import fs from 'fs'
import process from 'process'

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', ''),
  }
  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
}

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

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

getFiles('articles')
  .filter((path) => path.match(/index.md$/))
  .forEach((path) => {
    const metadata = readArticleMetadata(path)
    if (metadata) {
      fs.writeFileSync(
        `dist/${metadata.path}/index.html`,
        formatArticlePage(metadata, indexContent),
      )
      console.info(`Wrote dist/${metadata.path}/index.html`)
    }
  })