import {
  mdiCloseCircle,
  mdiCog,
  mdiFileDocumentOutline,
  mdiFileTreeOutline,
  mdiHome,
  mdiPlusCircle,
  mdiTableEdit,
} from '@mdi/js'
import { computed, onBeforeUnmount, onMounted, watch } from 'vue'
import { useRoute, useRouter } from 'vue-router'
import { SESSION_FORCE_LOGOUT_EVENT } from '@/services/session'
import { useAuthStore } from '@/stores/auth'
import { useBreadcrumbStore } from '@/stores/breadcrumbs'
import { useFavoritesStore } from '@/stores/favorites'
import { useMenuStore, type LayoutMenuItem } from '@/stores/menu'
import { useMessageStore } from '@/stores/messages'
import { useSnackbarStore } from '@/stores/snackbar'

const fixedMenuItems: LayoutMenuItem[] = [
  {
    title: '資料維護',
    navigable: false,
    subItems: [
      { title: '單筆資料維護', icon: mdiFileDocumentOutline, path: '/single-record-maintenance' },
      { title: '主從資料維護A', icon: mdiFileTreeOutline, path: '/master-detail-maintenance' },
      { title: '主從資料維護B', icon: mdiFileTreeOutline, path: '/master-detail-maintenance-b' },
      { title: '主從資料維護C', icon: mdiFileTreeOutline, path: '/master-detail-maintenance-c' },
      { title: '可編輯表格維護', icon: mdiTableEdit, path: '/editable-grid-maintenance' },
    ],
  },
  { title: '登入頁', path: '/login' },
]

const menuItemsExample: LayoutMenuItem[] = [
  { title: '首頁', icon: mdiHome, path: '/' },
  {
    title: '設定',
    icon: mdiCog,
    path: '/settings',
    navigable: false,
  },
  ...fixedMenuItems,
]

function buildMergedMenuItems(items: LayoutMenuItem[]) {
  const flatPaths = new Set<string>()
  const collectPaths = (list: LayoutMenuItem[]) => {
    for (const item of list || []) {
      if (item?.path) flatPaths.add(item.path)
      if (item?.subItems?.length) collectPaths(item.subItems)
    }
  }

  collectPaths(items)

  const mergeFixedItems = (list: LayoutMenuItem[]) => {
    return (list || []).map((item) => {
      if (!item?.subItems?.length) return item
      const subItems = item.subItems.filter((sub) => !sub?.path || !flatPaths.has(sub.path))
      return { ...item, subItems }
    })
  }

  const filteredFixedItems = mergeFixedItems(fixedMenuItems).filter((item) => {
    if (!item?.subItems?.length) return !item?.path || !flatPaths.has(item.path)
    return item.subItems.length > 0
  })

  return [...(items || []), ...filteredFixedItems]
}

type UseAppShellOptions = {
  onLogout?: () => void
}

export function useAppShell(options: UseAppShellOptions = {}) {
  const route = useRoute()
  const router = useRouter()
  const snackbar = useSnackbarStore()
  const authStore = useAuthStore()
  const menuStore = useMenuStore()
  const breadcrumbStore = useBreadcrumbStore()
  const favoritesStore = useFavoritesStore()
  const messageStore = useMessageStore()

  const mergedMenuItems = computed(() => buildMergedMenuItems(menuStore.menuItems))

  const mergedFavoriteItems = computed(() => {
    const combined = [...menuStore.favoriteItems, ...favoritesStore.layoutItems]
    const seen = new Set<string>()
    return combined.filter((item) => {
      const key = item.path ?? item.title
      if (!key) return false
      if (seen.has(key)) return false
      seen.add(key)
      return true
    })
  })

  const layoutProps = computed(() => {
    const layout = route.meta.layout
    if (layout === 'default') {
      return {
        systemTitle: '測試環境',
        favoriteItems: mergedFavoriteItems.value,
        menuItems: mergedMenuItems.value,
        breadcrumbItems: breadcrumbStore.breadcrumbItems,
      }
    }
    return {}
  })

  function handleSelect(item: LayoutMenuItem) {
    if (item.path) {
      router.push(item.path)
    }
  }

  function recursiveFindTitle(path: string, items: LayoutMenuItem[]): string | null {
    for (const item of items) {
      if (item.path === path) return item.title
      if (item.subItems?.length) {
        const found = recursiveFindTitle(path, item.subItems)
        if (found) return found
      }
    }
    return null
  }

  function findTitle(path: string) {
    const menuTitle = recursiveFindTitle(path, menuStore.menuItems)
    if (menuTitle) return menuTitle

    const favoriteTitle = recursiveFindTitle(path, menuStore.favoriteItems)
    if (favoriteTitle) return favoriteTitle

    const exampleTitle = recursiveFindTitle(path, menuItemsExample)
    if (exampleTitle) return exampleTitle

    if (path === '/') return '首頁'

    return path
  }

  function findMenuItem(path: string) {
    const recursiveFind = (items: LayoutMenuItem[]): LayoutMenuItem | null => {
      for (const item of items) {
        if (item.path === path) return item
        if (item.subItems?.length) {
          const found = recursiveFind(item.subItems)
          if (found) return found
        }
      }
      return null
    }

    return recursiveFind(mergedMenuItems.value)
  }

  const currentFavoriteInfo = computed(() => {
    const path = route.path
    const menuItem = findMenuItem(path)
    const title =
      menuItem?.title ||
      (typeof route.meta?.title === 'string' ? route.meta.title : null) ||
      findTitle(path)
    return {
      title,
      path,
      icon: menuItem?.icon,
    }
  })

  const isCurrentFavorite = computed(() => favoritesStore.isFavorite(route.path))
  const isFavoriteActionDisabled = computed(
    () => !currentFavoriteInfo.value?.path || route.path === '/'
  )
  const favoriteActionLabel = computed(() => (isCurrentFavorite.value ? '移除常用' : '加入常用'))
  const favoriteActionIcon = computed(() =>
    isCurrentFavorite.value ? mdiCloseCircle : mdiPlusCircle
  )

  function toggleFavoriteItem(item: LayoutMenuItem) {
    if (!item?.path || item.path === '/') return
    favoritesStore.toggle({
      title: item.title || findTitle(item.path),
      path: item.path,
      icon: item.icon,
    })
  }

  function toggleFavorite() {
    toggleFavoriteItem(currentFavoriteInfo.value)
  }

  function handleRemoveFavorite(item: LayoutMenuItem) {
    toggleFavoriteItem(item)
  }

  function goHome() {
    router.push('/')
  }

  function updateBreadcrumbs() {
    const resolvedTitle = findTitle(route.path)
    const fallbackTitle =
      resolvedTitle && resolvedTitle !== route.path
        ? resolvedTitle
        : typeof route.meta?.title === 'string'
          ? route.meta.title
          : null

    breadcrumbStore.setBreadcrumbs({
      path: route.path,
      menuItems: mergedMenuItems.value,
      favoriteItems: mergedFavoriteItems.value,
      fallbackTitle,
      homeLabel: '首頁',
      homeIcon: mdiHome,
    })
  }

  function handleLayoutAction(type: string) {
    if (type === 'messages') {
      messageStore.open()
    }
  }

  function performLogout(feedback: { message: string; color: string }) {
    authStore.logout()
    options.onLogout?.()
    snackbar.show(feedback)
    router.replace({ name: 'login' })
  }

  function handleLogout() {
    performLogout({ message: '登出成功', color: 'success' })
  }

  function handleForceLogout(event: Event) {
    const message = (event as CustomEvent)?.detail?.message || '請重新登入'
    performLogout({ message, color: 'warning' })
  }

  watch(
    [
      () => route.path,
      () => menuStore.menuItems,
      () => menuStore.favoriteItems,
      () => favoritesStore.items,
    ],
    () => updateBreadcrumbs(),
    { immediate: true, deep: true }
  )

  onMounted(() => {
    window.addEventListener(SESSION_FORCE_LOGOUT_EVENT, handleForceLogout)
  })

  onBeforeUnmount(() => {
    window.removeEventListener(SESSION_FORCE_LOGOUT_EVENT, handleForceLogout)
  })

  return {
    favoriteActionIcon,
    favoriteActionLabel,
    favoritesStore,
    goHome,
    handleLayoutAction,
    handleLogout,
    handleRemoveFavorite,
    handleSelect,
    isFavoriteActionDisabled,
    layoutProps,
    menuStore,
    mergedMenuItems,
    toggleFavorite,
  }
}