unity-atoms/Packages/BaseAtoms/Editor/AtomsSearchableAssetCreationMenu.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEditor;
using UnityEditor.IMGUI.Controls;
using UnityEngine;

namespace UnityAtoms.Editor
{
    public static class AtomsSearchableAssetCreationMenu
    {
        class StringTree<T>
        {
            public Dictionary<string, StringTree<T>> SubTrees { get; } = new Dictionary<string, StringTree<T>>();
            public T Value { get; private set; }

            public void Insert(string path, T value, int idx = 0)
            {
                Internal_Insert(path.Split('/'), idx, value);
            }

            private void Internal_Insert(string[] path, int idx, T value)
            {
                if (idx >= path.Length)
                {
                    Value = value;
                    return;
                }

                if (!SubTrees.ContainsKey(path[idx])) SubTrees.Add(path[idx], new StringTree<T>());
                SubTrees[path[idx]].Internal_Insert(path, idx + 1, value);
            }
        }

        [MenuItem(itemName: "Assets/Create/Atoms Search &1", isValidateFunction: false, priority: -1)] // Adds to the project window's create menu
        public static void AtomsSearchMenu()
        {
            StringTree<Type> typeTree = new StringTree<Type>();

            foreach (var type in TypeCache.GetTypesWithAttribute<CreateAssetMenuAttribute>()
                .Where(t => t.GetCustomAttribute<AtomsSearchable>(true) != null))
            {
                var name = type.GetCustomAttribute<CreateAssetMenuAttribute>().menuName;
                var i = name.LastIndexOf('/');
                name = (i == -1) ? name : name.Substring(0, i + 1) + type.Name;
                typeTree.Insert(name, type, 1);
            }

            var projectBrowserType = typeof(UnityEditor.Editor).Assembly.GetType("UnityEditor.ProjectBrowser");
            var projectBrowser = EditorWindow.GetWindow(projectBrowserType);

            Vector2 xy = new Vector2(projectBrowser.position.x + 10, projectBrowser.position.y + 60);

            var dropdown = new SearchTypeDropdown(new AdvancedDropdownState(), typeTree,
                (s) =>
                {
                    EditorApplication.ExecuteMenuItem("Assets/Create/" + s.GetCustomAttribute<CreateAssetMenuAttribute>().menuName);
                })
            {
                MinimumSize = new Vector2(projectBrowser.position.width - 20, projectBrowser.position.height - 80)
            };

            var rect = new Rect(xy.x, xy.y, projectBrowser.position.width - 20, projectBrowser.position.height);

            dropdown.Show(new Rect()); // don't use this to position the
            var window = typeof(SearchTypeDropdown).GetField("m_WindowInstance", BindingFlags.Instance | BindingFlags.NonPublic)?.GetValue(dropdown) as EditorWindow;
            window.position = rect;
        }

        private class SearchTypeDropdown : AdvancedDropdown
        {
            private readonly StringTree<Type> _list;
            private readonly Action<Type> _func;

            private readonly List<Type> _lookup = new List<Type>();

            public Vector2 MinimumSize
            {
                get => minimumSize;
                set => minimumSize = value;
            }

            public SearchTypeDropdown(AdvancedDropdownState state, StringTree<Type> list, Action<Type> func) : base(state)
            {
                _list = list;
                _func = func;
            }

            protected override void ItemSelected(AdvancedDropdownItem item)
            {
                base.ItemSelected(item);
                _func?.Invoke(_lookup[item.id]);
            }

            private void Render(StringTree<Type> tree, string key, AdvancedDropdownItem parentGroup)
            {
                if (tree.Value != null)
                {
                    _lookup.Add(tree.Value);
                    parentGroup.AddChild(new AdvancedDropdownItem(key) { id = _lookup.Count - 1 });
                }
                else
                {
                    var self = new AdvancedDropdownItem(key);
                    foreach (var subtree in tree.SubTrees)
                    {
                        Render(subtree.Value, subtree.Key, self);
                    }

                    parentGroup.AddChild(self);
                }
            }

            protected override AdvancedDropdownItem BuildRoot()
            {
                var root = new AdvancedDropdownItem("Unity Atoms");

                foreach (var subtree in _list.SubTrees)
                {
                    Render(subtree.Value, subtree.Key, root);
                }

                return root;
            }
        }
    }
}