using System.Collections.Generic;
using UnityEngine;

[DisallowMultipleComponent]
[RequireComponent(typeof(Collider))]
public sealed class NetworkItemInputSlot : MonoBehaviour
{
    [SerializeField] private NetworkItemProcessingWorkstation workstation;

    private readonly Dictionary<NetworkItem, HashSet<Collider>> overlaps = new();

    private void Reset()
    {
        workstation = GetComponentInParent<NetworkItemProcessingWorkstation>();
        GetComponent<Collider>().isTrigger = true;
    }

    private void Awake()
    {
        if (workstation == null)
            workstation = GetComponentInParent<NetworkItemProcessingWorkstation>();
    }

    private void OnDisable() => overlaps.Clear();

    private void OnTriggerEnter(Collider other)
    {
        RegisterOverlap(other);
        TryAccept(other);
    }

    private void OnTriggerStay(Collider other)
    {
        RegisterOverlap(other);
        TryAccept(other);
    }

    private void OnTriggerExit(Collider other)
    {
        if (workstation == null || !workstation.IsServer)
            return;

        NetworkItem item = other.GetComponentInParent<NetworkItem>();
        if (item == null || !overlaps.TryGetValue(item, out HashSet<Collider> colliders))
            return;

        colliders.Remove(other);
        if (colliders.Count > 0)
            return;

        overlaps.Remove(item);
        workstation.NotifyItemExited(item);
    }

    private void TryAccept(Collider other)
    {
        if (workstation == null || !workstation.IsServer || !workstation.IsSpawned)
            return;

        NetworkItem item = other.GetComponentInParent<NetworkItem>();
        if (item != null)
            workstation.TryAcceptItem(item);
    }

    private void RegisterOverlap(Collider other)
    {
        NetworkItem item = other.GetComponentInParent<NetworkItem>();
        if (item == null)
            return;

        if (!overlaps.TryGetValue(item, out HashSet<Collider> colliders))
        {
            colliders = new HashSet<Collider>();
            overlaps.Add(item, colliders);
        }

        colliders.Add(other);
    }
}