import { defineEventHandler, setHeader } from 'h3'
import { useRuntimeConfig } from '#imports'

/**
 * robots.txt
 * GET /api/robots.txt
 * 根据环境动态生成 robots.txt
 */
export default defineEventHandler((event) => {
  const config = useRuntimeConfig()

  // 开发环境禁止抓取
  const isDev = process.env.NODE_ENV === 'development' || !process.env.NODE_ENV

  // canonical host 优先用真实访问域名；缺失时回退到「主域清单首个 + 默认租户号」，
  // 不再硬编码 site- 前缀（支持多前缀 + 多主域）
  const baseDomains = (config.public.baseDomains as string[]) || []
  const fallbackDomain = baseDomains[0] || (config.public.baseDomain as string) || 'shoplnk.cn'
  const host = event.node?.req?.headers?.host ||
    `${config.public.tenantId ? `site-${config.public.tenantId}.` : ''}${fallbackDomain}`
  const origin = `https://${host}`

  let content: string

  if (isDev) {
    content = `User-agent: *
Disallow: /`
  } else {
    content = `User-agent: *
Allow: /
Disallow: /api/

Sitemap: ${origin}/api/sitemap.xml`
  }

  setHeader(event, 'Content-Type', 'text/plain')
  return content
})