mu4e: Factor address fetching into `message-fetch-addresses'

.emacs.d/lisp/init-mu4e.el

@@ -143,21 +143,43 @@ This function is suitable for `mu4e-compose-mode-hook'."
       (mml-secure-message-sign-pgpmime)))))
 (add-hook 'mu4e-compose-mode-hook 'ambrevar/mu4e-compose-maybe-signed-and-crypted)
 
+(defun ambrevar/message-fetch-addresses ()
+  "Return a list of (NAME EMAIL) from the message header.
+The \"From\", \"To\", \"Cc\" and \"Bcc\" fields are looked up.
+Addresses in `mu4e-user-mail-address-list' are filtered out.
+Duplicates are removed."
+  (require 'cl)
+  (cl-delete-duplicates
+   (seq-remove
+    (lambda (contact) (member (cadr contact) mu4e-user-mail-address-list))
+    (apply 'append
+           (if (eq major-mode 'mu4e-compose-mode)
+               (save-restriction
+                 (message-narrow-to-headers)
+                 (mapcar
+                  (lambda (addr) (mail-extract-address-components (message-fetch-field addr) t))
+                  (seq-filter 'message-fetch-field
+                              '("From" "To" "Cc" "Bcc"))))
+             (unless (buffer-live-p (mu4e-get-headers-buffer))
+               (mu4e-error "no headers buffer connected"))
+             (delq nil
+                   (mapcar (lambda (field)
+                             ;; `mu4e-message-field' returns a list of (NAME . EMAIL).
+                             (mapcar (lambda (addr) (list (car addr) (cdr addr)))
+                                     (mu4e-message-field
+                                      (with-current-buffer (mu4e-get-headers-buffer)
+                                        ;; When loading messages, point might
+                                        ;; not be over a message yet.
+                                        (mu4e-message-at-point))
+                                      field)))
+                           '(:from :to :cc :bcc))))))))
+
 (defun ambrevar/message-send-maybe-crypted ()
   "Crypt message if all recipients have a trusted key.
 This will prompt the user if only some recipients have a suitable public key.
 Suitable for `message-send-hook'."
-  (let (recipients valid-addresses untrusted-recipients)
-    (setq recipients
-          (save-restriction
-            (message-narrow-to-headers)
-            (apply 'append
-                   (mapcar
-                    (lambda (header)
-                      (mapcar 'cadr (mail-extract-address-components
-                                     (message-fetch-field header) t)))
-                    (seq-filter 'message-fetch-field
-                                '("To" "Cc" "Bcc"))))))
+  (let ((recipients (mapcar 'cadr (ambrevar/message-fetch-addresses)))
+        valid-addresses untrusted-recipients)
     (dolist (key (epg-list-keys (epg-make-context epa-protocol)))
       (dolist (user-id (epg-key-user-id-list key))
         (when (memq (epg-user-id-validity user-id) '(marginal full ultimate))
@@ -288,15 +310,8 @@ This function could be useful in `mu4e-compose-mode-hook'."
     "Return a list of (NAME . ADDRESS).
 If point has an `email' property, move it to the front of the list.
 Addresses in `mu4e-user-mail-address-list' are skipped."
-    (let (result
+    (let ((result (ambrevar/message-fetch-addresses))
           (message org-store-link-plist))
-      (setq result (seq-remove
-                    (lambda (contact) (member (cadr contact) mu4e-user-mail-address-list))
-                    (apply 'append
-                           (mapcar (lambda (addr) (mail-extract-address-components addr t))
-                                   (delq nil
-                                         (mapcar (lambda (field) (mu4e-message-field message field))
-                                                 '(:from :to :cc :bcc)))))))
       ;; Move contact at point to front.
       (let ((email-at-point (get-text-property (point) 'email))
             (contacts result))