/**
 * 관리자 설정 화면 좌측 내비 구역 정의
 * @type {ReadonlyArray<{ heading: string, items: ReadonlyArray<{ id: string, label: string, keywords: string, iconId?: string }> }>}
 */
const ADMIN_SETTINGS_NAV_GROUPS = [
  {
    heading: '일반',
    items: [
      { id: 'admin-settings-section-title', label: '블로그 제목·설명', keywords: 'title description site name', iconId: 'title-desc' },
      { id: 'admin-settings-section-misc', label: '사이트 정보', keywords: 'logo url copyright favicon site info', iconId: 'site-info' },
      { id: 'admin-settings-section-social', label: 'SNS 정보', keywords: 'social follow sns x github instagram youtube rss', iconId: 'social' }
    ]
  },
  {
    heading: '게시물',
    items: [
      { id: 'admin-settings-section-post', label: 'POST 설정', keywords: 'post updated date display 수정일', iconId: 'post-settings' }
    ]
  },
  {
    heading: '사이트',
    items: [
      { id: 'admin-settings-section-home-cover', label: '메인 화면', keywords: 'home cover hero banner image', iconId: 'home-cover' },
      { id: 'admin-settings-section-brand', label: '브랜드', keywords: 'brand design accent color point 포인트 컬러', iconId: 'brand' },
      { id: 'admin-settings-section-announcement', label: '어나운스 바', keywords: 'announcement banner notice', iconId: 'announcement' },
      { id: 'admin-settings-section-site-code', label: '사이트 코드', keywords: 'ads ads.txt head footer script code adsense', iconId: 'site-code' },
      { id: 'admin-settings-section-ads', label: 'Ads', keywords: 'ads ad slot advertisement adsense 광고 애드센스', iconId: 'ads' }
    ]
  },
  {
    heading: '콘텐츠·안전',
    items: [
      { id: 'admin-settings-section-backup-summary', label: '사이트 용량', keywords: 'storage media count volume 용량 통계 사이트', iconId: 'post-export' },
      { id: 'admin-settings-section-export', label: '게시물 내보내기', keywords: 'export backup 내보내기', iconId: 'post-export' },
      { id: 'admin-settings-section-import', label: '게시물 가져오기', keywords: 'import restore 가져오기', iconId: 'post-import' },
      { id: 'admin-settings-section-spam', label: '스팸 필터', keywords: 'spam moderation comments', iconId: 'spam' }
    ]
  }
]

/**
 * 관리자 설정 내비게이션 검색과 스크롤 스파이 상태를 만든다.
 * @returns {{ mainScrollRef: import('vue').Ref<HTMLElement|null>, settingsNavGroups: typeof ADMIN_SETTINGS_NAV_GROUPS, filteredSettingsNavGroups: import('vue').ComputedRef<typeof ADMIN_SETTINGS_NAV_GROUPS>, navSearchInput: import('vue').Ref<string>, onNavSearchInput: (event: Event) => void, onNavSearchCompositionEnd: (event: Event) => void, activeSectionId: import('vue').Ref<string>, onMainScroll: () => void, refreshActiveSection: () => void, scrollToSection: (sectionId: string) => void, cleanupSettingsNavigation: () => void }}
 */
export const useAdminSettingsNavigation = () => {
  const mainScrollRef = ref(null)
  const navSearchQuery = ref('')
  const {
    displayValue: navSearchInput,
    onInput: onNavSearchInput,
    onCompositionEnd: onNavSearchCompositionEnd
  } = useImeSearchInput(navSearchQuery)
  const activeSectionId = ref(ADMIN_SETTINGS_NAV_GROUPS[0].items[0].id)
  const scrollSpySuspended = ref(false)
  let scrollSpyFrame = null

  /**
   * 검색어에 맞춰 내비 그룹을 필터링한다.
   * @returns {typeof ADMIN_SETTINGS_NAV_GROUPS} 표시할 그룹 목록
   */
  const filteredSettingsNavGroups = computed(() => {
    const q = navSearchQuery.value.trim().toLowerCase()
    if (!q) {
      return ADMIN_SETTINGS_NAV_GROUPS
    }

    return ADMIN_SETTINGS_NAV_GROUPS
      .map((group) => {
        const items = group.items.filter((item) => {
          const hay = `${item.label} ${item.keywords}`.toLowerCase()
          return hay.includes(q)
        })
        return { ...group, items }
      })
      .filter((group) => group.items.length > 0)
  })

  /**
   * 본문 스크롤 위치에 맞춰 활성 섹션 id를 갱신한다.
   * @returns {void}
   */
  const updateActiveSectionFromScroll = () => {
    const root = mainScrollRef.value
    if (!root || scrollSpySuspended.value) {
      return
    }

    const marker = root.getBoundingClientRect().top + 56
    let nextId = ADMIN_SETTINGS_NAV_GROUPS[0].items[0].id
    const flatIds = ADMIN_SETTINGS_NAV_GROUPS.flatMap((group) => group.items.map((item) => item.id))

    for (const id of flatIds) {
      const el = document.getElementById(id)
      if (!el) {
        continue
      }
      const top = el.getBoundingClientRect().top
      if (top <= marker) {
        nextId = id
      }
    }

    activeSectionId.value = nextId
  }

  /**
   * 스크롤 스파이 핸들러를 실행한다.
   * @returns {void}
   */
  const onMainScroll = () => {
    if (scrollSpyFrame) {
      cancelAnimationFrame(scrollSpyFrame)
    }
    scrollSpyFrame = requestAnimationFrame(() => {
      scrollSpyFrame = null
      updateActiveSectionFromScroll()
    })
  }

  /**
   * 해당 섹션으로 부드럽게 스크롤한다.
   * @param {string} sectionId - 섹션 요소 id
   * @returns {void}
   */
  const scrollToSection = (sectionId) => {
    const el = document.getElementById(sectionId)
    if (!el) {
      return
    }

    scrollSpySuspended.value = true
    activeSectionId.value = sectionId
    el.scrollIntoView({ behavior: 'smooth', block: 'start' })
    window.setTimeout(() => {
      scrollSpySuspended.value = false
      updateActiveSectionFromScroll()
    }, 520)
  }

  /**
   * 예약된 스크롤 스파이 프레임을 정리한다.
   * @returns {void}
   */
  const cleanupSettingsNavigation = () => {
    if (scrollSpyFrame) {
      cancelAnimationFrame(scrollSpyFrame)
      scrollSpyFrame = null
    }
  }

  return {
    mainScrollRef,
    settingsNavGroups: ADMIN_SETTINGS_NAV_GROUPS,
    filteredSettingsNavGroups,
    navSearchInput,
    onNavSearchInput,
    onNavSearchCompositionEnd,
    activeSectionId,
    onMainScroll,
    refreshActiveSection: updateActiveSectionFromScroll,
    scrollToSection,
    cleanupSettingsNavigation
  }
}