import { isAxiosError } from 'axios'

import { apiGet } from '@/lib/api'
import { switchLocalePath } from '@/lib/locales'
import { fetchTag, fetchTagByName } from '@/lib/tags'

import type { LocaleCode } from '@/lib/locales'
import type { LocaleSwitchRequest } from '@/lib/routeLocales'
import type { Tag, WikiAutolinkCandidate, WikiPage,
	      WikiPageChange, WikiTagReference } from '@/types'


export const fetchWikiAutolinkCandidates = (
    language: string,
    locale: LocaleCode,
): Promise<WikiAutolinkCandidate[]> =>
    apiGet ('/wiki/autolink_candidates', { locale, params: { language } })


export const fetchWikiChanges = (
    params: { id?: string },
    locale: LocaleCode = 'ja',
): Promise<WikiPageChange[]> => apiGet ('/wiki/changes', { locale, params })


export const fetchWikiPages = async (
    { title }:  { title?: string },
    locale: LocaleCode = 'ja',
): Promise<WikiPage[]> =>
    await apiGet ('/wiki', { locale, params: { title } })


export const fetchWikiPage = async (
    id:           string,
    { version }:  { version?: string },
    locale: LocaleCode = 'ja',
): Promise<WikiPage> =>
    await apiGet (`/wiki/${ encodeURIComponent (id) }`, {
	locale, params: version ? { version } : { } })


export const fetchWikiPageByTitle = async (
    title:        string,
    { version }:  { version?: string },
    locale: LocaleCode = 'ja',
): Promise<WikiPage | null> => {
  try
  {
    return await apiGet (`/wiki/title/${ encodeURIComponent (title) }`, { locale, params: { version } })
  }
  catch (error)
  {
    if (isAxiosError (error) && error.response?.status === 404)
      return null
    throw error
  }
}


export const fetchWikiPageByReference = async (
    reference: string,
    params: { version?: string },
    locale: LocaleCode,
): Promise<WikiPage | null> => {
  try
  {
    return /^\d+$/.test (reference)
	? await fetchWikiPage (reference, params, locale)
	: await fetchWikiPageByTitle (reference, params, locale)
  }
  catch (error)
  {
    if (!isAxiosError (error) || error.response?.status !== 404)
      throw error
    const tag = await fetchWikiTag ({ wikiId: reference }, locale)
    return tag == null ? null : fetchWikiPageByTitle (tag.name, params, locale)
  }
}


export const fetchWikiTag = async (
    reference: WikiTagReference,
    locale: LocaleCode,
): Promise<Tag | null> => {
  if ('name' in reference)
    return fetchTagByName (reference.name, locale)
  try
  {
    return await apiGet (`/wiki/${encodeURIComponent (reference.wikiId)}/tag`, { locale })
  }
  catch (error)
  {
    if (!isAxiosError (error) || error.response?.status !== 404)
      throw error
    return fetchTagByName (reference.wikiId, locale)
  }
}


export const switchWikiLocale = async (
    { location, params, locale, targetLocale }: LocaleSwitchRequest,
    view: 'detail' | 'edit' | 'diff' | 'history' = 'detail',
): Promise<string> => {
  const query = new URLSearchParams (location.search)
  const reference = params.title ?? params.id ?? query.get ('id')
  if (reference == null)
    return switchLocalePath (location, targetLocale)
  const page = await fetchWikiPageByReference (reference, { }, locale)
  const sourceTag = page == null ? await fetchWikiTag (
      /^\d+$/.test (reference) ? { wikiId: reference } : { name: reference }, locale) : null
  if (page == null && sourceTag == null)
    return switchLocalePath (location, targetLocale)
  const translated = page == null ? null
      : await fetchWikiPageByReference (String (page.id), { }, targetLocale)
  const tag = sourceTag != null
      ? await fetchTag (String (sourceTag.id), targetLocale)
      : ((translated == null && page?.resourceType === 'tag_description')
	 ? await fetchWikiTag ({ wikiId: String (page.id) }, targetLocale) : null)
  const destination = tag?.name ?? translated?.id ?? page?.id
  if (destination == null)
    throw new Error ('Wiki resource could not be resolved')
  for (const key of ['version', 'from', 'to'])
    query.delete (key)
  const historyId = view === 'history' ? translated?.id : null
  if (historyId != null)
    query.set ('id', String (historyId))
  else
    query.delete ('id')
  const suffix = (translated != null && (view === 'edit' || view === 'diff'))
      ? `/${view}` : ''
  return switchLocalePath ({
      pathname: view === 'history'
	  ? location.pathname
	  : `/wiki/${encodeURIComponent (destination)}${suffix}`,
      search: query.size === 0 ? '' : `?${query}`,
      hash: location.hash }, targetLocale)
}