Filter obfuscation option

app/assets/javascripts/filters.js

@@ -16,6 +16,23 @@ document.addEventListener("turbolinks:load", function() {
         }
     });
 
+    // Turn obfuscated filter links into real ones
+    $('[data-filter-link]').each(function () {
+        const element = $(this)[0];
+        const a = document.createElement('a');
+        a.href = atob(element.dataset['filterLink'].replace(/-/g, '+').replace(/_/g, '/'));
+        // Copy attributes
+        for (const attr of element.attributes) {
+            if (attr.name !== 'data-filter-link') {
+                a.setAttribute(attr.name, attr.value);
+            }
+        }
+        // Move child elements
+        while (element.firstChild) {
+            a.appendChild(element.firstChild);
+        }
+        element.replaceWith(a);
+    });
 });
 
 function updateShowMore($el) {

app/assets/javascripts/show_private_groups.js

@@ -1,21 +1,25 @@
 // executed for space form
 function show_private_groups() {
-    let checkbox = document.getElementById("space_is_private")
-    let container = document.getElementById("groups_container")
+    let checkbox = document.getElementById("space_is_private");
+    let container = document.getElementById("groups_container");
+
+    if (!checkbox || !container) {
+        return;
+    }
 
     const toggleGroups = () => {
         if (checkbox && checkbox.checked) {
-            container.style.display = "block"
+            container.style.display = "block";
         } else {
-            container.style.display = "none"
+            container.style.display = "none";
         }
     }
 
     if (checkbox) {
-        checkbox.addEventListener("change", toggleGroups)
+        checkbox.addEventListener("change", toggleGroups);
     }
 
-    toggleGroups()
+    toggleGroups();
 }
 
 window.addEventListener('turbolinks:load', function() {

app/helpers/search_helper.rb

@@ -1,3 +1,5 @@
+require 'base64'
+
 # The helper for searches
 module SearchHelper
 
@@ -43,7 +45,13 @@ def filter_link(name, value, count, html_options = {}, &block)
 
       content_tag(:span, html_options, &content)
     else
-      link_to parameters, html_options, &content
+      link = url_for(parameters)
+
+      if TeSS::Config.obfuscate_filters
+        content_tag('span', html_options.merge('data-filter-link': Base64.urlsafe_encode64(link, padding: false)), &content)
+      else
+        link_to(link, html_options, &content)
+      end
     end
   end
 

config/tess.example.yml

@@ -289,6 +289,7 @@ default: &default
       primary: '#260252'
       secondary: '#5c29b1'
   filter_limit: # Maximum number of filter values allowed for anonymous users
+  obfuscate_filters: false # Whether to obfuscate filter links from initial HTML load to deter crawlers
 development:
   <<: *default
 

test/controllers/materials_controller_test.rb

@@ -1842,4 +1842,22 @@ class MaterialsControllerTest < ActionController::TestCase
       end
     end
   end
+
+  test 'filters can be obfuscated' do
+    Material.stub(:search_and_filter, MockSearch.new(Material.all)) do
+      with_settings(solr_enabled: true, obfuscate_filters: false) do
+        get :index
+
+        assert_select 'a.facet-option[href=?]', materials_path(target_audience: 'Fish')
+        assert_select 'span.facet-option', count: 0
+      end
+
+      with_settings(solr_enabled: true, obfuscate_filters: true) do
+        get :index
+
+        assert_select 'a.facet-option[href=?]', materials_path(target_audience: 'Fish'), count: 0
+        assert_select 'span.facet-option[data-filter-link]'
+      end
+    end
+  end
 end