;;                                                     -*- Emacs-Lisp -*-

;;; lessfile.el --- Use the lessfile inputfilter for view-file  

;; Copyright (C) 2002 Claus Brunzema <mail@cbrunzema.de>

;; Version: 0.9.3
;; $Id: lessfile.el,v 1.5 2002/06/28 14:17:54 chb Exp $

;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 2, or
;; (at your option) any later version.
;;
;; It is distributed in the hope that it will be useful, but WITHOUT
;; ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
;; or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
;; License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program; see the file COPYING.  If not, write to the
;; Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
;; -----------------------------------------------------------------------


;;; Commentary:

;; Motivation:
;;
;; I often use locate to find files, especially lisp source
;; files. Unfortunately on my debian system the xemacs sources are gzipped by
;; default. I could always use less on the commandline to view these
;; files, but I wanted to do all this within my xemacs. So here it is...
;;
;; After I released lessfile into the public, ivank told me about
;; auto-compression-mode.... but lessfile.el is still useful to view
;; stuff xemacs doesn't handle automatically (e.g. with a
;; sophisticated lessfile script you could view html pages without
;; using the (rather slow) w3).

;; Prerequisites:
;;
;; I made query-replace-by-example with the following xemacs:
;; XEmacs 21.4 (patch 6) "Common Lisp" [Lucid] (i386-debian-linux) of Sat Apr  6 2002 on eeyore"
;; Please let me know if other versions work.

;; Installation:
;;
;; put this file in your load-path and the following in your init
;; file (~/.emacs or ~/.xemacs/init.el):
;;
;; (require 'lessfile)
;;
;; Some users (most notably SuSE users) may want to add
;;
;; (setq lessfile-lessopen  "lessopen.sh %s")
;; (setq lessfile-lessclose "lessclose.sh %s %s")
;;
;; The default (see below) works on a debian GNU/Linux installation.

;; Usage:
;;
;; This module uses advice to change the behaviour of view-file. Just
;; use view-file like before, it now works with all the filetypes your
;; lessfile can handle.

;; History:
;; 2002-06-28  Claus Brunzema
;;         * Comment about auto-compression-mode... Version 0.9.3
;;
;; 2002-06-20  Claus Brunzema
;;         * More Docs. Version 0.9.2
;;
;; 2002-06-15  Claus Brunzema
;;         * Initial version.

;; ToDo:
;;
;; - Get the values for lessfile-lessopen and lessfile-lessclose by
;;   parsing the output of lessfile.


;;; Code:

;; -- Customisation -------------------------------------------------------
(defvar lessfile-lessopen  "/usr/bin/lessfile %s")    ; see 'man lessfile'
(defvar lessfile-lessclose "/usr/bin/lessfile %s %s")


;; ------------------------------------------------------------------------
(require 'advice)

(defadvice view-file (around lessfile-inputfilter activate)
  (let* ((internal-filename (ad-get-arg 0))
	 (internal-tmpfilename
	  (concat (butlast
		   (string-to-list
		    (shell-command-to-string
		     (format lessfile-lessopen
			     (shell-quote-argument internal-filename))))))))
    (unless (zerop (length internal-tmpfilename))
      (ad-set-arg 0 internal-tmpfilename))
    ad-do-it
    (unless (zerop (length internal-tmpfilename))
      (rename-buffer (concat "less:"
			     (generate-new-buffer-name
			      (file-name-nondirectory internal-filename))))
      (shell-command (format lessfile-lessclose
			     (shell-quote-argument internal-filename)
			     (shell-quote-argument internal-tmpfilename))))))
(provide 'lessfile)

;;; lessfile.el ends here