summaryrefslogtreecommitdiff
path: root/lisp/gnus/gnus-registry.el
blob: 9a8d77d3b24062d03e598bfe40d74bc1eb24f1dd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
;;; gnus-registry.el --- article registry for Gnus
;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
;;        Free Software Foundation, Inc.

;; Author: Ted Zlatanov <tzz@lifelogs.com>
;; Keywords: 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 2, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; This is the gnus-registry.el package, works with other backends
;; besides nnmail.  The major issue is that it doesn't go across
;; backends, so for instance if an article is in nnml:sys and you see
;; a reference to it in nnimap splitting, the article will end up in
;; nnimap:sys

;; gnus-registry.el intercepts article respooling, moving, deleting,
;; and copying for all backends.  If it doesn't work correctly for
;; you, submit a bug report and I'll be glad to fix it.  It needs
;; documentation in the manual (also on my to-do list).

;; Put this in your startup file (~/.gnus.el for instance)

;; (setq gnus-registry-max-entries 2500
;;       gnus-registry-use-long-group-names t)

;; (gnus-registry-initialize)

;; Then use this in your fancy-split:

;; (: gnus-registry-split-fancy-with-parent)

;; TODO:

;; - get the correct group on spool actions

;; - articles that are spooled to a different backend should be handled

;;; Code:

(eval-when-compile (require 'cl))

(require 'gnus)
(require 'gnus-int)
(require 'gnus-sum)
(require 'nnmail)

(defvar gnus-registry-dirty t
 "Boolean set to t when the registry is modified")

(defgroup gnus-registry nil
  "The Gnus registry."
  :group 'gnus)

(defvar gnus-registry-hashtb nil
  "*The article registry by Message ID.")

(defcustom gnus-registry-unfollowed-groups '("delayed" "drafts" "queue")
  "List of groups that gnus-registry-split-fancy-with-parent won't follow.
The group names are matched, they don't have to be fully qualified."
  :group 'gnus-registry
  :type '(repeat string))

(defcustom gnus-registry-install nil
  "Whether the registry should be installed."
  :group 'gnus-registry
  :type 'boolean)

(defcustom gnus-registry-clean-empty t
  "Whether the empty registry entries should be deleted.
Registry entries are considered empty when they have no groups."
  :group 'gnus-registry
  :type 'boolean)

(defcustom gnus-registry-use-long-group-names nil
  "Whether the registry should use long group names (BUGGY)."
  :group 'gnus-registry
  :type 'boolean)

(defcustom gnus-registry-track-extra nil
  "Whether the registry should track extra data about a message.
The Subject and Sender (From:) headers are currently tracked this
way."
  :group 'gnus-registry
  :type      
  '(set :tag "Tracking choices"
    (const :tag "Track by subject (Subject: header)" subject)
    (const :tag "Track by sender (From: header)"  sender)))

(defcustom gnus-registry-entry-caching t
  "Whether the registry should cache extra information."
  :group 'gnus-registry
  :type 'boolean)

(defcustom gnus-registry-minimum-subject-length 5
  "The minimum length of a subject before it's considered trackable."
  :group 'gnus-registry
  :type 'integer)

(defcustom gnus-registry-trim-articles-without-groups t
  "Whether the registry should clean out message IDs without groups."
  :group 'gnus-registry
  :type 'boolean)

(defcustom gnus-registry-cache-file "~/.gnus.registry.eld"
  "File where the Gnus registry will be stored."
  :group 'gnus-registry
  :type 'file)

(defcustom gnus-registry-max-entries nil
  "Maximum number of entries in the registry, nil for unlimited."
  :group 'gnus-registry
  :type '(radio (const :format "Unlimited " nil)
		(integer :format "Maximum number: %v\n" :size 0)))

;; Function(s) missing in Emacs 20
(when (memq nil (mapcar 'fboundp '(puthash)))
  (require 'cl)
  (unless (fboundp 'puthash)
    ;; alias puthash is missing from Emacs 20 cl-extra.el
    (defalias 'puthash 'cl-puthash)))

(defun gnus-registry-track-subject-p ()
  (memq 'subject gnus-registry-track-extra))

(defun gnus-registry-track-sender-p ()
  (memq 'sender gnus-registry-track-extra))

(defun gnus-registry-cache-read ()
  "Read the registry cache file."
  (interactive)
  (let ((file gnus-registry-cache-file))
    (when (file-exists-p file)
      (gnus-message 5 "Reading %s..." file)
      (gnus-load file)
      (gnus-message 5 "Reading %s...done" file))))

(defun gnus-registry-cache-save ()
  "Save the registry cache file."
  (interactive)
  (let ((file gnus-registry-cache-file))
    (save-excursion
      (set-buffer (gnus-get-buffer-create " *Gnus-registry-cache*"))
      (make-local-variable 'version-control)
    (setq version-control gnus-backup-startup-file)
    (setq buffer-file-name file)
    (setq default-directory (file-name-directory buffer-file-name))
    (buffer-disable-undo)
    (erase-buffer)
    (gnus-message 5 "Saving %s..." file)
    (if gnus-save-startup-file-via-temp-buffer
	(let ((coding-system-for-write gnus-ding-file-coding-system)
	      (standard-output (current-buffer)))
	  (gnus-gnus-to-quick-newsrc-format t "gnus registry startup file" 'gnus-registry-alist)
	  (gnus-registry-cache-whitespace file)
	  (save-buffer))
      (let ((coding-system-for-write gnus-ding-file-coding-system)
	    (version-control gnus-backup-startup-file)
	    (startup-file file)
	    (working-dir (file-name-directory file))
	    working-file
	    (i -1))
	;; Generate the name of a non-existent file.
	(while (progn (setq working-file
			    (format
			     (if (and (eq system-type 'ms-dos)
				      (not (gnus-long-file-names)))
				 "%s#%d.tm#" ; MSDOS limits files to 8+3
			       (if (memq system-type '(vax-vms axp-vms))
				   "%s$tmp$%d"
				 "%s#tmp#%d"))
			     working-dir (setq i (1+ i))))
		      (file-exists-p working-file)))
	
	(unwind-protect
	    (progn
	      (gnus-with-output-to-file working-file
		(gnus-gnus-to-quick-newsrc-format t "gnus registry startup file" 'gnus-registry-alist))
	      
	      ;; These bindings will mislead the current buffer
	      ;; into thinking that it is visiting the startup
	      ;; file.
	      (let ((buffer-backed-up nil)
		    (buffer-file-name startup-file)
		    (file-precious-flag t)
		    (setmodes (file-modes startup-file)))
		;; Backup the current version of the startup file.
		(backup-buffer)
		
		;; Replace the existing startup file with the temp file.
		(rename-file working-file startup-file t)
		(set-file-modes startup-file setmodes)))
	  (condition-case nil
	      (delete-file working-file)
	    (file-error nil)))))
    
    (gnus-kill-buffer (current-buffer))
    (gnus-message 5 "Saving %s...done" file))))

;; Idea from Dan Christensen <jdc@chow.mat.jhu.edu>
;; Save the gnus-registry file with extra line breaks.
(defun gnus-registry-cache-whitespace (filename)
  (gnus-message 5 "Adding whitespace to %s" filename)
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward "^(\\|(\\\"" nil t)
      (replace-match "\n\\&" t))
    (goto-char (point-min))
    (while (re-search-forward " $" nil t)
      (replace-match "" t t))))

(defun gnus-registry-save (&optional force)
  (when (or gnus-registry-dirty force)
    (let ((caching gnus-registry-entry-caching))
      ;; turn off entry caching, so mtime doesn't get recorded
      (setq gnus-registry-entry-caching nil)
      ;; remove entry caches
      (maphash
       (lambda (key value)
	 (if (hash-table-p value)
	     (remhash key gnus-registry-hashtb)))
       gnus-registry-hashtb)
      ;; remove empty entries
      (when gnus-registry-clean-empty 
	(gnus-registry-clean-empty-function))
      ;; now trim the registry appropriately
      (setq gnus-registry-alist (gnus-registry-trim 
				 (hashtable-to-alist gnus-registry-hashtb)))
      ;; really save
      (gnus-registry-cache-save)
      (setq gnus-registry-entry-caching caching)
      (setq gnus-registry-dirty nil))))

(defun gnus-registry-clean-empty-function ()
  "Remove all empty entries from the registry.  Returns count thereof."
  (let ((count 0))
    (maphash
     (lambda (key value)
       (unless (gnus-registry-fetch-group key)
	 (incf count)
	 (remhash key gnus-registry-hashtb)))
     gnus-registry-hashtb)
    count))

(defun gnus-registry-read ()
  (gnus-registry-cache-read)
  (setq gnus-registry-hashtb (alist-to-hashtable gnus-registry-alist))
  (setq gnus-registry-dirty nil))

(defun gnus-registry-trim (alist)
  "Trim alist to size, using gnus-registry-max-entries."
  (if (null gnus-registry-max-entries)
      alist				; just return the alist
    ;; else, when given max-entries, trim the alist
    (let ((timehash (make-hash-table 			    
		     :size 4096
		     :test 'equal)))
      (maphash
       (lambda (key value)
	 (puthash key (gnus-registry-fetch-extra key 'mtime) timehash))
       gnus-registry-hashtb)

      ;; we use the return value of this setq, which is the trimmed alist
      (setq alist
	    (nthcdr
	     (- (length alist) gnus-registry-max-entries)
	     (sort alist 
		   (lambda (a b)
		     (time-less-p 
		      (cdr (gethash (car a) timehash))
		      (cdr (gethash (car b) timehash))))))))))

(defun alist-to-hashtable (alist)
  "Build a hashtable from the values in ALIST."
  (let ((ht (make-hash-table 			    
	     :size 4096
	     :test 'equal)))
    (mapc
     (lambda (kv-pair)
       (puthash (car kv-pair) (cdr kv-pair) ht))
     alist)
     ht))

(defun hashtable-to-alist (hash)
  "Build an alist from the values in HASH."
  (let ((list nil))
    (maphash
     (lambda (key value)
       (setq list (cons (cons key value) list)))
     hash)
    list))

(defun gnus-registry-action (action data-header from &optional to method)
  (let* ((id (mail-header-id data-header))
	 (subject (gnus-registry-simplify-subject 
		   (mail-header-subject data-header)))
	 (sender (mail-header-from data-header))
	 (from (gnus-group-guess-full-name-from-command-method from))
	 (to (if to (gnus-group-guess-full-name-from-command-method to) nil))
	 (to-name (if to to "the Bit Bucket"))
	 (old-entry (gethash id gnus-registry-hashtb)))
    (gnus-message 5 "Registry: article %s %s from %s to %s"
		  id
		  (if method "respooling" "going")
		  from
		  to)

    ;; All except copy will need a delete
    (gnus-registry-delete-group id from)

    (when (equal 'copy action) 
      (gnus-registry-add-group id from subject sender)) ; undo the delete

    (gnus-registry-add-group id to subject sender)))

(defun gnus-registry-spool-action (id group &optional subject sender)
  (let ((group (gnus-group-guess-full-name-from-command-method group)))
    (when (and (stringp id) (string-match "\r$" id))
      (setq id (substring id 0 -1)))
    (gnus-message 5 "Registry: article %s spooled to %s"
		  id
		  group)
    (gnus-registry-add-group id group subject sender)))

;; Function for nn{mail|imap}-split-fancy: look up all references in
;; the cache and if a match is found, return that group.
(defun gnus-registry-split-fancy-with-parent ()
  "Split this message into the same group as its parent.  The parent
is obtained from the registry.  This function can be used as an entry
in `nnmail-split-fancy' or `nnimap-split-fancy', for example like
this: (: gnus-registry-split-fancy-with-parent) 

For a message to be split, it looks for the parent message in the
References or In-Reply-To header and then looks in the registry to
see which group that message was put in.  This group is returned.

See the Info node `(gnus)Fancy Mail Splitting' for more details."
  (let ((refstr (or (message-fetch-field "references")
		    (message-fetch-field "in-reply-to")))
	(nnmail-split-fancy-with-parent-ignore-groups
	 (if (listp nnmail-split-fancy-with-parent-ignore-groups)
	     nnmail-split-fancy-with-parent-ignore-groups
	   (list nnmail-split-fancy-with-parent-ignore-groups)))
	references res)
    (if refstr
	(progn
	  (setq references (nreverse (gnus-split-references refstr)))
	  (mapcar (lambda (x)
		    (setq res (or (gnus-registry-fetch-group x) res))
		    (when (or (gnus-registry-grep-in-list
			       res
			       gnus-registry-unfollowed-groups)
			      (gnus-registry-grep-in-list 
			       res
			       nnmail-split-fancy-with-parent-ignore-groups))
		      (setq res nil)))
		  references))

      ;; else: there were no references, now try the extra tracking
      (let ((sender (message-fetch-field "from"))
	    (subject (gnus-registry-simplify-subject
		      (message-fetch-field "subject")))
	    (single-match t))
	(when (and single-match
		   (gnus-registry-track-sender-p)
		   sender)
	  (maphash
	   (lambda (key value)
	     (let ((this-sender (cdr 
				 (gnus-registry-fetch-extra key 'sender))))
	       (when (and single-match
			  this-sender
			  (equal sender this-sender))
		 ;; too many matches, bail
		 (unless (equal res (gnus-registry-fetch-group key))
		   (setq single-match nil))
		 (setq res (gnus-registry-fetch-group key))
		 (gnus-message
		  ;; raise level of messaging if gnus-registry-track-extra
		  (if gnus-registry-track-extra 5 9)
		  "%s (extra tracking) traced sender %s to group %s"
		  "gnus-registry-split-fancy-with-parent"
		  sender
		  (if res res "nil")))))
	   gnus-registry-hashtb))
	(when (and single-match
		   (gnus-registry-track-subject-p)
		   subject
		   (< gnus-registry-minimum-subject-length (length subject)))
	  (maphash
	   (lambda (key value)
	     (let ((this-subject (cdr 
				  (gnus-registry-fetch-extra key 'subject))))
	       (when (and single-match
			  this-subject
			  (equal subject this-subject))
		 ;; too many matches, bail
		 (unless (equal res (gnus-registry-fetch-group key))
		   (setq single-match nil))
		 (setq res (gnus-registry-fetch-group key))
		 (gnus-message
		  ;; raise level of messaging if gnus-registry-track-extra
		  (if gnus-registry-track-extra 5 9)
		  "%s (extra tracking) traced subject %s to group %s"
		  "gnus-registry-split-fancy-with-parent"
		  subject
		  (if res res "nil")))))
	   gnus-registry-hashtb))
	(unless single-match
	  (gnus-message
	   5
	   "gnus-registry-split-fancy-with-parent: too many extra matches for %s"
	   refstr)
	  (setq res nil))))
    (gnus-message
     5 
     "gnus-registry-split-fancy-with-parent traced %s to group %s"
     refstr (if res res "nil"))

    (when (and res gnus-registry-use-long-group-names)
      (let ((m1 (gnus-find-method-for-group res))
	    (m2 (or gnus-command-method 
		    (gnus-find-method-for-group gnus-newsgroup-name)))
	    (short-res (gnus-group-short-name res)))
      (if (gnus-methods-equal-p m1 m2)
	  (progn
	    (gnus-message
	     9 
	     "gnus-registry-split-fancy-with-parent stripped group %s to %s"
	     res
	     short-res)
	    (setq res short-res))
	;; else...
	(gnus-message
	 5 
	 "gnus-registry-split-fancy-with-parent ignored foreign group %s"
	 res)
	(setq res nil))))
    res))

(defun gnus-registry-register-message-ids ()
  "Register the Message-ID of every article in the group"
  (unless (gnus-parameter-registry-ignore gnus-newsgroup-name)
    (dolist (article gnus-newsgroup-articles)
      (let ((id (gnus-registry-fetch-message-id-fast article)))
	(unless (gnus-registry-fetch-group id)
	  (gnus-message 9 "Registry: Registering article %d with group %s" 
			article gnus-newsgroup-name)
	  (gnus-registry-add-group 
	   (gnus-registry-fetch-message-id-fast article)
	   gnus-newsgroup-name
	   (gnus-registry-fetch-simplified-message-subject-fast article)
	   (gnus-registry-fetch-sender-fast article)))))))

(defun gnus-registry-fetch-message-id-fast (article)
  "Fetch the Message-ID quickly, using the internal gnus-data-list function"
  (if (and (numberp article)
	   (assoc article (gnus-data-list nil)))
      (mail-header-id (gnus-data-header (assoc article (gnus-data-list nil))))
    nil))

(defun gnus-registry-simplify-subject (subject)
  (if (stringp subject)
      (gnus-simplify-subject subject)
    nil))

(defun gnus-registry-fetch-simplified-message-subject-fast (article)
  "Fetch the Subject quickly, using the internal gnus-data-list function"
  (if (and (numberp article)
	   (assoc article (gnus-data-list nil)))
      (gnus-registry-simplify-subject
       (mail-header-subject (gnus-data-header
			     (assoc article (gnus-data-list nil)))))
    nil))

(defun gnus-registry-fetch-sender-fast (article)
  "Fetch the Sender quickly, using the internal gnus-data-list function"
  (if (and (numberp article)
	   (assoc article (gnus-data-list nil)))
      (mail-header-from (gnus-data-header
			 (assoc article (gnus-data-list nil))))
    nil))

(defun gnus-registry-grep-in-list (word list)
  (when word
    (memq nil
	  (mapcar 'not
		  (mapcar 
		   (lambda (x)
		     (string-match x word))
		   list)))))

(defun gnus-registry-fetch-extra (id &optional entry)
  "Get the extra data of a message, based on the message ID.
Returns the first place where the trail finds a nonstring."
  (let ((entry-cache (gethash entry gnus-registry-hashtb)))
    (if (and entry
	     (hash-table-p entry-cache)
	     (gethash id entry-cache))
	(gethash id entry-cache)
      ;; else, if there is no caching possible...
      (let ((trail (gethash id gnus-registry-hashtb)))
	(when (listp trail)
	  (dolist (crumb trail)
	    (unless (stringp crumb)
	      (return (gnus-registry-fetch-extra-entry crumb entry id)))))))))

(defun gnus-registry-fetch-extra-entry (alist &optional entry id)
  "Get the extra data of a message, or a specific entry in it.
Update the entry cache if needed."
  (if (and entry id)
      (let ((entry-cache (gethash entry gnus-registry-hashtb))
	    entree)
	(when gnus-registry-entry-caching
	  ;; create the hash table
	  (unless (hash-table-p entry-cache)
	    (setq entry-cache (make-hash-table
			       :size 4096
			       :test 'equal))
	    (puthash entry entry-cache gnus-registry-hashtb))

	  ;; get the entree from the hash table or from the alist
	  (setq entree (gethash id entry-cache)))
	
	(unless entree
	  (setq entree (assq entry alist))
	  (when gnus-registry-entry-caching
	    (puthash id entree entry-cache)))
	entree)
    alist))

(defun gnus-registry-store-extra (id extra)
  "Store the extra data of a message, based on the message ID.
The message must have at least one group name."
  (when (gnus-registry-group-count id)
    ;; we now know the trail has at least 1 group name, so it's not empty
    (let ((trail (gethash id gnus-registry-hashtb))
	  (old-extra (gnus-registry-fetch-extra id))
	  entry-cache)
      (dolist (crumb trail)
	(unless (stringp crumb)
	  (dolist (entry crumb)
	    (setq entry-cache (gethash (car entry) gnus-registry-hashtb))
	  (when entry-cache
	    (remhash id entry-cache))))
      (puthash id (cons extra (delete old-extra trail))
	       gnus-registry-hashtb)
      (setq gnus-registry-dirty t)))))

(defun gnus-registry-store-extra-entry (id key value)
  "Put a specific entry in the extras field of the registry entry for id."
  (let* ((extra (gnus-registry-fetch-extra id))
	 (alist (cons (cons key value)
		 (gnus-assq-delete-all key (gnus-registry-fetch-extra id)))))
    (gnus-registry-store-extra id alist)))

(defun gnus-registry-fetch-group (id)
  "Get the group of a message, based on the message ID.
Returns the first place where the trail finds a group name."
  (when (gnus-registry-group-count id)
    ;; we now know the trail has at least 1 group name
    (let ((trail (gethash id gnus-registry-hashtb)))
      (dolist (crumb trail)
	(when (stringp crumb)
	  (return (if gnus-registry-use-long-group-names 
		       crumb 
		     (gnus-group-short-name crumb))))))))

(defun gnus-registry-group-count (id)
  "Get the number of groups of a message, based on the message ID."
  (let ((trail (gethash id gnus-registry-hashtb)))
    (if (and trail (listp trail))
	(apply '+ (mapcar (lambda (x) (if (stringp x) 1 0)) trail))
      0)))

(defun gnus-registry-delete-group (id group)
  "Delete a group for a message, based on the message ID."
  (when group
    (when id
      (let ((trail (gethash id gnus-registry-hashtb))
	    (group (gnus-group-short-name group)))
	(puthash id (if trail
			(delete group trail)
		      nil)
		 gnus-registry-hashtb))
      ;; now, clear the entry if there are no more groups
      (when gnus-registry-trim-articles-without-groups
	(unless (gnus-registry-group-count id)
	  (gnus-registry-delete-id id)))
      (gnus-registry-store-extra-entry id 'mtime (current-time)))))

(defun gnus-registry-delete-id (id)
  "Delete a message ID from the registry."
  (when (stringp id)
    (remhash id gnus-registry-hashtb)
    (maphash
     (lambda (key value)
       (when (hash-table-p value)
	 (remhash id value)))
     gnus-registry-hashtb)))

(defun gnus-registry-add-group (id group &optional subject sender)
  "Add a group for a message, based on the message ID."
  (when group
    (when (and id
	       (not (string-match "totally-fudged-out-message-id" id)))
      (let ((full-group group)
	    (group (if gnus-registry-use-long-group-names 
		       group 
		     (gnus-group-short-name group))))
	(gnus-registry-delete-group id group)

	(unless gnus-registry-use-long-group-names ;; unnecessary in this case
	  (gnus-registry-delete-group id full-group))

	(let ((trail (gethash id gnus-registry-hashtb)))
	  (puthash id (if trail
			  (cons group trail)
			(list group))
		   gnus-registry-hashtb)

	  (when (and (gnus-registry-track-subject-p)
		     subject)
	    (gnus-registry-store-extra-entry
	     id 
	     'subject 
	     (gnus-registry-simplify-subject subject)))
	  (when (and (gnus-registry-track-sender-p)
		     sender)
	    (gnus-registry-store-extra-entry
	     id 
	     'sender
	     sender))
	  
	  (gnus-registry-store-extra-entry id 'mtime (current-time)))))))

(defun gnus-registry-clear ()
  "Clear the Gnus registry."
  (interactive)
  (setq gnus-registry-alist nil)
  (setq gnus-registry-hashtb (alist-to-hashtable gnus-registry-alist))
  (setq gnus-registry-dirty t))

;;;###autoload
(defun gnus-registry-initialize ()
  (interactive)
  (setq gnus-registry-install t)
  (gnus-registry-install-hooks)
  (gnus-registry-read))

;;;###autoload
(defun gnus-registry-install-hooks ()
  "Install the registry hooks."
  (interactive)
  (add-hook 'gnus-summary-article-move-hook 'gnus-registry-action) 
  (add-hook 'gnus-summary-article-delete-hook 'gnus-registry-action)
  (add-hook 'gnus-summary-article-expire-hook 'gnus-registry-action)
  (add-hook 'nnmail-spool-hook 'gnus-registry-spool-action)
  
  (add-hook 'gnus-save-newsrc-hook 'gnus-registry-save)
  (add-hook 'gnus-read-newsrc-el-hook 'gnus-registry-read)

  (add-hook 'gnus-summary-prepare-hook 'gnus-registry-register-message-ids))

(defun gnus-registry-unload-hook ()
  "Uninstall the registry hooks."
  (interactive)
  (remove-hook 'gnus-summary-article-move-hook 'gnus-registry-action) 
  (remove-hook 'gnus-summary-article-delete-hook 'gnus-registry-action)
  (remove-hook 'gnus-summary-article-expire-hook 'gnus-registry-action)
  (remove-hook 'nnmail-spool-hook 'gnus-registry-spool-action)
  
  (remove-hook 'gnus-save-newsrc-hook 'gnus-registry-save)
  (remove-hook 'gnus-read-newsrc-el-hook 'gnus-registry-read)

  (remove-hook 'gnus-summary-prepare-hook 'gnus-registry-register-message-ids))

(when gnus-registry-install
  (gnus-registry-install-hooks)
  (gnus-registry-read))

;; TODO: a lot of things

(provide 'gnus-registry)

;;; arch-tag: 5cba0a32-718a-4a97-8c91-0a15af21da94
;;; gnus-registry.el ends here