;;; gnus-summary-update-subject.el --- Display subject on the first line, dynamically

;;; Time-stamp: <2004-03-07 18:02:03 bojohan>
;; <http://www.dd.chalmers.se/~bojohan/emacs/gnus-summary-update-subject.html>

;; Modified by Sacha to work with subjects anywhere in the summary line.
;; Note that this probably only works with my .gnus.
;; User beware.

;; <bojohan> i guess you could fix the problem with filling and
;;          truncation of the subject. a spec like ">%20s" with a
;;          short subject will become ">XXXXXXXXXXXXXsubject", i
;;          think, where X are spaces and the `s' is the first
;;          character to have the text property. then you have to
;;          fill or truncate the overlay accordingly.
;; <bojohan> or you could replace the %B spec with a user format
;;          function, and put the text property on that, and get rid
;;          of the regexp search.
;; <bojohan> simply
;; <bojohan> (defun gnus-user-format-function-thread (dummy)
;; <bojohan>   (propertize gnus-tmp-thread-tree-header-string
;; <bojohan> 	      'prop 'val))
;; <bojohan> "%u&thread;"

;;; Code:

(defvar gnus-summary-update-subject-overlay nil)
(setq gnus-summary-same-subject (propertize " " 'gnus-summary-same-subject t))

(defvar gnus-summary-update-subject-thread-marker ">")

(defun gnus-summary-update-subject (&optional window start)
  (when gnus-summary-update-subject-overlay
    (save-excursion
      (goto-char (or start (window-start)))
      (when (re-search-forward gnus-summary-update-subject-thread-marker
                               (line-end-position) t)
        (if (not (text-property-any (line-beginning-position)
                                    (line-end-position)
                                    'gnus-summary-same-subject t))
            (delete-overlay gnus-summary-update-subject-overlay)
          (let ((subject (gnus-summary-subject-string
                          (gnus-summary-article-number))))
            (move-overlay gnus-summary-update-subject-overlay
                          (1+ point) (+ point 1 (length subject)))
          ;;(overlay-put gnus-summary-subject-overlay 'window (selected-window))
            (overlay-put gnus-summary-update-subject-overlay
                         'invisible t)
            (overlay-put gnus-summary-update-subject-overlay
                         'intangible t)
            (overlay-put gnus-summary-update-subject-overlay
                         'after-string subject)))))))

(defun gnus-summary-update-subject-setup ()
  (add-hook 'window-scroll-functions 'gnus-summary-update-subject nil t)
  (set (make-local-variable 'gnus-summary-update-subject-overlay)
       (make-overlay 0 0)))
(add-hook 'gnus-summary-prepared-hook 'gnus-summary-update-subject-setup)

(defadvice gnus-summary-position-point (after summary-update-subject activate)
  (gnus-summary-update-subject))

(provide 'gnus-summary-update-subject)

;;; gnus-summary-update-subject.el ends here