// The startup drift check (D-20c): compares the CMS's content-type URL
// patterns, pagination form and segments and HTML-sitemap paths (the site
// answer, GET <apiBase>/site) with the build's routes (#seo-routes) and the
// layer's seo.pagination and seo.htmlSitemap options, and logs one
// "[vue-seo-layer] drift: ..." warning per mismatch. It runs once after the
// plugin returns, never blocks the start and never fails it; a backend
// without a site answer (before SEO v0.2.0) or one that does not answer is
// skipped. Off with the layer off or while prerendering.

import { routePatterns } from '#seo-routes'
import { seoServerConfig } from '../lib/config.ts'
import { driftWarnings, type LayerPaginationOption } from '../lib/drift.ts'
import { siteAnswer } from '../lib/site.ts'

export default defineNitroPlugin(() => {
  if (import.meta.prerender) return
  const config = useRuntimeConfig()
  const cfg = seoServerConfig(config)
  if (!cfg.enabled) return
  const pub = ((config.public as Record<string, unknown>).seo ?? {}) as {
    pagination?: LayerPaginationOption
    htmlSitemap?: { paths?: Record<string, string> } | false
  }
  const pagination: LayerPaginationOption = {
    form: pub.pagination?.form === 'path' ? 'path' : 'query',
    param: pub.pagination?.param || 'page',
    segments: { ...(pub.pagination?.segments ?? {}) },
  }
  const htmlSitemap = pub.htmlSitemap === false || (pub.htmlSitemap as unknown) === 'false' ? false : { ...(pub.htmlSitemap?.paths ?? {}) }

  setTimeout(async () => {
    try {
      const state = await siteAnswer(cfg, {})
      if (state.state !== 'ok') return
      for (const warning of driftWarnings({ site: state.site, routes: routePatterns, pagination, htmlSitemap })) console.warn(warning)
    } catch (err) {
      console.warn('[vue-seo-layer] drift check failed:', (err as Error)?.message ?? err)
    }
  }, 0).unref?.()
})