import type { FieldHook } from 'payload'

/**
 * Field validation for the favicon upload: Google rejects favicons under 48×48,
 * so warn the editor at save time if the uploaded icon is too small or not
 * square. This ENFORCES the requirement instead of silently shipping a favicon
 * Google won't display.
 *
 * Attach to the favicon field's validate (or as a beforeValidate hook on the
 * Media relationship). Non-blocking by default — returns a warning string that
 * Payload surfaces; make it throw if you want a hard block.
 *
 * Note: dimensions come from the related Media doc (Payload stores width/height
 * for image uploads), so this checks the resolved upload, not the raw file.
 */
export const validateFaviconField: FieldHook = async ({ req, value }) => {
  if (!value) {return value} // no favicon set → nothing to validate (optional field)

  try {
    const media = await req.payload.findByID({
      id: typeof value === 'object' ? (value as { id: string }).id : value,
      collection: 'media',
      depth: 0,
    })

    const width = (media as { width?: number }).width
    const height = (media as { height?: number }).height
    const mimeType = (media as { mimeType?: string }).mimeType

    // SVG scales infinitely — skip size checks.
    if (mimeType === 'image/svg+xml') {return value}

    if (typeof width === 'number' && typeof height === 'number') {
      if (width < 48 || height < 48) {
        req.payload.logger.warn(
          `[ipal] Favicon is ${width}×${height}px. Google requires ≥48×48 to ` +
            `display it in search results. Upload a larger square icon (96 or 192px).`,
        )
      }
      if (width !== height) {
        req.payload.logger.warn(
          `[ipal] Favicon is not square (${width}×${height}). Use a square icon ` +
            `so it isn't cropped in the browser tab or search results.`,
        )
      }
    }
  } catch {
    // Media lookup failed — don't block the save over a validation warning.
  }

  return value
}