summaryrefslogtreecommitdiff
path: root/program/js/treelist.js
blob: c034f77b84c3d652db836a31d83a75ec37dc5950 (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
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
/**
 * Roundcube Treelist Widget
 *
 * This file is part of the Roundcube Webmail client
 *
 * @licstart  The following is the entire license notice for the
 * JavaScript code in this file.
 *
 * Copyright (c) 2013-2014, The Roundcube Dev Team
 *
 * The JavaScript code in this page is free software: you can
 * redistribute it and/or modify it under the terms of the GNU
 * General Public License (GNU GPL) as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option)
 * any later version.  The code is distributed WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute non-source (e.g., minimized or compacted) forms of
 * that code without the copy of the GNU GPL normally required by
 * section 4, provided you include this license notice and a URL
 * through which recipients can access the Corresponding Source.
 *
 * @licend  The above is the entire license notice
 * for the JavaScript code in this file.
 *
 * @author Thomas Bruederli <roundcube@gmail.com>
 * @requires jquery.js, common.js
 */


/**
 * Roundcube Treelist widget class
 * @contructor
 */
function rcube_treelist_widget(node, p)
{
  // apply some defaults to p
  p = $.extend({
    id_prefix: '',
    autoexpand: 1000,
    selectable: false,
    scroll_delay: 500,
    scroll_step: 5,
    scroll_speed: 20,
    save_state: false,
    keyboard: true,
    tabexit: true,
    parent_focus: false,
    check_droptarget: function(node) { return !node.virtual; }
  }, p || {});

  var container = $(node),
    data = p.data || [],
    indexbyid = {},
    selection = null,
    drag_active = false,
    search_active = false,
    last_search = '',
    has_focus = false,
    box_coords = {},
    item_coords = [],
    autoexpand_timer,
    autoexpand_item,
    body_scroll_top = 0,
    list_scroll_top = 0,
    scroll_timer,
    searchfield,
    tree_state,
    ui_droppable,
    ui_draggable,
    draggable_opts,
    droppable_opts,
    list_id = (container.attr('id') || p.id_prefix || '0'),
    me = this;


  /////// export public members and methods

  this.container = container;
  this.expand = expand;
  this.collapse = collapse;
  this.select = select;
  this.render = render;
  this.reset = reset;
  this.drag_start = drag_start;
  this.drag_end = drag_end;
  this.intersects = intersects;
  this.droppable = droppable;
  this.draggable = draggable;
  this.update = update_node;
  this.insert = insert;
  this.remove = remove;
  this.get_item = get_item;
  this.get_node = get_node;
  this.get_selection = get_selection;
  this.is_search = is_search;
  this.reset_search = reset_search;

  /////// startup code (constructor)

  // abort if node not found
  if (!container.length)
    return;

  if (p.data)
    index_data({ children:data });
  // load data from DOM
  else
    update_data();

  // register click handlers on list
  container.on('click', 'div.treetoggle', function(e){
    toggle(dom2id($(this).parent()));
    e.stopPropagation();
  });

  container.on('click', 'li', function(e) {
    // do not select record on checkbox/input click
    if ($(e.target).is('input'))
      return true;

    var node = p.selectable ? indexbyid[dom2id($(this))] : null;
    if (node && !node.virtual) {
      select(node.id);
      e.stopPropagation();
    }
  });

  // mute clicks on virtual folder links (they need tabindex="0" in order to be selectable by keyboard)
  container.on('mousedown', 'a', function(e) {
    var link = $(e.target), node = indexbyid[dom2id(link.closest('li'))];
    if (node && node.virtual && !link.attr('href')) {
      e.preventDefault();
      e.stopPropagation();
      return false;
    }
  });

  // activate search function
  if (p.searchbox) {
    searchfield = $(p.searchbox).on('keyup', function(e) {
      var key = rcube_event.get_keycode(e),
        mod = rcube_event.get_modifier(e);

      switch (key) {
        case 9:   // tab
          break;

        case 13:  // enter
          search(this.value, true);
          return rcube_event.cancel(e);

        case 27:  // escape
          reset_search();
          break;

        case 38:  // arrow up
        case 37:  // left
        case 39:  // right
        case 40:  // arrow down
          return;  // ignore arrow keys

        default:
          search(this.value, false);
          break;
      }
    }).attr('autocomplete', 'off');

    // find the reset button for this search field
    searchfield.parent().find('a.reset').click(function(e) {
      reset_search();
      return false;
    })
  }

  container.on('focusin', function(e){
      // TODO: only accept focus on virtual nodes from keyboard events
      has_focus = true;
    })
    .on('focusout', function(e){
      has_focus = false;
    });

  container.attr('role', 'tree');

  $(document.body)
    .bind('keydown', keypress);

  // catch focus when clicking the list container area
  if (p.parent_focus) {
    container.parent(':not(body)').click(function(e) {
      if (!has_focus && selection) {
        $(get_item(selection)).find(':focusable').first().focus();
      }
      else if (!has_focus) {
        container.children('li:has(:focusable)').first().find(':focusable').first().focus();
      }
    });
  }

  /////// private methods

  /**
   * Collaps a the node with the given ID
   */
  function collapse(id, recursive, set)
  {
    var node;

    if (node = indexbyid[id]) {
      node.collapsed = typeof set == 'undefined' || set;
      update_dom(node);

      if (recursive && node.children) {
        for (var i=0; i < node.children.length; i++) {
          collapse(node.children[i].id, recursive, set);
        }
      }

      me.triggerEvent(node.collapsed ? 'collapse' : 'expand', node);
      save_state(id, node.collapsed);
    }
  }

  /**
   * Expand a the node with the given ID
   */
  function expand(id, recursive)
  {
    collapse(id, recursive, false);
  }

  /**
   * Toggle collapsed state of a list node
   */
  function toggle(id, recursive)
  {
    var node;
    if (node = indexbyid[id]) {
      collapse(id, recursive, !node.collapsed);
    }
  }

  /**
   * Select a tree node by it's ID
   */
  function select(id)
  {
    if (selection) {
      id2dom(selection, true).removeClass('selected').removeAttr('aria-selected');
      if (search_active)
          id2dom(selection).removeClass('selected').removeAttr('aria-selected');
      selection = null;
    }

    if (!id)
      return;

    var li = id2dom(id, true);
    if (li.length) {
      li.addClass('selected').attr('aria-selected', 'true');
      selection = id;
      // TODO: expand all parent nodes if collapsed

      if (search_active)
        id2dom(id).addClass('selected').attr('aria-selected', 'true');

      scroll_to_node(li);
    }

    me.triggerEvent('select', indexbyid[id]);
  }

  /**
   * Getter for the currently selected node ID
   */
  function get_selection()
  {
    return selection;
  }

  /**
   * Return the DOM element of the list item with the given ID
   */
  function get_node(id)
  {
    return indexbyid[id];
  }

  /**
   * Return the DOM element of the list item with the given ID
   */
  function get_item(id, real)
  {
    return id2dom(id, real).get(0);
  }

  /**
   * Insert the given node
   */
  function insert(node, parent_id, sort)
  {
    var li, parent_li,
      parent_node = parent_id ? indexbyid[parent_id] : null
      search_ = search_active;

    // ignore, already exists
    if (indexbyid[node.id]) {
      return;
    }

    // apply saved state
    state = get_state(node.id, node.collapsed);
    if (state !== undefined) {
      node.collapsed = state;
    }

    // insert as child of an existing node
    if (parent_node) {
      node.level = parent_node.level + 1;
      if (!parent_node.children)
        parent_node.children = [];

      search_active = false;
      parent_node.children.push(node);
      parent_li = id2dom(parent_id);

      // re-render the entire subtree
      if (parent_node.children.length == 1) {
        render_node(parent_node, parent_li.parent(), parent_li);
        li = id2dom(node.id);
      }
      else {
        // append new node to parent's child list
        li = render_node(node, parent_li.children('ul').first());
      }

      // list is in search mode
      if (search_) {
        search_active = search_;

        // add clone to current search results (top level)
        if (!li.is(':visible')) {
          $('<li>')
            .attr('id', li.attr('id') + '--xsR')
            .attr('class', li.attr('class'))
            .addClass('searchresult__')
            .append(li.children().first().clone(true, true))
            .appendTo(container);
        }
      }
    }
    // insert at top level
    else {
      node.level = 0;
      data.push(node);
      li = render_node(node, container);
    }

    indexbyid[node.id] = node;

    if (sort) {
      resort_node(li, typeof sort == 'string' ? '[class~="' + sort + '"]' : '');
    }
  }

  /**
   * Update properties of an existing node
   */
  function update_node(id, updates, sort)
  {
    var li, parent_ul, parent_node, old_parent,
      node = indexbyid[id];

    if (node) {
      li = id2dom(id);
      parent_ul = li.parent();

      if (updates.id || updates.html || updates.children || updates.classes || updates.parent) {
        if (updates.parent && (parent_node = indexbyid[updates.parent])) {
          // remove reference from old parent's child list
          if (parent_ul.closest('li').length && (old_parent = indexbyid[dom2id(parent_ul.closest('li'))])) {
            old_parent.children = $.grep(old_parent.children, function(elem, i){ return elem.id != node.id; });
          }

          // append to new parent node
          parent_ul = id2dom(updates.parent).children('ul').first();
          if (!parent_node.children)
            parent_node.children = [];
          parent_node.children.push(node);
        }
        else if (updates.parent !== undefined) {
          parent_ul = container;
        }

        $.extend(node, updates);
        li = render_node(node, parent_ul, li);
      }

      if (node.id != id) {
        delete indexbyid[id];
        indexbyid[node.id] = node;
      }

      if (sort) {
        resort_node(li, typeof sort == 'string' ? '[class~="' + sort + '"]' : '');
      }
    }
  }

  /**
   * Helper method to sort the list of the given item
   */
  function resort_node(li, filter)
  {
    var first, sibling,
      myid = li.get(0).id,
      sortname = li.children().first().text().toUpperCase();

    li.parent().children('li' + filter).each(function(i, elem) {
      if (i == 0)
        first = elem;
      if (elem.id == myid) {
        // skip
      }
      else if (elem.id != myid && sortname >= $(elem).children().first().text().toUpperCase()) {
        sibling = elem;
      }
      else {
        return false;
      }
    });

    if (sibling) {
      li.insertAfter(sibling);
    }
    else if (first && first.id != myid) {
      li.insertBefore(first);
    }

    // reload data from dom
    update_data();
  }

  /**
   * Remove the item with the given ID
   */
  function remove(id)
  {
    var node, li;

    if (node = indexbyid[id]) {
      li = id2dom(id, true);
      li.remove();

      node.deleted = true;
      delete indexbyid[id];

      if (search_active) {
        id2dom(id, false).remove();
      }

      return true;
    }

    return false;
  }

  /**
   * (Re-)read tree data from DOM
   */
  function update_data()
  {
    data = walk_list(container, 0);
  }

  /**
   * Apply the 'collapsed' status of the data node to the corresponding DOM element(s)
   */
  function update_dom(node)
  {
    var li = id2dom(node.id, true);
    li.attr('aria-expanded', node.collapsed ? 'false' : 'true');
    li.children('ul').first()[(node.collapsed ? 'hide' : 'show')]();
    li.children('div.treetoggle').removeClass('collapsed expanded').addClass(node.collapsed ? 'collapsed' : 'expanded');
    me.triggerEvent('toggle', node);
  }

  /**
   *
   */
  function reset(keep_content)
  {
    select('');

    data = [];
    indexbyid = {};
    drag_active = false;

    if (keep_content) {
      if (draggable_opts) {
        if (ui_draggable)
          draggable('destroy');
        draggable(draggable_opts);
      }

      if (droppable_opts) {
        if (ui_droppable)
          droppable('destroy');
        droppable(droppable_opts);
      }

      update_data();
    }
    else {
      container.html('');
    }

    reset_search();
  }

  /**
   * 
   */
  function search(q, enter)
  {
    q = String(q).toLowerCase();

    if (!q.length)
      return reset_search();
    else if (q == last_search && !enter)
      return 0;

    var hits = [];
    var search_tree = function(items) {
      $.each(items, function(i, node) {
        var li, sli;
        if (!node.virtual && !node.deleted && String(node.text).toLowerCase().indexOf(q) >= 0 && hits.indexOf(node.id) < 0) {
          li = id2dom(node.id);

          // skip already filtered nodes
          if (li.data('filtered'))
            return;

          sli = $('<li>')
            .attr('id', li.attr('id') + '--xsR')
            .attr('class', li.attr('class'))
            .addClass('searchresult__')
            // append all elements like links and inputs, but not sub-trees
            .append(li.children(':not(div.treetoggle,ul)').clone(true, true))
            .appendTo(container);
            hits.push(node.id);
        }

        if (node.children && node.children.length) {
          search_tree(node.children);
        }
      });
    };

    // reset old search results
    if (search_active) {
      $(container).children('li.searchresult__').remove();
      search_active = false;
    }

    // hide all list items
    $(container).children('li').hide().removeClass('selected');

    // search recursively in tree (to keep sorting order)
    search_tree(data);
    search_active = true;
    last_search = q;

    me.triggerEvent('search', { query: q, last: last_search, count: hits.length, ids: hits, execute: enter||false });

    return hits.count;
  }

  /**
   * 
   */
  function reset_search()
  {
    if (searchfield)
      searchfield.val('');

    $(container).children('li.searchresult__').remove();
    $(container).children('li').filter(function() { return !$(this).data('filtered'); }).show();

    search_active = false;

    me.triggerEvent('search', { query: false, last: last_search });
    last_search = '';

    if (selection)
      select(selection);
  }

  /**
   *
   */
  function is_search()
  {
    return search_active;
  }

  /**
   * Render the tree list from the internal data structure
   */
  function render()
  {
    if (me.triggerEvent('renderBefore', data) === false)
      return;

    // remove all child nodes
    container.html('');

    // render child nodes
    for (var i=0; i < data.length; i++) {
      data[i].level = 0;
      render_node(data[i], container);
    }

    me.triggerEvent('renderAfter', container);
  }

  /**
   * Render a specific node into the DOM list
   */
  function render_node(node, parent, replace)
  {
    if (node.deleted)
      return;

    var li = $('<li>')
      .attr('id', p.id_prefix + (p.id_encode ? p.id_encode(node.id) : node.id))
      .attr('role', 'treeitem')
      .addClass((node.classes || []).join(' '))
      .data('id', node.id);

    if (replace) {
      replace.replaceWith(li);
      if (parent)
        li.appendTo(parent);
    }
    else
      li.appendTo(parent);

    if (typeof node.html == 'string')
      li.html(node.html);
    else if (typeof node.html == 'object')
      li.append(node.html);

    if (!node.text)
      node.text = li.children().first().text();

    if (node.virtual)
      li.addClass('virtual');
    if (node.id == selection)
      li.addClass('selected');

    // add child list and toggle icon
    if (node.children && node.children.length) {
      li.attr('aria-expanded', node.collapsed ? 'false' : 'true');
      $('<div class="treetoggle '+(node.collapsed ? 'collapsed' : 'expanded') + '">&nbsp;</div>').appendTo(li);
      var ul = $('<ul>').appendTo(li).attr('class', node.childlistclass).attr('role', 'group');
      if (node.collapsed)
        ul.hide();

      for (var i=0; i < node.children.length; i++) {
        node.children[i].level = node.level + 1;
        render_node(node.children[i], ul);
      }
    }

    return li;
  }

  /**
   * Recursively walk the DOM tree and build an internal data structure
   * representing the skeleton of this tree list.
   */
  function walk_list(ul, level)
  {
    var result = [];
    ul.children('li').each(function(i,e){
      var state, li = $(e), sublist = li.children('ul');
      var node = {
        id: dom2id(li),
        classes: String(li.attr('class')).split(' '),
        virtual: li.hasClass('virtual'),
        level: level,
        html: li.children().first().get(0).outerHTML,
        text: li.children().first().text(),
        children: walk_list(sublist, level+1)
      }

      if (sublist.length) {
        node.childlistclass = sublist.attr('class');
      }
      if (node.children.length) {
        if (node.collapsed === undefined)
          node.collapsed = sublist.css('display') == 'none';

        // apply saved state
        state = get_state(node.id, node.collapsed);
        if (state !== undefined) {
          node.collapsed = state;
          sublist[(state?'hide':'show')]();
        }

        if (!li.children('div.treetoggle').length)
          $('<div class="treetoggle '+(node.collapsed ? 'collapsed' : 'expanded') + '">&nbsp;</div>').appendTo(li);

        li.attr('aria-expanded', node.collapsed ? 'false' : 'true');
      }
      if (li.hasClass('selected')) {
        li.attr('aria-selected', 'true');
        selection = node.id;
      }

      li.data('id', node.id);

      // declare list item as treeitem
      li.attr('role', 'treeitem').attr('aria-level', node.level+1);

      // allow virtual nodes to receive focus
      if (node.virtual) {
        li.children('a:first').attr('tabindex', '0');
      }

      result.push(node);
      indexbyid[node.id] = node;
    });

    ul.attr('role', level == 0 ? 'tree' : 'group');

    return result;
  }

  /**
   * Recursively walk the data tree and index nodes by their ID
   */
  function index_data(node)
  {
    if (node.id) {
      indexbyid[node.id] = node;
    }
    for (var c=0; node.children && c < node.children.length; c++) {
      index_data(node.children[c]);
    }
  }

  /**
   * Get the (stripped) node ID from the given DOM element
   */
  function dom2id(li)
  {
    var domid = String(li.attr('id')).replace(new RegExp('^' + (p.id_prefix) || '%'), '').replace(/--xsR$/, '');
    return p.id_decode ? p.id_decode(domid) : domid;
  }

  /**
   * Get the <li> element for the given node ID
   */
  function id2dom(id, real)
  {
    var domid = p.id_encode ? p.id_encode(id) : id,
      suffix = search_active && !real ? '--xsR' : '';

    return $('#' + p.id_prefix + domid + suffix, container);
  }

  /**
   * Scroll the parent container to make the given list item visible
   */
  function scroll_to_node(li)
  {
    var scroller = container.parent(),
      current_offset = scroller.scrollTop(),
      rel_offset = li.offset().top - scroller.offset().top;

    if (rel_offset < 0 || rel_offset + li.height() > scroller.height())
      scroller.scrollTop(rel_offset + current_offset);
  }

  /**
   * Save node collapse state to localStorage
   */
  function save_state(id, collapsed)
  {
    if (p.save_state && window.rcmail) {
      var key = 'treelist-' + list_id;
      if (!tree_state) {
        tree_state = rcmail.local_storage_get_item(key, {});
      }

      if (tree_state[id] != collapsed) {
        tree_state[id] = collapsed;
        rcmail.local_storage_set_item(key, tree_state);
      }
    }
  }

  /**
   * Read node collapse state from localStorage
   */
  function get_state(id)
  {
    if (p.save_state && window.rcmail) {
      if (!tree_state) {
        tree_state = rcmail.local_storage_get_item('treelist-' + list_id, {});
      }
      return tree_state[id];
    }

    return undefined;
  }

  /**
   * Handler for keyboard events on treelist
   */
  function keypress(e)
  {
    var target = e.target || {},
      keyCode = rcube_event.get_keycode(e);

    if (!has_focus || target.nodeName == 'INPUT' && keyCode != 38 && keyCode != 40 || target.nodeName == 'TEXTAREA' || target.nodeName == 'SELECT')
      return true;

    switch (keyCode) {
      case 38:
      case 40:
      case 63232: // 'up', in safari keypress
      case 63233: // 'down', in safari keypress
        var li = p.keyboard ? container.find(':focus').closest('li') : [];
        if (li.length) {
          focus_next(li, (mod = keyCode == 38 || keyCode == 63232 ? -1 : 1));
        }
        return rcube_event.cancel(e);

      case 37: // Left arrow key
      case 39: // Right arrow key
        var id, node, li = container.find(':focus').closest('li');
        if (li.length) {
          id = dom2id(li);
          node = indexbyid[id];
          if (node && node.children.length && node.collapsed != (keyCode == 37))
            toggle(id, rcube_event.get_modifier(e) == SHIFT_KEY);  // toggle subtree
        }
        return false;

      case 9:  // Tab
        if (p.keyboard && p.tabexit) {
          // jump to last/first item to move focus away from the treelist widget by tab
          var limit = rcube_event.get_modifier(e) == SHIFT_KEY ? 'first' : 'last';
          focus_noscroll(container.find('li[role=treeitem]:has(a)')[limit]().find('a:'+limit));
        }
        break;
    }

    return true;
  }

  function focus_next(li, dir, from_child)
  {
    var mod = dir < 0 ? 'prev' : 'next',
      next = li[mod](), limit, parent;

    if (dir > 0 && !from_child && li.children('ul[role=group]:visible').length) {
      li.children('ul').children('li:first').find('a:first').focus();
    }
    else if (dir < 0 && !from_child && next.children('ul[role=group]:visible').length) {
      next.children('ul').children('li:last').find('a:first').focus();
    }
    else if (next.length && next.find('a:first').focus().length) {
        // focused
    }
    else {
      parent = li.parent().closest('li[role=treeitem]');
      if (parent.length)
        if (dir < 0) {
          parent.find('a:first').focus();
        }
        else {
          focus_next(parent, dir, true);
        }
    }
  }

  /**
   * Focus the given element without scrolling the list container
   */
  function focus_noscroll(elem)
  {
    if (elem.length) {
      var frame = container.parent().get(0) || { scrollTop:0 },
        y = frame.scrollTop || frame.scrollY;
      elem.focus();
      frame.scrollTop = y;
    }
  }


  ///// drag & drop support

  /**
   * When dragging starts, compute absolute bounding boxes of the list and it's items
   * for faster comparisons while mouse is moving
   */
  function drag_start()
  {
    if (drag_active)
      return;

    drag_active = true;

    var li, item, height,
      pos = container.offset();

    body_scroll_top = bw.ie ? 0 : window.pageYOffset;
    list_scroll_top = container.parent().scrollTop();
    pos.top += list_scroll_top;

    box_coords = {
      x1: pos.left,
      y1: pos.top,
      x2: pos.left + container.width(),
      y2: pos.top + container.height()
    };

    item_coords = [];
    for (var id in indexbyid) {
      li = id2dom(id);
      item = li.children().first().get(0);
      if (height = item.offsetHeight) {
        pos = $(item).offset();
        pos.top += list_scroll_top;
        item_coords[id] = {
          x1: pos.left,
          y1: pos.top,
          x2: pos.left + item.offsetWidth,
          y2: pos.top + height,
          on: id == autoexpand_item
        };
      }
    }

    // enable auto-scrolling of list container
    if (container.height() > container.parent().height()) {
      container.parent()
        .mousemove(function(e) {
          var scroll = 0,
            mouse = rcube_event.get_mouse_pos(e);
          mouse.y -= container.parent().offset().top;

          if (mouse.y < 25 && list_scroll_top > 0) {
            scroll = -1; // up
          }
          else if (mouse.y > container.parent().height() - 25) {
            scroll = 1; // down
          }

          if (drag_active && scroll != 0) {
            if (!scroll_timer)
              scroll_timer = window.setTimeout(function(){ drag_scroll(scroll); }, p.scroll_delay);
          }
          else if (scroll_timer) {
            window.clearTimeout(scroll_timer);
            scroll_timer = null;
          }
        })
        .mouseleave(function() {
          if (scroll_timer) {
            window.clearTimeout(scroll_timer);
            scroll_timer = null;
          }
        });
    }
  }

  /**
   * Signal that dragging has stopped
   */
  function drag_end()
  {
    if (!drag_active)
      return;

    drag_active = false;
    scroll_timer = null;

    if (autoexpand_timer) {
      clearTimeout(autoexpand_timer);
      autoexpand_timer = null;
      autoexpand_item = null;
    }

    $('li.droptarget', container).removeClass('droptarget');
  }

  /**
   * Scroll list container in the given direction
   */
  function drag_scroll(dir)
  {
    if (!drag_active)
      return;

    var old_top = list_scroll_top;
    container.parent().get(0).scrollTop += p.scroll_step * dir;
    list_scroll_top = container.parent().scrollTop();
    scroll_timer = null;

    if (list_scroll_top != old_top)
      scroll_timer = window.setTimeout(function(){ drag_scroll(dir); }, p.scroll_speed);
  }

  /**
   * Determine if the given mouse coords intersect the list and one of its items
   */
  function intersects(mouse, highlight)
  {
    // offsets to compensate for scrolling while dragging a message
    var boffset = bw.ie ? -document.documentElement.scrollTop : body_scroll_top,
      moffset = container.parent().scrollTop(),
      result = null;

    mouse.top = mouse.y + moffset - boffset;

    // no intersection with list bounding box
    if (mouse.x < box_coords.x1 || mouse.x >= box_coords.x2 || mouse.top < box_coords.y1 || mouse.top >= box_coords.y2) {
      // TODO: optimize performance for this operation
      if (highlight)
        $('li.droptarget', container).removeClass('droptarget');
      return result;
    }

    // check intersection with visible list items
    var id, pos, node;
    for (id in item_coords) {
      pos = item_coords[id];
      if (mouse.x >= pos.x1 && mouse.x < pos.x2 && mouse.top >= pos.y1 && mouse.top < pos.y2) {
        node = indexbyid[id];

        // if the folder is collapsed, expand it after the configured time
        if (node.children && node.children.length && node.collapsed && p.autoexpand && autoexpand_item != id) {
          if (autoexpand_timer)
            clearTimeout(autoexpand_timer);

          autoexpand_item = id;
          autoexpand_timer = setTimeout(function() {
            expand(autoexpand_item);
            drag_start();  // re-calculate item coords
            autoexpand_item = null;
            if (ui_droppable)
              $.ui.ddmanager.prepareOffsets($.ui.ddmanager.current, null);
          }, p.autoexpand);
        }
        else if (autoexpand_timer && autoexpand_item != id) {
          clearTimeout(autoexpand_timer);
          autoexpand_item = null;
          autoexpand_timer = null;
        }

        // check if this item is accepted as drop target
        if (p.check_droptarget(node)) {
          if (highlight) {
            id2dom(id).addClass('droptarget');
            pos.on = true;
          }
          result = id;
        }
        else {
          result = null;
        }
      }
      else if (pos.on) {
        id2dom(id).removeClass('droptarget');
        pos.on = false;
      }
    }

    return result;
  }

  /**
   * Wrapper for jQuery.UI.droppable() activation on this widget
   *
   * @param object Options as passed to regular .droppable() function
   */
  function droppable(opts)
  {
    if (!opts) opts = {};

    if ($.type(opts) == 'string') {
      if (opts == 'destroy') {
        ui_droppable = null;
      }
      $('li:not(.virtual)', container).droppable(opts);
      return this;
    }

    droppable_opts = opts;

    var my_opts = $.extend({
        greedy: true,
        tolerance: 'pointer',
        hoverClass: 'droptarget',
        addClasses: false
      }, opts);

    my_opts.activate = function(e, ui) {
      drag_start();
      ui_droppable = ui;
      if (opts.activate)
        opts.activate(e, ui);
    };

    my_opts.deactivate = function(e, ui) {
      drag_end();
      ui_droppable = null;
      if (opts.deactivate)
        opts.deactivate(e, ui);
    };

    my_opts.over = function(e, ui) {
      intersects(rcube_event.get_mouse_pos(e), false);
      if (opts.over)
        opts.over(e, ui);
    };

    $('li:not(.virtual)', container).droppable(my_opts);

    return this;
  }

  /**
   * Wrapper for jQuery.UI.draggable() activation on this widget
   *
   * @param object Options as passed to regular .draggable() function
   */
  function draggable(opts)
  {
    if (!opts) opts = {};

    if ($.type(opts) == 'string') {
      if (opts == 'destroy') {
        ui_draggable = null;
      }
      $('li:not(.virtual)', container).draggable(opts);
      return this;
    }

    draggable_opts = opts;

    var my_opts = $.extend({
        appendTo: 'body',
        revert: 'invalid',
        iframeFix: true,
        addClasses: false,
        cursorAt: {left: -20, top: 5},
        create: function(e, ui) { ui_draggable = ui; },
        helper: function(e) {
          return $('<div>').attr('id', 'rcmdraglayer')
            .text($.trim($(e.target).first().text()));
        }
      }, opts);

    $('li:not(.virtual)', container).draggable(my_opts);

    return this;
  }
}

// use event processing functions from Roundcube's rcube_event_engine
rcube_treelist_widget.prototype.addEventListener = rcube_event_engine.prototype.addEventListener;
rcube_treelist_widget.prototype.removeEventListener = rcube_event_engine.prototype.removeEventListener;
rcube_treelist_widget.prototype.triggerEvent = rcube_event_engine.prototype.triggerEvent;