using UnityEngine;
using UnityEditor;

[CustomEditor(typeof(EnemySpawn))]
public class EnemySpawnEditor : Editor
{
    void OnSceneGUI()
    {
        EnemySpawn enemySpawn = target as EnemySpawn;
        Vector3 pos = enemySpawn.transform.position;

        // 計算4個角落
        Vector3 v0 = new Vector3(pos.x - enemySpawn.range / 2, pos.y, pos.z - enemySpawn.range / 2);
        Vector3 v1 = new Vector3(pos.x + enemySpawn.range / 2, pos.y, pos.z + enemySpawn.range / 2);

        float y = v0.y;
        Vector3[] corners = new Vector3[4];
        corners[0] = new Vector3(v0.x, y, v0.z);
        corners[1] = new Vector3(v0.x, y, v1.z);
        corners[2] = new Vector3(v1.x, y, v1.z);
        corners[3] = new Vector3(v1.x, y, v0.z);

        EditorGUI.BeginChangeCheck();
        float scaleValue = enemySpawn.range;
        float newRange = scaleValue;
        float sizeHandle = 1.0f;
        float realSize = sizeHandle * 0.1f; // 實際為0.15f，比它小才能更精確顯示滑鼠

        // 4個縮放值控制柄
        for (int i = 0; i < 4; ++i)
        {
            v0 = new Vector3(corners[i].x - realSize, y, corners[i].z - realSize);
            v1 = new Vector3(corners[i].x + realSize, y, corners[i].z + realSize);

            // 換算成GUI座標
            Vector2[] handles = new Vector2[4];
            handles[0] = HandleUtility.WorldToGUIPoint(new Vector3(v0.x, y, v0.z));
            handles[1] = HandleUtility.WorldToGUIPoint(new Vector3(v0.x, y, v1.z));
            handles[2] = HandleUtility.WorldToGUIPoint(new Vector3(v1.x, y, v1.z));
            handles[3] = HandleUtility.WorldToGUIPoint(new Vector3(v1.x, y, v0.z));

            Bounds b = new Bounds(handles[0], Vector3.zero);
            for (int j = 1; j < 4; ++j)
            {
                b.Encapsulate(handles[j]);
            }

            Vector2 min = b.min;
            Vector2 max = b.max;
            Rect rect = new Rect(min.x, min.y, max.x - min.x, max.y - min.y);

            // 除錯繪製是否計算正確
            Handles.BeginGUI();
            GUI.Box(rect, rect.ToString());
            Handles.EndGUI();

            // 是否滑鼠在控制柄上
            if (rect.Contains(Event.current.mousePosition))
            {
                // 顯示縮放圖示的箭頭
                EditorGUIUtility.AddCursorRect(rect, MouseCursor.ScaleArrow);
            }

            scaleValue = Handles.ScaleValueHandle(enemySpawn.range,
                        corners[i],
                        Quaternion.identity,
                        sizeHandle,
                        Handles.SphereCap,
                        1);
            newRange = scaleValue == enemySpawn.range ? newRange : scaleValue;

            Handles.Label(corners[i], i.ToString());
        }

        if (EditorGUI.EndChangeCheck())
        {
            // 記錄物件以便進行撤銷
            Undo.RecordObject(enemySpawn, "Change Range");
            enemySpawn.range = newRange;

            EditorUtility.SetDirty(target);
        }
    }
}