Neg_Utils/UiToolkit/MultiSelectChips/MultiSelectChips.cs

using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UIElements;
#if UNITY_EDITOR
using UnityEditor;
#endif

namespace NEG.Utils.UiToolkits
{
    public class MultiSelectChips : VisualElement
    {
        private readonly VisualTreeAsset itemPrefab;
        private readonly List<MultiSelectChipItem> spawnedItems = new();

        private ICollection<IMultiSelectChipItem> itemsSource;

        private Label label;

        private VisualElement realItemsParent;

        public MultiSelectChips()
        {
#if UNITY_EDITOR
            string path =
                AssetDatabase.GUIDToAssetPath(AssetDatabase.FindAssets($"t:Script {nameof(MultiSelectChips)}")[0]);
            path = path.Remove(path.LastIndexOf('/'));

            SetVisuals(AssetDatabase.LoadAssetAtPath<VisualTreeAsset>($"{path}/Resources/MultiSelectChips.uxml"));
            itemPrefab = AssetDatabase.LoadAssetAtPath<VisualTreeAsset>($"{path}/Resources/MultiSelectChipItem.uxml");
#else
            SetVisuals(Resources.Load<VisualTreeAsset>("MultiSelectChips.uxml"));
            itemPrefab = Resources.Load<VisualTreeAsset>("MultiSelectChipItem.uxml");
#endif
        }

        public string LabelText
        {
            get => label.text;
            set
            {
                if (!string.IsNullOrEmpty(value))
                {
                    if (label == null) InitLabel();

                    label.text = value;
                }
                else if (label != null)
                {
                    label.RemoveFromHierarchy();
                    label = null;
                }
            }
        }

        public ICollection<IMultiSelectChipItem> ItemsSource
        {
            get => itemsSource;

            set
            {
                itemsSource = value;
                UpdateItems();
            }
        }

        public event Action<IMultiSelectChipItem> OnTryingToRemoveItem;
        public event Action<Rect> OnTryingToAddItem;

        public void UpdateItems()
        {
            if (itemPrefab == null || itemsSource == null || realItemsParent == null)
                return;

            var itemsToDestroy = new List<MultiSelectChipItem>(spawnedItems);

            itemsToDestroy.RemoveAll(x => itemsSource.Contains(x.ChipItem));

            foreach (var item in itemsToDestroy)
            {
                realItemsParent.Remove(item.VisualElement);
                spawnedItems.Remove(item);
            }

            List<IMultiSelectChipItem> itemsToAdd = new(itemsSource);

            foreach (var item in spawnedItems)
            {
                if (itemsToAdd.Contains(item.ChipItem))
                    itemsToAdd.Remove(item.ChipItem);
            }

            foreach (var item in itemsToAdd)
            {
                VisualElement chipItemVisuals = itemPrefab.Instantiate();
                realItemsParent.Insert(0, chipItemVisuals);
                spawnedItems.Add(new MultiSelectChipItem(chipItemVisuals, item, this));
            }
        }

        public void TryRemoveItem(IMultiSelectChipItem item) => OnTryingToRemoveItem?.Invoke(item);

        private void InitLabel()
        {
            label = new Label { pickingMode = PickingMode.Ignore };
            Insert(0, label);
        }

        private void SetVisuals(VisualTreeAsset treeAsset)
        {
            realItemsParent = treeAsset.Instantiate();
            Add(realItemsParent);

            var button = realItemsParent.Q<Button>("AddItem");

            button.clicked += () => OnTryingToAddItem?.Invoke(button.worldBound);

            realItemsParent = button.parent;
        }

        public new class UxmlFactory : UxmlFactory<MultiSelectChips, UxmlTraits>
        {
        }

        public new class UxmlTraits : VisualElement.UxmlTraits
        {
            private readonly UxmlStringAttributeDescription label;

            public UxmlTraits()
            {
                label = new UxmlStringAttributeDescription { name = "label" };
            }

            public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
            {
                base.Init(ve, bag, cc);
                ((MultiSelectChips)ve).LabelText = label.GetValueFromBag(bag, cc);
            }
        }
    }
}