import { MetadataRoute } from 'next'
import { mockDb } from '@/lib/mockDb'
import { SITE_URL, LOCALES } from '@/lib/seo'

function localizedEntries(
  pathSuffix: string,
  opts: {
    lastModified?: Date
    changeFrequency?: NonNullable<MetadataRoute.Sitemap[number]['changeFrequency']>
    priority?: number
  }
): MetadataRoute.Sitemap {
  const languages: Record<string, string> = {}
  for (const locale of LOCALES) {
    languages[locale] = `${SITE_URL}/${locale}${pathSuffix}`
  }
  languages['x-default'] = `${SITE_URL}/tr${pathSuffix}`

  return LOCALES.map((locale) => ({
    url: `${SITE_URL}/${locale}${pathSuffix}`,
    lastModified: opts.lastModified || new Date(),
    changeFrequency: opts.changeFrequency,
    priority: opts.priority,
    alternates: { languages },
  }))
}

export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
  const entries: MetadataRoute.Sitemap = []

  // 1. Home
  entries.push(...localizedEntries('', { changeFrequency: 'weekly', priority: 1.0 }))

  // 2. Static routes
  const staticRoutes = ['/about', '/contact', '/add-business', '/collections', '/blog', '/events']
  for (const route of staticRoutes) {
    entries.push(...localizedEntries(route, { changeFrequency: 'weekly', priority: 0.7 }))
  }

  // 3. Category landing pages (slugs are DB-driven, not hardcoded)
  try {
    const categories = await mockDb.getCategories()
    for (const category of categories) {
      entries.push(...localizedEntries(`/${category.slug}`, { changeFrequency: 'daily', priority: 0.8 }))
    }
  } catch (e) {
    console.error('Sitemap categories fetch error:', e)
  }

  // 4. Listing detail pages
  try {
    const listings = await mockDb.getListings()
    for (const listing of listings) {
      const catSlug = listing.category?.slug || 'isletme'
      entries.push(
        ...localizedEntries(`/${catSlug}/${listing.slug}`, {
          lastModified: listing.updatedAt,
          changeFrequency: 'weekly',
          priority: 0.6,
        })
      )
    }
  } catch (e) {
    console.error('Sitemap listings fetch error:', e)
  }

  // 5. Neighborhood pages & Programmatic Neighborhood x Category landing pages
  try {
    const neighborhoods = await mockDb.getNeighborhoods()
    const categories = await mockDb.getCategories()

    for (const neighborhood of neighborhoods) {
      entries.push(
        ...localizedEntries(`/neighborhood/${neighborhood.slug}`, { changeFrequency: 'monthly', priority: 0.5 })
      )

      // Programmatic Neighborhood x Category combinations
      for (const category of categories) {
        const matchingListings = await mockDb.getListings({
          neighborhoodId: neighborhood.id,
          categoryId: category.id,
        })
        // Only include indexable programmatic pages in sitemap (at least 2 listings)
        if (matchingListings.length >= 2) {
          entries.push(
            ...localizedEntries(`/neighborhood/${neighborhood.slug}/${category.slug}`, {
              changeFrequency: 'weekly',
              priority: 0.7,
            })
          )
        }
      }
    }
  } catch (e) {
    console.error('Sitemap neighborhoods fetch error:', e)
  }

  // 6. Collections
  try {
    const collections = await mockDb.getCollections()
    for (const collection of collections) {
      entries.push(
        ...localizedEntries(`/collection/${collection.slug}`, {
          lastModified: collection.updatedAt,
          changeFrequency: 'monthly',
          priority: 0.5,
        })
      )
    }
  } catch (e) {
    console.error('Sitemap collections fetch error:', e)
  }

  // 7. Blog posts
  try {
    const posts = await mockDb.getBlogPosts(true)
    for (const post of posts) {
      entries.push(
        ...localizedEntries(`/blog/${post.slug}`, {
          lastModified: post.updatedAt,
          changeFrequency: 'monthly',
          priority: 0.5,
        })
      )
    }
  } catch (e) {
    console.error('Sitemap blog posts fetch error:', e)
  }

  // 8. AI-generated itineraries (long-tail SEO pages, PRD §3.3)
  // Each plan is generated in a single language (see params.locale) — unlike
  // other content types it has no translated counterpart, so it gets one
  // sitemap entry for its own locale rather than the tr/en/ru trio.
  try {
    entries.push(...localizedEntries('/plan-olustur', { changeFrequency: 'monthly', priority: 0.6 }))
    const itineraries = await mockDb.getItineraries()
    for (const itinerary of itineraries) {
      const itinLocale = LOCALES.includes((itinerary.params as any)?.locale) ? (itinerary.params as any).locale : 'tr'
      entries.push({
        url: `${SITE_URL}/${itinLocale}/plan/${itinerary.id}`,
        lastModified: itinerary.createdAt,
        changeFrequency: 'yearly',
        priority: 0.3,
      })
    }
  } catch (e) {
    console.error('Sitemap itineraries fetch error:', e)
  }

  return entries
}