private drillLocate()

in packages/plugin-outline-pane/src/controllers/pane-controller.ts [454:568]
102 lines of code
23 McCabe index (conditional complexity)

  private drillLocate(treeNode: TreeNode, e: IPublicModelLocateEvent): IPublicModelDropLocation | null {
    const { canvas, project } = this.pluginContext;
    const document = project.getCurrentDocument();
    const { dragObject, globalY } = e;
    if (!dragObject) {
      return null;
    }

    if (!checkRecursion(treeNode.node, dragObject)) {
      return null;
    }

    if (isDragAnyObject(dragObject)) {
      // TODO: future
      return null;
    }

    const container = treeNode.node as IPublicModelNode;
    const detail: IPublicTypeLocationChildrenDetail = {
      type: IPublicTypeLocationDetailType.Children,
    };
    const locationData: any = {
      target: container,
      detail,
      source: this.id,
      event: e,
    };
    const isSlotContainer = treeNode.hasSlots();
    const isContainer = treeNode.isContainer();

    if (container.isSlotNode && !treeNode.expanded) {
      // 未展开，直接定位到内部第一个节点
      if (isSlotContainer) {
        detail.index = null;
        detail.focus = { type: 'slots' };
        detail.valid = false;
      } else {
        detail.index = 0;
        detail.valid = document?.checkNesting(container, dragObject);
      }
    }

    let items: TreeNode[] | null = null;
    let slotsRect: DOMRect | undefined;
    let focusSlots = false;
    // isSlotContainer
    if (isSlotContainer) {
      slotsRect = this.getTreeSlotsRect(treeNode);
      if (slotsRect) {
        if (globalY <= slotsRect.bottom) {
          focusSlots = true;
          items = treeNode.slots;
        } else if (!isContainer) {
          // 不在 slots 范围，又不是 container 的情况，高亮 slots 区
          detail.index = null;
          detail.focus = { type: 'slots' };
          detail.valid = false;
          return canvas.createLocation(locationData);
        }
      }
    }

    if (!items && isContainer) {
      items = treeNode.children;
    }

    if (!items) {
      return null;
    }

    const l = items.length;
    let index = 0;
    let before = l < 1;
    let current: TreeNode | undefined;
    let currentIndex = index;
    for (; index < l; index++) {
      current = items[index];
      currentIndex = index;
      const rect = this.getTreeNodeRect(current);
      if (!rect) {
        continue;
      }

      // rect
      if (globalY < rect.top) {
        before = true;
        break;
      }

      if (globalY > rect.bottom) {
        continue;
      }

      const loc = this.getNear(current, e, index, rect);
      if (loc) {
        return loc;
      }
    }

    if (focusSlots) {
      detail.focus = { type: 'slots' };
      detail.valid = false;
      detail.index = null;
    } else {
      if (current) {
        detail.index = before ? currentIndex : currentIndex + 1;
        detail.near = { node: current.node, pos: before ? 'before' : 'after' };
      } else {
        detail.index = l;
      }
      detail.valid = document?.checkNesting(container, dragObject);
    }

    return canvas.createLocation(locationData);
  }