module-navigation-tool/Editor/Toolbar/Tools/ToolScenePicker.cs

using System;
using System.Text;
using JetBrains.Annotations;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.SceneManagement;

namespace Module.NavigationTool.Editor.Toolbar
{
    [UsedImplicitly]
    internal sealed class ToolScenePicker : AbstractToolbarDrawer
    {
        public override bool Visible => ToolbarScenePickerSettings.IsSceneEnabled;
        public override bool Enabled => !EditorApplication.isPlaying && !EditorApplication.isPlayingOrWillChangePlaymode;
        public override EToolbarPlacement Placement => EToolbarPlacement.Right;
        public override int Priority => (int)EToolbarPriority.Medium;
        
        private static readonly StringBuilder STRING_BUILDER = new StringBuilder();
        private static readonly ScenePickerList SCENE_LIST = new ScenePickerList();
        private static string SCENE_LABEL = string.Empty;
        private static bool IS_DIRTY = true;
        
        private static void Initialize()
        {
            if (!IS_DIRTY)
                return;
            
            SCENE_LIST.Refresh();
            RefreshSceneLabel();
            IS_DIRTY = false;
        }

        public override void Update()
        {
            Initialize();
        }

        protected override void Draw(Rect rect)
        {
            Initialize();
            
            var rect0 = new Rect(rect.x, rect.y, rect.width - Styles.BUTTON_WIDTH * 2.0f, rect.height);
            var rect1 = new Rect(rect0.xMax, rect.y, Styles.BUTTON_WIDTH, rect.height);
            var rect2 = new Rect(rect1.xMax, rect.y, Styles.BUTTON_WIDTH, rect.height);
            DrawSceneDropDown(rect0);
            DrawSceneLoadToggle(rect1);
            DrawSceneAddButton(rect2);
        }

        private void DrawSceneDropDown(Rect rect)
        {
            if (GUI.Button(rect, SCENE_LABEL, styles.popup))
                ShowDropDown(rect);
        }

        private void DrawSceneLoadToggle(Rect rect)
        {
            bool isScenePickerSetAsAdditive = ToolbarScenePickerSettings.IsScenePickerSetAsAdditive;
            bool tempIsAdditive = EditorGUI.Toggle(rect, isScenePickerSetAsAdditive, styles.button);

            if (tempIsAdditive)
            {
#if !UNITY_6000_0_OR_NEWER
                GUI.Label(rect, styles.iconSceneAdditive, styles.labelCenter);
#endif
                GUI.Label(rect, Styles.LABEL_SCENE_ADDITIVE, styles.labelCenter);
            }
            else
            {
#if !UNITY_6000_0_OR_NEWER
                GUI.Label(rect, styles.iconSceneSingle, styles.labelCenter);
#endif
                GUI.Label(rect, Styles.LABEL_SCENE_SINGLE, styles.labelCenter);
            }

            if (tempIsAdditive != isScenePickerSetAsAdditive)
                ToolbarScenePickerSettings.IsScenePickerSetAsAdditive = tempIsAdditive;
        }

        private void DrawSceneAddButton(Rect rect)
        {
            if (GUI.Button(rect, styles.iconPlusSmall, styles.button))
            {
                try
                {
                    int selection = EditorUtility.DisplayDialogComplex("Create new scene", "How do you want to add the scene?", "Single", "Additive", "Cancel");

                    if (selection == 2)
                        return;
                
                    Scene scene = EditorSceneManager.NewScene(NewSceneSetup.EmptyScene, selection == 0 ? NewSceneMode.Single : NewSceneMode.Additive);
                
                    if (EditorUtility.DisplayDialog("Create new scene", "Save scene to disk?", "Yes", "No"))
                        EditorSceneManager.SaveScene(scene);
                }
                catch (Exception e)
                {
                    EditorUtility.DisplayDialog("Failed to add scene", e.Message, "Ok");
                }
            }
            
            GUI.Label(rect, Styles.LABEL_SCENE_CREATE, styles.labelCenter);
        }

        private static void ShowDropDown(Rect rect)
        {
            var menu = new GenericMenu();
                
            for (var i = 0; i < SCENE_LIST.labels.Length; i++)
            {
                int sceneIndex = i;
                menu.AddItem(SCENE_LIST.labels[i], SCENE_LIST.selected.Contains(i), () => SelectScene(sceneIndex));
            }
            
            menu.DropDown(rect);
        }

        private static void SelectScene(int index)
        {
            try
            {
                ScenePickerList.SceneElement scenes = SCENE_LIST.scenes[index];
                bool isScenePickerSetAsAdditive = ToolbarScenePickerSettings.IsScenePickerSetAsAdditive;
                
                for (var i = 0; i < scenes.paths.Count; i++)
                {
                    string path = scenes.paths[i];
                    Scene scene = SceneManager.GetSceneByPath(path);

                    if (scenes.isGroup)
                    {
                        if (isScenePickerSetAsAdditive || i != 0)
                        {
                            EditorSceneManager.OpenScene(path, OpenSceneMode.Additive);
                            int sceneIndex = SCENE_LIST.IndexOfPath(path, false);
                            
                            if (sceneIndex != -1)
                                SCENE_LIST.selected.Add(sceneIndex);
                        }
                        else
                        {
                            EditorSceneManager.OpenScene(path, OpenSceneMode.Single);
                            int sceneIndex = SCENE_LIST.IndexOfPath(path, false);
                            
                            SCENE_LIST.selected.Clear();
                            
                            if (sceneIndex != -1)
                                SCENE_LIST.selected.Add(index);
                        }
                    }
                    else
                    {
                        if (scene.isLoaded)
                        {
                            if (SceneManager.sceneCount == 1)
                                return;
                
                            EditorSceneManager.CloseScene(scene, true);
                            SCENE_LIST.selected.Remove(index);
                        }
                        else if (isScenePickerSetAsAdditive)
                        {
                            EditorSceneManager.OpenScene(path, OpenSceneMode.Additive);
                            SCENE_LIST.selected.Add(index);
                        }
                        else
                        {
                            EditorSceneManager.OpenScene(path, OpenSceneMode.Single);
                            SCENE_LIST.selected.Clear();
                            SCENE_LIST.selected.Add(index);
                        }
                    }
                }
                
                RefreshSceneLabel();
            }
            catch (Exception e)
            {
                Debug.LogException(e);
            }
        }

        private static void RefreshSceneLabel()
        {
            STRING_BUILDER.Clear();

            if (SCENE_LIST.selected.Count != 0)
            {
                for (var i = 0; i < SCENE_LIST.selected.Count; i++)
                {
                    if (i > 0)
                        STRING_BUILDER.Append(", ");

                    STRING_BUILDER.Append(SCENE_LIST.scenes[SCENE_LIST.selected[i]].shortname);
                }
            }
            else
            {
                STRING_BUILDER.Append("Unsaved scene(s)");
            }
            
            SCENE_LABEL = STRING_BUILDER.ToString();
        }
        
        public override float CalculateWidth()
        {
            return 100.0f + Styles.BUTTON_WIDTH * 2.0f;
        }

        public static void SetAsDirty()
        {
            IS_DIRTY = true;
        }
        
        private static class Styles
        {
#if UNITY_6000_0_OR_NEWER
            public static readonly GUIContent LABEL_SCENE_ADDITIVE = new GUIContent("A", "Additive scene loading (toogle to Single)");
            public static readonly GUIContent LABEL_SCENE_SINGLE = new GUIContent("S", "Single scene loading (toggle to Additive)");
#else
            public static readonly GUIContent LABEL_SCENE_ADDITIVE = new GUIContent(string.Empty, "Additive scene loading (toogle to Single)");
            public static readonly GUIContent LABEL_SCENE_SINGLE = new GUIContent(string.Empty, "Single scene loading (toggle to Additive)");
#endif
            
            public static readonly GUIContent LABEL_SCENE_CREATE = new GUIContent(string.Empty, "Create a new scene");
            public const float BUTTON_WIDTH = 24.0f;
        }
    }
}