JSPWIKI-1317 Follow the dark colour scheme of the system when no skin was chosen

ChangeLog.md

@@ -37,6 +37,7 @@ under the License.
     * [JSPWIKI-1299](https://issues.apache.org/jira/browse/JSPWIKI-1299): `CryptoUtil`, `AbstractUserDatabase` and their tests
     * [JSPWIKI-1301](https://issues.apache.org/jira/browse/JSPWIKI-1301): session handling: `Session`, `WikiSession`, `SessionMonitor` and `DefaultAuthenticationManager`
 
+* [JSPWIKI-1317](https://issues.apache.org/jira/browse/JSPWIKI-1317): the default template follows the dark colour scheme of the system when no skin was chosen ([PR#555](https://github.com/apache/jspwiki/pull/555))
 * Fix for [JSPWIKI-1138](https://issues.apache.org/jira/browse/JSPWIKI-1138): Install.jsp echoed submitted values without escaping them; they are escaped now ([PR#323](https://github.com/apache/jspwiki/pull/323))
 * Fix for [JSPWIKI-1164](https://issues.apache.org/jira/browse/JSPWIKI-1164): a page reached from a search result showed `<` as `&lt;` when the query was highlighted ([PR#538](https://github.com/apache/jspwiki/pull/538))
 * Fix for [JSPWIKI-919](https://issues.apache.org/jira/browse/JSPWIKI-919): `VersioningFileProvider#pageExists()` ignored the first version of a page that has no history, so a page dropped into the page directory was reported as missing when the page cache is off ([PR#539](https://github.com/apache/jspwiki/pull/539))

jspwiki-main/src/main/java/org/apache/wiki/preferences/Preferences.java

@@ -36,11 +36,13 @@ Licensed to the Apache Software Foundation (ASF) under one
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Locale;
 import java.util.Map;
 import java.util.MissingResourceException;
 import java.util.Properties;
 import java.util.ResourceBundle;
+import java.util.Set;
 import java.util.TimeZone;
 
 
@@ -51,6 +53,9 @@ public class Preferences extends HashMap< String,String > {
 
     private static final long serialVersionUID = 1L;
 
+    /** The names of the preferences whose value comes from the user's cookie, and not from the defaults. */
+    private final Set< String > setByUser = new HashSet<>();
+
     /**
      * The name under which a Preferences object is stored in the HttpSession. Its value is {@value}.
      */
@@ -128,7 +133,7 @@ public static void reloadPreferences( final PageContext pageContext ) {
      * @param request
      * @param prefs The default hashmap of preferences
      */
-	private static void parseJSONPreferences( final HttpServletRequest request, final Preferences prefs ) {
+	static void parseJSONPreferences( final HttpServletRequest request, final Preferences prefs ) {
         final String prefVal = TextUtil.urlDecodeUTF8( HttpUtil.retrieveCookieValue( request, COOKIE_USER_PREFS_NAME ) );
         if( prefVal != null ) {
             // Convert prefVal JSON to a generic hashmap
@@ -139,11 +144,23 @@ private static void parseJSONPreferences( final HttpServletRequest request, fina
                 final Object value = map.get( key );
                 if( value != null ) {
                     prefs.put( key, value.toString() );
+                    prefs.setByUser.add( key );
                 }
             }
         }
     }
 
+    /**
+     *  Tells whether the user chose the value of a preference, as opposed to getting the default one.
+     *
+     *  @param name the name of the preference.
+     *  @return {@code true} if the value comes from the user's cookie.
+     *  @since 3.0.1
+     */
+    public boolean isSetByUser( final String name ) {
+        return setByUser.contains( name );
+    }
+
     /**
      *  Returns a preference value programmatically.
      *  FIXME

jspwiki-main/src/test/java/org/apache/wiki/preferences/PreferencesTest.java

@@ -0,0 +1,75 @@
+/*
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing,
+    software distributed under the License is distributed on an
+    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+    KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations
+    under the License.
+ */
+package org.apache.wiki.preferences;
+
+import jakarta.servlet.http.Cookie;
+import jakarta.servlet.http.HttpServletRequest;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
+
+
+class PreferencesTest {
+
+    private HttpServletRequest requestWithCookie( final String json ) {
+        final HttpServletRequest request = Mockito.mock( HttpServletRequest.class );
+        final Cookie cookie = new Cookie( Preferences.COOKIE_USER_PREFS_NAME, URLEncoder.encode( json, StandardCharsets.UTF_8 ) );
+        Mockito.doReturn( new Cookie[] { cookie } ).when( request ).getCookies();
+        return request;
+    }
+
+    @Test
+    void testNothingIsSetByUserWithoutCookie() {
+        final Preferences prefs = new Preferences();
+        prefs.put( "SkinName", "default" );
+
+        Preferences.parseJSONPreferences( Mockito.mock( HttpServletRequest.class ), prefs );
+
+        Assertions.assertFalse( prefs.isSetByUser( "SkinName" ) );
+        Assertions.assertEquals( "default", prefs.get( "SkinName" ) );
+    }
+
+    @Test
+    void testSkinChosenAsTheDefaultOneIsSetByUser() {
+        final Preferences prefs = new Preferences();
+        prefs.put( "SkinName", "default" );
+
+        Preferences.parseJSONPreferences( requestWithCookie( "{\"SkinName\":\"default\",\"Layout\":\"fluid\"}" ), prefs );
+
+        Assertions.assertTrue( prefs.isSetByUser( "SkinName" ) );
+        Assertions.assertTrue( prefs.isSetByUser( "Layout" ) );
+    }
+
+    @Test
+    void testPreferenceMissingFromCookieIsNotSetByUser() {
+        final Preferences prefs = new Preferences();
+        prefs.put( "SkinName", "default" );
+        prefs.put( "Layout", "fluid" );
+
+        Preferences.parseJSONPreferences( requestWithCookie( "{\"Layout\":\"fixed\"}" ), prefs );
+
+        Assertions.assertEquals( "fixed", prefs.get( "Layout" ) );
+        Assertions.assertTrue( prefs.isSetByUser( "Layout" ) );
+        Assertions.assertFalse( prefs.isSetByUser( "SkinName" ) );
+    }
+
+}

jspwiki-war/src/main/webapp/templates/default/commonheader.jsp

@@ -152,5 +152,10 @@ String.I18N.PREFIX = "javascript.";
 <script type="text/javascript"
          src="<wiki:Link format='url' templatefile='skins/' /><c:out value='${prefs.SkinName}/skin.js' />" ></script>
 </c:if>
+<%-- Without a skin of their own choosing, users whose system asks for a dark colour scheme get the dark skin --%>
+<c:if test='${(empty prefs.SkinName || prefs.SkinName=="default" || prefs.SkinName=="PlainVanilla") && !prefs.isSetByUser("SkinName") }'>
+<link rel="stylesheet" type="text/css" media="screen and (prefers-color-scheme: dark)"
+     href="<wiki:Link format='url' templatefile='skins/' />dark/skin.css" />
+</c:if>
 
 <wiki:Include page="localheader.jsp"/>