summaryrefslogtreecommitdiffstats
path: root/toolkit/components/satchel/FormHistory.jsm
blob: 3d4a9fc436a0f25c80613246c8441ecad49bee3f (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
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/**
 * FormHistory
 *
 * Used to store values that have been entered into forms which may later
 * be used to automatically fill in the values when the form is visited again.
 *
 * search(terms, queryData, callback)
 *   Look up values that have been previously stored.
 *     terms - array of terms to return data for
 *     queryData - object that contains the query terms
 *       The query object contains properties for each search criteria to match, where the value
 *       of the property specifies the value that term must have. For example,
 *       { term1: value1, term2: value2 }
 *     callback - callback that is called when results are available or an error occurs.
 *       The callback is passed a result array containing each found entry. Each element in
 *       the array is an object containing a property for each search term specified by 'terms'.
 * count(queryData, callback)
 *   Find the number of stored entries that match the given criteria.
 *     queryData - array of objects that indicate the query. See the search method for details.
 *     callback - callback that is called when results are available or an error occurs.
 *       The callback is passed the number of found entries.
 * update(changes, callback)
 *    Write data to form history storage.
 *      changes - an array of changes to be made. If only one change is to be made, it
 *                may be passed as an object rather than a one-element array.
 *        Each change object is of the form:
 *          { op: operation, term1: value1, term2: value2, ... }
 *        Valid operations are:
 *          add - add a new entry
 *          update - update an existing entry
 *          remove - remove an entry
 *          bump - update the last accessed time on an entry
 *        The terms specified allow matching of one or more specific entries. If no terms
 *        are specified then all entries are matched. This means that { op: "remove" } is
 *        used to remove all entries and clear the form history.
 *      callback - callback that is called when results have been stored.
 * getAutoCompeteResults(searchString, params, callback)
 *   Retrieve an array of form history values suitable for display in an autocomplete list.
 *   Returns an mozIStoragePendingStatement that can be used to cancel the operation if
 *   needed.
 *     searchString - the string to search for, typically the entered value of a textbox
 *     params - zero or more filter arguments:
 *       fieldname - form field name
 *       agedWeight
 *       bucketSize
 *       expiryDate
 *       maxTimeGroundings
 *       timeGroupingSize
 *       prefixWeight
 *       boundaryWeight
 *     callback - callback that is called with the array of results. Each result in the array
 *                is an object with four arguments:
 *                  text, textLowerCase, frecency, totalScore
 * schemaVersion
 *   This property holds the version of the database schema
 *
 * Terms:
 *  guid - entry identifier. For 'add', a guid will be generated.
 *  fieldname - form field name
 *  value - form value
 *  timesUsed - the number of times the entry has been accessed
 *  firstUsed - the time the the entry was first created
 *  lastUsed - the time the entry was last accessed
 *  firstUsedStart - search for entries created after or at this time
 *  firstUsedEnd - search for entries created before or at this time
 *  lastUsedStart - search for entries last accessed after or at this time
 *  lastUsedEnd - search for entries last accessed before or at this time
 *  newGuid - a special case valid only for 'update' and allows the guid for
 *            an existing record to be updated. The 'guid' term is the only
 *            other term which can be used (ie, you can not also specify a
 *            fieldname, value etc) and indicates the guid of the existing
 *            record that should be updated.
 *
 * In all of the above methods, the callback argument should be an object with
 * handleResult(result), handleFailure(error) and handleCompletion(reason) functions.
 * For search and getAutoCompeteResults, result is an object containing the desired
 * properties. For count, result is the integer count. For, update, handleResult is
 * not called. For handleCompletion, reason is either 0 if successful or 1 if
 * an error occurred.
 */

this.EXPORTED_SYMBOLS = ["FormHistory"];

const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;

Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
Components.utils.import("resource://gre/modules/Services.jsm");
Components.utils.import("resource://gre/modules/AppConstants.jsm");

XPCOMUtils.defineLazyServiceGetter(this, "uuidService",
                                   "@mozilla.org/uuid-generator;1",
                                   "nsIUUIDGenerator");

const DB_SCHEMA_VERSION = 4;
const DAY_IN_MS  = 86400000; // 1 day in milliseconds
const MAX_SEARCH_TOKENS = 10;
const NOOP = function noop() {};

var supportsDeletedTable = AppConstants.platform == "android";

var Prefs = {
  initialized: false,

  get debug() { this.ensureInitialized(); return this._debug; },
  get enabled() { this.ensureInitialized(); return this._enabled; },
  get expireDays() { this.ensureInitialized(); return this._expireDays; },

  ensureInitialized: function() {
    if (this.initialized)
      return;

    this.initialized = true;

    this._debug = Services.prefs.getBoolPref("browser.formfill.debug");
    this._enabled = Services.prefs.getBoolPref("browser.formfill.enable");
    this._expireDays = Services.prefs.getIntPref("browser.formfill.expire_days");
  }
};

function log(aMessage) {
  if (Prefs.debug) {
    Services.console.logStringMessage("FormHistory: " + aMessage);
  }
}

function sendNotification(aType, aData) {
  if (typeof aData == "string") {
    let strWrapper = Cc["@mozilla.org/supports-string;1"].
                     createInstance(Ci.nsISupportsString);
    strWrapper.data = aData;
    aData = strWrapper;
  }
  else if (typeof aData == "number") {
    let intWrapper = Cc["@mozilla.org/supports-PRInt64;1"].
                     createInstance(Ci.nsISupportsPRInt64);
    intWrapper.data = aData;
    aData = intWrapper;
  }
  else if (aData) {
    throw Components.Exception("Invalid type " + (typeof aType) + " passed to sendNotification",
                               Cr.NS_ERROR_ILLEGAL_VALUE);
  }

  Services.obs.notifyObservers(aData, "satchel-storage-changed", aType);
}

/**
 * Current database schema
 */

const dbSchema = {
  tables : {
    moz_formhistory : {
      "id"        : "INTEGER PRIMARY KEY",
      "fieldname" : "TEXT NOT NULL",
      "value"     : "TEXT NOT NULL",
      "timesUsed" : "INTEGER",
      "firstUsed" : "INTEGER",
      "lastUsed"  : "INTEGER",
      "guid"      : "TEXT",
    },
    moz_deleted_formhistory: {
        "id"          : "INTEGER PRIMARY KEY",
        "timeDeleted" : "INTEGER",
        "guid"        : "TEXT"
    }
  },
  indices : {
    moz_formhistory_index : {
      table   : "moz_formhistory",
      columns : [ "fieldname" ]
    },
    moz_formhistory_lastused_index : {
      table   : "moz_formhistory",
      columns : [ "lastUsed" ]
    },
    moz_formhistory_guid_index : {
      table   : "moz_formhistory",
      columns : [ "guid" ]
    },
  }
};

/**
 * Validating and processing API querying data
 */

const validFields = [
  "fieldname",
  "value",
  "timesUsed",
  "firstUsed",
  "lastUsed",
  "guid",
];

const searchFilters = [
  "firstUsedStart",
  "firstUsedEnd",
  "lastUsedStart",
  "lastUsedEnd",
];

function validateOpData(aData, aDataType) {
  let thisValidFields = validFields;
  // A special case to update the GUID - in this case there can be a 'newGuid'
  // field and of the normally valid fields, only 'guid' is accepted.
  if (aDataType == "Update" && "newGuid" in aData) {
    thisValidFields = ["guid", "newGuid"];
  }
  for (let field in aData) {
    if (field != "op" && thisValidFields.indexOf(field) == -1) {
      throw Components.Exception(
        aDataType + " query contains an unrecognized field: " + field,
        Cr.NS_ERROR_ILLEGAL_VALUE);
    }
  }
  return aData;
}

function validateSearchData(aData, aDataType) {
  for (let field in aData) {
    if (field != "op" && validFields.indexOf(field) == -1 && searchFilters.indexOf(field) == -1) {
      throw Components.Exception(
        aDataType + " query contains an unrecognized field: " + field,
        Cr.NS_ERROR_ILLEGAL_VALUE);
    }
  }
}

function makeQueryPredicates(aQueryData, delimiter = ' AND ') {
  return Object.keys(aQueryData).map(function(field) {
    if (field == "firstUsedStart") {
      return "firstUsed >= :" + field;
    } else if (field == "firstUsedEnd") {
      return "firstUsed <= :" + field;
    } else if (field == "lastUsedStart") {
      return "lastUsed >= :" + field;
    } else if (field == "lastUsedEnd") {
      return "lastUsed <= :" + field;
    }
    return field + " = :" + field;
  }).join(delimiter);
}

/**
 * Storage statement creation and parameter binding
 */

function makeCountStatement(aSearchData) {
  let query = "SELECT COUNT(*) AS numEntries FROM moz_formhistory";
  let queryTerms = makeQueryPredicates(aSearchData);
  if (queryTerms) {
    query += " WHERE " + queryTerms;
  }
  return dbCreateAsyncStatement(query, aSearchData);
}

function makeSearchStatement(aSearchData, aSelectTerms) {
  let query = "SELECT " + aSelectTerms.join(", ") + " FROM moz_formhistory";
  let queryTerms = makeQueryPredicates(aSearchData);
  if (queryTerms) {
    query += " WHERE " + queryTerms;
  }

  return dbCreateAsyncStatement(query, aSearchData);
}

function makeAddStatement(aNewData, aNow, aBindingArrays) {
  let query = "INSERT INTO moz_formhistory (fieldname, value, timesUsed, firstUsed, lastUsed, guid) " +
              "VALUES (:fieldname, :value, :timesUsed, :firstUsed, :lastUsed, :guid)";

  aNewData.timesUsed = aNewData.timesUsed || 1;
  aNewData.firstUsed = aNewData.firstUsed || aNow;
  aNewData.lastUsed = aNewData.lastUsed || aNow;
  return dbCreateAsyncStatement(query, aNewData, aBindingArrays);
}

function makeBumpStatement(aGuid, aNow, aBindingArrays) {
  let query = "UPDATE moz_formhistory SET timesUsed = timesUsed + 1, lastUsed = :lastUsed WHERE guid = :guid";
  let queryParams = {
    lastUsed : aNow,
    guid : aGuid,
  };

  return dbCreateAsyncStatement(query, queryParams, aBindingArrays);
}

function makeRemoveStatement(aSearchData, aBindingArrays) {
  let query = "DELETE FROM moz_formhistory";
  let queryTerms = makeQueryPredicates(aSearchData);

  if (queryTerms) {
    log("removeEntries");
    query += " WHERE " + queryTerms;
  } else {
    log("removeAllEntries");
    // Not specifying any fields means we should remove all entries. We
    // won't need to modify the query in this case.
  }

  return dbCreateAsyncStatement(query, aSearchData, aBindingArrays);
}

function makeUpdateStatement(aGuid, aNewData, aBindingArrays) {
  let query = "UPDATE moz_formhistory SET ";
  let queryTerms = makeQueryPredicates(aNewData, ', ');

  if (!queryTerms) {
    throw Components.Exception("Update query must define fields to modify.",
                               Cr.NS_ERROR_ILLEGAL_VALUE);
  }

  query += queryTerms + " WHERE guid = :existing_guid";
  aNewData["existing_guid"] = aGuid;

  return dbCreateAsyncStatement(query, aNewData, aBindingArrays);
}

function makeMoveToDeletedStatement(aGuid, aNow, aData, aBindingArrays) {
  if (supportsDeletedTable) {
    let query = "INSERT INTO moz_deleted_formhistory (guid, timeDeleted)";
    let queryTerms = makeQueryPredicates(aData);

    if (aGuid) {
      query += " VALUES (:guid, :timeDeleted)";
    } else {
      // TODO: Add these items to the deleted items table once we've sorted
      //       out the issues from bug 756701
      if (!queryTerms)
        return undefined;

      query += " SELECT guid, :timeDeleted FROM moz_formhistory WHERE " + queryTerms;
    }

    aData.timeDeleted = aNow;

    return dbCreateAsyncStatement(query, aData, aBindingArrays);
  }

  return null;
}

function generateGUID() {
  // string like: "{f60d9eac-9421-4abc-8491-8e8322b063d4}"
  let uuid = uuidService.generateUUID().toString();
  let raw = ""; // A string with the low bytes set to random values
  let bytes = 0;
  for (let i = 1; bytes < 12 ; i+= 2) {
    // Skip dashes
    if (uuid[i] == "-")
      i++;
    let hexVal = parseInt(uuid[i] + uuid[i + 1], 16);
    raw += String.fromCharCode(hexVal);
    bytes++;
  }
  return btoa(raw);
}

/**
 * Database creation and access
 */

var _dbConnection = null;
XPCOMUtils.defineLazyGetter(this, "dbConnection", function() {
  let dbFile;

  try {
    dbFile = Services.dirsvc.get("ProfD", Ci.nsIFile).clone();
    dbFile.append("formhistory.sqlite");
    log("Opening database at " + dbFile.path);

    _dbConnection = Services.storage.openUnsharedDatabase(dbFile);
    dbInit();
  } catch (e) {
    if (e.result != Cr.NS_ERROR_FILE_CORRUPTED)
      throw e;
    dbCleanup(dbFile);
    _dbConnection = Services.storage.openUnsharedDatabase(dbFile);
    dbInit();
  }

  return _dbConnection;
});


var dbStmts = new Map();

/*
 * dbCreateAsyncStatement
 *
 * Creates a statement, wraps it, and then does parameter replacement
 */
function dbCreateAsyncStatement(aQuery, aParams, aBindingArrays) {
  if (!aQuery)
    return null;

  let stmt = dbStmts.get(aQuery);
  if (!stmt) {
    log("Creating new statement for query: " + aQuery);
    stmt = dbConnection.createAsyncStatement(aQuery);
    dbStmts.set(aQuery, stmt);
  }

  if (aBindingArrays) {
    let bindingArray = aBindingArrays.get(stmt);
    if (!bindingArray) {
      // first time using a particular statement in update
      bindingArray = stmt.newBindingParamsArray();
      aBindingArrays.set(stmt, bindingArray);
    }

    if (aParams) {
      let bindingParams = bindingArray.newBindingParams();
      for (let field in aParams) {
        bindingParams.bindByName(field, aParams[field]);
      }
      bindingArray.addParams(bindingParams);
    }
  } else if (aParams) {
    for (let field in aParams) {
      stmt.params[field] = aParams[field];
    }
  }

  return stmt;
}

/**
 * dbInit
 *
 * Attempts to initialize the database. This creates the file if it doesn't
 * exist, performs any migrations, etc.
 */
function dbInit() {
  log("Initializing Database");

  if (!_dbConnection.tableExists("moz_formhistory")) {
    dbCreate();
    return;
  }

  // When FormHistory is released, we will no longer support the various schema versions prior to
  // this release that nsIFormHistory2 once did.
  let version = _dbConnection.schemaVersion;
  if (version < 3) {
    throw Components.Exception("DB version is unsupported.",
                               Cr.NS_ERROR_FILE_CORRUPTED);
  } else if (version != DB_SCHEMA_VERSION) {
    dbMigrate(version);
  }
}

function dbCreate() {
  log("Creating DB -- tables");
  for (let name in dbSchema.tables) {
    let table = dbSchema.tables[name];
    let tSQL = Object.keys(table).map(col => [col, table[col]].join(" ")).join(", ");
    log("Creating table " + name + " with " + tSQL);
    _dbConnection.createTable(name, tSQL);
  }

  log("Creating DB -- indices");
  for (let name in dbSchema.indices) {
    let index = dbSchema.indices[name];
    let statement = "CREATE INDEX IF NOT EXISTS " + name + " ON " + index.table +
                    "(" + index.columns.join(", ") + ")";
    _dbConnection.executeSimpleSQL(statement);
  }

  _dbConnection.schemaVersion = DB_SCHEMA_VERSION;
}

function dbMigrate(oldVersion) {
  log("Attempting to migrate from version " + oldVersion);

  if (oldVersion > DB_SCHEMA_VERSION) {
    log("Downgrading to version " + DB_SCHEMA_VERSION);
    // User's DB is newer. Sanity check that our expected columns are
    // present, and if so mark the lower version and merrily continue
    // on. If the columns are borked, something is wrong so blow away
    // the DB and start from scratch. [Future incompatible upgrades
    // should switch to a different table or file.]

    if (!dbAreExpectedColumnsPresent()) {
      throw Components.Exception("DB is missing expected columns",
                                 Cr.NS_ERROR_FILE_CORRUPTED);
    }

    // Change the stored version to the current version. If the user
    // runs the newer code again, it will see the lower version number
    // and re-upgrade (to fixup any entries the old code added).
    _dbConnection.schemaVersion = DB_SCHEMA_VERSION;
    return;
  }

  // Note that migration is currently performed synchronously.
  _dbConnection.beginTransaction();

  try {
    for (let v = oldVersion + 1; v <= DB_SCHEMA_VERSION; v++) {
      this.log("Upgrading to version " + v + "...");
      Migrators["dbMigrateToVersion" + v]();
    }
  } catch (e) {
    this.log("Migration failed: "  + e);
    this.dbConnection.rollbackTransaction();
    throw e;
  }

  _dbConnection.schemaVersion = DB_SCHEMA_VERSION;
  _dbConnection.commitTransaction();

  log("DB migration completed.");
}

var Migrators = {
  /*
   * Updates the DB schema to v3 (bug 506402).
   * Adds deleted form history table.
   */
  dbMigrateToVersion4: function dbMigrateToVersion4() {
    if (!_dbConnection.tableExists("moz_deleted_formhistory")) {
      let table = dbSchema.tables["moz_deleted_formhistory"];
      let tSQL = Object.keys(table).map(col => [col, table[col]].join(" ")).join(", ");
      _dbConnection.createTable("moz_deleted_formhistory", tSQL);
    }
  }
};

/**
 * dbAreExpectedColumnsPresent
 *
 * Sanity check to ensure that the columns this version of the code expects
 * are present in the DB we're using.
 */
function dbAreExpectedColumnsPresent() {
  for (let name in dbSchema.tables) {
    let table = dbSchema.tables[name];
    let query = "SELECT " +
                Object.keys(table).join(", ") +
                " FROM " + name;
    try {
      let stmt = _dbConnection.createStatement(query);
      // (no need to execute statement, if it compiled we're good)
      stmt.finalize();
    } catch (e) {
      return false;
    }
  }

  log("verified that expected columns are present in DB.");
  return true;
}

/**
 * dbCleanup
 *
 * Called when database creation fails. Finalizes database statements,
 * closes the database connection, deletes the database file.
 */
function dbCleanup(dbFile) {
  log("Cleaning up DB file - close & remove & backup");

  // Create backup file
  let backupFile = dbFile.leafName + ".corrupt";
  Services.storage.backupDatabaseFile(dbFile, backupFile);

  dbClose(false);
  dbFile.remove(false);
}

function dbClose(aShutdown) {
  log("dbClose(" + aShutdown + ")");

  if (aShutdown) {
    sendNotification("formhistory-shutdown", null);
  }

  // Connection may never have been created if say open failed but we still
  // end up calling dbClose as part of the rest of dbCleanup.
  if (!_dbConnection) {
    return;
  }

  log("dbClose finalize statements");
  for (let stmt of dbStmts.values()) {
    stmt.finalize();
  }

  dbStmts = new Map();

  let closed = false;
  _dbConnection.asyncClose(() => closed = true);

  if (!aShutdown) {
    let thread = Services.tm.currentThread;
    while (!closed) {
      thread.processNextEvent(true);
    }
  }
}

/**
 * updateFormHistoryWrite
 *
 * Constructs and executes database statements from a pre-processed list of
 * inputted changes.
 */
function updateFormHistoryWrite(aChanges, aCallbacks) {
  log("updateFormHistoryWrite  " + aChanges.length);

  // pass 'now' down so that every entry in the batch has the same timestamp
  let now = Date.now() * 1000;

  // for each change, we either create and append a new storage statement to
  // stmts or bind a new set of parameters to an existing storage statement.
  // stmts and bindingArrays are updated when makeXXXStatement eventually
  // calls dbCreateAsyncStatement.
  let stmts = [];
  let notifications = [];
  let bindingArrays = new Map();

  for (let change of aChanges) {
    let operation = change.op;
    delete change.op;
    let stmt;
    switch (operation) {
      case "remove":
        log("Remove from form history  " + change);
        let delStmt = makeMoveToDeletedStatement(change.guid, now, change, bindingArrays);
        if (delStmt && stmts.indexOf(delStmt) == -1)
          stmts.push(delStmt);
        if ("timeDeleted" in change)
          delete change.timeDeleted;
        stmt = makeRemoveStatement(change, bindingArrays);
        notifications.push([ "formhistory-remove", change.guid ]);
        break;
      case "update":
        log("Update form history " + change);
        let guid = change.guid;
        delete change.guid;
        // a special case for updating the GUID - the new value can be
        // specified in newGuid.
        if (change.newGuid) {
          change.guid = change.newGuid
          delete change.newGuid;
        }
        stmt = makeUpdateStatement(guid, change, bindingArrays);
        notifications.push([ "formhistory-update", guid ]);
        break;
      case "bump":
        log("Bump form history " + change);
        if (change.guid) {
          stmt = makeBumpStatement(change.guid, now, bindingArrays);
          notifications.push([ "formhistory-update", change.guid ]);
        } else {
          change.guid = generateGUID();
          stmt = makeAddStatement(change, now, bindingArrays);
          notifications.push([ "formhistory-add", change.guid ]);
        }
        break;
      case "add":
        log("Add to form history " + change);
        change.guid = generateGUID();
        stmt = makeAddStatement(change, now, bindingArrays);
        notifications.push([ "formhistory-add", change.guid ]);
        break;
      default:
        // We should've already guaranteed that change.op is one of the above
        throw Components.Exception("Invalid operation " + operation,
                                   Cr.NS_ERROR_ILLEGAL_VALUE);
    }

    // As identical statements are reused, only add statements if they aren't already present.
    if (stmt && stmts.indexOf(stmt) == -1) {
      stmts.push(stmt);
    }
  }

  for (let stmt of stmts) {
    stmt.bindParameters(bindingArrays.get(stmt));
  }

  let handlers = {
    handleCompletion : function(aReason) {
      if (aReason == Ci.mozIStorageStatementCallback.REASON_FINISHED) {
        for (let [notification, param] of notifications) {
          // We're either sending a GUID or nothing at all.
          sendNotification(notification, param);
        }
      }

      if (aCallbacks && aCallbacks.handleCompletion) {
        aCallbacks.handleCompletion(aReason == Ci.mozIStorageStatementCallback.REASON_FINISHED ? 0 : 1);
      }
    },
    handleError : function(aError) {
      if (aCallbacks && aCallbacks.handleError) {
        aCallbacks.handleError(aError);
      }
    },
    handleResult : NOOP
  };

  dbConnection.executeAsync(stmts, stmts.length, handlers);
}

/**
 * Functions that expire entries in form history and shrinks database
 * afterwards as necessary initiated by expireOldEntries.
 */

/**
 * expireOldEntriesDeletion
 *
 * Removes entries from database.
 */
function expireOldEntriesDeletion(aExpireTime, aBeginningCount) {
  log("expireOldEntriesDeletion(" + aExpireTime + "," + aBeginningCount + ")");

  FormHistory.update([
    {
      op: "remove",
      lastUsedEnd : aExpireTime,
    }], {
      handleCompletion: function() {
        expireOldEntriesVacuum(aExpireTime, aBeginningCount);
      },
      handleError: function(aError) {
        log("expireOldEntriesDeletionFailure");
      }
  });
}

/**
 * expireOldEntriesVacuum
 *
 * Counts number of entries removed and shrinks database as necessary.
 */
function expireOldEntriesVacuum(aExpireTime, aBeginningCount) {
  FormHistory.count({}, {
    handleResult: function(aEndingCount) {
      if (aBeginningCount - aEndingCount > 500) {
        log("expireOldEntriesVacuum");

        let stmt = dbCreateAsyncStatement("VACUUM");
        stmt.executeAsync({
          handleResult : NOOP,
          handleError : function(aError) {
            log("expireVacuumError");
          },
          handleCompletion : NOOP
        });
      }

      sendNotification("formhistory-expireoldentries", aExpireTime);
    },
    handleError: function(aError) {
      log("expireEndCountFailure");
    }
  });
}

this.FormHistory = {
  get enabled() {
    return Prefs.enabled;
  },

  search : function formHistorySearch(aSelectTerms, aSearchData, aCallbacks) {
    // if no terms selected, select everything
    aSelectTerms = (aSelectTerms) ?  aSelectTerms : validFields;
    validateSearchData(aSearchData, "Search");

    let stmt = makeSearchStatement(aSearchData, aSelectTerms);

    let handlers = {
      handleResult : function(aResultSet) {
        for (let row = aResultSet.getNextRow(); row; row = aResultSet.getNextRow()) {
          let result = {};
          for (let field of aSelectTerms) {
            result[field] = row.getResultByName(field);
          }

          if (aCallbacks && aCallbacks.handleResult) {
            aCallbacks.handleResult(result);
          }
        }
      },

      handleError : function(aError) {
        if (aCallbacks && aCallbacks.handleError) {
          aCallbacks.handleError(aError);
        }
      },

      handleCompletion : function searchCompletionHandler(aReason) {
        if (aCallbacks && aCallbacks.handleCompletion) {
          aCallbacks.handleCompletion(aReason == Ci.mozIStorageStatementCallback.REASON_FINISHED ? 0 : 1);
        }
      }
    };

    stmt.executeAsync(handlers);
  },

  count : function formHistoryCount(aSearchData, aCallbacks) {
    validateSearchData(aSearchData, "Count");
    let stmt = makeCountStatement(aSearchData);
    let handlers = {
      handleResult : function countResultHandler(aResultSet) {
        let row = aResultSet.getNextRow();
        let count = row.getResultByName("numEntries");
        if (aCallbacks && aCallbacks.handleResult) {
          aCallbacks.handleResult(count);
        }
      },

      handleError : function(aError) {
        if (aCallbacks && aCallbacks.handleError) {
          aCallbacks.handleError(aError);
        }
      },

      handleCompletion : function searchCompletionHandler(aReason) {
        if (aCallbacks && aCallbacks.handleCompletion) {
          aCallbacks.handleCompletion(aReason == Ci.mozIStorageStatementCallback.REASON_FINISHED ? 0 : 1);
        }
      }
    };

    stmt.executeAsync(handlers);
  },

  update : function formHistoryUpdate(aChanges, aCallbacks) {
    // Used to keep track of how many searches have been started. When that number
    // are finished, updateFormHistoryWrite can be called.
    let numSearches = 0;
    let completedSearches = 0;
    let searchFailed = false;

    function validIdentifier(change) {
      // The identifier is only valid if one of either the guid or the (fieldname/value) are set
      return Boolean(change.guid) != Boolean(change.fieldname && change.value);
    }

    if (!("length" in aChanges))
      aChanges = [aChanges];

    let isRemoveOperation = aChanges.every(change => change && change.op && change.op == "remove");
    if (!Prefs.enabled && !isRemoveOperation) {
      if (aCallbacks && aCallbacks.handleError) {
        aCallbacks.handleError({
          message: "Form history is disabled, only remove operations are allowed",
          result: Ci.mozIStorageError.MISUSE
        });
      }
      if (aCallbacks && aCallbacks.handleCompletion) {
        aCallbacks.handleCompletion(1);
      }
      return;
    }

    for (let change of aChanges) {
      switch (change.op) {
        case "remove":
          validateSearchData(change, "Remove");
          continue;
        case "update":
          if (validIdentifier(change)) {
            validateOpData(change, "Update");
            if (change.guid) {
              continue;
            }
          } else {
            throw Components.Exception(
              "update op='update' does not correctly reference a entry.",
              Cr.NS_ERROR_ILLEGAL_VALUE);
          }
          break;
        case "bump":
          if (validIdentifier(change)) {
            validateOpData(change, "Bump");
            if (change.guid) {
              continue;
            }
          } else {
            throw Components.Exception(
              "update op='bump' does not correctly reference a entry.",
              Cr.NS_ERROR_ILLEGAL_VALUE);
          }
          break;
        case "add":
          if (change.guid) {
            throw Components.Exception(
              "op='add' cannot contain field 'guid'. Either use op='update' " +
                "explicitly or make 'guid' undefined.",
              Cr.NS_ERROR_ILLEGAL_VALUE);
          } else if (change.fieldname && change.value) {
            validateOpData(change, "Add");
          }
          break;
        default:
          throw Components.Exception(
            "update does not recognize op='" + change.op + "'",
            Cr.NS_ERROR_ILLEGAL_VALUE);
      }

      numSearches++;
      let changeToUpdate = change;
      FormHistory.search(
        [ "guid" ],
        {
          fieldname : change.fieldname,
          value : change.value
        }, {
          foundResult : false,
          handleResult : function(aResult) {
            if (this.foundResult) {
              log("Database contains multiple entries with the same fieldname/value pair.");
              if (aCallbacks && aCallbacks.handleError) {
                aCallbacks.handleError({
                  message :
                    "Database contains multiple entries with the same fieldname/value pair.",
                  result : 19 // Constraint violation
                });
              }

              searchFailed = true;
              return;
            }

            this.foundResult = true;
            changeToUpdate.guid = aResult["guid"];
          },

          handleError : function(aError) {
            if (aCallbacks && aCallbacks.handleError) {
              aCallbacks.handleError(aError);
            }
          },

          handleCompletion : function(aReason) {
            completedSearches++;
            if (completedSearches == numSearches) {
              if (!aReason && !searchFailed) {
                updateFormHistoryWrite(aChanges, aCallbacks);
              }
              else if (aCallbacks && aCallbacks.handleCompletion) {
                aCallbacks.handleCompletion(1);
              }
            }
          }
        });
    }

    if (numSearches == 0) {
      // We don't have to wait for any statements to return.
      updateFormHistoryWrite(aChanges, aCallbacks);
    }
  },

  getAutoCompleteResults: function getAutoCompleteResults(searchString, params, aCallbacks) {
    // only do substring matching when the search string contains more than one character
    let searchTokens;
    let where = ""
    let boundaryCalc = "";
    if (searchString.length > 1) {
        searchTokens = searchString.split(/\s+/);

        // build up the word boundary and prefix match bonus calculation
        boundaryCalc = "MAX(1, :prefixWeight * (value LIKE :valuePrefix ESCAPE '/') + (";
        // for each word, calculate word boundary weights for the SELECT clause and
        // add word to the WHERE clause of the query
        let tokenCalc = [];
        let searchTokenCount = Math.min(searchTokens.length, MAX_SEARCH_TOKENS);
        for (let i = 0; i < searchTokenCount; i++) {
            tokenCalc.push("(value LIKE :tokenBegin" + i + " ESCAPE '/') + " +
                            "(value LIKE :tokenBoundary" + i + " ESCAPE '/')");
            where += "AND (value LIKE :tokenContains" + i + " ESCAPE '/') ";
        }
        // add more weight if we have a traditional prefix match and
        // multiply boundary bonuses by boundary weight
        boundaryCalc += tokenCalc.join(" + ") + ") * :boundaryWeight)";
    } else if (searchString.length == 1) {
        where = "AND (value LIKE :valuePrefix ESCAPE '/') ";
        boundaryCalc = "1";
        delete params.prefixWeight;
        delete params.boundaryWeight;
    } else {
        where = "";
        boundaryCalc = "1";
        delete params.prefixWeight;
        delete params.boundaryWeight;
    }

    params.now = Date.now() * 1000; // convert from ms to microseconds

    /* Three factors in the frecency calculation for an entry (in order of use in calculation):
     * 1) average number of times used - items used more are ranked higher
     * 2) how recently it was last used - items used recently are ranked higher
     * 3) additional weight for aged entries surviving expiry - these entries are relevant
     *    since they have been used multiple times over a large time span so rank them higher
     * The score is then divided by the bucket size and we round the result so that entries
     * with a very similar frecency are bucketed together with an alphabetical sort. This is
     * to reduce the amount of moving around by entries while typing.
     */

    let query = "/* do not warn (bug 496471): can't use an index */ " +
                "SELECT value, " +
                "ROUND( " +
                    "timesUsed / MAX(1.0, (lastUsed - firstUsed) / :timeGroupingSize) * " +
                    "MAX(1.0, :maxTimeGroupings - (:now - lastUsed) / :timeGroupingSize) * "+
                    "MAX(1.0, :agedWeight * (firstUsed < :expiryDate)) / " +
                    ":bucketSize "+
                ", 3) AS frecency, " +
                boundaryCalc + " AS boundaryBonuses " +
                "FROM moz_formhistory " +
                "WHERE fieldname=:fieldname " + where +
                "ORDER BY ROUND(frecency * boundaryBonuses) DESC, UPPER(value) ASC";

    let stmt = dbCreateAsyncStatement(query, params);

    // Chicken and egg problem: Need the statement to escape the params we
    // pass to the function that gives us the statement. So, fix it up now.
    if (searchString.length >= 1)
      stmt.params.valuePrefix = stmt.escapeStringForLIKE(searchString, "/") + "%";
    if (searchString.length > 1) {
      let searchTokenCount = Math.min(searchTokens.length, MAX_SEARCH_TOKENS);
      for (let i = 0; i < searchTokenCount; i++) {
        let escapedToken = stmt.escapeStringForLIKE(searchTokens[i], "/");
        stmt.params["tokenBegin" + i] = escapedToken + "%";
        stmt.params["tokenBoundary" + i] =  "% " + escapedToken + "%";
        stmt.params["tokenContains" + i] = "%" + escapedToken + "%";
      }
    } else {
      // no additional params need to be substituted into the query when the
      // length is zero or one
    }

    let pending = stmt.executeAsync({
      handleResult : function (aResultSet) {
        for (let row = aResultSet.getNextRow(); row; row = aResultSet.getNextRow()) {
          let value = row.getResultByName("value");
          let frecency = row.getResultByName("frecency");
          let entry = {
            text :          value,
            textLowerCase : value.toLowerCase(),
            frecency :      frecency,
            totalScore :    Math.round(frecency * row.getResultByName("boundaryBonuses"))
          };
          if (aCallbacks && aCallbacks.handleResult) {
            aCallbacks.handleResult(entry);
          }
        }
      },

      handleError : function (aError) {
        if (aCallbacks && aCallbacks.handleError) {
          aCallbacks.handleError(aError);
        }
      },

      handleCompletion : function (aReason) {
        if (aCallbacks && aCallbacks.handleCompletion) {
          aCallbacks.handleCompletion(aReason == Ci.mozIStorageStatementCallback.REASON_FINISHED ? 0 : 1);
        }
      }
    });
    return pending;
  },

  get schemaVersion() {
    return dbConnection.schemaVersion;
  },

  // This is used only so that the test can verify deleted table support.
  get _supportsDeletedTable() {
    return supportsDeletedTable;
  },
  set _supportsDeletedTable(val) {
    supportsDeletedTable = val;
  },

  // The remaining methods are called by FormHistoryStartup.js
  updatePrefs: function updatePrefs() {
    Prefs.initialized = false;
  },

  expireOldEntries: function expireOldEntries() {
    log("expireOldEntries");

    // Determine how many days of history we're supposed to keep.
    // Calculate expireTime in microseconds
    let expireTime = (Date.now() - Prefs.expireDays * DAY_IN_MS) * 1000;

    sendNotification("formhistory-beforeexpireoldentries", expireTime);

    FormHistory.count({}, {
      handleResult: function(aBeginningCount) {
        expireOldEntriesDeletion(expireTime, aBeginningCount);
      },
      handleError: function(aError) {
        log("expireStartCountFailure");
      }
    });
  },

  shutdown: function shutdown() { dbClose(true); }
};

// Prevent add-ons from redefining this API
Object.freeze(FormHistory);