canto/Assets/Scripts/UI/Screen/InventoryScreen.cs

using System.Collections.Generic;
using System.Linq;
using KitsuneCafe.ItemSystem;
using KitsuneCafe.SOAP;
using ObservableCollections;
using R3;
using UnityEngine;
using UnityEngine.UIElements;

namespace KitsuneCafe.UI
{
  public class InventoryScreen : MonoBehaviour
  {
    public const string ItemListIndicatorsName = "item-list-indicator-container";
    public const string ItemListName = "item-list";

    public const string ItemPreviewName = "item-preview";

    public const string ItemDetailsTitleName = "item-details-title-label";
    public const string ItemDetailsContentName = "item-details-content-label";

    [SerializeField]
    private UIDocument doc;

    [SerializeField]
    private Inventory inventory;

    [SerializeField]
    private VisualTreeAsset template;

    [SerializeField]
    private int displayCount = 5;

    [SerializeField]
    private ItemValue focusedItem;

    [SerializeField]
    private ItemValue selectedItem;

    [SerializeField]
    private FloatEvent inventoryInput;

    [SerializeField]
    private Vector2Value itemPreviewDelta;

    [SerializeField]
    private FloatValue itemZoom;

    [SerializeField]
    private ActionMapValue actionMap;

    private VisualElement root => doc.rootVisualElement;

    private List<VisualElement> indicators;
    private RecyclerView itemList;
    private VisualElement itemPreview;

    private void OnValidate()
    {
      if (doc == null)
      {
        doc = GetComponent<UIDocument>();
      }
    }

    private void Reset()
    {
      OnValidate();
    }

    private void ToggleVisibility()
    {
      root.visible = !root.visible;
    }

    private void Start()
    {
      root.visible = false;
      inventoryInput.AsObservable()
        .Subscribe(_ =>
        {
          ToggleVisibility();
          actionMap.Value = root.visible ? Input.ActionMap.UI : Input.ActionMap.Player;
        });

      CreateItemList();
      var preview = root.Q<PreviewView>();

      preview.RegisterCallback<RotateEvent>(evt =>
      {
        itemPreviewDelta.Value = evt.Delta;
      });

      preview.RegisterCallback<ZoomEvent>(evt =>
      {
        itemZoom.Value += evt.Amount;
      });
    }

    private void CreateItemList()
    {
      var indicatorContainer = root.Q<VisualElement>(ItemListIndicatorsName);
      indicators = indicatorContainer.Children().ToList();

      itemList = root.Q<RecyclerView>();
      itemList.ItemSource = inventory;

      itemList.RegisterCallback<FocusEvent>(evt =>
      {
        TrySetValue(focusedItem, evt.FocusedIndex);
      });

      itemList.RegisterCallback<NavigationSubmitEvent>(evt =>
      {
        TrySetValue(selectedItem, itemList.FocusedIndex);
      });

      itemList.RegisterCallback<NavigationCancelEvent>(evt =>
      {
        selectedItem.Value = null;
      });

      inventory.CollectionChanged += RebindItems;
    }

    private void TrySetValue(ReactiveValue<Item> value, int index)
    {
      if (inventory.TryGetValue(index, out var item))
      {
        value.Value = item.Item;
      }
      else
      {
        value.Value = null;
      }
    }

    private void RebindItems(in NotifyCollectionChangedEventArgs<InventoryItem> e)
    {
      itemList.Rebind();
    }
  }
}