lisp/gnus/message.el (message-insert-formatted-citation-line): Use the original author's time zone to express a date string

1 files changed, 32 insertions, 0 deletions

diff --git a/lisp/gnus/gmm-utils.el b/lisp/gnus/gmm-utils.el
index 63947e5f486..70ef27a7e90 100644
--- a/lisp/gnus/gmm-utils.el
+++ b/lisp/gnus/gmm-utils.el
@@ -443,6 +443,38 @@ rather than relying on `lexical-binding'.
 (put 'gmm-labels 'lisp-indent-function 1)
 (put 'gmm-labels 'edebug-form-spec '((&rest (sexp sexp &rest form)) &rest form))
 
+(defun gmm-format-time-string (format-string &optional time tz)
+  "Use FORMAT-STRING to format the time TIME, or now if omitted.
+The optional TZ specifies the time zone in a number of seconds; any
+other non-nil value will be treated as 0.  Note that both the format
+specifiers `%Z' and `%z' will be replaced with a numeric form. "
+;; FIXME: is there a smart way to replace %Z with a time zone name?
+  (if (and (numberp tz) (not (zerop tz)))
+      (let ((st 0)
+	    (case-fold-search t)
+	    ls nd rest)
+	(setq time (if time
+		       (copy-sequence time)
+		     (current-time)))
+	(if (>= (setq ls (- (cadr time) (car (current-time-zone)) (- tz))) 0)
+	    (setcar (cdr time) ls)
+	  (setcar (cdr time) (+ ls 65536))
+	  (setcar time (1- (car time))))
+	(setq tz (format "%s%02d%02d"
+			 (if (>= tz 0) "+" "-")
+			 (/ (abs tz) 3600)
+			 (/ (% (abs tz) 3600) 60)))
+	(while (string-match "%+z" format-string st)
+	  (if (zerop (% (- (setq nd (match-end 0)) (match-beginning 0)) 2))
+	      (progn
+		(push (substring format-string st (- nd 2)) rest)
+		(push tz rest))
+	    (push (substring format-string st nd) rest))
+	  (setq st nd))
+	(push (substring format-string st) rest)
+	(format-time-string (apply 'concat (nreverse rest)) time))
+    (format-time-string format-string time tz)))
+
 (provide 'gmm-utils)
 
 ;;; gmm-utils.el ends here