Menubar

---
/**
 * APG Menubar Pattern - Astro Implementation
 *
 * A horizontal bar of menu triggers that open dropdown menus.
 * Uses Web Components for enhanced control and proper focus management.
 *
 * @see https://www.w3.org/WAI/ARIA/apg/patterns/menubar/
 */

// MenuItem interface with discriminated union pattern
// type can be: 'item' | 'separator' | 'checkbox' | 'radio' | 'radiogroup' | 'submenu'
export interface MenuItem {
  type: string;
  id: string;
  label?: string;
  disabled?: boolean;
  checked?: boolean;
  name?: string; // for radiogroup
  items?: MenuItem[]; // for submenu and radiogroup
}

// Type guard helper for action items in submenus
type MenuItemAction = MenuItem & { type: 'item' | 'separator' };

export interface MenubarItem {
  id: string;
  label: string;
  items: MenuItem[];
}

export interface Props {
  items: MenubarItem[];
  class?: string;
  'aria-label'?: string;
  'aria-labelledby'?: string;
}

const {
  items = [],
  class: className = '',
  'aria-label': ariaLabel,
  'aria-labelledby': ariaLabelledby,
} = Astro.props;

// Generate unique ID for this instance
const instanceId = `menubar-${Math.random().toString(36).slice(2, 11)}`;
---

<apg-menubar>
  <nav class={`apg-menubar ${className}`.trim()}>
    <ul
      role="menubar"
      aria-label={ariaLabel}
      aria-labelledby={ariaLabelledby}
      class="apg-menubar-list"
      data-menubar
    >
      {
        items.map((menubarItem, index) => {
          const triggerId = `${instanceId}-${menubarItem.id}-trigger`;
          const menuId = `${instanceId}-${menubarItem.id}-menu`;
          const isFirstItem = index === 0;

          return (
            <li role="none">
              <span
                id={triggerId}
                role="menuitem"
                tabindex={isFirstItem ? 0 : -1}
                aria-haspopup="menu"
                aria-expanded="false"
                class="apg-menubar-trigger"
                data-menubar-trigger
                data-menubar-index={index}
              >
                {menubarItem.label}
                <svg
                  xmlns="http://www.w3.org/2000/svg"
                  width="12"
                  height="12"
                  viewBox="0 0 24 24"
                  fill="none"
                  stroke="currentColor"
                  stroke-width="2"
                  stroke-linecap="round"
                  stroke-linejoin="round"
                  aria-hidden="true"
                  style="position: relative; top: 1px; opacity: 0.7"
                >
                  <path d="m6 9 6 6 6-6" />
                </svg>
              </span>
              <ul
                id={menuId}
                role="menu"
                aria-labelledby={triggerId}
                class="apg-menubar-menu"
                aria-hidden="true"
                data-menubar-menu
                data-menubar-index={index}
              >
                {menubarItem.items.map((item) => {
                  if (item.type === 'separator') {
                    return (
                      <li role="none">
                        <hr role="separator" class="apg-menubar-separator" />
                      </li>
                    );
                  }

                  if (item.type === 'radiogroup') {
                    return (
                      <li role="none">
                        <ul role="group" aria-label={item.label} class="apg-menubar-group">
                          {item.items?.map((radioItem) => (
                            <li role="none">
                              <span
                                role="menuitemradio"
                                tabindex="-1"
                                aria-checked={radioItem.checked ? 'true' : 'false'}
                                aria-disabled={radioItem.disabled || undefined}
                                class="apg-menubar-menuitem apg-menubar-menuitemradio"
                                data-item-id={radioItem.id}
                                data-radio-group={item.name}
                              >
                                {radioItem.label}
                              </span>
                            </li>
                          ))}
                        </ul>
                      </li>
                    );
                  }

                  if (item.type === 'checkbox') {
                    return (
                      <li role="none">
                        <span
                          role="menuitemcheckbox"
                          tabindex="-1"
                          aria-checked={item.checked ? 'true' : 'false'}
                          aria-disabled={item.disabled || undefined}
                          class="apg-menubar-menuitem apg-menubar-menuitemcheckbox"
                          data-item-id={item.id}
                        >
                          {item.label}
                        </span>
                      </li>
                    );
                  }

                  if (item.type === 'submenu') {
                    const submenuTriggerId = `${instanceId}-${item.id}-submenu-trigger`;
                    const submenuId = `${instanceId}-${item.id}-submenu`;

                    return (
                      <li role="none" class="apg-menubar-submenu-container">
                        <span
                          id={submenuTriggerId}
                          role="menuitem"
                          tabindex="-1"
                          aria-haspopup="menu"
                          aria-expanded="false"
                          aria-disabled={item.disabled || undefined}
                          class="apg-menubar-menuitem apg-menubar-submenu-trigger"
                          data-item-id={item.id}
                          data-submenu-trigger
                        >
                          {item.label}
                          <svg
                            xmlns="http://www.w3.org/2000/svg"
                            width="12"
                            height="12"
                            viewBox="0 0 24 24"
                            fill="none"
                            stroke="currentColor"
                            stroke-width="2"
                            stroke-linecap="round"
                            stroke-linejoin="round"
                            aria-hidden="true"
                            style="margin-left: auto; position: relative; top: 1px"
                          >
                            <path d="m9 18 6-6-6-6" />
                          </svg>
                        </span>
                        <ul
                          id={submenuId}
                          role="menu"
                          aria-labelledby={submenuTriggerId}
                          class="apg-menubar-submenu"
                          aria-hidden="true"
                          data-submenu
                        >
                          {(item.items ?? [])
                            .filter(
                              (subItem): subItem is MenuItemAction =>
                                subItem.type === 'item' || subItem.type === 'separator'
                            )
                            .map((subItem) => {
                              if (subItem.type === 'separator') {
                                return (
                                  <li role="none">
                                    <hr role="separator" class="apg-menubar-separator" />
                                  </li>
                                );
                              }
                              return (
                                <li role="none">
                                  <span
                                    role="menuitem"
                                    tabindex="-1"
                                    aria-disabled={subItem.disabled || undefined}
                                    class="apg-menubar-menuitem"
                                    data-item-id={subItem.id}
                                  >
                                    {subItem.label}
                                  </span>
                                </li>
                              );
                            })}
                        </ul>
                      </li>
                    );
                  }

                  // Default: action item
                  return (
                    <li role="none">
                      <span
                        role="menuitem"
                        tabindex="-1"
                        aria-disabled={item.disabled || undefined}
                        class="apg-menubar-menuitem"
                        data-item-id={item.id}
                      >
                        {item.label}
                      </span>
                    </li>
                  );
                })}
              </ul>
            </li>
          );
        })
      }
    </ul>
  </nav>
</apg-menubar>

<script>
  class ApgMenubar extends HTMLElement {
    private menubar: HTMLUListElement | null = null;
    private menubarItems: HTMLElement[] = [];
    private rafId: number | null = null;

    // State
    private openMenuIndex = -1;
    private focusedMenubarIndex = 0;
    private typeAheadBuffer = '';
    private typeAheadTimeoutId: number | null = null;
    private readonly typeAheadTimeout = 500;

    // Checkbox/Radio states (stored separately since we're modifying aria-checked)
    private checkboxStates: Map<string, boolean> = new Map();
    private radioStates: Map<string, string> = new Map(); // group name -> checked id

    connectedCallback() {
      this.rafId = requestAnimationFrame(() => this.initialize());
    }

    private initialize() {
      this.rafId = null;
      this.menubar = this.querySelector('[data-menubar]');

      if (!this.menubar) {
        console.warn('apg-menubar: menubar element not found');
        return;
      }

      this.menubarItems = Array.from(
        this.menubar.querySelectorAll<HTMLElement>('[data-menubar-trigger]')
      );

      // Initialize checkbox/radio states from aria-checked
      this.initializeCheckboxRadioStates();

      // Attach event listeners
      this.menubar.addEventListener('click', this.handleClick);
      this.menubar.addEventListener('keydown', this.handleKeyDown);
      this.menubar.addEventListener('mouseover', this.handleMouseOver);
      document.addEventListener('pointerdown', this.handleClickOutside);
    }

    disconnectedCallback() {
      if (this.rafId !== null) {
        cancelAnimationFrame(this.rafId);
        this.rafId = null;
      }
      if (this.typeAheadTimeoutId !== null) {
        clearTimeout(this.typeAheadTimeoutId);
        this.typeAheadTimeoutId = null;
      }
      document.removeEventListener('pointerdown', this.handleClickOutside);
      this.menubar?.removeEventListener('click', this.handleClick);
      this.menubar?.removeEventListener('keydown', this.handleKeyDown);
      this.menubar?.removeEventListener('mouseover', this.handleMouseOver);
    }

    private initializeCheckboxRadioStates() {
      // Checkboxes
      const checkboxes = this.querySelectorAll<HTMLElement>('[role="menuitemcheckbox"]');
      checkboxes.forEach((cb) => {
        const id = cb.dataset.itemId;
        if (id) {
          this.checkboxStates.set(id, cb.getAttribute('aria-checked') === 'true');
        }
      });

      // Radio groups
      const radios = this.querySelectorAll<HTMLElement>('[role="menuitemradio"]');
      radios.forEach((radio) => {
        const id = radio.dataset.itemId;
        const group = radio.dataset.radioGroup;
        if (id && group && radio.getAttribute('aria-checked') === 'true') {
          this.radioStates.set(group, id);
        }
      });
    }

    private getMenuForIndex(index: number): HTMLElement | null {
      return this.querySelector(`[data-menubar-menu][data-menubar-index="${index}"]`);
    }

    private getMenuItems(menu: HTMLElement): HTMLElement[] {
      // Get direct menu items (not submenu items)
      // Note: Disabled items ARE included - they should be focusable but not activatable per APG
      const items: HTMLElement[] = [];
      const allItems = menu.querySelectorAll<HTMLElement>(
        '[role="menuitem"], [role="menuitemcheckbox"], [role="menuitemradio"]'
      );
      allItems.forEach((item) => {
        // Exclude items that are inside a nested submenu
        const parentMenu = item.closest('[role="menu"]');
        if (parentMenu === menu) {
          items.push(item);
        }
      });
      return items;
    }

    private openMenu(menubarIndex: number, focusPosition: 'first' | 'last' = 'first') {
      // Close any open menu first
      if (this.openMenuIndex >= 0 && this.openMenuIndex !== menubarIndex) {
        this.closeMenu();
      }

      const trigger = this.menubarItems[menubarIndex];
      const menu = this.getMenuForIndex(menubarIndex);
      if (!trigger || !menu) return;

      this.openMenuIndex = menubarIndex;
      trigger.setAttribute('aria-expanded', 'true');
      menu.setAttribute('aria-hidden', 'false');

      // Focus first/last available item
      const menuItems = this.getMenuItems(menu);
      if (menuItems.length > 0) {
        const targetIndex = focusPosition === 'first' ? 0 : menuItems.length - 1;
        menuItems[targetIndex]?.focus();
      }
    }

    private closeMenu() {
      if (this.openMenuIndex < 0) return;

      const trigger = this.menubarItems[this.openMenuIndex];
      const menu = this.getMenuForIndex(this.openMenuIndex);

      if (trigger) {
        trigger.setAttribute('aria-expanded', 'false');
      }
      if (menu) {
        menu.setAttribute('aria-hidden', 'true');

        // Close any open submenus
        const submenus = menu.querySelectorAll('[data-submenu]');
        submenus.forEach((submenu) => {
          submenu.setAttribute('aria-hidden', 'true');
          const submenuTrigger = submenu
            .closest('.apg-menubar-submenu-container')
            ?.querySelector('[data-submenu-trigger]');
          submenuTrigger?.setAttribute('aria-expanded', 'false');
        });
      }

      // Clear type-ahead
      this.typeAheadBuffer = '';
      if (this.typeAheadTimeoutId !== null) {
        clearTimeout(this.typeAheadTimeoutId);
        this.typeAheadTimeoutId = null;
      }

      this.openMenuIndex = -1;
    }

    private closeAllMenus() {
      this.closeMenu();
    }

    private updateMenubarTabindex(newIndex: number) {
      this.menubarItems.forEach((item, idx) => {
        item.tabIndex = idx === newIndex ? 0 : -1;
      });
      this.focusedMenubarIndex = newIndex;
    }

    private handleClick = (event: MouseEvent) => {
      if (!(event.target instanceof HTMLElement)) {
        return;
      }
      const target = event.target;

      // Handle menubar trigger click
      const menubarTrigger = target.closest('[data-menubar-trigger]');
      if (menubarTrigger instanceof HTMLElement) {
        const index = parseInt(menubarTrigger.dataset.menubarIndex || '0', 10);
        if (this.openMenuIndex === index) {
          this.closeMenu();
        } else {
          this.openMenu(index);
        }
        return;
      }

      // Handle submenu trigger click
      const submenuTrigger = target.closest('[data-submenu-trigger]');
      if (
        submenuTrigger instanceof HTMLElement &&
        submenuTrigger.getAttribute('aria-disabled') !== 'true'
      ) {
        const isExpanded = submenuTrigger.getAttribute('aria-expanded') === 'true';
        if (isExpanded) {
          const container = submenuTrigger.closest('.apg-menubar-submenu-container');
          const submenu = container?.querySelector('[data-submenu]');
          if (submenu instanceof HTMLElement) {
            this.closeSubmenu(submenu);
          }
        } else {
          this.openSubmenu(submenuTrigger);
        }
        return;
      }

      // Handle menu item click
      const menuItem = target.closest(
        '[role="menuitem"], [role="menuitemcheckbox"], [role="menuitemradio"]'
      );
      if (menuItem instanceof HTMLElement && menuItem.getAttribute('aria-disabled') !== 'true') {
        this.activateItem(menuItem);
      }
    };

    private handleMouseOver = (event: MouseEvent) => {
      // Only handle hover switching when a menu is already open
      if (this.openMenuIndex < 0) return;

      if (!(event.target instanceof HTMLElement)) {
        return;
      }
      const target = event.target;
      const menubarTrigger = target.closest('[data-menubar-trigger]');
      if (menubarTrigger instanceof HTMLElement) {
        const index = parseInt(menubarTrigger.dataset.menubarIndex || '0', 10);
        if (index !== this.openMenuIndex) {
          this.openMenu(index);
        }
      }
    };

    private handleKeyDown = (event: KeyboardEvent) => {
      if (!(event.target instanceof HTMLElement)) {
        return;
      }
      const target = event.target;

      // Determine if we're on menubar or inside menu
      const isOnMenubar = target.hasAttribute('data-menubar-trigger');
      const isInMenu = target.closest('[data-menubar-menu]') || target.closest('[data-submenu]');

      if (isOnMenubar) {
        this.handleMenubarKeyDown(event, target);
      } else if (isInMenu) {
        this.handleMenuKeyDown(event, target);
      }
    };

    private handleMenubarKeyDown(event: KeyboardEvent, target: HTMLElement) {
      const index = parseInt(target.dataset.menubarIndex || '0', 10);

      switch (event.key) {
        case 'ArrowRight': {
          event.preventDefault();
          const nextIndex = (index + 1) % this.menubarItems.length;
          this.updateMenubarTabindex(nextIndex);
          this.menubarItems[nextIndex]?.focus();
          if (this.openMenuIndex >= 0) {
            this.openMenu(nextIndex);
          }
          break;
        }
        case 'ArrowLeft': {
          event.preventDefault();
          const prevIndex = index === 0 ? this.menubarItems.length - 1 : index - 1;
          this.updateMenubarTabindex(prevIndex);
          this.menubarItems[prevIndex]?.focus();
          if (this.openMenuIndex >= 0) {
            this.openMenu(prevIndex);
          }
          break;
        }
        case 'ArrowDown':
        case 'Enter':
        case ' ': {
          event.preventDefault();
          this.openMenu(index, 'first');
          break;
        }
        case 'ArrowUp': {
          event.preventDefault();
          this.openMenu(index, 'last');
          break;
        }
        case 'Home': {
          event.preventDefault();
          this.updateMenubarTabindex(0);
          this.menubarItems[0]?.focus();
          break;
        }
        case 'End': {
          event.preventDefault();
          const lastIndex = this.menubarItems.length - 1;
          this.updateMenubarTabindex(lastIndex);
          this.menubarItems[lastIndex]?.focus();
          break;
        }
        case 'Escape': {
          event.preventDefault();
          this.closeMenu();
          break;
        }
        case 'Tab': {
          // Close menus when Tab is pressed from menubar
          this.closeAllMenus();
          break;
        }
      }
    }

    private handleMenuKeyDown(event: KeyboardEvent, target: HTMLElement) {
      const isSubmenuTrigger = target.hasAttribute('data-submenu-trigger');

      // Get the current menu context
      const currentMenu = target.closest('[role="menu"]');
      if (!(currentMenu instanceof HTMLElement)) {
        return;
      }

      const menuItems = this.getMenuItems(currentMenu);
      const currentIndex = menuItems.indexOf(target);

      switch (event.key) {
        case 'ArrowDown': {
          event.preventDefault();
          if (currentIndex >= 0) {
            const nextIndex = (currentIndex + 1) % menuItems.length;
            menuItems[nextIndex]?.focus();
          }
          break;
        }
        case 'ArrowUp': {
          event.preventDefault();
          if (currentIndex >= 0) {
            const prevIndex = currentIndex === 0 ? menuItems.length - 1 : currentIndex - 1;
            menuItems[prevIndex]?.focus();
          }
          break;
        }
        case 'ArrowRight': {
          event.preventDefault();
          if (isSubmenuTrigger) {
            // Open submenu
            this.openSubmenu(target);
          } else {
            // Move to next menubar item
            const nextIndex = (this.openMenuIndex + 1) % this.menubarItems.length;
            this.updateMenubarTabindex(nextIndex);
            this.openMenu(nextIndex);
          }
          break;
        }
        case 'ArrowLeft': {
          event.preventDefault();
          const parentSubmenu = target.closest('[data-submenu]');
          if (parentSubmenu instanceof HTMLElement) {
            // Close submenu and return to parent
            this.closeSubmenu(parentSubmenu);
          } else {
            // Move to previous menubar item
            const prevIndex =
              this.openMenuIndex === 0 ? this.menubarItems.length - 1 : this.openMenuIndex - 1;
            this.updateMenubarTabindex(prevIndex);
            this.openMenu(prevIndex);
          }
          break;
        }
        case 'Home': {
          event.preventDefault();
          menuItems[0]?.focus();
          break;
        }
        case 'End': {
          event.preventDefault();
          menuItems[menuItems.length - 1]?.focus();
          break;
        }
        case 'Enter':
        case ' ': {
          event.preventDefault();
          if (isSubmenuTrigger) {
            this.openSubmenu(target);
          } else {
            this.activateItem(target);
          }
          break;
        }
        case 'Escape': {
          event.preventDefault();
          const parentSubmenu = target.closest('[data-submenu]');
          if (parentSubmenu instanceof HTMLElement) {
            this.closeSubmenu(parentSubmenu);
          } else {
            this.closeMenu();
            this.menubarItems[this.focusedMenubarIndex]?.focus();
          }
          break;
        }
        case 'Tab': {
          this.closeAllMenus();
          break;
        }
        default: {
          // Type-ahead
          if (event.key.length === 1 && !event.ctrlKey && !event.metaKey && !event.altKey) {
            event.preventDefault();
            this.handleTypeAhead(event.key, menuItems, currentIndex);
          }
        }
      }
    }

    private openSubmenu(trigger: HTMLElement) {
      const container = trigger.closest('.apg-menubar-submenu-container');
      const submenu = container?.querySelector('[data-submenu]');
      if (!(submenu instanceof HTMLElement)) {
        return;
      }

      trigger.setAttribute('aria-expanded', 'true');
      submenu.setAttribute('aria-hidden', 'false');

      // Focus first item in submenu
      const items = this.getMenuItems(submenu);
      items[0]?.focus();
    }

    private closeSubmenu(submenu: HTMLElement) {
      const container = submenu.closest('.apg-menubar-submenu-container');
      const trigger = container?.querySelector('[data-submenu-trigger]');
      if (trigger instanceof HTMLElement) {
        trigger.setAttribute('aria-expanded', 'false');
        trigger.focus();
      }
      submenu.setAttribute('aria-hidden', 'true');
    }

    private activateItem(item: HTMLElement) {
      // Disabled items should not be activatable
      if (item.getAttribute('aria-disabled') === 'true') {
        return;
      }

      const role = item.getAttribute('role');
      const itemId = item.dataset.itemId;

      if (role === 'menuitemcheckbox') {
        // Toggle checkbox
        const currentChecked = item.getAttribute('aria-checked') === 'true';
        const newChecked = !currentChecked;
        item.setAttribute('aria-checked', String(newChecked));
        if (itemId) {
          this.checkboxStates.set(itemId, newChecked);
        }
        this.dispatchEvent(
          new CustomEvent('checkboxchange', {
            detail: { itemId, checked: newChecked },
            bubbles: true,
          })
        );
        // Don't close menu for checkbox
        return;
      }

      if (role === 'menuitemradio') {
        // Update radio group
        const group = item.dataset.radioGroup;
        if (group) {
          // Uncheck all radios in the group
          const groupRadios = this.querySelectorAll<HTMLElement>(
            `[role="menuitemradio"][data-radio-group="${group}"]`
          );
          groupRadios.forEach((radio) => {
            radio.setAttribute('aria-checked', 'false');
          });
          // Check the selected one
          item.setAttribute('aria-checked', 'true');
          if (itemId) {
            this.radioStates.set(group, itemId);
          }
          this.dispatchEvent(
            new CustomEvent('radiochange', {
              detail: { group, itemId },
              bubbles: true,
            })
          );
        }
        // Don't close menu for radio
        return;
      }

      // Regular menu item - dispatch event and close
      if (itemId) {
        this.dispatchEvent(
          new CustomEvent('itemselect', {
            detail: { itemId },
            bubbles: true,
          })
        );
      }
      this.closeAllMenus();
      this.menubarItems[this.focusedMenubarIndex]?.focus();
    }

    private handleTypeAhead(char: string, menuItems: HTMLElement[], currentIndex: number) {
      if (menuItems.length === 0) return;

      if (this.typeAheadTimeoutId !== null) {
        clearTimeout(this.typeAheadTimeoutId);
      }

      this.typeAheadBuffer += char.toLowerCase();

      const buffer = this.typeAheadBuffer;
      const isSameChar = buffer.length > 1 && buffer.split('').every((c) => c === buffer[0]);

      let startIndex: number;
      let searchStr: string;

      if (isSameChar) {
        this.typeAheadBuffer = buffer[0];
        searchStr = buffer[0];
        startIndex = currentIndex >= 0 ? (currentIndex + 1) % menuItems.length : 0;
      } else if (buffer.length === 1) {
        searchStr = buffer;
        startIndex = currentIndex >= 0 ? (currentIndex + 1) % menuItems.length : 0;
      } else {
        searchStr = buffer;
        startIndex = currentIndex >= 0 ? currentIndex : 0;
      }

      for (let i = 0; i < menuItems.length; i++) {
        const index = (startIndex + i) % menuItems.length;
        const item = menuItems[index];
        const label = item.textContent?.trim().toLowerCase() || '';
        if (label.startsWith(searchStr)) {
          item.focus();
          break;
        }
      }

      this.typeAheadTimeoutId = window.setTimeout(() => {
        this.typeAheadBuffer = '';
        this.typeAheadTimeoutId = null;
      }, this.typeAheadTimeout);
    }

    private handleClickOutside = (event: PointerEvent) => {
      const target = event.target as Node;
      if (this.openMenuIndex >= 0 && !this.contains(target)) {
        this.closeAllMenus();
      }
    };
  }

  if (!customElements.get('apg-menubar')) {
    customElements.define('apg-menubar', ApgMenubar);
  }
</script>

---
import Menubar, { type MenubarItem } from '@patterns/menubar/Menubar.astro';
import '@patterns/menubar/menubar.css';

const menuItems: MenubarItem[] = [
  {
    id: 'file',
    label: 'File',
    items: [
      { type: 'item', id: 'new', label: 'New' },
      { type: 'item', id: 'save', label: 'Save' },
    ],
  },
];
---

<Menubar items={menuItems} aria-label="Application" />