import fs from 'fs'
import process from 'process'
import { Feed } from 'feed'

process.loadEnvFile()

function getFiles(dir: string): string[] {
  return fs.readdirSync(dir).flatMap((name) => {
    const path = `${dir}/${name}`
    if (fs.statSync(path).isDirectory()) {
      return getFiles(path)
    } else {
      return [path]
    }
  })
}

const METADATA_BLOCK_REGEX = /^---\n([\s\S]*?)---\n/m
const METADATA_REGEX = /^(\w+):(.*)$/gm

function readArticleMetadata(path: string): Record<string, string> | null {
  const content = fs.readFileSync(path, { encoding: 'utf8' })
  const match: RegExpExecArray | null = METADATA_BLOCK_REGEX.exec(content)
  if (!match || !match[1]) {
    console.warn(`No metadata for: ${path}`)
    return null
  }
  let subMatch: RegExpExecArray | null = null
  const metadata: Record<string, string> = {
    path: path.replaceAll('/index.md', ''),
  }
  const dateMatch = path.match(/(\d{4}\/\d{2}\/\d{2})/)
  if (dateMatch && dateMatch[1]) {
    metadata['date'] = dateMatch[1].replaceAll('/', '-')
  }
  do {
    subMatch = METADATA_REGEX.exec(match[1])
    if (subMatch && subMatch[1] && subMatch[2]) {
      metadata[subMatch[1]] = subMatch[2].trim()
    }
  } while (subMatch)
  return metadata
}

function formatArticlePage(metadata: Record<string, string>, baseHtml: string): string {
  let outHtml = baseHtml
  outHtml = outHtml.replace(/<.*?property="og:url".*?>/gm, '')
  outHtml = outHtml.replace(
    /<\/head>/gm,
    `<meta property="og:url" content="${process.env.VITE_BASE_URL}${metadata.path}/">\n</head>`,
  )
  const blog_title = process.env.VITE_APP_TITLE?.replace(/(<([^>]+)>)/gi, '').trim()
  if (metadata.title) {
    const title = metadata.title.replace(/(<([^>]+)>)/gi, '').trim()
    outHtml = outHtml.replace(/<title>.*?<\/title>/gm, `<title>${blog_title} — ${title}</title>`)
    outHtml = outHtml.replace(/<.*?property="og:title".*?>/gm, '')
    outHtml = outHtml.replace(
      /<\/head>/gm,
      `<meta property="og:title" content="${title}">\n</head>`,
    )
    outHtml = outHtml.replace(/<.*?property="og:description".*?>/gm, '')
    outHtml = outHtml.replace(
      /<\/head>/gm,
      `<meta property="og:description" content="${blog_title}">\n</head>`,
    )
  }
  if (metadata.thumbnail) {
    outHtml = outHtml.replace(/<.*?property="og:image".*?>/gm, '')
    outHtml = outHtml.replace(
      /<\/head>/gm,
      `<meta property="og:image" content="${metadata.thumbnail.replace('./', process.env.VITE_BASE_URL + metadata.path + '/')}">\n</head>`,
    )
  }
  return outHtml
}

function addFeedArticle(metadata: Record<string, string>, feed: Feed) {
  if (metadata.draft !== 'true') {
    feed.addItem({
      title: metadata.title.replace(/(<([^>]+)>)/gi, '').trim(),
      id: metadata.path,
      link: `${process.env.VITE_BASE_URL}${metadata.path}/`,
      date: new Date(Date.parse(metadata.date)),
      image: metadata.thumbnail.replace('./', process.env.VITE_BASE_URL + metadata.path + '/'),
    })
  }
}

const indexContent = fs.readFileSync('dist/index.html', { encoding: 'utf8' })

if (!indexContent) {
  console.error('Could not read dist/index.html')
  process.exit(1)
}

const metadatas = getFiles('articles')
  .filter((path) => path.match(/\d{4}\/\d{2}\/\d{2}\/index.md$/))
  .map((path) => readArticleMetadata(path))
  .filter((metadata) => !!metadata)

const feed = new Feed({
  title: process.env.VITE_APP_TITLE?.replace(/(<([^>]+)>)/gi, '').trim() ?? '',
  id: process.env.VITE_BASE_URL,
  link: process.env.VITE_BASE_URL,
  language: process.env.VITE_APP_LANG,
  favicon: process.env.VITE_BASE_URL + '/articles/favicon.ico',
  generator: 'md-blog',
  feedLinks: {
    json: process.env.VITE_BASE_URL + 'feed.json',
    atom: process.env.VITE_BASE_URL + 'atom.xml',
    rss: process.env.VITE_BASE_URL + 'rss',
  },
  updated: new Date(
    Math.max(
      0,
      ...metadatas
        .filter((metadata) => metadata.draft !== 'true')
        .map((metadata) => Date.parse(metadata.date)),
    ),
  ),
})

metadatas.forEach((metadata) => {
  fs.writeFileSync(`dist/${metadata.path}/index.html`, formatArticlePage(metadata, indexContent))
  console.info(`Wrote dist/${metadata.path}/index.html`)
  addFeedArticle(metadata, feed)
})

fs.writeFileSync('dist/feed.json', feed.json1())
fs.writeFileSync('dist/atom.xml', feed.atom1())
fs.writeFileSync('dist/rss', feed.rss2())