using UnityEngine;
using UnityEngine.Events;
using System.Collections;

/// <summary>
/// Attach on trigger and set validate rule. Invoke events if validation is successful.
/// </summary>
public class TriggerHanlder : MonoBehaviour {
	public enum ValidateRule {
		ANY, BOTH
	}

	[SerializeField] protected LayerMask triggerLayers;
	[SerializeField] protected string[] triggerTags;
	[SerializeField] protected ValidateRule validate;

	[SerializeField] protected UnityEvent onTriggerEnter;
	[SerializeField] protected UnityEvent onTriggerStay;
	[SerializeField] protected UnityEvent onTriggerExit;

	private Collider2D col2D;

	protected virtual bool Validate(Collider2D other) {
		bool layerValid = false;
		bool tagValid = false;

		// Always return true if layermask and tags are unassigned.
		if (triggerLayers.value == 0 && (triggerTags == null || triggerTags.Length == 0))
			return true;

		bool isAny = validate == ValidateRule.ANY || triggerLayers.value == 0 || triggerTags == null || triggerTags.Length == 0;

		LayerMask mask = 1 << other.gameObject.layer;
		if ((triggerLayers & mask) == mask) {
			layerValid = true;
			if (isAny)
				return true;
		}

		for (int i = 0; i < triggerTags.Length; i++) {
			if (other.CompareTag(triggerTags[i])) {
				tagValid = true;
				if (isAny)
					return true;
			}
		}

		return layerValid && tagValid;
	}

	protected virtual void OnTriggerEnter2D(Collider2D other) {
		if (Validate(other) && onTriggerEnter != null) {
			onTriggerEnter.Invoke();
		}
	}

	protected virtual void OnTriggerStay2D(Collider2D other) {
		if (Validate(other) && onTriggerStay != null)
			onTriggerStay.Invoke();
	}

	protected virtual void OnTriggerExit2D(Collider2D other) {
		if (Validate(other) && onTriggerExit != null)
			onTriggerExit.Invoke();
	}
}