summaryrefslogtreecommitdiff
path: root/lisp/gnus/gnus-icalendar.el
blob: 79f1e2fe2030cad8859a5582e777fdfd4c171875 (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
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
;;; gnus-icalendar.el --- reply to iCalendar meeting requests

;; Copyright (C) 2013-2014 Free Software Foundation, Inc.

;; Author: Jan Tatarik <Jan.Tatarik@gmail.com>
;; Keywords: mail, icalendar, org

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

;; This program 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; To install:
;; (require 'gnus-icalendar)
;; (gnus-icalendar-setup)

;; to enable optional iCalendar->Org sync functionality
;; NOTE: both the capture file and the headline(s) inside must already exist
;; (setq gnus-icalendar-org-capture-file "~/org/notes.org")
;; (setq gnus-icalendar-org-capture-headline '("Calendar"))
;; (gnus-icalendar-org-setup)


;;; Code:

(require 'icalendar)
(require 'eieio)
(require 'gmm-utils)
(require 'mm-decode)
(require 'gnus-sum)

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

(defun gnus-icalendar-find-if (pred seq)
  (catch 'found
    (while seq
      (when (funcall pred (car seq))
        (throw 'found (car seq)))
      (pop seq))))

;;;
;;; ical-event
;;;

(defclass gnus-icalendar-event ()
  ((organizer :initarg :organizer
              :accessor gnus-icalendar-event:organizer
              :initform ""
              :type (or null string))
   (summary :initarg :summary
            :accessor gnus-icalendar-event:summary
            :initform ""
            :type (or null string))
   (description :initarg :description
                :accessor gnus-icalendar-event:description
                :initform ""
                :type (or null string))
   (location :initarg :location
             :accessor gnus-icalendar-event:location
             :initform ""
             :type (or null string))
   (start-time :initarg :start-time
          :accessor gnus-icalendar-event:start-time
          :initform ""
          :type (or null t))
   (end-time :initarg :end-time
        :accessor gnus-icalendar-event:end-time
        :initform ""
        :type (or null t))
   (recur :initarg :recur
          :accessor gnus-icalendar-event:recur
          :initform ""
          :type (or null string))
   (uid :initarg :uid
        :accessor gnus-icalendar-event:uid
        :type string)
   (method :initarg :method
           :accessor gnus-icalendar-event:method
           :initform "PUBLISH"
           :type (or null string))
   (rsvp :initarg :rsvp
         :accessor gnus-icalendar-event:rsvp
         :initform nil
         :type (or null boolean))
   (participation-type :initarg :participation-type
         :accessor gnus-icalendar-event:participation-type
         :initform 'non-participant
         :type (or null t))
   (req-participants :initarg :req-participants
         :accessor gnus-icalendar-event:req-participants
         :initform nil
         :type (or null t))
   (opt-participants :initarg :opt-participants
         :accessor gnus-icalendar-event:opt-participants
         :initform nil
         :type (or null t)))
  "generic iCalendar Event class")

(defclass gnus-icalendar-event-request (gnus-icalendar-event)
  nil
  "iCalendar class for REQUEST events")

(defclass gnus-icalendar-event-cancel (gnus-icalendar-event)
  nil
  "iCalendar class for CANCEL events")

(defclass gnus-icalendar-event-reply (gnus-icalendar-event)
  nil
  "iCalendar class for REPLY events")

(defmethod gnus-icalendar-event:recurring-p ((event gnus-icalendar-event))
  "Return t if EVENT is recurring."
  (not (null (gnus-icalendar-event:recur event))))

(defmethod gnus-icalendar-event:recurring-freq ((event gnus-icalendar-event))
  "Return recurring frequency of EVENT."
  (let ((rrule (gnus-icalendar-event:recur event)))
    (string-match "FREQ=\\([[:alpha:]]+\\)" rrule)
    (match-string 1 rrule)))

(defmethod gnus-icalendar-event:recurring-interval ((event gnus-icalendar-event))
  "Return recurring interval of EVENT."
  (let ((rrule (gnus-icalendar-event:recur event))
        (default-interval 1))

    (string-match "INTERVAL=\\([[:digit:]]+\\)" rrule)
    (or (match-string 1 rrule)
        default-interval)))

(defmethod gnus-icalendar-event:start ((event gnus-icalendar-event))
  (format-time-string "%Y-%m-%d %H:%M" (gnus-icalendar-event:start-time event)))

(defun gnus-icalendar-event--decode-datefield (ical field)
  (let* ((date (icalendar--get-event-property ical field))
         (date-props (icalendar--get-event-property-attributes ical field))
         (tz (plist-get date-props 'TZID)))

    (date-to-time (timezone-make-date-arpa-standard date nil tz))))

(defun gnus-icalendar-event--find-attendee (ical name-or-email)
  (let* ((event (car (icalendar--all-events ical)))
         (event-props (caddr event)))
    (gmm-labels ((attendee-name (att) (plist-get (cadr att) 'CN))
                 (attendee-email (att)
                   (replace-regexp-in-string "^.*MAILTO:" "" (caddr att)))
                 (attendee-prop-matches-p (prop)
                   (and (eq (car prop) 'ATTENDEE)
                        (or (member (attendee-name prop) name-or-email)
                            (let ((att-email (attendee-email prop)))
                              (gnus-icalendar-find-if (lambda (email)
                                                        (string-match email att-email))
                                                      name-or-email))))))

      (gnus-icalendar-find-if #'attendee-prop-matches-p event-props))))

(defun gnus-icalendar-event--get-attendee-names (ical)
  (let* ((event (car (icalendar--all-events ical)))
         (attendee-props (gnus-remove-if-not
                          (lambda (p) (eq (car p) 'ATTENDEE))
                          (caddr event))))

    (gmm-labels ((attendee-role (prop) (plist-get (cadr prop) 'ROLE))
                 (attendee-name (prop) (plist-get (cadr prop) 'CN))
                 (attendees-by-type (type)
                   (gnus-remove-if-not
                    (lambda (p) (string= (attendee-role p) type))
                    attendee-props))
                 (attendee-names-by-type (type)
                    (mapcar #'attendee-name (attendees-by-type type))))

      (list
       (attendee-names-by-type "REQ-PARTICIPANT")
       (attendee-names-by-type "OPT-PARTICIPANT")))))

(defun gnus-icalendar-event-from-ical (ical &optional attendee-name-or-email)
  (let* ((event (car (icalendar--all-events ical)))
         (organizer (replace-regexp-in-string
                     "^.*MAILTO:" ""
                     (or (icalendar--get-event-property event 'ORGANIZER) "")))
         (prop-map '((summary . SUMMARY)
                     (description . DESCRIPTION)
                     (location . LOCATION)
                     (recur . RRULE)
                     (uid . UID)))
         (method (caddr (assoc 'METHOD (caddr (car (nreverse ical))))))
         (attendee (when attendee-name-or-email
                     (gnus-icalendar-event--find-attendee ical attendee-name-or-email)))
         (attendee-names (gnus-icalendar-event--get-attendee-names ical))
         (role (plist-get (cadr attendee) 'ROLE))
         (participation-type (pcase role
                              ("REQ-PARTICIPANT" 'required)
                              ("OPT-PARTICIPANT" 'optional)
                              (_                 'non-participant)))
         (args (list :method method
                     :organizer organizer
                     :start-time (gnus-icalendar-event--decode-datefield event 'DTSTART)
                     :end-time (gnus-icalendar-event--decode-datefield event 'DTEND)
                     :rsvp (string= (plist-get (cadr attendee) 'RSVP) "TRUE")
                     :participation-type participation-type
                     :req-participants (car attendee-names)
                     :opt-participants (cadr attendee-names)))
         (event-class (cond
                       ((string= method "REQUEST") 'gnus-icalendar-event-request)
                       ((string= method "CANCEL") 'gnus-icalendar-event-cancel)
                       ((string= method "REPLY") 'gnus-icalendar-event-reply)
                       (t 'gnus-icalendar-event))))

    (gmm-labels ((map-property (prop)
                   (let ((value (icalendar--get-event-property event prop)))
                     (when value
                       ;; ugly, but cannot get
                       ;;replace-regexp-in-string work with "\\" as
                       ;;REP, plus we should also handle "\\;"
                       (replace-regexp-in-string
                        "\\\\," ","
                        (replace-regexp-in-string
                         "\\\\n" "\n" (substring-no-properties value))))))
                 (accumulate-args (mapping)
                   (destructuring-bind (slot . ical-property) mapping
                     (setq args (append (list
                                         (intern (concat ":" (symbol-name slot)))
                                         (map-property ical-property))
                                        args)))))

      (mapc #'accumulate-args prop-map)
      (apply 'make-instance event-class args))))

(defun gnus-icalendar-event-from-buffer (buf &optional attendee-name-or-email)
  "Parse RFC5545 iCalendar in buffer BUF and return an event object.

Return a gnus-icalendar-event object representing the first event
contained in the invitation. Return nil for calendars without an event entry.

ATTENDEE-NAME-OR-EMAIL is a list of strings that will be matched
against the event's attendee names and emails. Invitation rsvp
status will be retrieved from the first matching attendee record."
  (let ((ical (with-current-buffer (icalendar--get-unfolded-buffer (get-buffer buf))
                (goto-char (point-min))
                (icalendar--read-element nil nil))))

    (when ical
      (gnus-icalendar-event-from-ical ical attendee-name-or-email))))

;;;
;;; gnus-icalendar-event-reply
;;;

(defun gnus-icalendar-event--build-reply-event-body (ical-request status identities)
  (let ((summary-status (capitalize (symbol-name status)))
        (attendee-status (upcase (symbol-name status)))
        reply-event-lines)
    (gmm-labels ((update-summary (line)
                   (if (string-match "^[^:]+:" line)
                       (replace-match (format "\\&%s: " summary-status) t nil line)
                     line))
                 (update-dtstamp ()
                   (format-time-string "DTSTAMP:%Y%m%dT%H%M%SZ" nil t))
                 (attendee-matches-identity (line)
                   (gnus-icalendar-find-if (lambda (name) (string-match-p name line))
                                           identities))
                 (update-attendee-status (line)
                   (when (and (attendee-matches-identity line)
                              (string-match "\\(PARTSTAT=\\)[^;]+" line))
                     (replace-match (format "\\1%s" attendee-status) t nil line)))
                 (process-event-line (line)
                   (when (string-match "^\\([^;:]+\\)" line)
                     (let* ((key (match-string 0 line))
                            ;; NOTE: not all of the below fields are mandatory,
                            ;; but they are often present in other clients'
                            ;; replies. Can be helpful for debugging, too.
                            (new-line
                             (cond
                              ((string= key "ATTENDEE") (update-attendee-status line))
                              ((string= key "SUMMARY") (update-summary line))
                              ((string= key "DTSTAMP") (update-dtstamp))
                              ((member key '("ORGANIZER" "DTSTART" "DTEND"
                                             "LOCATION" "DURATION" "SEQUENCE"
                                             "RECURRENCE-ID" "UID")) line)
                              (t nil))))
                       (when new-line
                         (push new-line reply-event-lines))))))

      (mapc #'process-event-line (split-string ical-request "\n"))

      (unless (gnus-icalendar-find-if (lambda (x) (string-match "^ATTENDEE" x))
                          reply-event-lines)
        (error "Could not find an event attendee matching given identity"))

      (mapconcat #'identity `("BEGIN:VEVENT"
                              ,@(nreverse reply-event-lines)
                              "END:VEVENT")
                 "\n"))))

(defun gnus-icalendar-event-reply-from-buffer (buf status identities)
  "Build a calendar event reply for request contained in BUF.
The reply will have STATUS (`accepted', `tentative' or  `declined').
The reply will be composed for attendees matching any entry
on the IDENTITIES list."
  (gmm-labels ((extract-block (blockname)
               (save-excursion
                 (let ((block-start-re (format "^BEGIN:%s" blockname))
                       (block-end-re (format "^END:%s" blockname))
                       start)
                   (when (re-search-forward block-start-re nil t)
                     (setq start (line-beginning-position))
                     (re-search-forward block-end-re)
                     (buffer-substring-no-properties start (line-end-position)))))))

    (let (zone event)
      (with-current-buffer (icalendar--get-unfolded-buffer (get-buffer buf))
        (goto-char (point-min))
        (setq zone (extract-block "VTIMEZONE")
              event (extract-block "VEVENT")))

      (when event
        (let ((contents (list "BEGIN:VCALENDAR"
                              "METHOD:REPLY"
                              "PRODID:Gnus"
                              "VERSION:2.0"
                              zone
                              (gnus-icalendar-event--build-reply-event-body event status identities)
                              "END:VCALENDAR")))

          (mapconcat #'identity (delq nil contents) "\n"))))))

;;;
;;; gnus-icalendar-org
;;;
;;; TODO: this is an optional feature, and it's only available with org-mode
;;; 7+, so will need to properly handle emacsen with no/outdated org-mode

(require 'org)
(require 'org-capture)

(defgroup gnus-icalendar-org nil
  "Settings for Calendar Event gnus/org integration."
  :version "24.4"
  :group 'gnus-icalendar
  :prefix "gnus-icalendar-org-")

(defcustom gnus-icalendar-org-capture-file nil
  "Target Org file for storing captured calendar events."
  :type '(choice (const nil) file)
  :group 'gnus-icalendar-org)

(defcustom gnus-icalendar-org-capture-headline nil
  "Target outline in `gnus-icalendar-org-capture-file' for storing captured events."
  :type '(repeat string)
  :group 'gnus-icalendar-org)

(defcustom gnus-icalendar-org-template-name "used by gnus-icalendar-org"
  "Org-mode template name."
  :type '(string)
  :group 'gnus-icalendar-org)

(defcustom gnus-icalendar-org-template-key "#"
  "Org-mode template hotkey."
  :type '(string)
  :group 'gnus-icalendar-org)

(defvar gnus-icalendar-org-enabled-p nil)


(defmethod gnus-icalendar-event:org-repeat ((event gnus-icalendar-event))
  "Return `org-mode' timestamp repeater string for recurring EVENT.
Return nil for non-recurring EVENT."
  (when (gnus-icalendar-event:recurring-p event)
    (let* ((freq-map '(("HOURLY" . "h")
                       ("DAILY" . "d")
                       ("WEEKLY" . "w")
                       ("MONTHLY" . "m")
                       ("YEARLY" . "y")))
           (org-freq (cdr (assoc (gnus-icalendar-event:recurring-freq event) freq-map))))

      (when org-freq
        (format "+%s%s" (gnus-icalendar-event:recurring-interval event) org-freq)))))

(defmethod gnus-icalendar-event:org-timestamp ((event gnus-icalendar-event))
  "Build `org-mode' timestamp from EVENT start/end dates and recurrence info."
  (let* ((start (gnus-icalendar-event:start-time event))
         (end (gnus-icalendar-event:end-time event))
         (start-date (format-time-string "%Y-%m-%d %a" start))
         (start-time (format-time-string "%H:%M" start))
         (start-at-midnight (string= start-time "00:00"))
         (end-date (format-time-string "%Y-%m-%d %a" end))
         (end-time (format-time-string "%H:%M" end))
         (end-at-midnight (string= end-time "00:00"))
         (start-end-date-diff (/ (float-time (time-subtract
                                        (date-to-time end-date)
                                        (date-to-time start-date)))
                                 86400))
         (org-repeat (gnus-icalendar-event:org-repeat event))
         (repeat (if org-repeat (concat " " org-repeat) ""))
         (time-1-day '(0 86400)))

    ;; NOTE: special care is needed with appointments ending at midnight
    ;; (typically all-day events): the end time has to be changed to 23:59 to
    ;; prevent org agenda showing the event on one additional day
    (cond
     ;; start/end midnight
     ;; A 0:0 - A+1 0:0 -> A
     ;; A 0:0 - A+n 0:0 -> A - A+n-1
     ((and start-at-midnight end-at-midnight) (if (> start-end-date-diff 1)
                                                  (let ((end-ts (format-time-string "%Y-%m-%d %a" (time-subtract end time-1-day))))
                                                    (format "<%s>--<%s>" start-date end-ts))
                                                (format "<%s%s>" start-date repeat)))
     ;; end midnight
     ;; A .:. - A+1 0:0 -> A .:.-23:59
     ;; A .:. - A+n 0:0 -> A .:. - A_n-1
     (end-at-midnight (if (= start-end-date-diff 1)
                          (format "<%s %s-23:59%s>" start-date start-time repeat)
                        (let ((end-ts (format-time-string "%Y-%m-%d %a" (time-subtract end time-1-day))))
                          (format "<%s %s>--<%s>" start-date start-time end-ts))))
     ;; start midnight
     ;; A 0:0 - A .:. -> A 0:0-.:. (default 1)
     ;; A 0:0 - A+n .:. -> A - A+n .:.
     ((and start-at-midnight
           (plusp start-end-date-diff)) (format "<%s>--<%s %s>" start-date end-date end-time))
     ;; default
     ;; A .:. - A .:. -> A .:.-.:.
     ;; A .:. - B .:.
     ((zerop start-end-date-diff) (format "<%s %s-%s%s>" start-date start-time end-time repeat))
     (t (format "<%s %s>--<%s %s>" start-date start-time end-date end-time)))))

(defun gnus-icalendar--format-summary-line (summary &optional location)
  (if location
      (format "%s (%s)" summary location)
    (format "%s" summary)))


(defun gnus-icalendar--format-participant-list (participants)
  (mapconcat #'identity participants ", "))

;; TODO: make the template customizable
(defmethod gnus-icalendar-event->org-entry ((event gnus-icalendar-event) reply-status)
  "Return string with new `org-mode' entry describing EVENT."
  (with-temp-buffer
    (org-mode)
    (with-slots (organizer summary description location
                           recur uid) event
      (let* ((reply (if reply-status (capitalize (symbol-name reply-status))
                      "Not replied yet"))
             (props `(("ICAL_EVENT" . "t")
                      ("ID" . ,uid)
                      ("DT" . ,(gnus-icalendar-event:org-timestamp event))
                      ("ORGANIZER" . ,(gnus-icalendar-event:organizer event))
                      ("LOCATION" . ,(gnus-icalendar-event:location event))
                      ("PARTICIPATION_TYPE" . ,(symbol-name (gnus-icalendar-event:participation-type event)))
                      ("REQ_PARTICIPANTS" . ,(gnus-icalendar--format-participant-list (gnus-icalendar-event:req-participants event)))
                      ("OPT_PARTICIPANTS" . ,(gnus-icalendar--format-participant-list (gnus-icalendar-event:opt-participants event)))
                      ("RRULE" . ,(gnus-icalendar-event:recur event))
                      ("REPLY" . ,reply))))

        (insert (format "* %s\n\n"
                        (gnus-icalendar--format-summary-line summary location)))
        (mapc (lambda (prop)
                (org-entry-put (point) (car prop) (cdr prop)))
              props))

      (when description
        (save-restriction
          (narrow-to-region (point) (point))
          (insert description)
          (indent-region (point-min) (point-max) 2)
          (fill-region (point-min) (point-max))))

      (buffer-string))))

(defun gnus-icalendar--deactivate-org-timestamp (ts)
  (replace-regexp-in-string "[<>]"
                            (lambda (m) (cond ((string= m "<") "[")
                                              ((string= m ">") "]")))
                            ts))

(defun gnus-icalendar-find-org-event-file (event &optional org-file)
  "Return the name of the file containing EVENT org entry.
Return nil when not found.

All org agenda files are searched for the EVENT entry.  When
the optional ORG-FILE argument is specified, only that one file
is searched."
  (let ((uid (gnus-icalendar-event:uid event))
        (files (or org-file (org-agenda-files t 'ifmode))))
    (gmm-labels
        ((find-event-in (file)
           (org-check-agenda-file file)
           (with-current-buffer (find-file-noselect file)
             (let ((event-pos (org-find-entry-with-id uid)))
               (when (and event-pos
                          (string= (cdr (assoc "ICAL_EVENT" (org-entry-properties event-pos)))
                                   "t"))
                 (throw 'found file))))))

      (gnus-icalendar-find-if #'find-event-in files))))


(defun gnus-icalendar--show-org-event (event &optional org-file)
  (let ((file (gnus-icalendar-find-org-event-file event org-file)))
    (when file
      (switch-to-buffer (find-file file))
      (goto-char (org-find-entry-with-id (gnus-icalendar-event:uid event)))
      (org-show-entry))))


(defun gnus-icalendar--update-org-event (event reply-status &optional org-file)
  (let ((file (gnus-icalendar-find-org-event-file event org-file)))
    (when file
      (with-current-buffer (find-file-noselect file)
        (with-slots (uid summary description organizer location recur
                         participation-type req-participants opt-participants) event
          (let ((event-pos (org-find-entry-with-id uid)))
            (when event-pos
              (goto-char event-pos)

              ;; update the headline, keep todo, priority and tags, if any
              (save-excursion
                (let* ((priority (org-entry-get (point) "PRIORITY"))
                       (headline (delq nil (list
                                            (org-entry-get (point) "TODO")
                                            (when priority (format "[#%s]" priority))
                                            (gnus-icalendar--format-summary-line summary location)
                                            (org-entry-get (point) "TAGS")))))

                  (re-search-forward "^\\*+ " (line-end-position))
                  (delete-region (point) (line-end-position))
                  (insert (mapconcat #'identity headline " "))))

              ;; update props and description
              (let ((entry-end (org-entry-end-position))
                    (entry-outline-level (org-outline-level)))

                ;; delete body of the entry, leave org drawers intact
                (save-restriction
                  (org-narrow-to-element)
                  (goto-char entry-end)
                  (re-search-backward "^[\t ]*:END:")
                  (forward-line)
                  (delete-region (point) entry-end))

                ;; put new event description in the entry body
                (when description
                  (save-restriction
                    (narrow-to-region (point) (point))
                    (insert "\n" (replace-regexp-in-string "[\n]+$" "\n" description) "\n")
                    (indent-region (point-min) (point-max) (1+ entry-outline-level))
                    (fill-region (point-min) (point-max))))

                ;; update entry properties
                (org-entry-put event-pos "DT" (gnus-icalendar-event:org-timestamp event))
                (org-entry-put event-pos "ORGANIZER" organizer)
                (org-entry-put event-pos "LOCATION" location)
                (org-entry-put event-pos "PARTICIPATION_TYPE" (symbol-name participation-type))
                (org-entry-put event-pos "REQ_PARTICIPANTS" (gnus-icalendar--format-participant-list req-participants))
                (org-entry-put event-pos "OPT_PARTICIPANTS" (gnus-icalendar--format-participant-list opt-participants))
                (org-entry-put event-pos "RRULE" recur)
                (when reply-status (org-entry-put event-pos "REPLY"
                                                  (capitalize (symbol-name reply-status))))
                (save-buffer)))))))))


(defun gnus-icalendar--cancel-org-event (event &optional org-file)
  (let ((file (gnus-icalendar-find-org-event-file event org-file)))
    (when file
      (with-current-buffer (find-file-noselect file)
        (let ((event-pos (org-find-entry-with-id (gnus-icalendar-event:uid event))))
          (when event-pos
            (let ((ts (org-entry-get event-pos "DT")))
              (when ts
                (org-entry-put event-pos "DT" (gnus-icalendar--deactivate-org-timestamp ts))
                (save-buffer)))))))))


(defun gnus-icalendar--get-org-event-reply-status (event &optional org-file)
  (let ((file (gnus-icalendar-find-org-event-file event org-file)))
    (when file
      (save-excursion
        (with-current-buffer (find-file-noselect file)
          (let ((event-pos (org-find-entry-with-id (gnus-icalendar-event:uid event))))
            (org-entry-get event-pos "REPLY")))))))


(defun gnus-icalendar-insinuate-org-templates ()
  (unless (gnus-icalendar-find-if (lambda (x) (string= (cadr x) gnus-icalendar-org-template-name))
                      org-capture-templates)
    (setq org-capture-templates
          (append `((,gnus-icalendar-org-template-key
                     ,gnus-icalendar-org-template-name
                     entry
                     (file+olp ,gnus-icalendar-org-capture-file ,@gnus-icalendar-org-capture-headline)
                     "%i"
                     :immediate-finish t))
                  org-capture-templates))

    ;; hide the template from interactive template selection list
    ;; (org-capture)
    ;; NOTE: doesn't work when capturing from string
    ;; (when (boundp 'org-capture-templates-contexts)
    ;;   (push `(,gnus-icalendar-org-template-key "" ((in-mode . "gnus-article-mode")))
    ;;         org-capture-templates-contexts))
    ))

(defun gnus-icalendar:org-event-save (event reply-status)
  (with-temp-buffer
    (org-capture-string (gnus-icalendar-event->org-entry event reply-status)
                        gnus-icalendar-org-template-key)))

(defun gnus-icalendar-show-org-agenda (event)
  (let* ((time-delta (time-subtract (gnus-icalendar-event:end-time event)
                                    (gnus-icalendar-event:start-time event)))
         (duration-days (1+ (/ (+ (* (car time-delta) (expt 2 16))
                                  (cadr time-delta))
                               86400))))

    (org-agenda-list nil (gnus-icalendar-event:start event) duration-days)))

(defmethod gnus-icalendar-event:sync-to-org ((event gnus-icalendar-event-request) reply-status)
  (if (gnus-icalendar-find-org-event-file event)
      (gnus-icalendar--update-org-event event reply-status)
    (gnus-icalendar:org-event-save event reply-status)))

(defmethod gnus-icalendar-event:sync-to-org ((event gnus-icalendar-event-cancel) reply-status)
  (when (gnus-icalendar-find-org-event-file event)
    (gnus-icalendar--cancel-org-event event)))

(defun gnus-icalendar-org-setup ()
  (if (and gnus-icalendar-org-capture-file gnus-icalendar-org-capture-headline)
      (progn
        (gnus-icalendar-insinuate-org-templates)
        (setq gnus-icalendar-org-enabled-p t))
    (message "Cannot enable Calendar->Org: missing capture file, headline")))

;;;
;;; gnus-icalendar
;;;

(defgroup gnus-icalendar nil
  "Settings for inline display of iCalendar invitations."
  :version "24.4"
  :group 'gnus-article
  :prefix "gnus-icalendar-")

(defcustom gnus-icalendar-reply-bufname "*CAL*"
  "Buffer used for building iCalendar invitation reply."
  :type '(string)
  :group 'gnus-icalendar)

(defcustom gnus-icalendar-additional-identities nil
  "We need to know your identity to make replies to calendar requests work.

Gnus will only offer you the Accept/Tentative/Decline buttons for
calendar events if any of your identities matches at least one
RSVP participant.

Your identity is guessed automatically from the variables `user-full-name',
`user-mail-address', and `gnus-ignored-from-addresses'.

If you need even more aliases you can define them here.  It really
only makes sense to define names or email addresses."

  :type '(repeat string)
  :group 'gnus-icalendar)

(make-variable-buffer-local
 (defvar gnus-icalendar-reply-status nil))

(make-variable-buffer-local
 (defvar gnus-icalendar-event nil))

(make-variable-buffer-local
 (defvar gnus-icalendar-handle nil))

(defun gnus-icalendar-identities ()
  "Return list of regexp-quoted names and email addresses belonging to the user.

These will be used to retrieve the RSVP information from ical events."
  (apply #'append
         (mapcar (lambda (x) (if (listp x) x (list x)))
                 (list user-full-name (regexp-quote user-mail-address)
                       ; NOTE: these can be lists
                       gnus-ignored-from-addresses ; already regexp-quoted
                       (mapcar #'regexp-quote gnus-icalendar-additional-identities)))))

;; TODO: make the template customizable
(defmethod gnus-icalendar-event->gnus-calendar ((event gnus-icalendar-event) &optional reply-status)
  "Format an overview of EVENT details."
  (gmm-labels ((format-header (x)
            (format "%-12s%s"
                    (propertize (concat (car x) ":") 'face 'bold)
                    (cadr x))))

    (with-slots (organizer summary description location recur uid
                           method rsvp participation-type) event
      (let ((headers `(("Summary" ,summary)
                      ("Location" ,(or location ""))
                      ("Time" ,(gnus-icalendar-event:org-timestamp event))
                      ("Organizer" ,organizer)
                      ("Attendance" ,(if (eq participation-type 'non-participant)
                                         "You are not listed as an attendee"
                                       (capitalize (symbol-name participation-type))))
                      ("Method" ,method))))

       (when (and (not (gnus-icalendar-event-reply-p event)) rsvp)
         (setq headers (append headers
                               `(("Status" ,(or reply-status "Not replied yet"))))))

       (concat
        (mapconcat #'format-header headers "\n")
        "\n\n"
        description)))))

(defmacro gnus-icalendar-with-decoded-handle (handle &rest body)
  "Execute BODY in buffer containing the decoded contents of HANDLE."
  (let ((charset (make-symbol "charset")))
    `(let ((,charset (cdr (assoc 'charset (mm-handle-type ,handle)))))
       (with-temp-buffer
         (mm-insert-part ,handle)
         (when (string= ,charset "utf-8")
           (mm-decode-coding-region (point-min) (point-max) 'utf-8))

         ,@body))))


(defun gnus-icalendar-event-from-handle (handle &optional attendee-name-or-email)
  (gnus-icalendar-with-decoded-handle handle
                       (gnus-icalendar-event-from-buffer (current-buffer) attendee-name-or-email)))

(defun gnus-icalendar-insert-button (text callback data)
  ;; FIXME: the gnus-mime-button-map keymap does not make sense for this kind
  ;; of button.
  (let ((start (point)))
    (gnus-add-text-properties
     start
     (progn
       (insert "[ " text " ]")
       (point))
     `(gnus-callback
       ,callback
       keymap ,gnus-mime-button-map
       face ,gnus-article-button-face
       gnus-data ,data))
    (widget-convert-button 'link start (point)
                           :action 'gnus-widget-press-button
                           :button-keymap gnus-widget-button-keymap)))

(defun gnus-icalendar-send-buffer-by-mail (buffer-name subject)
  (let ((message-signature nil))
    (with-current-buffer gnus-summary-buffer
      (gnus-summary-reply)
      (message-goto-body)
      (mml-insert-multipart "alternative")
      (mml-insert-empty-tag 'part 'type "text/plain")
      (mml-attach-buffer buffer-name "text/calendar; method=REPLY; charset=UTF-8")
      (message-goto-subject)
      (delete-region (line-beginning-position) (line-end-position))
      (insert "Subject: " subject)
      (message-send-and-exit))))

(defun gnus-icalendar-reply (data)
  (let* ((handle (car data))
         (status (cadr data))
         (event (caddr data))
         (reply (gnus-icalendar-with-decoded-handle handle
                  (gnus-icalendar-event-reply-from-buffer
                   (current-buffer) status (gnus-icalendar-identities)))))

    (when reply
      (gmm-labels ((fold-icalendar-buffer ()
               (goto-char (point-min))
               (while (re-search-forward "^\\(.\\{72\\}\\)\\(.+\\)$" nil t)
                 (replace-match "\\1\n \\2")
                 (goto-char (line-beginning-position)))))
        (let ((subject (concat (capitalize (symbol-name status))
                               ": " (gnus-icalendar-event:summary event))))

          (with-current-buffer (get-buffer-create gnus-icalendar-reply-bufname)
            (delete-region (point-min) (point-max))
            (insert reply)
            (fold-icalendar-buffer)
            (gnus-icalendar-send-buffer-by-mail (buffer-name) subject))

          ;; Back in article buffer
          (setq-local gnus-icalendar-reply-status status)
          (when gnus-icalendar-org-enabled-p
            (gnus-icalendar--update-org-event event status)
            ;; refresh article buffer to update the reply status
            (with-current-buffer gnus-summary-buffer
              (gnus-summary-show-article))))))))

(defun gnus-icalendar-sync-event-to-org (event)
  (gnus-icalendar-event:sync-to-org event gnus-icalendar-reply-status))

(defmethod gnus-icalendar-event:inline-reply-buttons ((event gnus-icalendar-event) handle)
  (when (gnus-icalendar-event:rsvp event)
    `(("Accept" gnus-icalendar-reply (,handle accepted ,event))
      ("Tentative" gnus-icalendar-reply (,handle tentative ,event))
      ("Decline" gnus-icalendar-reply (,handle declined ,event)))))

(defmethod gnus-icalendar-event:inline-reply-buttons ((event gnus-icalendar-event-reply) handle)
  "No buttons for REPLY events."
  nil)

(defmethod gnus-icalendar-event:inline-reply-status ((event gnus-icalendar-event))
  (or (when gnus-icalendar-org-enabled-p
        (gnus-icalendar--get-org-event-reply-status event))
      "Not replied yet"))

(defmethod gnus-icalendar-event:inline-reply-status ((event gnus-icalendar-event-reply))
  "No reply status for REPLY events."
  nil)


(defmethod gnus-icalendar-event:inline-org-buttons ((event gnus-icalendar-event))
  (let* ((org-entry-exists-p (gnus-icalendar-find-org-event-file event))
         (export-button-text (if org-entry-exists-p "Update Org Entry" "Export to Org")))

    (delq nil (list
               `("Show Agenda" gnus-icalendar-show-org-agenda ,event)
               (when (gnus-icalendar-event-request-p event)
                 `(,export-button-text gnus-icalendar-sync-event-to-org ,event))
               (when org-entry-exists-p
                 `("Show Org Entry" gnus-icalendar--show-org-event ,event))))))


(defmethod gnus-icalendar-event:inline-org-buttons ((event gnus-icalendar-event-cancel))
  (let ((org-entry-exists-p (gnus-icalendar-find-org-event-file event)))

    (delq nil (list
               `("Show Agenda" gnus-icalendar-show-org-agenda ,event)
               (when org-entry-exists-p
                 `("Update Org Entry" gnus-icalendar-sync-event-to-org ,event))
               (when org-entry-exists-p
                 `("Show Org Entry" gnus-icalendar--show-org-event ,event))))))


(defun gnus-icalendar-mm-inline (handle)
  (let ((event (gnus-icalendar-event-from-handle handle (gnus-icalendar-identities))))

    (setq gnus-icalendar-reply-status nil)

    (when event
      (gmm-labels ((insert-button-group (buttons)
                (when buttons
                  (mapc (lambda (x)
                          (apply 'gnus-icalendar-insert-button x)
                          (insert "    "))
                        buttons)
                  (insert "\n\n"))))

        (insert-button-group
	 (gnus-icalendar-event:inline-reply-buttons event handle))

        (when gnus-icalendar-org-enabled-p
          (insert-button-group (gnus-icalendar-event:inline-org-buttons event)))

        (setq gnus-icalendar-event event
              gnus-icalendar-handle handle)

        (insert (gnus-icalendar-event->gnus-calendar
                 event
                 (gnus-icalendar-event:inline-reply-status event)))))))

(defun gnus-icalendar-save-part (handle)
  (let (event)
    (when (and (equal (car (mm-handle-type handle)) "text/calendar")
               (setq event (gnus-icalendar-event-from-handle handle (gnus-icalendar-identities))))

      (gnus-icalendar-event:sync-to-org event))))


(defun gnus-icalendar-save-event ()
  "Save the Calendar event in the text/calendar part under point."
  (interactive)
  (gnus-article-check-buffer)
  (let ((data (get-text-property (point) 'gnus-data)))
    (when data
      (gnus-icalendar-save-part data))))

(defun gnus-icalendar-reply-accept ()
  "Accept invitation in the current article."
  (interactive)
  (with-current-buffer gnus-article-buffer
    (gnus-icalendar-reply (list gnus-icalendar-handle 'accepted gnus-icalendar-event))
    (setq-local gnus-icalendar-reply-status 'accepted)))

(defun gnus-icalendar-reply-tentative ()
  "Send tentative response to invitation in the current article."
  (interactive)
  (with-current-buffer gnus-article-buffer
    (gnus-icalendar-reply (list gnus-icalendar-handle 'tentative gnus-icalendar-event))
    (setq-local gnus-icalendar-reply-status 'tentative)))

(defun gnus-icalendar-reply-decline ()
  "Decline invitation in the current article."
  (interactive)
  (with-current-buffer gnus-article-buffer
    (gnus-icalendar-reply (list gnus-icalendar-handle 'declined gnus-icalendar-event))
    (setq-local gnus-icalendar-reply-status 'declined)))

(defun gnus-icalendar-event-export ()
  "Export calendar event to `org-mode', or update existing agenda entry."
  (interactive)
  (with-current-buffer gnus-article-buffer
    (gnus-icalendar-sync-event-to-org gnus-icalendar-event))
  ;; refresh article buffer in case the reply had been sent before initial org
  ;; export
  (with-current-buffer gnus-summary-buffer
    (gnus-summary-show-article)))

(defun gnus-icalendar-event-show ()
  "Display `org-mode' agenda entry related to the calendar event."
  (interactive)
  (gnus-icalendar--show-org-event
   (with-current-buffer gnus-article-buffer
     gnus-icalendar-event)))

(defun gnus-icalendar-event-check-agenda ()
  "Display `org-mode' agenda for days between event start and end dates."
  (interactive)
  (gnus-icalendar-show-org-agenda
   (with-current-buffer gnus-article-buffer gnus-icalendar-event)))

(defvar gnus-mime-action-alist)         ; gnus-art

(defun gnus-icalendar-setup ()
  (add-to-list 'mm-inlined-types "text/calendar")
  (add-to-list 'mm-automatic-display "text/calendar")
  (add-to-list 'mm-inline-media-tests '("text/calendar" gnus-icalendar-mm-inline identity))

  (gnus-define-keys (gnus-summary-calendar-map "i" gnus-summary-mode-map)
    "a" gnus-icalendar-reply-accept
    "t" gnus-icalendar-reply-tentative
    "d" gnus-icalendar-reply-decline
    "c" gnus-icalendar-event-check-agenda
    "e" gnus-icalendar-event-export
    "s" gnus-icalendar-event-show)

  (require 'gnus-art)
  (add-to-list 'gnus-mime-action-alist
               (cons "save calendar event" 'gnus-icalendar-save-event)
               t))

(provide 'gnus-icalendar)

;;; gnus-icalendar.el ends here