using UnityEngine;

#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.SceneManagement;
#endif

public class BookShelfAutoFill : MonoBehaviour
{
    [Header("책 프리팹들")]
    public GameObject[] bookPrefabs;

    [Header("책장 배치 설정")]
    public int rows = 4;
    public int booksPerRow = 12;

    [Tooltip("첫 번째 책 위치. 이 오브젝트 기준 로컬 좌표")]
    public Vector3 startLocalPosition = new Vector3(-1.0f, 0f, 0f);

    [Tooltip("책 사이 간격. X는 옆으로, Y는 위 칸으로")]
    public Vector3 spacing = new Vector3(0.13f, 0.42f, 0f);

    [Header("책 랜덤 느낌")]
    public Vector2 randomXOffset = new Vector2(-0.015f, 0.015f);
    public Vector2 randomYOffset = new Vector2(-0.015f, 0.015f);
    public Vector2 randomZOffset = new Vector2(-0.01f, 0.01f);

    public Vector2 randomHeightScale = new Vector2(0.85f, 1.15f);
    public Vector2 randomWidthScale = new Vector2(0.9f, 1.1f);
    public Vector2 randomDepthScale = new Vector2(0.9f, 1.05f);

    public Vector2 randomYRotation = new Vector2(-3f, 3f);
    public Vector2 randomZRotation = new Vector2(-2f, 2f);

    [Header("기본 회전")]
    public Vector3 baseRotation = Vector3.zero;

    [Header("기타")]
    public bool clearBeforeGenerate = true;
    public int seed = 10;

    private const string GeneratedParentName = "Generated_Books";

    [ContextMenu("책 자동 배치")]
    public void GenerateBooks()
    {
        if (bookPrefabs == null || bookPrefabs.Length == 0)
        {
            Debug.LogWarning("[BookShelfAutoFill] Book Prefabs에 책 프리팹을 넣어줘.");
            return;
        }

        Random.InitState(seed);

        if (clearBeforeGenerate)
        {
            ClearBooks();
        }

        GameObject parent = new GameObject(GeneratedParentName);
        parent.transform.SetParent(transform);
        parent.transform.localPosition = Vector3.zero;
        parent.transform.localRotation = Quaternion.identity;
        parent.transform.localScale = Vector3.one;

#if UNITY_EDITOR
        if (!Application.isPlaying)
        {
            Undo.RegisterCreatedObjectUndo(parent, "Create Generated Books Parent");
        }
#endif

        for (int r = 0; r < rows; r++)
        {
            float currentX = startLocalPosition.x;

            for (int c = 0; c < booksPerRow; c++)
            {
                GameObject prefab = bookPrefabs[Random.Range(0, bookPrefabs.Length)];

                if (prefab == null)
                    continue;

                GameObject book = CreateBook(prefab, parent.transform);

                if (book == null)
                    continue;

                float offsetX = Random.Range(randomXOffset.x, randomXOffset.y);
                float offsetY = Random.Range(randomYOffset.x, randomYOffset.y);
                float offsetZ = Random.Range(randomZOffset.x, randomZOffset.y);

                book.transform.localPosition = new Vector3(
                    currentX + offsetX,
                    startLocalPosition.y + r * spacing.y + offsetY,
                    startLocalPosition.z + offsetZ
                );

                book.transform.localRotation = Quaternion.Euler(
                    baseRotation.x,
                    baseRotation.y + Random.Range(randomYRotation.x, randomYRotation.y),
                    baseRotation.z + Random.Range(randomZRotation.x, randomZRotation.y)
                );

                Vector3 originalScale = book.transform.localScale;

                book.transform.localScale = new Vector3(
                    originalScale.x * Random.Range(randomWidthScale.x, randomWidthScale.y),
                    originalScale.y * Random.Range(randomHeightScale.x, randomHeightScale.y),
                    originalScale.z * Random.Range(randomDepthScale.x, randomDepthScale.y)
                );

                currentX += spacing.x;
            }
        }

#if UNITY_EDITOR
        if (!Application.isPlaying)
        {
            EditorUtility.SetDirty(gameObject);
            EditorSceneManager.MarkSceneDirty(gameObject.scene);
        }
#endif

        Debug.Log("[BookShelfAutoFill] 책 자동 배치 완료. 마음에 들면 Ctrl+S 저장 후 이 스크립트 컴포넌트는 삭제해도 됨.");
    }

    [ContextMenu("생성된 책 삭제")]
    public void ClearBooks()
    {
        Transform old = transform.Find(GeneratedParentName);

        if (old == null)
        {
            Debug.Log("[BookShelfAutoFill] 삭제할 Generated_Books가 없음.");
            return;
        }

#if UNITY_EDITOR
        if (!Application.isPlaying)
        {
            // Inspector가 삭제될 오브젝트를 보고 있으면 에러가 나서 선택을 부모로 돌림
            if (Selection.activeGameObject != null)
            {
                Transform selected = Selection.activeGameObject.transform;

                if (selected == old || selected.IsChildOf(old))
                {
                    Selection.activeGameObject = gameObject;
                }
            }

            Undo.DestroyObjectImmediate(old.gameObject);

            EditorUtility.SetDirty(gameObject);
            EditorSceneManager.MarkSceneDirty(gameObject.scene);

            Debug.Log("[BookShelfAutoFill] 생성된 책 삭제 완료.");
            return;
        }
#endif

        Destroy(old.gameObject);
    }

    private GameObject CreateBook(GameObject prefab, Transform parent)
    {
#if UNITY_EDITOR
        if (!Application.isPlaying)
        {
            GameObject obj = PrefabUtility.InstantiatePrefab(prefab, parent) as GameObject;

            if (obj != null)
            {
                Undo.RegisterCreatedObjectUndo(obj, "Create Book");
            }

            return obj;
        }
#endif

        return Instantiate(prefab, parent);
    }
}