using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(CircleCollider2D))]
public class AttackHitbox : MonoBehaviour
{
    private CircleCollider2D _collider;
    private int _damage;
    private Vector2 _hitVelocity;
    private string _hitReactionState;
    private LayerMask _targetLayer;
    private readonly HashSet<IDamageable> _alreadyHit = new();

    private void Awake()
    {
        _collider = GetComponent<CircleCollider2D>();
        // The player body does not collide with enemies; this trigger is the only attack contact.
        _collider.isTrigger = true;
        _collider.enabled = false;
    }

    public void Activate(ActionData data, Vector2 localPosition, Vector2 hitVelocity, LayerMask targetLayer)
    {
        transform.localPosition = localPosition;
        _collider.radius = data.Radius;
        _damage = data.Damage;
        _hitVelocity = hitVelocity;
        _hitReactionState = data.HitReactionAnimationState;
        _targetLayer = targetLayer;
        _alreadyHit.Clear();
        _collider.enabled = true;

        // Catch enemies already inside the hitbox on the same frame it opens.
        ScanImmediateOverlap();
    }

    public void Deactivate()
    {
        _collider.enabled = false;
        _alreadyHit.Clear();
    }

    private void ScanImmediateOverlap()
    {
        Collider2D[] hits = Physics2D.OverlapCircleAll(transform.position, _collider.radius, _targetLayer);
        foreach (var hit in hits)
            TryDamage(hit);
    }

    private void OnTriggerEnter2D(Collider2D other) => TryDamage(other);
    private void OnTriggerStay2D(Collider2D other) => TryDamage(other);

    private void TryDamage(Collider2D other)
    {
        if ((_targetLayer.value & (1 << other.gameObject.layer)) == 0) return;

        // Hurtboxes may live on child objects, while damage handling usually lives on the root.
        if (!other.TryGetComponent<IDamageable>(out var target))
            target = other.GetComponentInParent<IDamageable>();
        if (target == null) return;
        if (_alreadyHit.Contains(target)) return;

        _alreadyHit.Add(target);
        target.TakeDamage(_damage, _hitVelocity, _hitReactionState);
    }
}