// server/routes/robots.txt.ts
type RobotsConfig = {
  userAgent?: string | string[]
  allow?: string[]
  disallow?: string[]
  sitemap?: string | string[]
  host?: string
  cache?: { sMaxAge?: number; staleWhileRevalidate?: number }
}

export default defineEventHandler(async event => {
  const host =
    (getHeader(event, 'host') || getRequestHost(event)).toString() || ''
  const baseDomain = process.env.BASE_DOMAIN
  const isGameAliasExtractable = host.includes(baseDomain)

  let gameAlias = ''
  if (isGameAliasExtractable) {
    gameAlias = host.split('.')[0].replace(/-dev$/, '')
  }

  let config: RobotsConfig

  try {
    const staticUrl = process.env.STATIC_URL
    const runType = process.env.RUN_TYPE

    // gameAlias가 있을 때만 sitemap 포함
    const sitemapUrl = gameAlias
      ? [`${staticUrl}/${runType}/template/${gameAlias}/sitemap.xml`]
      : undefined

    config = {
      userAgent: '*',
      allow: ['/'],
      disallow: ['/error', '/inspection/*', '/html/*'],
      sitemap: sitemapUrl,
      host: gameAlias ? `${gameAlias}.onstove.com` : undefined,
      cache: { sMaxAge: 300, staleWhileRevalidate: 600 },
    }
  } catch (error) {
    console.error('Failed to fetch robots config:', error)

    // 에러 발생 시 기본값 반환
    config = {
      userAgent: '*',
      allow: ['/'],
      disallow: ['/error', '/inspection/*', '/html/*'],
      cache: { sMaxAge: 300, staleWhileRevalidate: 600 },
    }
  }

  setHeader(event, 'Content-Type', 'text/plain; charset=utf-8')

  // 캐시 헤더 (CDN 친화)
  const sMax = config.cache?.sMaxAge ?? 300
  const swr = config.cache?.staleWhileRevalidate ?? 600
  setHeader(
    event,
    'Cache-Control',
    `public, s-maxage=${sMax}, stale-while-revalidate=${swr}`
  )

  // 여러 user-agent 지원
  const agents = Array.isArray(config.userAgent)
    ? config.userAgent
    : [config.userAgent ?? '*']

  const lines: string[] = []
  for (const ua of agents) {
    lines.push(`User-agent: ${ua}`)
    for (const p of config.allow ?? []) lines.push(`Allow: ${p}`)
    for (const p of config.disallow ?? []) lines.push(`Disallow: ${p}`)
    lines.push('') // 블록 구분 공백
  }

  const sitemaps = Array.isArray(config.sitemap)
    ? config.sitemap
    : config.sitemap
      ? [config.sitemap]
      : []
  for (const sm of sitemaps) lines.push(`Sitemap: ${sm}`)
  if (config.host) lines.push(`Host: ${config.host}`)

  // 마지막 개행
  return lines.join('\n').trim() + '\n'
})