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[bpt/emacs.git] / lisp / gnus / deuglify.el

;;; deuglify.el --- deuglify broken Outlook (Express) articles

;; Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
;;   Free Software Foundation, Inc.

;; Author: Raymond Scholz <rscholz@zonix.de>
;;         Thomas Steffen
;; (unwrapping algorithm, based on an idea of Stefan Monnier)
;; Keywords: mail, news

;; This file is part of GNU Emacs.

;; GNU Emacs 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 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This file enables Gnus to repair broken citations produced by
;; common user agents like MS Outlook (Express).  It may repair
;; articles of other user agents too.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;
;; Outlook sometimes wraps cited lines before sending a message as
;; seen in this example:
;;
;; Example #1
;; ----------
;;
;; John Doe wrote:
;;
;; > This sentence no verb.  This sentence no verb.  This sentence
;; no
;; > verb.  This sentence no verb.  This sentence no verb.  This
;; > sentence no verb.
;;
;; The function `gnus-article-outlook-unwrap-lines' tries to recognize those
;; erroneously wrapped lines and will unwrap them.  I.e. putting the
;; wrapped parts ("no" in this example) back where they belong (at the
;; end of the cited line above).
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Note that some people not only use broken user agents but also
;; practice a bad citation style by omitting blank lines between the
;; cited text and their own text.
;:
;; Example #2
;; ----------
;;
;; John Doe wrote:
;;
;; > This sentence no verb.  This sentence no verb.  This sentence no
;; You forgot in all your sentences.
;; > verb.  This sentence no verb.  This sentence no verb.  This
;; > sentence no verb.
;;
;; Unwrapping "You forgot in all your sentences." would be invalid as
;; this part wasn't intended to be cited text.
;; `gnus-article-outlook-unwrap-lines' will only unwrap lines if the resulting
;; citation line will be of a certain maximum length.  You can control
;; this by adjusting `gnus-outlook-deuglify-unwrap-max'.  Also
;; unwrapping will only be done if the line above the (possibly)
;; wrapped line has a minimum length of `gnus-outlook-deuglify-unwrap-min'.
;;
;; Furthermore no unwrapping will be undertaken if the last character
;; is one of the chars specified in
;; `gnus-outlook-deuglify-unwrap-stop-chars'.  Setting this to ".?!"
;; inhibits unwrapping if the cited line ends with a full stop,
;; question mark or exclamation mark.  Note that this variable
;; defaults to `nil', triggering a few false positives but generally
;; giving you better results.
;;
;; Unwrapping works on every level of citation.  Thus you will be able
;; repair broken citations of broken user agents citing broken
;; citations of broken user agents citing broken citations...
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Citations are commonly introduced with an attribution line
;; indicating who wrote the cited text.  Outlook adds superfluous
;; information that can be found in the header of the message to this
;; line and often wraps it.
;;
;; If that weren't enough, lots of people write their own text above
;; the cited text and cite the complete original article below.
;;
;; Example #3
;; ----------
;;
;; Hey, John.  There's no in all your sentences!
;;
;; John Doe <john.doe@some.domain> wrote in message
;; news:a87usw8$dklsssa$2@some.news.server...
;; > This sentence no verb.  This sentence no verb.  This sentence
;; no
;; > verb.  This sentence no verb.  This sentence no verb.  This
;; > sentence no verb.
;; >
;; > Bye, John
;;
;; Repairing the attribution line will be done by function
;; `gnus-article-outlook-repair-attribution which calls other function that
;; try to recognize and repair broken attribution lines.  See variable
;; `gnus-outlook-deuglify-attrib-cut-regexp' for stuff that should be
;; cut off from the beginning of an attribution line and variable
;; `gnus-outlook-deuglify-attrib-verb-regexp' for the verbs that are
;; required to be found in an attribution line.  These function return
;; the point where the repaired attribution line starts.
;;
;; Rearranging the article so that the cited text appears above the
;; new text will be done by function
;; `gnus-article-outlook-rearrange-citation'.  This function calls
;; `gnus-article-outlook-repair-attribution to find and repair an attribution
;; line.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Well, and that's what the message will look like after applying
;; deuglification:
;;
;; Example #3 (deuglified)
;; -----------------------
;;
;; John Doe <john.doe@some.domain> wrote:
;;
;; > This sentence no verb.  This sentence no verb.  This sentence no
;; > verb.  This sentence no verb.  This sentence no verb.  This
;; > sentence no verb.
;; >
;; > Bye, John
;;
;; Hey, John.  There's no in all your sentences!
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Usage
;; -----
;;
;; Press `W k' in the Summary Buffer.
;;
;; Non recommended usage :-)
;; ---------------------
;;
;; To automatically invoke deuglification on every article you read,
;; put something like that in your .gnus:
;;
;; (add-hook 'gnus-article-decode-hook 'gnus-article-outlook-unwrap-lines)
;;
;; or _one_ of the following lines:
;;
;; ;; repair broken attribution lines
;; (add-hook 'gnus-article-decode-hook 'gnus-article-outlook-repair-attribution)
;;
;; ;; repair broken attribution lines and citations
;; (add-hook 'gnus-article-decode-hook 'gnus-article-outlook-rearrange-citation)
;;
;; Note that there always may be some false positives, so I suggest
;; using the manual invocation.  After deuglification you may want to
;; refill the whole article using `W w'.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Limitations
;; -----------
;;
;; As I said before there may (or will) be a few false positives on
;; unwrapping cited lines with `gnus-article-outlook-unwrap-lines'.
;;
;; `gnus-article-outlook-repair-attribution will only fix the first
;; attribution line found in the article.  Furthermore it fixed to
;; certain kinds of attributions.  And there may be horribly many
;; false positives, vanishing lines and so on -- so don't trust your
;; eyes.  Again I recommend manual invocation.
;;
;; `gnus-article-outlook-rearrange-citation' carries all the limitations of
;; `gnus-article-outlook-repair-attribution.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; See ChangeLog for other changes.
;;
;; Revision 1.5  2002/01/27 14:39:17  rscholz
;; * New variable `gnus-outlook-deuglify-no-wrap-chars' to inhibit
;;   unwrapping if one these chars is first in the possibly wrapped line.
;; * Improved rearranging of the article.
;; * New function `gnus-outlook-repair-attribution-block' for repairing
;;   those big "Original Message (following some headers)" attributions.
;;
;; Revision 1.4  2002/01/03 14:05:00  rscholz
;; Renamed `gnus-outlook-deuglify-article' to
;; `gnus-article-outlook-deuglify-article'.
;; Made it easier to deuglify the article while being in Gnus' Article
;; Edit Mode.  (suggested by Phil Nitschke)
;;
;;
;; Revision 1.3  2002/01/02 23:35:54  rscholz
;; Fix a bug that caused succeeding long attribution lines to be
;; unwrapped.  Minor doc fixes and regular expression tuning.
;;
;; Revision 1.2  2001/12/30 20:14:34  rscholz
;; Clean up source.
;;
;; Revision 1.1  2001/12/30 20:13:32  rscholz
;; Initial revision
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;; Code:

(require 'gnus-art)
(require 'gnus-sum)

(defconst gnus-outlook-deuglify-version "1.5 Gnus version"
  "Version of gnus-outlook-deuglify.")

;;; User Customizable Variables:

(defgroup gnus-outlook-deuglify nil
  "Deuglify articles generated by broken user agents like MS Outlook (Express)."
  :version "22.1"
  :group 'gnus)

(defcustom gnus-outlook-deuglify-unwrap-min 45
  "Minimum length of the cited line above the (possibly) wrapped line."
  :version "22.1"
  :type 'integer
  :group 'gnus-outlook-deuglify)

(defcustom gnus-outlook-deuglify-unwrap-max 95
  "Maximum length of the cited line after unwrapping."
  :version "22.1"
  :type 'integer
  :group 'gnus-outlook-deuglify)

(defcustom gnus-outlook-deuglify-cite-marks ">|#%"
  "Characters that indicate cited lines."
  :version "22.1"
  :type 'string
  :group 'gnus-outlook-deuglify)

(defcustom gnus-outlook-deuglify-unwrap-stop-chars nil ;; ".?!" or nil
  "Characters that inhibit unwrapping if they are the last one on the cited line above the possible wrapped line."
  :version "22.1"
  :type '(radio (const :format "None  " nil)
		(string :value ".?!"))
  :group 'gnus-outlook-deuglify)

(defcustom gnus-outlook-deuglify-no-wrap-chars "`"
  "Characters that inhibit unwrapping if they are the first one in the possibly wrapped line."
  :version "22.1"
  :type 'string
  :group 'gnus-outlook-deuglify)

(defcustom  gnus-outlook-deuglify-attrib-cut-regexp
  "\\(On \\|Am \\)?\\(Mon\\|Tue\\|Wed\\|Thu\\|Fri\\|Sat\\|Sun\\),[^,]+, "
  "Regular expression matching the beginning of an attribution line that should be cut off."
  :version "22.1"
  :type 'string
  :group 'gnus-outlook-deuglify)

(defcustom gnus-outlook-deuglify-attrib-verb-regexp