import path from 'path'
import fs from 'fs'
import rdir from 'recursive-readdir'
import mustache from 'mustache'
import { unified } from 'unified'
import remarkParser from 'remark-parse'
import remarkCompiler from 'remark-stringify'
import remarkFrontmatter from 'remark-frontmatter'
import remarkFrontmatterExtractor from 'remark-extract-frontmatter'
import { readSync } from 'to-vfile'
import yaml from 'js-yaml'
import { mdIntro } from './md-intro.mjs'

/*
 * There's an issue in crowdin where it changes the frontmatter marker:
 * ---
 * into this:
 * - - -
 * which breaks stuff. So this method takes the input and replaces all
 * - - - with ---
 */
export const fixCrowdinBugs = (md) => {
  md.value = md.value.split('- - -\n').join('---\n')
  return md
}

/*
 * Helper method to get the title and meta data from an MDX file
 *
 * Parameters:
 *
 *  - file: the full path to the file
 */
const mdxMetaInfo = async (file) => {
  let result
  try {
    result = await unified()
      .use(remarkParser)
      .use(remarkCompiler)
      .use(remarkFrontmatter)
      .use(remarkFrontmatterExtractor, { yaml: yaml.load })
      .process(fixCrowdinBugs(readSync(file, { encoding: 'utf-8' })))
  } catch (err) {
    console.log(err)
  }

  return result
}

/*
 * Helper method to get a list of MDX files in a folder.
 * Will traverse recursively to get all files from a given root folder.
 *
 * Parameters:
 *
 *  - folder: the root folder to look in
 *  - lang: the language files to looks for
 *
 *  Exported because it's also used by the Algolia index script
 */
export const getMdxFileList = async (folder, lang) => {
  let allFiles
  try {
    allFiles = await rdir(folder)
  } catch (err) {
    console.log(err)
    return false
  }

  // Filter out all that's not a language-specific markdown file
  // and avoid including the 'ui' files
  const files = []
  for (const file of allFiles) {
    if (file.slice(-5) === `${lang}.md`) files.push(file)
  }

  return files.sort()
}

/*
 * Helper method to get the website slug (path) from the file path
 */
export const fileToSlug = (file, site, lang) =>
  file.slice(-6) === `/${lang}.md` ? file.split(`/markdown/${site}/`).pop().slice(0, -6) : false

/*
 * Main method that does what needs doing
 */
export const prebuildDocs = async (site) => {
  // Say hi
  console.log()
  console.log(`Prebuilding docs pages for freesewing.${site}`)

  // Setup MDX root path

  const root = ['..', '..', 'markdown', site]
  if (site === 'org') root.push('docs')
  const mdxRoot = path.resolve(...root)

  // Load page template
  const template = fs.readFileSync(
    path.resolve('..', 'shared', 'page-templates', `docs.${site}.mjs.mustache`),
    'utf-8'
  )

  // Languages
  const locales = site === 'dev' ? ['en'] : ['en', 'fr', 'es', 'nl', 'de']

  const pages = {}

  // Loop over languages
  for (const lang of locales) {
    pages[lang] = {}
    // Get list of filenames
    const list = await getMdxFileList(mdxRoot, lang)

    // Loop over files
    for (const file of list) {
      const slug = fileToSlug(file, site, lang)
      const meta = await mdxMetaInfo(file)
      if (meta.data?.title) {
        pages[lang][slug] = { t: meta.data.title }
        if (meta.data.order) pages[lang][slug].o = `${meta.data.order}${meta.data.title}`
      } else {
        if (pages.en[slug]) {
          console.log(`⚠️l Falling back to EN metadata for ${slug}`)
          pages[lang][slug] = pages.en[slug]
        } else {
          console.log(`❌ [${lang}] Failed to extract meta info from: ${slug}`)
          if (meta.messages.length > 0) console.log(meta.messages)
        }
      }
      const intros = {}
      intros[lang] = await mdIntro(lang, site, slug)
      if (process.env.GENERATE_OG_IMAGES) {
        // Create og image
        await generateOgImage({ lang, site, slug, title: meta.data.title, intro: intros[lang] })
      }

      // Things to only do for English
      if (lang === 'en') {
        // Write page to disk
        const dir = path.resolve('..', site, 'pages', ...slug.split('/'))
        fs.mkdirSync(dir, { recursive: true })
        fs.writeFileSync(
          path.resolve(dir, `index.mjs`),
          mustache.render(template, {
            slug,
            slugArray: JSON.stringify(slug.split('/')),
            introEN: intros.en || 'fixme',
            introES: intros.es || 'fixme',
            introDE: intros.de || 'fixme',
            introFR: intros.fr || 'fixme',
            introNL: intros.nl || 'fixme',
          })
        )
      }
    }
  }

  return pages
}