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

public class MissingScriptUtility : EditorWindow
{
    Vector2 scroll;
    List<Object> projectObjectsWithMissingScripts = new List<Object>();
    int sceneMissingCount = 0;

    [MenuItem("Tools/Missing Script Utility")]
    static void Init()
    {
        GetWindow<MissingScriptUtility>("Missing Script Utility");
    }

    void OnGUI()
    {
        GUILayout.Label("Scene Scan", EditorStyles.boldLabel);

        if (GUILayout.Button("Find Missing Scripts in Scene"))
        {
            sceneMissingCount = ScanScene();
        }

        EditorGUILayout.LabelField($"Missing scripts in scene: {sceneMissingCount}");

        if (GUILayout.Button("Remove Missing Scripts from Selected GameObjects"))
        {
            RemoveFromSelectedInScene();
        }

        GUILayout.Space(20);
        GUILayout.Label("Project Scan (Assets)", EditorStyles.boldLabel);

        if (GUILayout.Button("Scan Entire Project for Missing Scripts"))
        {
            ScanProject();
        }

        EditorGUILayout.LabelField($"Assets with missing scripts: {projectObjectsWithMissingScripts.Count}");

        if (projectObjectsWithMissingScripts.Count > 0)
        {
            scroll = EditorGUILayout.BeginScrollView(scroll, GUILayout.Height(150));
            foreach (var obj in projectObjectsWithMissingScripts)
            {
                EditorGUILayout.ObjectField(obj, typeof(Object), false);
            }
            EditorGUILayout.EndScrollView();
        }

        if (GUILayout.Button("Remove Missing Scripts from Selected Assets"))
        {
            RemoveFromSelectedAssets();
        }

        if (GUILayout.Button("Auto-fix All Prefabs in Project (Remove Missing Scripts)"))
        {
            bool confirm = EditorUtility.DisplayDialog(
                "Are you sure?",
                "This will permanently remove all missing script references from ALL prefab assets in your project.\n\nThis action cannot be undone. Do you want to continue?",
                "Yes, proceed",
                "Cancel"
            );

            if (confirm)
            {
                AutoFixAllPrefabs();
            }
        }
    }

    int ScanScene()
    {
        int count = 0;
        List<GameObject> objectsWithMissing = new List<GameObject>();

        GameObject[] go = GameObject.FindObjectsOfType<GameObject>();

        foreach (GameObject g in go)
        {
            Component[] components = g.GetComponents<Component>();
            for (int i = 0; i < components.Length; i++)
            {
                if (components[i] == null)
                {
                    Debug.LogWarning("Missing script on GameObject: " + g.name, g);
                    objectsWithMissing.Add(g);
                    count++;
                    break;
                }
            }
        }

        if (objectsWithMissing.Count > 0)
        {
            Selection.objects = objectsWithMissing.ToArray(); // Select in editor
            Debug.Log($"Selected {objectsWithMissing.Count} objects with missing scripts.");
        }
        else
        {
            Debug.Log("No missing scripts found in scene.");
        }

        return count;
    }

    void RemoveFromSelectedInScene()
    {
        GameObject[] selectedObjects = Selection.gameObjects;
        int totalRemoved = 0;

        foreach (GameObject go in selectedObjects)
        {
            Undo.RegisterCompleteObjectUndo(go, "Remove Missing Scripts");
            int removed = GameObjectUtility.RemoveMonoBehavioursWithMissingScript(go);

            if (removed > 0)
            {
                Debug.Log($"Removed {removed} missing scripts from: {go.name}", go);
                totalRemoved += removed;
            }
        }

        Debug.Log($"Done. Removed total {totalRemoved} missing script components from selection.");
    }

    void ScanProject()
    {
        projectObjectsWithMissingScripts.Clear();

        string[] allGUIDs = AssetDatabase.FindAssets("t:Prefab t:Scene t:ScriptableObject");

        foreach (string guid in allGUIDs)
        {
            string path = AssetDatabase.GUIDToAssetPath(guid);
            Object obj = AssetDatabase.LoadMainAssetAtPath(path);
            if (obj == null) continue;

            GameObject go = obj as GameObject;
            if (go != null)
            {
                if (HasMissingScript(go))
                    projectObjectsWithMissingScripts.Add(go);
            }
            else
            {
                var contents = AssetDatabase.LoadAllAssetsAtPath(path);
                foreach (var item in contents)
                {
                    if (item == null) continue;
                    SerializedObject so = new SerializedObject(item);
                    if (HasMissingScriptSerialized(so))
                    {
                        projectObjectsWithMissingScripts.Add(item);
                        break;
                    }
                }
            }
        }

        Debug.Log($"Project scan complete. Found {projectObjectsWithMissingScripts.Count} assets with missing scripts.");
    }

    bool HasMissingScript(GameObject go)
    {
        Component[] components = go.GetComponentsInChildren<Component>(true);
        foreach (Component comp in components)
        {
            if (comp == null)
                return true;
        }
        return false;
    }

    bool HasMissingScriptSerialized(SerializedObject so)
    {
        SerializedProperty prop = so.FindProperty("m_Script");
        return prop != null && prop.objectReferenceValue == null;
    }

    void RemoveFromSelectedAssets()
    {
        foreach (var obj in Selection.objects)
        {
            GameObject go = obj as GameObject;
            if (go == null) continue;

            string path = AssetDatabase.GetAssetPath(go);
            GameObject instance = PrefabUtility.LoadPrefabContents(path);
            int removed = GameObjectUtility.RemoveMonoBehavioursWithMissingScript(instance);

            if (removed > 0)
            {
                Debug.Log($"Removed {removed} missing scripts from prefab: {go.name}", go);
                PrefabUtility.SaveAsPrefabAsset(instance, path);
            }

            PrefabUtility.UnloadPrefabContents(instance);
        }

        AssetDatabase.SaveAssets();
    }

    void AutoFixAllPrefabs()
    {
        string[] prefabGUIDs = AssetDatabase.FindAssets("t:Prefab");
        int totalFixed = 0;

        foreach (string guid in prefabGUIDs)
        {
            string path = AssetDatabase.GUIDToAssetPath(guid);
            GameObject prefab = AssetDatabase.LoadAssetAtPath<GameObject>(path);
            if (prefab == null) continue;

            GameObject instance = PrefabUtility.LoadPrefabContents(path);
            int removed = GameObjectUtility.RemoveMonoBehavioursWithMissingScript(instance);

            if (removed > 0)
            {
                PrefabUtility.SaveAsPrefabAsset(instance, path);
                totalFixed += removed;
                Debug.Log($"Auto-fixed prefab '{path}' – removed {removed} missing scripts.");
            }

            PrefabUtility.UnloadPrefabContents(instance);
        }

        AssetDatabase.SaveAssets();
        Debug.Log($"Auto-fix complete. Removed missing scripts from {totalFixed} components.");
    }
}