#if !UNITY_2022_1_OR_NEWER
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEditor.Toolbars;
using UnityEngine;
using UnityEngine.UIElements;

namespace UnityEditor.Splines
{
    abstract class CreateToolbarBase : UnityEditor.Editor
    {
        protected abstract IEnumerable<string> toolbarElements { get; }

        const string k_ElementClassName = "unity-editor-toolbar-element";
        const string k_StyleSheetsPath = "StyleSheets/Toolbars/";

        protected static VisualElement CreateToolbar()
        {
            var target = new VisualElement();
            var path = k_StyleSheetsPath + "EditorToolbar";

            var common = EditorGUIUtility.Load($"{path}Common.uss") as StyleSheet;
            if (common != null)
                target.styleSheets.Add(common);

            var themeSpecificName = EditorGUIUtility.isProSkin ? "Dark" : "Light";
            var themeSpecific = EditorGUIUtility.Load($"{path}{themeSpecificName}.uss") as StyleSheet;
            if (themeSpecific != null)
                target.styleSheets.Add(themeSpecific);

            target.AddToClassList("unity-toolbar-overlay");
            target.style.flexDirection = FlexDirection.Row;
            return target;
        }

        public override VisualElement CreateInspectorGUI()
        {
            var root = CreateToolbar();

            var elements = TypeCache.GetTypesWithAttribute(typeof(EditorToolbarElementAttribute));

            foreach (var element in toolbarElements)
            {
                var type = elements.FirstOrDefault(x =>
                {
                    var attrib = x.GetCustomAttribute<EditorToolbarElementAttribute>();
                    return attrib != null && attrib.id == element;
                });

                if (type != null)
                {
                    try
                    {
                        const BindingFlags flags =  BindingFlags.Instance |
                            BindingFlags.Public |
                            BindingFlags.NonPublic |
                            BindingFlags.CreateInstance;

                        var ve = (VisualElement)Activator.CreateInstance(type, flags, null, null, null, null);
                        ve.AddToClassList(k_ElementClassName);
                        root.Add(ve);
                    }
                    catch (Exception e)
                    {
                        Debug.LogError($"Failed creating toolbar element from ID \"{element}\".\n{e}");
                    }
                }
            }

            EditorToolbarUtility.SetupChildrenAsButtonStrip(root);

            return root;
        }
    }
}
#endif