Index: apachesolr.module
===================================================================
--- apachesolr.module	(revision 23516)
+++ apachesolr.module	(working copy)
@@ -735,6 +736,14 @@
     '#default_value' => isset($limits[$module][$delta]) ? $limits[$module][$delta] : variable_get('apachesolr_facet_query_limit_default', 20),
   );
 
+  $reflect_hierarchy = variable_get('apachesolr_facet_reflect_hierarchy', array());
+  $form['apachesolr_facet_reflect_hierarchy'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Links reflect hierarchy'),
+    '#description' => t('Facet will be sorted hierarchically if it bases on a hierarchical taxonomy vocabulary.'),
+    '#default_value' => !empty($reflect_hierarchy[$module][$delta]),
+  );
+
   return $form;
 }
 
@@ -752,6 +761,9 @@
   $initial = variable_get('apachesolr_facet_query_initial_limits', array());
   $initial[$module][$delta] = (int)$edit['apachesolr_facet_query_initial_limit'];
   variable_set('apachesolr_facet_query_initial_limits', $initial);
+  $reflect_hierarchy = variable_get('apachesolr_facet_reflect_hierarchy', array());
+  $reflect_hierarchy[$module][$delta] = $edit['apachesolr_facet_reflect_hierarchy'];
+  variable_set('apachesolr_facet_reflect_hierarchy', $reflect_hierarchy);
 }
 
 /**
@@ -969,6 +981,9 @@
     'apachesolr_facet_item' => array(
       'arguments' => array('name' => NULL, 'count' => NULL, 'path' => NULL, 'querystring' => '', 'active' => FALSE, 'unclick_link' => NULL, 'num_found' => NULL),
     ),
+    'apachesolr_facet_item_indent' => array(
+      'arguments' => array('indent' => 0),
+    ),
     'apachesolr_unclick_link' => array(
       'arguments' => array('url' => NULL, 'querystring' => ''),
     ),
@@ -984,17 +999,25 @@
   );
 }
 
-function theme_apachesolr_facet_item($name, $count, $path, $querystring = '', $active = FALSE, $unclick_link = NULL, $num_found = NULL) {
+function theme_apachesolr_facet_item($name, $count, $path, $querystring = '', $active = FALSE, $unclick_link = NULL, $num_found = NULL, $indent = 0) {
   $attributes = array();
   if ($active) {
     $attributes['class'] = 'active';
   }
+  $link = '';
   if ($unclick_link) {
-    return $unclick_link . ' '. check_plain($name);
+    $link = $unclick_link . ' '. check_plain($name);
   }
   else {
-    return apachesolr_l($name ." ($count)",  $path, array('attributes' => $attributes, 'query' => $querystring));
+    $link = apachesolr_l($name ." ($count)",  $path, array('attributes' => $attributes, 'query' => $querystring));
   }
+  return theme('apachesolr_facet_item_indent', $indent).$link;
+}
+
+function theme_apachesolr_facet_item_indent($indent = 0) {
+  if ($indent > 0) {
+    return str_repeat('  ', $indent) .' > ';
+  }
 }
 
 function apachesolr_l($text, $path, $options = array()) {
Index: apachesolr_search.module
===================================================================
--- apachesolr_search.module	(revision 23516)
+++ apachesolr_search.module	(working copy)
@@ -368,50 +368,71 @@
         $initial_limits = variable_get('apachesolr_facet_query_initial_limits', array());
         $limit_default = variable_get('apachesolr_facet_query_initial_limit_default', 10);
 
+        $reflect_hierarchy = variable_get('apachesolr_facet_reflect_hierarchy', array());
+
         // Handle taxonomy vocabulary facets
         if ((strpos($delta, 'im_vid_') === 0) && module_exists('taxonomy')) {
 
           if (is_object($response->facet_counts->facet_fields->$delta)) {
-            $contains_active = FALSE;
-            $terms = array();
+            $vid = substr($delta, 7);
+            if (is_numeric($vid)) {
+              $vocab = taxonomy_vocabulary_load($vid);
+              $terms = array();
 
-            foreach ($response->facet_counts->facet_fields->$delta as $tid => $count) {
-              $unclick_link = '';
-              unset($active);
-              $term = taxonomy_get_term($tid);
-              $new_query = clone $query;
-              if ($active = $query->has_field('tid', $tid)) {
-                $contains_active = TRUE;
-                $new_query->remove_field('tid', $term->tid);
-                $path = 'search/' . arg(1) . '/' . $new_query->get_query_basic();
-                $querystring = $new_query->get_url_querystring();
-                $unclick_link = theme('apachesolr_unclick_link', $path, $querystring);
-              }
-              else {
-                $new_query->add_field('tid', $term->tid);
-                $path = 'search/' . arg(1) . '/' . $new_query->get_query_basic();
-                $querystring = $new_query->get_url_querystring();
-              }
-              $countsort = $count == 0 ? '' : 1 / $count;
-              // if numdocs == 1 and !active, don't add.
-              if ($response->numFound == 1 && !$active) {
-                // skip
+              foreach ($response->facet_counts->facet_fields->$delta as $tid => $count) {
+                $unclick_link = '';
+                unset($active);
+
+                $parents = array();
+                if ($reflect_hierarchy['apachesolr_search'][$delta]) {
+                  $parents = taxonomy_get_parents_all($tid);
+                  if (!empty($parents[1]) && !$query->has_field('tid', $parents[1]->tid)) {
+                    continue;
+                  }
+                }
+                else {
+                  $parents[] = taxonomy_get_term($tid);
+                }
+
+                $new_query = clone $query;
+
+                $active = $query->has_field('tid', $tid);
+                if ($active) {
+                  $unclick_link = apachesolr_get_unclick_link($query, 'tid', $tid, $reflect_hierarchy['apachesolr_search'][$delta] ? $vid : FALSE);
+                }
+                else {
+                  $new_query->add_field('tid', $tid);
+                  $path = 'search/' . arg(1) . '/' . $new_query->get_query_basic();
+                  $querystring = $new_query->get_url_querystring();
+                }
+
+                // if numdocs == 1 and !active, don't add.
+                if ($response->numFound == 1 && !$active) {
+                  // skip
+                }
+                else {
+                  $sort_key = '';
+                  $term = NULL;
+                  foreach (array_reverse($parents) as $term) {
+                    $count = $response->facet_counts->facet_fields->$delta->{$term->tid};
+                    $countsort = $count == 0 ? '' : 1 / $count;
+                    $countsort = $query->has_field('tid', $term->tid) ? $countsort : 1 + $countsort;
+                    $sort_key .= $countsort.$term->name;
+                  }
+                  $terms[$term->vid][$sort_key] = theme('apachesolr_facet_item', $term->name, $count, $path, $querystring, $active, $unclick_link, $response->numFound, count($parents) - 1);
+                }
               }
-              else {
-                $terms[$term->vid][$active ? $countsort . $term->name : 1 + $countsort . $term->name] = theme('apachesolr_facet_item', $term->name, $count, $path, $querystring, $active, $unclick_link, $response->numFound);
+
+              if (is_array($terms) && isset($terms[$vid]) && is_array($terms[$vid])) {
+                ksort($terms[$vid]);
+                $limit = isset($initial_limits['apachesolr_search'][$delta]) ? $initial_limits['apachesolr_search'][$delta] : $limit_default;
+                return array(
+                  'subject' => t('Filter by @name', array('@name' => $vocab->name)),
+                  'content' => theme('apachesolr_facet_list', $terms[$vid], $limit),
+                );
               }
             }
           }
-          $vid = substr($delta, 7);
-          $vocab = taxonomy_vocabulary_load($vid);
-          if (is_numeric($vid) && is_array($terms) && isset($terms[$vid]) && is_array($terms[$vid])) {
-            ksort($terms[$vid]);
-            $limit = isset($initial_limits['apachesolr_search'][$delta]) ? $initial_limits['apachesolr_search'][$delta] : $limit_default;
-            return array(
-              'subject' => t('Filter by @name', array('@name' => $vocab->name)),
-              'content' => theme('apachesolr_facet_list', $terms[$vid], $limit),
-            );
-          }
           return;
         }
 
@@ -427,11 +448,14 @@
             $links[] = apachesolr_l($search_keys, $path, $options);
             foreach($fields as $field) {
               if ($field['#name']) {
-                $new_query = clone $query;
-                $new_query->remove_field($field['#name'], $field['#value']);
-                $path = 'search/'. arg(1) .'/'. $new_query->get_query_basic();
-                $querystring = $new_query->get_url_querystring();
-                $unclick_link = theme('apachesolr_unclick_link', $path, $querystring);
+                $vid = FALSE;
+                if (module_exists('taxonomy') && 'tid' == $field['#name']) {
+                  $term = taxonomy_get_term($field['#value']);
+                  if ($reflect_hierarchy['apachesolr_search']['im_vid_'.$term->vid]) {
+                    $vid = $term->vid;
+                  }
+                }
+                $unclick_link = apachesolr_get_unclick_link($query, $field['#name'], $field['#value'], $vid);
                 if (! $fielddisplay = theme("apachesolr_breadcrumb_". $field['#name'], $field['#value'])) {
                   $fielddisplay = $field['#value'];
                 }
@@ -476,6 +500,30 @@
   }
 }
 
+function apachesolr_get_unclick_link(&$query, $field_name, $field_value, $vid = FALSE) {
+  static $unclick_links = array();
+
+  if (empty($unclick_links[$field_name][$field_value])) {
+    $new_query = clone $query;
+
+    $new_query->remove_field($field_name, $field_value);
+
+    if ($vid && 'tid' == $field_name) {
+      $childs = taxonomy_get_tree($vid, $field_value);
+      foreach ($childs as $child) {
+        $new_query->remove_field('tid', $child->tid);
+      }
+    }
+
+    $path = 'search/' . arg(1) . '/' . $new_query->get_query_basic();
+    $querystring = $new_query->get_url_querystring();
+
+    $unclick_links[$field_name][$field_value] = theme('apachesolr_unclick_link', $path, $querystring);
+  }
+
+  return $unclick_links[$field_name][$field_value];
+}
+
 /**
  * Callback function for the 'Filter by name' facet block.
  */