(define-module (calp server socket)
  :use-module (srfi srfi-88)
  :use-module (web server)
  :export (setup-socket
           run-at-any-port)
  )

;; NOTE The default make-default-socket is broken for IPv6.
;; A patch has been submitted to the mailing list. 2020-03-31
;;
;; This sets up the socket manually, and sends that to @code{http-open}.
(define* (make-default-socket/fixed family addr port)
  (let ((sock (socket family SOCK_STREAM 0)))
    (setsockopt sock SOL_SOCKET SO_REUSEADDR 1)
    (bind sock family addr port)
    sock))

(define* (setup-socket key:
                       (host #f)
                       (family AF_INET)
                       (addr (if host (inet-pton family host)
                                 INADDR_LOOPBACK))
                       (port 8080))
  (make-default-socket/fixed family addr port))


(define* (run-at-any-port handler key:
                          (min-port 8081)
                          msg-port)
  (unless msg-port
    (scm-error 'misc-error "run-at-any-port"
               "msg-port required"
               '() #f))
  (let loop ((port min-port))
    (catch 'system-error
      (lambda ()
        (let ((socket (setup-socket port: port)))
          (let ((addr (format #f "http://localhost:~a~%" port)))
            (display addr msg-port)
            (force-output msg-port)
            (format #t "Server started at ~s~%" addr)
            (run-server handler 'http
                        `(socket: ,socket))
            (format #t "Server closed~%"))))
      (lambda (err proc fmt args data)
        (if (= EADDRINUSE (car data))
            (loop (1+ port))
            (apply throw err proc fmt args data))))))