAlive = true;

	private bool isEnteringArea = true;
	private Vector3 initialPosition;

	float genCoord(float min_distance, float max_distance) {
		return (Random.value - Random.value) * (min_distance + Random.value * (max_distance-min_distance));
	}

	void Start()
	{
		if(shipType==ShipType.SMALL_SHIP)
		{
			this.transform.position = Random.onUnitSphere * SMALL_ENEMY_INITIAL_RANGE;
			Transform spaceShip = GameManager.GetHero();
			if (spaceShip != null) 
			{
				this.transform.LookAt(spaceShip.position);
				return;
			}

		}
		else
		{
			this.transform.position = new Vector3(
				genCoord(BIG_ENEMY_MIN_RANGE, BIG_ENEMY_MAX_RANGE),
				genCoord(BIG_ENEMY_MIN_RANGE, BIG_ENEMY_MAX_RANGE),
				genCoord(BIG_ENEMY_MIN_RANGE, BIG_ENEMY_MAX_RANGE) );
		}
		this.transform.rotation = Random.rotation;
	}

	public void getHitted(float hit)
	{
		if(!isAlive) return;

		life -= hit;
		if(life<=0)
		{
			isAlive = false;
			Instantiate(GameManager.Instance.explosionEffect, this.transform.position, this.transform.rotation);

			CommunicationCenter.Instance.DestroyOneEnemy(this.gameObject);
			/*if(shipType==ShipType.SMALL_SHIP)
			{
				Destroy(this.transform.parent.gameObject);
			}
			else
			{
				Destroy(this.transform.gameObject);
			}*/
			Destroy(this.gameObject);
		}
	}

	void Update()
	{
		if(shipType==ShipType.SMALL_SHIP)
		{
			DoSmallShip();
		}
	}

	void OnComplete()
	{
	}

	void Fire()
	{

		foreach (Vector3 _wmp in weaponMountPoints) 
		{
			Quaternion small = Quaternion.Euler(Random.Range(-WEAPON_AIM,WEAPON_AIM),
			                                    Random.Range(-WEAPON_AIM,WEAPON_AIM),
			                                    Random.Range(-WEAPON_AIM,WEAPON_AIM)
			                                    );
			small = small*this.transform.rotation;

			Vector3 _pos = transform.position + transform.right * _wmp.x + transform.up * _wmp.y + transform.forward * _wmp.z;
			Transform _laserShot = (Transform) Instantiate(laserShotPrefab, _pos, small);
			_laserShot.GetComponent<SU_LaserShot>().firedBy = transform;
		}

		if (soundEffectFire != null) 
		{
			audio.PlayOneShot(soundEffectFire);
		}
	}

	void DoSmallShip()
	{
		Transform spaceShip = GameManager.GetHero();//GameManager.Instance.spaceShip;

		if (spaceShip==null) return;

		if (isEnteringArea)
		{
			if (Vector3.Distance(this.transform.position, spaceShip.position) > SMALL_ENEMY_START_RANGE)
			{
				this.transform.Translate( Vector3.forward * WARP_SPEED * Time.deltaTime );
				return;
			}
			else 
			{
				isEnteringArea = false;
			}
		}

		/***
		 * Navigation routine
		 */
		float distance = Vector3.Distance(this.transform.position,spaceShip.position);
		
		// The step size is equal to speed times frame time.
		float step = ROTATION_SPEED * Time.deltaTime;

		float speed = topSpeed * Time.deltaTime;

		Vector3 targetDir;

		if (distance < EVADE_DISTANCE) {
			// evade!!
			targetDir = Vector3.Cross (this.transform.forward, spaceShip.right);


		} else {
			targetDir = spaceShip.position - this.transform.position;
			targetDir.Normalize();
		}

		//Debug.DrawLine (this.transform.position, this.transform.position + targetDir*100.0f, Color.green);

		Vector3 newDir = Vector3.RotateTowards (this.transform.forward, targetDir, step, 0.0f);
		this.transform.rotation = Quaternion.LookRotation (newDir);

		this.transform.Translate( Vector3.forward * speed );

		/***
		 * Fire routine
		 */

		timeToShot -= Time.deltaTime;
		if(timeToShot>0.0f) {
			return;
		}

		targetDir = spaceShip.position - this.transform.position;
		if (targetDir.magnitude > shootRange) return;

		float cosAlpha = Vector3.Dot (this.transform.forward, targetDir);
		if (cosAlpha < 0.5f) return;

		if (availableShoots > 0) {
			availableShoots--;
			Fire();
			timeToShot += fireRate;
		} else {
			timeToShot = reloadTime;
			availableShoots += maxShoots;
		}
	}
}