import type { Metadata } from 'next'

type MediaLike =
  | { height?: null | number; mimeType?: null | string; url?: null | string; width?: null | number }
  | null
  | undefined

/**
 * Builds Next.js `icons` metadata (favicon / apple-touch-icon) from the panel's
 * favicon upload, so the browser tab AND Google get a proper <link rel="icon">.
 *
 * Why the plugin must do this (not the project): favicon-in-Google has strict
 * rules — a real <link rel="icon"> in <head>, square, ≥48×48, at a stable URL.
 * Leaving it to each project meant inconsistent hand-rolled tags and no favicon
 * in search results. This generates the tags correctly, every time, from the
 * panel field.
 *
 * Favicon is GLOBAL (same across pages), so call this once in the ROOT layout's
 * generateMetadata — not per page:
 *
 *   import { buildIconsMetadata } from '@intecion/ipal-kit'
 *   export async function generateMetadata(): Promise<Metadata> {
 *     const settings = await getSettings(locale)
 *     return buildIconsMetadata(settings.favicon)
 *   }
 *
 * Google notes: it caches favicons separately and slowly (days/weeks), and only
 * shows them for icons it deems valid. Warn on too-small icons at upload time
 * (see the media validation hook) so editors don't ship a <48px favicon Google
 * will reject.
 */
export function buildIconsMetadata(favicon: MediaLike): Metadata {
  const url = favicon?.url
  if (!url) {return {}}

  const isSvg = favicon?.mimeType === 'image/svg+xml' || url.endsWith('.svg')

  return {
    icons: {
      // Main favicon. SVG scales; PNG should be ≥48×48 (ideally 96 or 192).
      icon: isSvg ? [{ type: 'image/svg+xml', url }] : [{ sizes: 'any', url }],
      // Apple touch icon (home-screen bookmark on iOS). Reuses the same asset.
      apple: [{ url }],
    },
  }
}