#if UNITY_EDITOR
using UnityEditor;
#endif

using UnityEngine;

[ExecuteAlways]
public class DoorNumber : MonoBehaviour
{
    [SerializeField] private string roomNumber = "1234";

    [SerializeField] private GameObject[] digitPrefabs = new GameObject[10];

    [SerializeField] private Transform[] digitSlots = new Transform[4];

    private void OnValidate()
    {
#if UNITY_EDITOR
        if (!Application.isPlaying)
        {
            EditorApplication.delayCall += DelayedUpdate;
            return;
        }
#endif

        UpdateNumber();
    }

#if UNITY_EDITOR
    private void DelayedUpdate()
    {
        if (this == null)
            return;

        UpdateNumber();
    }
#endif

    private void ClearSlot(Transform slot)
    {
        if (slot == null)
            return;

        for (int i = slot.childCount - 1; i >= 0; i--)
        {
            DestroyImmediate(slot.GetChild(i).gameObject);
        }
    }

    private void UpdateNumber()
    {
        if (digitPrefabs == null || digitPrefabs.Length != 10)
            return;

        if (digitSlots == null || digitSlots.Length != 4)
            return;

        string number = roomNumber.PadLeft(4, '0');

        if (number.Length > 4)
            number = number.Substring(number.Length - 4);

        for (int i = 0; i < 4; i++)
        {
            Transform slot = digitSlots[i];

            if (slot == null)
                continue;

            ClearSlot(slot);

            int digit = number[i] - '0';

            if (digitPrefabs[digit] == null)
                continue;

            GameObject newDigit = Instantiate(
                digitPrefabs[digit],
                slot
            );

            newDigit.transform.localPosition = Vector3.zero;
            newDigit.transform.localRotation = Quaternion.identity;
            newDigit.transform.localScale = Vector3.one;
        }
    }
}