[PATCH 13/13] notmuch.el: Add a function to insert a notmuch user-agent header

[Sebastian Spaeth <Sebastian@SSpaeth.de>]

This adds a function (and a hook) to have notmuch insert a User-Agent header
into composed mails (even if invoked from not-notmuch ways, such as with
ctrl-x m. This is invariably added for now without the possibility to
turn it off, a task left as a homework for others.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
---
 emacs/notmuch.el |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/emacs/notmuch.el b/emacs/notmuch.el
index 517c53a..8a7df15 100644
--- a/emacs/notmuch.el
+++ b/emacs/notmuch.el
@@ -54,6 +54,30 @@
 (require 'notmuch-lib)
 (require 'notmuch-show)
 
+(defun notmuch-set-user-agent-header ()
+  "Sets variables so that  message mode inserts a notmuch User-Agent 
+   header into send mails"
+  ;; check if User-Agent is a 'required' mail header and set it if not
+  (if (not (memq 'User-Agent message-required-mail-headers))
+      (setq message-required-mail-headers 
+            (append message-required-mail-headers '(User-Agent))))
+  ;; hide the User-Agent header when composing a mail
+  (if (not (memq '"^User-Agent:" message-hidden-headers))
+      (setq message-hidden-headers 
+            (append message-hidden-headers '("^User-Agent:"))))
+  ;; create the notmuch user agent string
+  (let ((notmuch-user-agent (concat 
+                             (substring (shell-command-to-string 
+                                         (concat notmuch-command 
+                                                 " --version")) 0 -1)
+                             " (Emacs " emacs-version "/"
+                             system-configuration ")")))
+    (setq message-newsreader notmuch-user-agent)))
+
+;; set the User-Agent string whenever we invoke message mode
+;; TODO: use a variable that allows disabling.
+(add-hook 'message-mode-hook 'notmuch-set-user-agent-header)
+
 (defun notmuch-select-tag-with-completion (prompt &rest search-terms)
   (let ((tag-list
 	 (with-output-to-string
-- 
1.6.3.3