;;
;; util-mail.scm
;;
;; Helper for sending emails.
;;
;; ISC License
;;
;; Copyright 2023 Brmlab, z.s.
;; Dominik Pantůček <dominik.pantucek@trustica.cz>
;;
;; Permission to use, copy, modify, and/or distribute this software
;; for any purpose with or without fee is hereby granted, provided
;; that the above copyright notice and this permission notice appear
;; in all copies.
;; 
;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
;;

(declare (unit util-mail))

(module
 util-mail
 (
  *mailto-override*
  send-mail
  )

 (import scheme
	 (chicken base)
	 (chicken keyword)
	 (chicken string)
	 util-io
	 util-utf8
	 util-string)

 ;; All emails go to this override
 (define *mailto-override* (make-parameter #f))

 ;; Ensures the subject has proper encoding
 (define (encode-subject subj)
   (if (string-utf8? subj)
       (string-append "=?UTF-8?Q?"
		      (string->qp subj)
		      "?=")
       subj))

 ;; Sends an email using the UNIX mail(1) utility.
 (define (send-mail body-lines . args)
   (let ((from (get-keyword #:from args))
	 (to (get-keyword #:to args))
	 (subject (get-keyword #:subject args)))
     (when (not to)
       (error 'send-mail "requires #:to argument"))
     (when (not subject)
       (error 'send-mail "requires #:subject argument"))
     (let* ((tos (if (list? to)
		     to
		     (list to)))
	    (real-tos (if (*mailto-override*)
			  (list (*mailto-override*))
			  tos)))
       (apply process-send/recv
	      "mail"
	      (append (if from
			  (list "-r" from)
			  '())
		      (list "-s" (encode-subject subject))
		      real-tos)
	      body-lines))))

 )