# All files / tree useTreeMovement.ts

100% Statements 206/206
100% Branches 20/20
100% Functions 5/5
100% Lines 206/206

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     import type {
      FocusEventHandler,
      KeyboardEventHandler,
      MouseEventHandler,
    } from "react";
    import { useRef } from "react";
    import type { KeyboardMovementProviderImplementation } from "../movement";
    import {
      getNextFocusableIndex,
      useKeyboardMovementProvider,
    } from "../movement";
    import type { NonNullMutableRef } from "../types";
    import type { TreeItemMetadataLookup } from "./TreeProvider";
    import type { TreeData, TreeItemNode } from "./types";
    import type { TreeExpansion } from "./useTreeExpansion";
    import type { TreeItemChildIds } from "./useTreeItems";

    /**
     * This helps catch the edge case where the collapse transition has occurred for
     * a tree item group, but the user uses the `ArrowDown` key before it has
     * finished. So to do this:
     *
     * - find the parent group of the tree item
     * - find the tree item that controls the group (the element before the group)
     * - check if the `aria-expanded` state is `"false"` meaning it is considered
     *   closed
     *
     * @internal
     * @remarks \@since 6.0.0
     */
    const isParentItemCollapsing = (item: HTMLElement): boolean =>
      item
        .closest("[role='group']")
        ?.previousElementSibling?.getAttribute("aria-expanded") === "false";

    /**
     * @remarks \@since 6.0.0
     * @internal
     */
    const getVisibleTreeItems = (
      container: HTMLElement
    ): readonly HTMLElement[] => {
      const items = [
        ...container.querySelectorAll<HTMLElement>('[role="treeitem"]'),
      ];

      return items.filter(
        (item) =>
          // do not include items that have a `hidden` parent group
          item.offsetParent &&
          // do not include items that are about to become hidden
          !isParentItemCollapsing(item)
      );
    };

    /**
     * @remarks \@since 6.0.0
     * @internal
     */
    interface TreeMovementOptions<T extends TreeItemNode> extends TreeExpansion {
      data: TreeData<T>;
      onClick: MouseEventHandler<HTMLUListElement> | undefined;
      onFocus: FocusEventHandler<HTMLUListElement> | undefined;
      onKeyDown: KeyboardEventHandler<HTMLUListElement> | undefined;
      selectedIds: ReadonlySet<string>;
      treeItemChildIds: TreeItemChildIds;
    }

    /**
     * @remarks \@since 6.0.0
     * @internal
     */
    interface TreeMovement
      extends KeyboardMovementProviderImplementation<HTMLUListElement> {
      /**
       * This will be mutated by the `TreeItem` component and used to handle
       * keyboard movement.
       */
      metadataLookup: NonNullMutableRef<TreeItemMetadataLookup>;
    }

    /**
     * @remarks \@since 6.0.0
     * @internal
     */
    export function useTreeMovement<T extends TreeItemNode>(
      options: TreeMovementOptions<T>
    ): TreeMovement {
      const {
        onClick,
        onFocus,
        onKeyDown,
        data,
        expandedIds,
        selectedIds,
        treeItemChildIds,
        toggleTreeItemExpansion,
        expandMultipleTreeItems,
      } = options;

      const metadataLookup = useRef<TreeItemMetadataLookup>({
        expandable: {},
        disabledItems: {},
        elementToItem: {},
        itemToElement: {},
      });
      const movement = useKeyboardMovementProvider({
        onClick,
        onFocus,
        onKeyDown,
        extendKeyDown(movementData) {
          const { event, activeDescendantId, currentFocusIndex, setFocusIndex } =
            movementData;
          const { expandable, disabledItems, elementToItem, itemToElement } =
            metadataLookup.current;
          const itemId = elementToItem[activeDescendantId];
          const item = data[itemId];

          /* c8 ignore start */
          if (!item) {
            return;
          }
          /* c8 ignore end */

          const disabled = disabledItems[itemId];
          const expanded = expandedIds.has(itemId);

          let flagged = false;
          switch (event.key) {
            case "ArrowLeft":
              if (expanded && !disabled) {
                flagged = true;
                toggleTreeItemExpansion(itemId);
              } else if (item.parentId) {
                // do not flag for this case since setFocusIndex already does this
                const parentId = itemToElement[item.parentId];
                const focusables = getVisibleTreeItems(event.currentTarget);
                const index = focusables.findIndex(
                  (element) => element.id === parentId
                );
                setFocusIndex(index, focusables);
              }

              break;
            case "ArrowRight":
              if (expandable[itemId] && !disabled) {
                if (!expanded) {
                  flagged = true;
                  toggleTreeItemExpansion(itemId);
                } else {
                  // do not flag for this case since setFocusIndex already does this
                  const focusables = getVisibleTreeItems(event.currentTarget);
                  const index = getNextFocusableIndex({
                    loopable: false,
                    increment: true,
                    focusables,
                    includeDisabled: true,
                    currentFocusIndex: currentFocusIndex.current,
                  });

                  setFocusIndex(index, focusables);
                }
              }

              break;
            case "*": {
              flagged = true;
              const itemIds = treeItemChildIds.get(item.parentId);
              if (itemIds) {
                const expandableIds = [...itemIds].filter(
                  (itemId) => expandable[itemId]
                );
                if (expandableIds.length) {
                  expandMultipleTreeItems(
                    (prev) => new Set([...prev, ...expandableIds])
                  );
                  currentFocusIndex.current = -1;
                }
              }
              break;
            }
          }

          if (flagged) {
            event.stopPropagation();
            event.preventDefault();
          }
        },
        searchable: true,
        tabIndexBehavior: "virtual",
        getFocusableElements: getVisibleTreeItems,
        getDefaultFocusedIndex(options) {
          const { focusables } = options;
          const { elementToItem } = metadataLookup.current;

          return focusables.findIndex((element) =>
            selectedIds.has(elementToItem[element.id])
          );
        },
      });

      return {
        metadataLookup,
        ...movement,
      };
    }