Function createFileResponse

packages/response/src/lib/file.ts:126–302

(
  file: file,
  request: Request,
  options: FileResponseOptions<file> = {},
)

 * })
 */
export async function createFileResponse<file extends FileLike>(
  file: file,
  request: Request,
  options: FileResponseOptions<file> = {},
): Promise<Response> {
  let {
    cacheControl,
    etag: etagStrategy = 'weak',
    digest: digestOption = 'SHA-256',
    lastModified: lastModifiedEnabled = true,
    acceptRanges: acceptRangesOption,
  } = options

  let headers = request.headers

  let contentType = mimeTypeToContentType(file.type)
  let contentLength = file.size

  let etag: string | undefined
  if (etagStrategy === 'weak') {
    etag = generateWeakETag(file)
  } else if (etagStrategy === 'strong') {
    let digest = await computeDigest(file, digestOption)
    etag = `"${digest}"`
  }

  let lastModified: number | undefined
  if (lastModifiedEnabled) {
    lastModified = file.lastModified
  }

  // Determine if we should accept ranges
  // Default: enable ranges only for non-compressible MIME types
  let acceptRangesEnabled =
    acceptRangesOption !== undefined ? acceptRangesOption : !isCompressibleMimeType(contentType)

  let acceptRanges: 'bytes' | undefined
  if (acceptRangesEnabled) {
    acceptRanges = 'bytes'
  }

  let hasIfMatch = headers.has('If-Match')

  // If-Match support: https://httpwg.org/specs/rfc9110.html#field.if-match
  if (etag && hasIfMatch) {
    let ifMatch = IfMatch.from(headers.get('If-Match'))
    if (!ifMatch.matches(etag)) {
      return new Response('Precondition Failed', {
        status: 412,
        headers: buildResponseHeaders({
          etag,
          lastModified,
          acceptRanges,
        }),
      })
    }
  }