feat(core): menu hierarchy helper

packages/core/src/index.ts

@@ -39,3 +39,4 @@ export * from './overlays'
 export * from './block'
 export * from './recaptcha'
 export * from './recaptcha-field'
+export * from './menu'

packages/core/src/menu/MenuLevelBuilder.tsx

@@ -0,0 +1,67 @@
+import {ReactNode} from 'react'
+
+export interface BaseMenuItem {
+  id: string
+  title: ReactNode
+}
+
+export type MenuTree<Item extends BaseMenuItem> = Item & {
+  sub?: MenuTree<Item>[]
+}
+
+export class MenuLevel<Item extends BaseMenuItem> {
+  constructor(public items: Item[] = [], public activeId: string = '') {}
+}
+
+export class MenuLevelBuilder<Item extends BaseMenuItem> {
+  constructor(protected items: MenuTree<Item>[]) {}
+
+  protected buildLevels(
+    activeId: string,
+    items: MenuTree<Item>[],
+    levels: MenuLevel<Item>[],
+    depth = 0,
+    parentActive = false
+  ): boolean {
+    if (levels.length <= depth) levels[depth] = new MenuLevel()
+    const level = levels[depth]
+    let activeItem: MenuTree<Item> | undefined
+    for (let item of items) {
+      const currentActive = item.id === activeId
+      const sub = item.sub
+      const childActive =
+        sub && sub.length > 0
+          ? this.buildLevels(
+              activeId,
+              sub,
+              levels,
+              depth + 1,
+              currentActive || parentActive
+            )
+          : false
+      if (currentActive) activeItem = item
+      if (childActive && !activeItem) activeItem = item
+    }
+
+    if (activeItem) {
+      level.items = items
+      level.activeId = activeItem.id
+    } else if (parentActive) {
+      level.items = items
+      level.activeId = items[0].id
+    }
+
+    return !!activeItem
+  }
+
+  /**
+   * Split MenuTree structure to levels.
+   *
+   * @param activeId current menu item id
+   */
+  levels(activeId: string): MenuLevel<Item>[] {
+    const result: MenuLevel<Item>[] = []
+    this.buildLevels(activeId, this.items, result)
+    return result
+  }
+}

packages/core/src/menu/index.ts

@@ -0,0 +1 @@
+export * from './MenuLevelBuilder'