import { usePageData, useRouteLocale } from '@vuepress/client'
import { computed } from 'vue'
import type { PlumeThemePageData } from '../../shared/index.js'
import { ensureStartingSlash } from '../utils/index.js'
import { useThemeData } from './themeData.js'
import { normalizePath } from './sidebar.js'

export function useLangs({
  removeCurrent = true,
  correspondingLink = false,
} = {}) {
  const page = usePageData<PlumeThemePageData>()
  const theme = useThemeData()
  const routeLocale = useRouteLocale()
  const currentLang = computed(() => {
    const link = routeLocale.value
    return {
      label: theme.value.locales?.[link]?.selectLanguageName,
      link,
    }
  })

  const addPath = computed(() => {
    if (page.value.frontmatter.home || (page.value.type && page.value.type !== 'friends'))
      return true

    return correspondingLink
  })

  const getBlogLink = (locale: string) => {
    const blog = theme.value.locales?.[`/${locale}/`]?.blog
    const defaultBlog = theme.value.locales?.['/']?.blog ?? theme.value.blog
    const link = blog?.link ? blog.link : normalizePath(`${locale}${defaultBlog?.link || 'blog/'}`)
    return link
  }

  const localeLinks = computed(() =>
    Object.entries(theme.value.locales || {}).flatMap(([key, value]) =>
      removeCurrent && currentLang.value.label === value.selectLanguageName
        ? []
        : {
            text: value.selectLanguageName,
            link: page.value.isBlogPost
              ? getBlogLink(key)
              : normalizeLink(
                key,
                addPath.value,
                page.value.path.slice(currentLang.value.link.length - 1),
                true,
              ),
          },
    ),
  )

  return { localeLinks, currentLang }
}

function normalizeLink(
  link: string,
  addPath: boolean,
  path: string,
  addExt: boolean,
) {
  return addPath
    ? link.replace(/\/$/, '')
    + ensureStartingSlash(
      path
        .replace(/(^|\/)?index.md$/, '$1')
        .replace(/\.md$/, addExt ? '.html' : ''),
    )
    : link
}