genWeekEtag

etag.nim

proc genWeekEtag*(filepath: string): string =
  # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag
  let
    info = getFileInfo(filepath)
    ns = info.lastWriteTime.toUnix().uint64 * 1e9.uint64 + info.lastWriteTime.nanosecond.uint64
    time = toHex(ns, sizeof(uint64)).toLowerAscii()
    size = toHex(info.size, sizeof(uint64)).toLowerAscii()
  result = "W/" & '"' & size & '-' & time & '"'

proc serveFile*(req: Request, path: string) {.async.} =
  let etag = genWeekEtag(path)
  if req.headers.hasKey("If-None-Match") and req.headers["If-None-Match"] == etag:
    await req.respond(Http304, "")
  else:
    let data = readFile(path)
    let headers = newHttpHeaders()
    headers["Content-Type"] = mimeType(path)
    headers["ETag"] = etag
    await req.respond(
      Http200,
      data,
      headers,
    )