import { useQuery } from '@tanstack/react-query'
import { AnimatePresence, LayoutGroup, MotionConfig, motion } from 'framer-motion'
import { Fragment, Suspense, lazy, useEffect, useLayoutEffect, useMemo, useState } from 'react'
import { useTranslation } from 'react-i18next'
import { createBrowserRouter,
	 Navigate,
	 Route,
	 RouterProvider,
	 Routes,
	 useLocation,
	 useParams } from 'react-router-dom'

import DevModeWatermark from '@/components/DevModeWatermark'
import RouteBlockerOverlay from '@/components/RouteBlockerOverlay'
import TopNav from '@/components/TopNav'
import DialogueProvider from '@/components/dialogues/DialogueProvider'
import PageHead from '@/components/common/PageHead'
import { Toaster } from '@/components/ui/toaster'
import { apiPost, isApiError } from '@/lib/api'
import { fetchLocales, isLocaleCode, legacyLocalePath, switchLocalePath } from '@/lib/locales'
import { localesKeys } from '@/lib/queryKeys'
import { requiredPageLocale } from '@/lib/routeLocales'
import { useLocale } from '@/lib/useLocale'
import { applyClientAnimationMode,
	 applyClientAppearance,
	 fetchUserThemeSlots,
	 fetchUserSettings,
	 getClientThemeMode,
	 hasStoredClientThemeSelection,
	 normaliseUserThemeSlots,
	 setCachedUserThemeSlots,
	 seedClientThemeMode } from '@/lib/settings'
import { useClientBehaviourSettings } from '@/lib/useClientBehaviourSettings'
import { UnsavedChangesGuardProvider } from '@/lib/useUnsavedChangesGuard'
import { KeyboardShortcutsProvider } from '@/lib/useKeyboardShortcuts'
import DeerjikistDetailPage from '@/pages/deerjikists/DeerjikistDetailPage'
import MaterialBasePage from '@/pages/materials/MaterialBasePage'
import MaterialDetailPage from '@/pages/materials/MaterialDetailPage'
import MaterialHistoryPage from '@/pages/materials/MaterialHistoryPage'
import MaterialListPage from '@/pages/materials/MaterialListPage'
import MaterialNewPage from '@/pages/materials/MaterialNewPage'
import MaterialSyncSuppressionsPage from '@/pages/materials/MaterialSyncSuppressionsPage'
import MorePage from '@/pages/MorePage'
import GekanatorUnavailablePage from '@/pages/GekanatorUnavailablePage'
import NicoTagListPage from '@/pages/tags/NicoTagListPage'
import NotFound from '@/pages/NotFound'
import TOSPage from '@/pages/TOSPage'
import HelpDetailPage from '@/pages/help/HelpDetailPage'
import HelpChangesPage from '@/pages/help/HelpChangesPage'
import HelpDiffPage from '@/pages/help/HelpDiffPage'
import HelpListPage from '@/pages/help/HelpListPage'
import PostDetailPage from '@/pages/posts/PostDetailPage'
import PostHistoryPage from '@/pages/posts/PostHistoryPage'
import PostNewPage from '@/pages/posts/PostNewPage'
import PostListPage from '@/pages/posts/PostListPage'
import PostSearchPage from '@/pages/posts/PostSearchPage'
import ServiceUnavailable from '@/pages/ServiceUnavailable'
import SettingPage from '@/pages/users/SettingPage'
import TagDetailPage from '@/pages/tags/TagDetailPage'
import TagHistoryPage from '@/pages/tags/TagHistoryPage'
import TagListPage from '@/pages/tags/TagListPage'
import TheatreDetailPage from '@/pages/theatres/TheatreDetailPage'
import WikiDetailPage from '@/pages/wiki/WikiDetailPage'
import WikiDiffPage from '@/pages/wiki/WikiDiffPage'
import WikiEditPage from '@/pages/wiki/WikiEditPage'
import WikiHistoryPage from '@/pages/wiki/WikiHistoryPage'
import WikiNewPage from '@/pages/wiki/WikiNewPage'
import WikiSearchPage from '@/pages/wiki/WikiSearchPage'

import type { Dispatch, FC, SetStateAction } from 'react'

import type { ClientAnimationMode } from '@/lib/settings'
import type { AvailableLocale } from '@/lib/locales'
import type { User } from '@/types'

const GekanatorPage = lazy (() => import ('@/pages/GekanatorPage'))


const GekanatorRoute = ({ user }: { user: User | null }) => {
  const locale = useLocale ()
  const location = useLocation ()
  const pageLocale = requiredPageLocale (location.pathname)

  if (pageLocale != null && pageLocale !== locale)
    return <GekanatorUnavailablePage/>

  return (
      <Suspense fallback={null}>
	<GekanatorPage user={user}/>
      </Suspense>)
}


const RouteTransitionWrapper = ({ animationMode, user, setUser }: {
    animationMode:  ClientAnimationMode
    user:           User | null
    setUser:        Dispatch<SetStateAction<User | null>> }) => {
  const location = useLocation ()

  const routes = (
      <Routes location={location}>
	<Route path="" element={<LocaleRedirect to="/posts"/>}/>
	<Route path="posts" element={<PostListPage/>}/>
	<Route path="posts/new" element={<PostNewPage user={user}/>}/>
	<Route path="posts/search" element={<PostSearchPage/>}/>
	<Route path="posts/:id" element={<PostDetailRoute user={user}/>}/>
	<Route path="posts/changes" element={<PostHistoryPage/>}/>
	<Route path="tags" element={<TagListPage/>}/>
	<Route path="tags/:id" element={<TagDetailPage/>}/>
	<Route path="tags/:id/deerjikists" element={<DeerjikistDetailPage/>}/>
	<Route path="tags/nico" element={<NicoTagListPage user={user}/>}/>
	<Route path="nico/tags" element={<NicoTagListPage user={user}/>}/>
	<Route path="tags/changes" element={<TagHistoryPage/>}/>
	<Route path="theatres/:id" element={<TheatreDetailPage user={user}/>}/>
	<Route path="materials" element={<MaterialBasePage/>}>
	  <Route index element={<MaterialListPage/>}/>
	  <Route path="changes" element={<MaterialHistoryPage/>}/>
	  <Route path="new" element={<MaterialNewPage/>}/>
	  <Route path="suppressions" element={<MaterialSyncSuppressionsPage/>}/>
	  <Route path=":id" element ={<MaterialDetailPage/>}/>
	</Route>
	<Route path="wiki" element={<WikiSearchPage/>}/>
	<Route path="wiki/:title" element={<WikiDetailPage/>}/>
	<Route path="wiki/new" element={<WikiNewPage user={user}/>}/>
	<Route path="wiki/:id/edit" element={<WikiEditPage user={user}/>}/>
	<Route path="wiki/:id/diff" element={<WikiDiffPage/>}/>
	<Route path="wiki/changes" element={<WikiHistoryPage/>}/>
	<Route path="help" element={<HelpListPage/>}/>
	<Route path="help/changes" element={<HelpChangesPage/>}/>
	<Route path="help/:identifier/diff" element={<HelpDiffPage/>}/>
	<Route path="help/:identifier" element={<HelpDetailPage/>}/>
	<Route path="users/settings" element={<SettingPage user={user} setUser={setUser}/>}/>
	<Route path="settings" element={<LocaleRedirect to="/users/settings"/>}/>
	<Route path="tos" element={<TOSPage/>}/>
	<Route path="gekanator" element={<GekanatorRoute user={user}/>}/>
	<Route path="more" element={<MorePage/>}/>
	<Route path="*" element={<NotFound/>}/>
      </Routes>)

  if (animationMode === 'off')
    return routes

  return (
      <AnimatePresence mode="wait">
	{routes}
      </AnimatePresence>)
}


const PostDetailRoute = ({ user }: { user: User | null }) => {
  const location = useLocation ()
  const key = location.pathname
  return <PostDetailPage key={key} user={user}/>
}


const RoutedApp = ({ locales }: { locales: AvailableLocale[] }) => {
  const [user, setUser] = useState<User | null> (null)
  const [status, setStatus] = useState (200)
  const behaviourSettings = useClientBehaviourSettings ()
  const animationMode = behaviourSettings.animation ?? 'normal'
  const LayoutWrapper = animationMode === 'off' ? Fragment : LayoutGroup

  const appLayoutTransition = useMemo (
      () => (
	  animationMode === 'off'
	  ? { duration: 0 }
	  : (animationMode === 'reduced'
	     ? { duration: .08, ease: 'linear' as const }
	     : { duration: .2, ease: 'easeOut' as const })
      ),
      [animationMode],
  )

  useEffect (() => {
    applyClientAppearance ()

    const mediaQuery = window.matchMedia ('(prefers-color-scheme: dark)')
    const handleThemeChange = () => {
      if (getClientThemeMode () === 'system')
	applyClientAppearance ()
    }

    mediaQuery.addEventListener ('change', handleThemeChange)
    return () => mediaQuery.removeEventListener ('change', handleThemeChange)
  }, [])

  useEffect (() => {
    applyClientAnimationMode (animationMode)
  }, [animationMode])

  useEffect (() => {
    const createUser = async () => {
      const data = await apiPost<{ code: string; user: User }> ('/users')
      if (data.code)
	{
	  localStorage.setItem ('user_code', data.code)
	  setUser (data.user)
	}
    }

    const code = localStorage.getItem ('user_code')
    if (code)
      {
	void (async () => {
	  try
	  {
	    const data = await apiPost<{ valid: boolean; user: User }> ('/users/verify', { code })
	    if (data.valid)
	      setUser (data.user)
	    else
	      await createUser ()
	  }
	  catch (err)
	  {
	    if (isApiError (err))
	      setStatus (err.response?.status ?? 200)
	  }
	}) ()
      }
    else
      createUser ()
  }, [])

  useEffect (() => {
    if (!(user))
      return

    void (async () => {
	try
	{
	  const [settings, themeSlots] = await Promise.all ([
	      fetchUserSettings (),
	      fetchUserThemeSlots (),
	  ])
	  const storedThemeSlots = normaliseUserThemeSlots (themeSlots)
	  setCachedUserThemeSlots (storedThemeSlots)
	  if (!(hasStoredClientThemeSelection ()))
	    seedClientThemeMode (settings.theme)
	  applyClientAppearance ()
	}
      catch
      {
	return
      }
    }) ()
  }, [user])

  switch (status)
  {
  case 503:
    return <ServiceUnavailable/>
  }

  return (
      <DialogueProvider>
	<PageHead/>
	<UnsavedChangesGuardProvider>
	  <KeyboardShortcutsProvider>
	  <MotionConfig
	      reducedMotion={
		  animationMode === 'normal'
		  ? 'never'
		  : animationMode === 'reduced'
		    ? 'user'
		    : 'always'
	      }>
	    <LayoutWrapper>
	      <motion.div
		  layout={animationMode === 'off' ? false : 'position'}
		  transition={{ layout: appLayoutTransition }}
		  className="relative flex h-dvh w-full flex-col overflow-y-hidden">
		<TopNav user={user} locales={locales}/>
		<RouteTransitionWrapper
		    animationMode={animationMode}
		    user={user}
		    setUser={setUser}/>
	      </motion.div>
	    </LayoutWrapper>
	  </MotionConfig>

	  <Toaster/>
	  </KeyboardShortcutsProvider>
	</UnsavedChangesGuardProvider>
      </DialogueProvider>)
}


const LocaleRoute: FC = () => {
  const { locale } = useParams ()
  const location = useLocation ()
  const { i18n } = useTranslation ()
  const { data, isPending, isError, refetch } = useQuery ({
      queryKey: localesKeys.index,
      queryFn: fetchLocales,
      staleTime: 0,
      refetchOnMount: 'always',
      refetchOnWindowFocus: 'always',
      refetchOnReconnect: 'always' })
  const activeLocale =
      (isLocaleCode (locale)
       && data?.locales.some (entry => entry.code === locale))
      ? locale
      : null

  useLayoutEffect (() => {
    if (activeLocale != null)
      document.documentElement.lang = activeLocale
    if (activeLocale != null && i18n.language !== activeLocale)
      void i18n.changeLanguage (activeLocale)
  }, [activeLocale, i18n])

  useEffect (() => {
    void refetch ()
  }, [location.key, refetch])

  const redirect = legacyLocalePath (location)
  if (!(isLocaleCode (locale)) && redirect == null)
    return <NotFound/>
  if (isError)
    return <ServiceUnavailable/>
  if (isPending)
    return null
  if (isLocaleCode (locale))
  {
    return data.locales.some (entry => entry.code === locale)
        ? <RoutedApp locales={data.locales}/>
        : <NotFound/>
  }

  return redirect == null ? <NotFound/> : <Navigate to={redirect} replace/>
}


const LocaleRedirect = ({ to }: { to: string }) => {
  const locale = useLocale ()
  const location = useLocation ()
  return <Navigate to={switchLocalePath ({ ...location, pathname: to }, locale)} replace/>
}


const router = createBrowserRouter ([
    { path: '/:locale/*', element: <LocaleRoute/> },
    { path: '*', element: <LocaleRoute/> }])


const App: FC = () => (
    <>
      <RouteBlockerOverlay/>
      {import.meta.env.DEV && <DevModeWatermark/>}
      <RouterProvider router={router}/>
    </>)


export default App