emacs: Add `notmuch-show-forward-open-messages'.

Add a function to forward all open messages in the current view of a
thread. Bind this to "F".

emacs/notmuch-mua.el

@@ -427,6 +427,54 @@ the From: address first."
     (message-hide-headers)
     (set-buffer-modified-p nil)))
 
+(defun notmuch-mua-new-forward-messages (messages &optional prompt-for-sender)
+  "Compose a new message forwarding MESSAGES.
+
+If PROMPT-FOR-SENDER is non-nil, the user will be prompteed for
+the From: address."
+  (let* ((other-headers
+	  (when (or prompt-for-sender notmuch-always-prompt-for-sender)
+	    (list (cons 'From (notmuch-mua-prompt-for-sender)))))
+	 forward-subject) ;; Comes from the first message and is
+			  ;; applied later.
+
+    ;; Generate the template for the outgoing message.
+    (notmuch-mua-mail nil "" other-headers nil (notmuch-mua-get-switch-function))
+
+    (save-excursion
+      ;; Insert all of the forwarded messages.
+      (mapc (lambda (id)
+	      (let ((temp-buffer (get-buffer-create
+				  (concat "*notmuch-fwd-raw-" id "*"))))
+		;; Get the raw version of this message in the buffer.
+		(with-current-buffer temp-buffer
+		  (erase-buffer)
+		  (let ((coding-system-for-read 'no-conversion))
+		    (call-process notmuch-command nil t nil "show" "--format=raw" id))
+		  ;; Because we process the messages in reverse order,
+		  ;; always generate a forwarded subject, then use the
+		  ;; last (i.e. first) one.
+		  (setq forward-subject (message-make-forward-subject)))
+		;; Make a copy ready to be forwarded in the
+		;; composition buffer.
+		(message-forward-make-body temp-buffer)
+		;; Kill the temporary buffer.
+		(kill-buffer temp-buffer)))
+	    ;; `message-forward-make-body' always puts the message at
+	    ;; the top, so do them in reverse order.
+	    (reverse messages))
+
+      ;; Add in the appropriate subject.
+      (save-restriction
+	(message-narrow-to-headers)
+	(message-remove-header "Subject")
+	(message-add-header (concat "Subject: " forward-subject)))
+
+      ;; `message-forward-make-body' shows the User-agent header.  Hide
+      ;; it again.
+      (message-hide-headers)
+      (set-buffer-modified-p nil))))
+
 (defun notmuch-mua-new-reply (query-string &optional prompt-for-sender reply-all)
   "Compose a reply to the message identified by QUERY-STRING.
 

emacs/notmuch-show.el

@@ -1431,6 +1431,7 @@ reset based on the original query."
     (define-key map (kbd "<backtab>") 'notmuch-show-previous-button)
     (define-key map (kbd "TAB") 'notmuch-show-next-button)
     (define-key map "f" 'notmuch-show-forward-message)
+    (define-key map "F" 'notmuch-show-forward-open-messages)
     (define-key map "l" 'notmuch-show-filter-thread)
     (define-key map "r" 'notmuch-show-reply-sender)
     (define-key map "R" 'notmuch-show-reply)
@@ -1858,6 +1859,16 @@ any effects from previous calls to
   (with-current-notmuch-show-message
    (notmuch-mua-new-forward-message prompt-for-sender)))
 
+(put 'notmuch-show-forward-open-messages 'notmuch-prefix-doc
+     "... and prompt for sender")
+(defun notmuch-show-forward-open-messages (&optional prompt-for-sender)
+  "Forward the currently open messages."
+  (interactive "P")
+  (let ((open-messages (notmuch-show-get-message-ids-for-open-messages)))
+    (unless open-messages
+      (error "No open messages to forward."))
+    (notmuch-mua-new-forward-messages open-messages prompt-for-sender)))
+
 (defun notmuch-show-next-message (&optional pop-at-end)
   "Show the next message.