[locale] Support multi-level selection from JSON data

- Some providers don't provide a single flat JSON object
   (e.g. "{time_zone: foo}") but a nested structure
   (e.g. "{location: {time_zone: foo}}"), so allow dots
   in the selector to do multi-level selection.

src/modules/locale/GeoIPJSON.cpp

@@ -19,6 +19,7 @@
 
 #include "GeoIPJSON.h"
 
+#include "utils/CalamaresUtils.h"
 #include "utils/Logger.h"
 #include "utils/YamlUtils.h"
 
@@ -31,6 +32,24 @@ GeoIPJSON::GeoIPJSON(const QString& attribute)
 {
 }
 
+static QString
+selectMap( const QVariantMap& m, const QStringList& l, int index)
+{
+    if ( index >= l.count() )
+        return QString();
+
+    QString attributeName = l[index];
+    if ( index == l.count() - 1 )
+        return CalamaresUtils::getString( m, attributeName );
+    else
+    {
+        bool success = false;  // bogus
+        if ( m.contains( attributeName ) )
+            return selectMap( CalamaresUtils::getSubMap( m, attributeName, success ), l, index+1 );
+        return QString();
+    }
+}
+
 GeoIP::RegionZonePair
 GeoIPJSON::processReply( const QByteArray& data )
 {
@@ -43,12 +62,7 @@ GeoIPJSON::processReply( const QByteArray& data )
             var.isValid() &&
             var.type() == QVariant::Map )
         {
-            QVariantMap map = var.toMap();
-            if ( map.contains( m_element ) &&
-                !map.value( m_element ).toString().isEmpty() )
-            {
-                return splitTZString( map.value( m_element ).toString() );
-            }
+            return splitTZString( selectMap( var.toMap(), m_element.split('.'), 0 ) );
         }
         else
             cWarning() << "Invalid YAML data for GeoIPJSON";

src/modules/locale/locale.conf

@@ -78,4 +78,15 @@ zone:                       "New_York"
 # a different attribute name (e.g. "timezone") in JSON or a
 # different element tag (e.g. "<Time_Zone>") in XML, set this
 # string to the name or tag to be used.
+#
+# In JSON:
+#  - if the string contains "." characters, this is used as a
+#    multi-level selector, e.g. "a.b" will select the timezone
+#    from data "{a: {b: "Europe/Amsterdam" } }".
+#  - each part of the string split by "." characters is used as
+#    a key into the JSON data.
+# In XML:
+#  - all elements with the named tag (e.g. all TimeZone) elements
+#    from the document are checked; the first one with non-empty
+#    text value is used.
 #geoipSelector: ""