three1.scala

val baseEndpoint: Endpoint[Unit, (StatusCode, ErrorInfo), Unit, Nothing] = 
  endpoint
    .in("api" / "v1.0")
    .errorOut(statusCode.and(jsonBody[ErrorInfo]))

val booksQueryInput: EndpointInput[BooksQuery] = 
  query[Option[Year]]("year")
    .and(query[Option[Int]]("limit"))
    .mapTo(BooksQuery)

val getBooks: Endpoint[BooksQuery, (StatusCode, ErrorInfo), List[Book], Nothing] = 
  baseEndpoint
    .get
    .in("books")
    .in(booksQueryInput)
    .out(jsonBody[List[Book]].example(List(Database.books.head)))

val getBookCover: Endpoint[UUID, (StatusCode, ErrorInfo), Source[ByteString, Any], 
                           Source[ByteString, Any]] = 
  baseEndpoint
    .get
    .in("books" / path[UUID]("bookId") / "cover")
    .out(streamBody[Source[ByteString, Any]](schemaFor[Array[Byte]], 
                                             MediaType.OctetStream()))

val addBook: Endpoint[(AuthToken, NewBook), (StatusCode, ErrorInfo), Unit, Nothing] = 
  baseEndpoint
    .post
    .in(auth.bearer)
    .in("books")
    .in(multipartBody[NewBook])