src/plugins/tracker/rygel-tracker-search-container.vala

   1 /*
   2  * Copyright (C) 2008 Zeeshan Ali <zeenix@gmail.com>.
   3  * Copyright (C) 2008 Nokia Corporation.
   4  *
   5  * Author: Zeeshan Ali <zeenix@gmail.com>
   6  *         Ivan Frade <ivan.frade@nokia.com>
   7  *
   8  * This file is part of Rygel.
   9  *
  10  * Rygel is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * Rygel is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with this program; if not, write to the Free Software Foundation,
  22  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  23  */
  24
  25 using GUPnP;
  26 using Gee;
  27
  28 /**
  29  * A container listing a Tracker search result.
  30  */
  31 public class Rygel.Tracker.SearchContainer : Rygel.MediaContainer {
  32     /* class-wide constants */
  33     private const string TRACKER_SERVICE = "org.freedesktop.Tracker1";
  34     private const string RESOURCES_PATH = "/org/freedesktop/Tracker1/Resources";
  35
  36     private const string ITEM_VARIABLE = "?item";
  37     private const string MODIFIED_PREDICATE = "nfo:fileLastModified";
  38     private const string MODIFIED_VARIABLE = "?modified";
  39     private const string URL_PREDICATE = "nie:url";
  40     private const string URL_VARIABLE = "?url";
  41
  42     public SelectionQuery query;
  43     public ItemFactory item_factory;
  44
  45     private ResourcesIface resources;
  46
  47     public SearchContainer (string             id,
  48                             MediaContainer     parent,
  49                             string             title,
  50                             ItemFactory        item_factory,
  51                             QueryTriplets?     triplets = null,
  52                             ArrayList<string>? filters = null) {
  53         base (id, parent, title, 0);
  54
  55         this.item_factory = item_factory;
  56
  57         var variables = new ArrayList<string> ();
  58         variables.add (ITEM_VARIABLE);
  59         variables.add (URL_VARIABLE);
  60
  61         QueryTriplets our_triplets;
  62         if (triplets != null) {
  63             our_triplets = triplets;
  64         } else {
  65             our_triplets = new QueryTriplets ();
  66         }
  67
  68         our_triplets.add_triplet (new QueryTriplet (ITEM_VARIABLE,
  69                                                     "a",
  70                                                     item_factory.category));
  71         our_triplets.add_triplet (new QueryTriplet (ITEM_VARIABLE,
  72                                                     MODIFIED_PREDICATE,
  73                                                     MODIFIED_VARIABLE));
  74         our_triplets.add_triplet (new QueryTriplet (ITEM_VARIABLE,
  75                                                     URL_PREDICATE,
  76                                                     URL_VARIABLE));
  77
  78         foreach (var chain in this.item_factory.key_chains) {
  79             var variable = ITEM_VARIABLE;
  80
  81             foreach (var key in chain) {
  82                 variable = key + "(" + variable + ")";
  83             }
  84
  85             variables.add (variable);
  86         }
  87
  88         this.query = new SelectionQuery (variables,
  89                                          our_triplets,
  90                                          filters,
  91                                          MODIFIED_VARIABLE);
  92
  93         try {
  94             this.resources = Bus.get_proxy_sync (BusType.SESSION,
  95                                                  TRACKER_SERVICE,
  96                                                  RESOURCES_PATH);
  97
  98             this.get_children_count.begin ();
  99         } catch (IOError error) {
 100             critical (_("Failed to connect to session bus: %s"), error.message);
 101         }
 102     }
 103
 104     public override async MediaObjects? get_children (uint         offset,
 105                                                       uint         max_count,
 106                                                       Cancellable? cancellable)
 107                                                       throws GLib.Error {
 108         var expression = new RelationalExpression ();
 109         expression.op = SearchCriteriaOp.EQ;
 110         expression.operand1 = "@parentID";
 111         expression.operand2 = this.id;
 112
 113         uint total_matches;
 114
 115         return yield this.search (expression,
 116                                   offset,
 117                                   max_count,
 118                                   out total_matches,
 119                                   cancellable);
 120     }
 121
 122     public override async MediaObjects? search (SearchExpression? expression,
 123                                                 uint              offset,
 124                                                 uint              max_count,
 125                                                 out uint          total_matches,
 126                                                 Cancellable?      cancellable)
 127                                                 throws GLib.Error {
 128         var results = new MediaObjects ();
 129
 130         if (expression == null || !(expression is RelationalExpression)) {
 131             return yield base.search (expression,
 132                                       offset,
 133                                       max_count,
 134                                       out total_matches,
 135                                       cancellable);
 136         }
 137
 138         var query = this.create_query (expression as RelationalExpression,
 139                                        (int) offset,
 140                                        (int) max_count);
 141         if (query != null) {
 142             yield query.execute (this.resources);
 143
 144             /* Iterate through all items */
 145             for (uint i = 0; i < query.result.length[0]; i++) {
 146                 var id = this.create_child_id_for_urn (query.result[i, 0]);
 147                 var uri = query.result[i, 1];
 148                 string[] metadata = this.slice_strvv_tail (query.result, i, 2);
 149
 150                 var item = this.item_factory.create (id, uri, this, metadata);
 151                 results.add (item);
 152             }
 153         }
 154
 155         total_matches = results.size;
 156
 157         return results;
 158     }
 159
 160     public override async MediaObject? find_object (string       id,
 161                                                     Cancellable? cancellable)
 162                                                     throws GLib.Error {
 163         if (this.is_our_child (id)) {
 164             return yield base.find_object (id, cancellable);
 165         } else {
 166             return null;
 167         }
 168     }
 169
 170     public string create_child_id_for_urn (string urn) {
 171         return this.id + "," + urn;
 172     }
 173
 174     private bool is_our_child (string id) {
 175         return id.has_prefix (this.id + ",");
 176     }
 177
 178     private async void get_children_count () {
 179         try {
 180             var query = new SelectionQuery.clone (this.query);
 181
 182             query.variables = new ArrayList<string> ();
 183             query.variables.add ("COUNT(" + ITEM_VARIABLE + ") AS x");
 184
 185             yield query.execute (this.resources);
 186
 187             this.child_count = query.result[0,0].to_int ();
 188             this.updated ();
 189         } catch (GLib.Error error) {
 190             critical (_("Error getting item count under category '%s': %s"),
 191                       this.item_factory.category,
 192                       error.message);
 193
 194             return;
 195         }
 196     }
 197
 198     private SelectionQuery? create_query (RelationalExpression? expression,
 199                                           int                   offset,
 200                                           int                   max_count) {
 201         if (expression.operand1 == "upnp:class" &&
 202             !this.item_factory.upnp_class.has_prefix (expression.operand2)) {
 203             return null;
 204         }
 205
 206         var query = new SelectionQuery.clone (this.query);
 207
 208         if (expression.operand1 == "@parentID") {
 209             if (!expression.compare_string (this.id)) {
 210                 return null;
 211             }
 212         } else if (expression.operand1 != "upnp:class") {
 213             var filter = create_filter_for_child (expression);
 214             if (filter != null) {
 215                 query.filters.insert (0, filter);
 216             } else {
 217                 return null;
 218             }
 219         }
 220
 221         query.offset = offset;
 222         query.max_count = max_count;
 223
 224         return query;
 225     }
 226
 227     private string? create_filter_for_child (RelationalExpression expression) {
 228         string filter = null;
 229         string variable = null;
 230         string value = null;
 231
 232         if (expression.operand1 == "@id") {
 233             variable = ITEM_VARIABLE;
 234
 235             string parent_id;
 236
 237             var urn = this.get_item_info (expression.operand2, out parent_id);
 238             if (urn == null || parent_id == null || parent_id != this.id) {
 239                 return null;
 240             }
 241
 242             switch (expression.op) {
 243                 case SearchCriteriaOp.EQ:
 244                     value = "<" + urn + ">";
 245                     break;
 246                 case SearchCriteriaOp.CONTAINS:
 247                     value = expression.operand2;
 248                     break;
 249             }
 250         }
 251
 252         if (variable == null || value == null) {
 253             return null;
 254         }
 255
 256         switch (expression.op) {
 257             case SearchCriteriaOp.EQ:
 258                 filter = variable + " = " + value;
 259                 break;
 260             case SearchCriteriaOp.CONTAINS:
 261                 // We need to escape this twice for Tracker
 262                 var regex = this.escape_string (Regex.escape_string (value));
 263
 264                 filter = "regex(" + variable + ", \"" + regex + "\", \"i\")";
 265                 break;
 266         }
 267
 268         return filter;
 269     }
 270
 271     // Returns the URN and the ID of the parent this item belongs to, or null
 272     // if item_id is invalid
 273     private string? get_item_info (string     item_id,
 274                                    out string parent_id) {
 275         var tokens = item_id.split (",", 2);
 276
 277         if (tokens[0] != null && tokens[1] != null) {
 278             parent_id = tokens[0];
 279
 280             return tokens[1];
 281         } else {
 282             return null;
 283         }
 284     }
 285
 286     /**
 287      * Chops the tail of a particular row in a 2-dimensional string array.
 288      *
 289      * param strvv the 2-dimenstional string array to chop the tail of.
 290      * param row the row whose tail needs to be chopped off.
 291      * param index index of the first element in the tail.
 292      *
 293      * FIXME: Stop using it once vala supports array slicing syntax for
 294      *        multi-dimentional arrays.
 295      */
 296     private string[] slice_strvv_tail (string[,] strvv, uint row, uint index) {
 297         var slice = new string[strvv.length[1] - index];
 298
 299         for (var i = 0; i < slice.length; i++) {
 300             slice[i] = strvv[row, i + index];
 301         }
 302
 303         return slice;
 304     }
 305
 306     /**
 307      * tracker_sparql_escape_string:
 308      * @literal: a string to escape
 309      *
 310      * Escapes a string so that it can be used in a SPARQL query. Copied from
 311      * Tracker project.
 312      *
 313      * Returns: a newly-allocated string with the escaped version of @literal.
 314      *  The returned string should be freed with g_free() when no longer needed.
 315      */
 316     private string escape_string (string literal) {
 317         StringBuilder str = new StringBuilder ();
 318         char *p = literal;
 319
 320         while (*p != '\0') {
 321             size_t len = Posix.strcspn ((string) p, "\t\n\r\b\f\"\\");
 322             str.append_len ((string) p, (long) len);
 323             p += len;
 324
 325             switch (*p) {
 326                 case '\t':
 327                     str.append ("\\t");
 328                     break;
 329                 case '\n':
 330                     str.append ("\\n");
 331                     break;
 332                 case '\r':
 333                     str.append ("\\r");
 334                     break;
 335                 case '\b':
 336                     str.append ("\\b");
 337                     break;
 338                 case '\f':
 339                     str.append ("\\f");
 340                     break;
 341                 case '"':
 342                     str.append ("\\\"");
 343                     break;
 344                 case '\\':
 345                     str.append ("\\\\");
 346                     break;
 347                 default:
 348                     continue;
 349             }
 350
 351             p++;
 352         }
 353
 354         return str.str;
 355     }
 356 }
 357