1;;; ol-gnus.el --- Links to Gnus Groups and Messages -*- lexical-binding: t; -*-
2
3;; Copyright (C) 2004-2021 Free Software Foundation, Inc.
4
5;; Author: Carsten Dominik <carsten.dominik@gmail.com>
6;;         Tassilo Horn <tassilo at member dot fsf dot org>
7;; Keywords: outlines, hypermedia, calendar, wp
8;; Homepage: https://orgmode.org
9;;
10;; This file is part of GNU Emacs.
11;;
12;; GNU Emacs is free software: you can redistribute it and/or modify
13;; it under the terms of the GNU General Public License as published by
14;; the Free Software Foundation, either version 3 of the License, or
15;; (at your option) any later version.
16
17;; GNU Emacs is distributed in the hope that it will be useful,
18;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20;; GNU General Public License for more details.
21
22;; You should have received a copy of the GNU General Public License
23;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
24;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
25;;
26;;; Commentary:
27
28;; This file implements links to Gnus groups and messages from within Org.
29;; Org mode loads this module by default - if this is not what you want,
30;; configure the variable `org-modules'.
31
32;;; Code:
33
34(require 'gnus-sum)
35(require 'gnus-util)
36(require 'nnheader)
37(or (require 'nnselect nil t)           ; Emacs >= 28
38    (require 'nnir nil t))              ; Emacs < 28
39(require 'ol)
40
41
42;;; Declare external functions and variables
43
44(declare-function gnus-activate-group "gnus-start" (group &optional scan dont-check method dont-sub-check))
45(declare-function gnus-find-method-for-group "gnus" (group &optional info))
46(declare-function gnus-article-show-summary "gnus-art" ())
47(declare-function gnus-group-group-name "gnus-group")
48(declare-function gnus-group-jump-to-group "gnus-group" (group &optional prompt))
49(declare-function gnus-group-read-group "gnus-group" (&optional all no-article group select-articles))
50(declare-function message-fetch-field "message" (header &optional not-all))
51(declare-function message-generate-headers "message" (headers))
52(declare-function message-narrow-to-headers "message")
53(declare-function message-tokenize-header "message" (header &optional separator))
54(declare-function message-unquote-tokens "message" (elems))
55(declare-function nnvirtual-map-article "nnvirtual" (article))
56
57(defvar gnus-newsgroup-name)
58(defvar gnus-summary-buffer)
59(defvar gnus-other-frame-object)
60
61
62;;; Customization variables
63
64(defcustom org-gnus-prefer-web-links nil
65  "If non-nil, `org-store-link' creates web links to Google groups.
66\\<org-mode-map>When nil, Gnus will be used for such links.
67Using a prefix argument to the command `\\[org-store-link]' (`org-store-link')
68negates this setting for the duration of the command."
69  :group 'org-link-store
70  :type 'boolean)
71
72(defcustom org-gnus-no-server nil
73  "Should Gnus be started using `gnus-no-server'?"
74  :group 'org-gnus
75  :version "24.4"
76  :package-version '(Org . "8.0")
77  :type 'boolean)
78
79
80;;; Install the link type
81
82(org-link-set-parameters "gnus"
83			 :follow #'org-gnus-open
84			 :store #'org-gnus-store-link)
85
86;;; Implementation
87
88(defun org-gnus-group-link (group)
89  "Create a link to the Gnus group GROUP.
90If GROUP is a newsgroup and `org-gnus-prefer-web-links' is
91non-nil, create a link to groups.google.com.  Otherwise create a
92link to the group inside Gnus.
93
94If `org-store-link' was called with a prefix arg the meaning of
95`org-gnus-prefer-web-links' is reversed."
96  (let ((unprefixed-group (replace-regexp-in-string "^[^:]+:" "" group)))
97    (if (and (string-prefix-p "nntp" group) ;; Only for nntp groups
98	     (org-xor current-prefix-arg
99		      org-gnus-prefer-web-links))
100	(concat "https://groups.google.com/group/" unprefixed-group)
101      (concat "gnus:" group))))
102
103(defun org-gnus-article-link (group newsgroups message-id x-no-archive)
104  "Create a link to a Gnus article.
105
106The article is specified by its MESSAGE-ID.  Additional
107parameters are the Gnus GROUP, the NEWSGROUPS the article was
108posted to and the X-NO-ARCHIVE header value of that article.
109
110If GROUP is a newsgroup and `org-gnus-prefer-web-links' is
111non-nil, create a link to groups.google.com.
112Otherwise create a link to the article inside Gnus.
113
114If `org-store-link' was called with a prefix arg the meaning of
115`org-gnus-prefer-web-links' is reversed."
116  (if (and (org-xor current-prefix-arg org-gnus-prefer-web-links)
117	   newsgroups		  ;make web links only for nntp groups
118	   (not x-no-archive))	  ;and if X-No-Archive isn't set
119      (format "https://groups.google.com/groups/search?as_umsgid=%s"
120	      (url-encode-url message-id))
121    (concat "gnus:" group "#" message-id)))
122
123(defun org-gnus-store-link ()
124  "Store a link to a Gnus folder or message."
125  (pcase major-mode
126    (`gnus-group-mode
127     (let ((group (gnus-group-group-name)))
128       (when group
129	 (org-link-store-props :type "gnus" :group group)
130	 (let ((description (org-gnus-group-link group)))
131	   (org-link-add-props :link description :description description)
132	   description))))
133    ((or `gnus-summary-mode `gnus-article-mode)
134     (let* ((group
135	     (pcase (gnus-find-method-for-group gnus-newsgroup-name)
136	       (`(nnvirtual . ,_)
137		(save-excursion
138		  (car (nnvirtual-map-article (gnus-summary-article-number)))))
139	       (`(,(or `nnselect `nnir) . ,_)  ; nnir is for Emacs < 28.
140		(save-excursion
141		  (cond
142		   ((fboundp 'nnselect-article-group)
143		    (nnselect-article-group (gnus-summary-article-number)))
144		   ((fboundp 'nnir-article-group)
145		    (nnir-article-group (gnus-summary-article-number)))
146		   (t
147		    (error "No article-group variant bound")))))
148	       (_ gnus-newsgroup-name)))
149	    (header (if (eq major-mode 'gnus-article-mode)
150			;; When in an article, first move to summary
151			;; buffer, with point on the summary of the
152			;; current article before extracting headers.
153			(save-window-excursion
154			  (save-excursion
155			    (gnus-article-show-summary)
156			    (gnus-summary-article-header)))
157		      (gnus-summary-article-header)))
158	    (from (mail-header-from header))
159	    (message-id (org-unbracket-string "<" ">" (mail-header-id header)))
160	    (date (org-trim (mail-header-date header)))
161	    ;; Remove text properties of subject string to avoid Emacs
162	    ;; bug #3506.
163	    (subject (org-no-properties
164		      (copy-sequence (mail-header-subject header))))
165	    (to (cdr (assq 'To (mail-header-extra header))))
166	    newsgroups x-no-archive)
167       ;; Fetching an article is an expensive operation; newsgroup and
168       ;; x-no-archive are only needed for web links.
169       (when (org-xor current-prefix-arg org-gnus-prefer-web-links)
170	 ;; Make sure the original article buffer is up-to-date.
171	 (save-window-excursion (gnus-summary-select-article))
172	 (setq to (or to (gnus-fetch-original-field "To")))
173	 (setq newsgroups (gnus-fetch-original-field "Newsgroups"))
174	 (setq x-no-archive (gnus-fetch-original-field "x-no-archive")))
175       (org-link-store-props :type "gnus" :from from :date date :subject subject
176			     :message-id message-id :group group :to to)
177       (let ((link (org-gnus-article-link
178		    group newsgroups message-id x-no-archive))
179	     (description (org-link-email-description)))
180	 (org-link-add-props :link link :description description)
181	 link)))
182    (`message-mode
183     (setq org-store-link-plist nil)	;reset
184     (save-excursion
185       (save-restriction
186	 (message-narrow-to-headers)
187	 (unless (message-fetch-field "Message-ID")
188	   (message-generate-headers '(Message-ID)))
189	 (goto-char (point-min))
190	 (re-search-forward "^Message-ID:" nil t)
191	 (put-text-property (line-beginning-position) (line-end-position)
192			    'message-deletable nil)
193	 (let ((gcc (org-last (message-unquote-tokens
194			       (message-tokenize-header
195				(mail-fetch-field "gcc" nil t) " ,"))))
196	       (id (org-unbracket-string "<" ">"
197		     (mail-fetch-field "Message-ID")))
198	       (to (mail-fetch-field "To"))
199	       (from (mail-fetch-field "From"))
200	       (subject (mail-fetch-field "Subject"))
201	       ) ;; newsgroup xarchive	;those are always nil for gcc
202	   (unless gcc (error "Can not create link: No Gcc header found"))
203	   (org-link-store-props :type "gnus" :from from :subject subject
204				 :message-id id :group gcc :to to)
205	   (let ((link (org-gnus-article-link gcc nil id nil)) ;;newsgroup xarchive
206		 (description (org-link-email-description)))
207	     (org-link-add-props :link link :description description)
208	     link)))))))
209
210(defun org-gnus-open-nntp (path)
211  "Follow the nntp: link specified by PATH."
212  (let* ((spec (split-string path "/"))
213	 (server (split-string (nth 2 spec) "@"))
214	 (group (nth 3 spec))
215	 (article (nth 4 spec)))
216    (org-gnus-follow-link
217     (format "nntp+%s:%s" (or (cdr server) (car server)) group)
218     article)))
219
220(defun org-gnus-open (path _)
221  "Follow the Gnus message or folder link specified by PATH."
222  (unless (string-match "\\`\\([^#]+\\)\\(#\\(.*\\)\\)?" path)
223    (error "Error in Gnus link %S" path))
224  (let ((group (match-string-no-properties 1 path))
225	(article (match-string-no-properties 3 path)))
226    (org-gnus-follow-link group article)))
227
228(defun org-gnus-follow-link (&optional group article)
229  "Follow a Gnus link to GROUP and ARTICLE."
230  (require 'gnus)
231  (funcall (cdr (assq 'gnus org-link-frame-setup)))
232  (when gnus-other-frame-object (select-frame gnus-other-frame-object))
233  (let ((group (org-no-properties group))
234	(article (org-no-properties article)))
235    (cond
236     ((and group article)
237      (gnus-activate-group group)
238      (condition-case nil
239	  (let ((msg "Couldn't follow Gnus link.  Summary couldn't be opened."))
240	    (pcase (gnus-find-method-for-group group)
241	      (`(nndoc . ,_)
242	       (if (gnus-group-read-group t nil group)
243		   (gnus-summary-goto-article article nil t)
244		 (message msg)))
245	      (_
246	       (let ((articles 1)
247		     group-opened)
248		 (while (and (not group-opened)
249			     ;; Stop on integer overflows.  Note: We
250			     ;; can drop this once we require at least
251			     ;; Emacs 27, which supports bignums.
252			     (> articles 0))
253		   (setq group-opened (gnus-group-read-group articles t group))
254		   (setq articles (if (< articles 16)
255				      (1+ articles)
256				    (* articles 2))))
257		 (if group-opened
258		     (gnus-summary-goto-article article nil t)
259		   (message msg))))))
260	(quit
261	 (message "Couldn't follow Gnus link.  The linked group is empty."))))
262     (group (gnus-group-jump-to-group group)))))
263
264(defun org-gnus-no-new-news ()
265  "Like `\\[gnus]' but doesn't check for new news."
266  (cond ((gnus-alive-p) nil)
267	(org-gnus-no-server (gnus-no-server))
268	(t (gnus))))
269
270(provide 'ol-gnus)
271
272;;; ol-gnus.el ends here
273