[tracker/wip/carlosg/sparql1.1: 51/56] libtracker-data: Implement TIMEZONE sparql function

[Carlos Garnacho <carlosg src gnome org>]

commit 674b832bfa2701e527dd11a73e6b287a099722cf
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Jun 4 13:10:44 2019 +0200

    libtracker-data: Implement TIMEZONE sparql function
    
    This returns a xsd:dayTimeDuration, in the form of [+-]PTxHyMzS.

 src/libtracker-data/tracker-db-interface-sqlite.c | 65 +++++++++++++++++++++++
 src/libtracker-data/tracker-sparql.c              |  8 ++-
 2 files changed, 72 insertions(+), 1 deletion(-)
---
diff --git a/src/libtracker-data/tracker-db-interface-sqlite.c 
b/src/libtracker-data/tracker-db-interface-sqlite.c
index 84216e2b3..bf005cbcc 100644
--- a/src/libtracker-data/tracker-db-interface-sqlite.c
+++ b/src/libtracker-data/tracker-db-interface-sqlite.c
@@ -597,6 +597,69 @@ function_sparql_time_zone_substr (sqlite3_context *context,
        }
 }
 
+static gchar *
+offset_to_duration (gint offset)
+{
+       GString *str = g_string_new (NULL);
+       gint hours, minutes, seconds;
+
+       if (offset > 0)
+               g_string_append (str, "+PT");
+       else
+               g_string_append (str, "-PT");
+
+       offset = ABS (offset);
+       hours = offset / 3600;
+       minutes = offset % 3600 / 60;
+       seconds = offset % 60;
+
+       if (hours > 0)
+               g_string_append_printf (str, "%dH", hours);
+       if (minutes > 0)
+               g_string_append_printf (str, "%dM", minutes);
+       if (seconds > 0)
+               g_string_append_printf (str, "%dS", seconds);
+
+       return g_string_free (str, FALSE);
+}
+
+static void
+function_sparql_time_zone (sqlite3_context *context,
+                           int              argc,
+                           sqlite3_value   *argv[])
+{
+       if (argc != 1) {
+               sqlite3_result_error (context, "Invalid argument count", -1);
+               return;
+       }
+
+       if (sqlite3_value_type (argv[0]) == SQLITE_NULL) {
+               sqlite3_result_null (context);
+               return;
+       } else if (sqlite3_value_numeric_type (argv[0]) == SQLITE_INTEGER) {
+               sqlite3_result_text (context, "PT0S", -1, NULL);
+       } else if (sqlite3_value_type (argv[0]) == SQLITE_TEXT) {
+               GError *error = NULL;
+               const gchar *str;
+               gchar *duration;
+               gint offset;
+
+               str = sqlite3_value_text (argv[0]);
+               tracker_string_to_date (str, &offset, &error);
+
+               if (error) {
+                       sqlite3_result_error (context, "Invalid date", -1);
+                       g_error_free (error);
+                       return;
+               }
+
+               duration = offset_to_duration (offset);
+               sqlite3_result_text (context, g_strdup (duration), -1, g_free);
+       } else {
+               sqlite3_result_error (context, "Invalid argument type", -1);
+       }
+}
+
 static void
 function_sparql_cartesian_distance (sqlite3_context *context,
                                     int              argc,
@@ -1610,6 +1673,8 @@ initialize_functions (TrackerDBInterface *db_interface)
                  function_sparql_time_zone_duration },
                { "SparqlTimezoneString", 1, SQLITE_ANY | SQLITE_DETERMINISTIC,
                  function_sparql_time_zone_substr },
+               { "SparqlTimezone", 1, SQLITE_ANY | SQLITE_DETERMINISTIC,
+                 function_sparql_time_zone },
                /* Paths and filenames */
                { "SparqlStringFromFilename", 1, SQLITE_ANY | SQLITE_DETERMINISTIC,
                  function_sparql_string_from_filename },
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 6b976b6f3..04eb1ced1 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -5935,7 +5935,13 @@ translate_BuiltInCall (TrackerSparql  *sparql,
                        return FALSE;
                sparql->current_state.expression_type = TRACKER_PROPERTY_TYPE_DOUBLE;
        } else if (_accept (sparql, RULE_TYPE_LITERAL, LITERAL_TIMEZONE)) {
-               _unimplemented ("TIMEZONE");
+               sparql->current_state.convert_to_string = TRUE;
+               _expect (sparql, RULE_TYPE_LITERAL, LITERAL_OPEN_PARENS);
+               _append_string (sparql, "SparqlTimezone (");
+               _call_rule (sparql, NAMED_RULE_Expression, error);
+               _expect (sparql, RULE_TYPE_LITERAL, LITERAL_CLOSE_PARENS);
+               _append_string (sparql, ") ");
+               sparql->current_state.expression_type = TRACKER_PROPERTY_TYPE_STRING;
        } else if (_accept (sparql, RULE_TYPE_LITERAL, LITERAL_TZ)) {
                sparql->current_state.convert_to_string = TRUE;
                _expect (sparql, RULE_TYPE_LITERAL, LITERAL_OPEN_PARENS);