[RFC PATCH 3/4] emacs: add notmuch hello refresh hook to display message count change

[Jani Nikula]

Add a notmuch hello refresh hook to display a message about change in
message count in the database since the notmuch-hello buffer was last
refreshed manually (no-display is nil).
---
 emacs/notmuch-hello.el |   23 +++++++++++++++++++++++
 1 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/emacs/notmuch-hello.el b/emacs/notmuch-hello.el
index 0596bbe..13da146 100644
--- a/emacs/notmuch-hello.el
+++ b/emacs/notmuch-hello.el
@@ -148,6 +148,7 @@ International Bureau of Weights and Measures."
 (defcustom notmuch-hello-refresh-hook nil
   "Functions called after updating a `notmuch-hello' buffer."
   :type 'hook
+  :options '(notmuch-hello-refresh-status-message)
   :group 'notmuch-hello
   :group 'notmuch-hooks)
 
@@ -729,6 +730,28 @@ following:
     (let ((fill-column (- (window-width) notmuch-hello-indent)))
       (center-region start (point)))))
 
+(defvar notmuch-hello-refresh-count 0
+  "Number of messages in the database when `notmuch-hello' was last run.
+
+Used internally by `notmuch-hello-refresh-status-message'.")
+
+(defun notmuch-hello-refresh-status-message (no-display)
+  "Hook to display a status message when refreshing notmuch-hello buffer."
+  (unless no-display
+    (let* ((new-count
+	    (string-to-number (car (process-lines notmuch-command "count"))))
+	   (diff-count (- new-count notmuch-hello-refresh-count)))
+      (if (= notmuch-hello-refresh-count 0)
+	  (message "You have %s messages."
+		   (notmuch-hello-nice-number new-count))
+	(if (not (= diff-count 0))
+	    (if (>= diff-count 0)
+		(message "You have %s more messages since last refresh."
+			 (notmuch-hello-nice-number diff-count))
+	      (message "You have %s fewer messages since last refresh."
+		       (notmuch-hello-nice-number (- diff-count))))))
+      (setq notmuch-hello-refresh-count new-count))))
+
 ;;;###autoload
 (defun notmuch-hello (&optional no-display)
   "Run notmuch and display saved searches, known tags, etc."
-- 
1.7.1