using SepCore.Battle;
using SepCore.Components;
using SepCore.Definition;
using SepCore.CustomUtility;
using UnityEngine;

namespace SepCore.Entity
{
    /// <summary>
    /// 可作为目标的实体类。
    /// </summary>
    public abstract class TargetableObject : EntityBase
    {
        protected abstract TargetableObjectData _targetableObjectData { get; }

        public bool IsDead => _healthComponent.CurrentHealth <= 0;

        protected HealthComponent _healthComponent;

        public abstract ImpactData GetImpactData();

        public void ApplyDamage(EntityBase attacker, in DamageResult damageResult, Vector3? hitPosition = null)
        {
            if (damageResult.IsDodge)
            {
                _healthComponent.TakeDamage(0, false, true, hitPosition);
                return;
            }

            float fromHPRatio = _healthComponent.HealthRatio;
            _healthComponent.TakeDamage(damageResult.Damage, damageResult.IsCrit, false, hitPosition);
            float toHPRatio = _healthComponent.HealthRatio;
            if (fromHPRatio > toHPRatio)
            {
                GameEntry.HPBar.ShowHPBar(this, fromHPRatio, toHPRatio);
            }

            if (damageResult.IsLifeSteal && attacker != null)
            {
                HealthComponent attackerHealth = attacker.GetComponent<HealthComponent>();
                if (attackerHealth == null && attacker is WeaponBase weapon)
                {
                    attackerHealth = weapon.GetComponentInParent<HealthComponent>();
                }

                if (attackerHealth != null)
                {
                    attackerHealth.TryTriggerLifeSteal(damageResult.LifeStealAmount);
                }
            }

            if (_healthComponent.CurrentHealth <= 0)
            {
                OnDead(attacker);
            }
        }

        public void ApplyDamage(EntityBase attacker, int damageHP)
        {
            ApplyDamage(attacker, new DamageResult
            {
                Damage = damageHP,
                IsDodge = false,
                IsCrit = false,
                IsLifeSteal = false,
                LifeStealAmount = 0
            });
        }

        protected override void OnInit(object userData)
        {
            base.OnInit(userData);

            _healthComponent = GetComponent<HealthComponent>();
        }

        protected override void OnShow(object userData)
        {
            base.OnShow(userData);
        }

        protected virtual void OnDead(EntityBase attacker)
        {
            GameEntry.Entity.HideEntity(this);
        }

        private void OnTriggerEnter(Collider other)
        {
            EntityBase entity = other.GetComponentInParent<EntityBase>();
            if (entity == null || entity == this)
            {
                return;
            }

            if (entity is TargetableObject && entity.Id < Id)
            {
                // 碰撞事件由 Id 大的一方处理
                // 在这里约定 Enemy 的 Id 为非负数（通常从 0 开始）
                // 而其他的 Entity (Player, Weapon, Bullet) 的 Id 均小于 0
                return;
            }

            AIUtility.PerformCollision(this, entity);
        }
    }
}