import type { Metadata } from 'next'

export const SITE_URL = 'https://marmarislocal.com'
export const LOCALES = ['tr', 'en', 'ru'] as const

/**
 * Builds self-referencing canonical + reciprocal hreflang alternates for a given
 * request pathname (as set by proxy.ts on `x-pathname`, e.g. "/en/restoran/foo").
 * x-default falls back to the site's default locale (tr).
 */
export function buildAlternates(pathname: string): Metadata['alternates'] {
  const segments = pathname.split('/').filter(Boolean)
  const currentLocale = LOCALES.includes(segments[0] as any) ? segments[0] : 'tr'
  const rest = segments.slice(LOCALES.includes(segments[0] as any) ? 1 : 0).join('/')
  const suffix = rest ? `/${rest}` : ''

  const languages: Record<string, string> = {}
  for (const locale of LOCALES) {
    languages[locale] = `${SITE_URL}/${locale}${suffix}`
  }
  languages['x-default'] = `${SITE_URL}/tr${suffix}`

  return {
    canonical: `${SITE_URL}/${currentLocale}${suffix}`,
    languages,
  }
}

export function ogLocale(locale: string): string {
  return locale === 'en' ? 'en_US' : locale === 'ru' ? 'ru_RU' : 'tr_TR'
}

/**
 * Metadata for pages that only need a localized title/description, but still
 * want their own Open Graph/Twitter tags instead of inheriting the layout's
 * generic sitewide fallback (which would otherwise show on every such page).
 *
 * Next.js doesn't deep-merge `openGraph`/`twitter` objects across the segment
 * tree — a page that returns its own `openGraph` here replaces (not extends)
 * the root layout's, which would silently drop the shared opengraph-image.tsx
 * fallback. So the share image is added back explicitly.
 */
export function basicMetadata(title: string, description: string, locale: string, pathSuffix: string = ''): Metadata {
  const image = `${SITE_URL}/${locale}/opengraph-image`
  const pathname = `/${locale}${pathSuffix.startsWith('/') ? pathSuffix : pathSuffix ? `/${pathSuffix}` : ''}`
  return {
    title,
    description,
    alternates: buildAlternates(pathname),
    openGraph: { title, description, url: `${SITE_URL}${pathname}`, locale: ogLocale(locale), type: 'website', images: [image] },
    twitter: { card: 'summary_large_image', title, description, images: [image] },
  }
}