using Core.Utilities;
using UnityEngine;

namespace Core.Health
{
	/// <summary>
	/// Simple class to instantiate a ParticleSystem on a given Damageable's death
	/// 这个类只有一个功能，播放死亡特效。
	/// 这个类的函数附加到Damageable的died Action上.
	/// </summary>
	public class DeathEffect : MonoBehaviour
	{
		/// <summary>
		/// The DamageableBehaviour that will be used to assign the damageable
		/// </summary>
		[Tooltip("This field does not need to be populated here, it can be set up in code using AssignDamageable")]
		public DamageableBehaviour damageableBehaviour;
		
		/// <summary>
		/// Death particle system
		/// </summary>
		public ParticleSystem deathParticleSystemPrefab;

		/// <summary>
		/// World space offset of the <see cref="deathParticleSystemPrefab"/> position
		/// </summary>
		public Vector3 deathEffectOffset;

		/// <summary>
		/// The damageable
		/// </summary>
		protected Damageable m_Damageable;

		/// <summary>
		/// Subscribes to the damageable's died event
		/// </summary>
		/// <param name="damageable"></param>
		public void AssignDamageable(Damageable damageable)
		{
			if (m_Damageable != null)
			{
				m_Damageable.died -= OnDied;
			}
			m_Damageable = damageable;
			m_Damageable.died += OnDied;
		}

		/// <summary>
		/// If damageableBehaviour is populated, assigns the damageable
		/// </summary>
		protected virtual void Awake () 
		{
			if (damageableBehaviour != null)
			{
				AssignDamageable(damageableBehaviour.configuration);
			}
		}

		/// <summary>
		/// Instantiate a death particle system
		/// </summary>
		void OnDied(HealthChangeInfo healthChangeInfo)
		{
			if (deathParticleSystemPrefab == null)
			{
				return;
			}

			var pfx = Poolable.TryGetPoolable<ParticleSystem>(deathParticleSystemPrefab.gameObject);
			pfx.transform.position = transform.position + deathEffectOffset;
			// TEST CODE TO DELTE: ATTENTION TO OPP: 加入更加成熟的机制来加强效果：
			//pfx.transform.localScale = new Vector3(1.0f, 1.0f, 1.0f);
			pfx.Simulate(1.2f); // TEST CODE TO DELETE:
			pfx.Play();
		}
	}
}