using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

public class BatchAddTreesToTerrain : EditorWindow
{
    Terrain targetTerrain;
    List<GameObject> treePrefabs = new List<GameObject>();

    [MenuItem("Tools/Terrain/Batch Add Trees")]
    static void OpenWindow()
    {
        GetWindow<BatchAddTreesToTerrain>("Batch Add Trees");
    }

    void OnGUI()
    {
        GUILayout.Label("🌲 批量添加树到 Terrain", EditorStyles.boldLabel);
        targetTerrain = (Terrain)EditorGUILayout.ObjectField("目标 Terrain", targetTerrain, typeof(Terrain), true);

        EditorGUILayout.Space();
        GUILayout.Label("树 Prefab 列表", EditorStyles.boldLabel);

        // 拖拽区域
        var dropArea = GUILayoutUtility.GetRect(0, 50, GUILayout.ExpandWidth(true));
        GUI.Box(dropArea, "将 Tree Prefab 拖到这里");

        // 检测拖入
        Event evt = Event.current;
        if (evt.type == EventType.DragUpdated || evt.type == EventType.DragPerform)
        {
            if (dropArea.Contains(evt.mousePosition))
            {
                DragAndDrop.visualMode = DragAndDropVisualMode.Copy;

                if (evt.type == EventType.DragPerform)
                {
                    DragAndDrop.AcceptDrag();
                    foreach (var obj in DragAndDrop.objectReferences)
                    {
                        if (obj is GameObject go)
                        {
                            if (!treePrefabs.Contains(go))
                                treePrefabs.Add(go);
                        }
                    }
                    evt.Use();
                }
            }
        }

        // 展示列表 + 删除按钮
        int removeIndex = -1;
        for (int i = 0; i < treePrefabs.Count; i++)
        {
            EditorGUILayout.BeginHorizontal();
            treePrefabs[i] = (GameObject)EditorGUILayout.ObjectField(treePrefabs[i], typeof(GameObject), false);
            if (GUILayout.Button("X", GUILayout.Width(20)))
                removeIndex = i;
            EditorGUILayout.EndHorizontal();
        }

        if (removeIndex >= 0)
            treePrefabs.RemoveAt(removeIndex);

        EditorGUILayout.Space();

        if (GUILayout.Button("✅ 添加到 Terrain"))
        {
            AddTreesToTerrain();
        }
    }

    void AddTreesToTerrain()
    {
        if (targetTerrain == null)
        {
            Debug.LogWarning("请指定目标 Terrain！");
            return;
        }

        TerrainData terrainData = targetTerrain.terrainData;
        List<TreePrototype> existingPrototypes = new List<TreePrototype>(terrainData.treePrototypes);

        int added = 0;
        foreach (var prefab in treePrefabs)
        {
            if (prefab == null) continue;

            bool alreadyExists = existingPrototypes.Exists(p => p.prefab == prefab);
            if (!alreadyExists)
            {
                TreePrototype newProto = new TreePrototype { prefab = prefab };
                existingPrototypes.Add(newProto);
                added++;
            }
        }

        terrainData.treePrototypes = existingPrototypes.ToArray();

        Debug.Log($"✅ 已添加 {added} 个新树种到 Terrain！");
    }
}