Make SiteMesh 3 the default GSP layout

grails-forge/grails-forge-core/src/main/java/org/grails/forge/feature/sitemesh3/Sitemesh3.java

@@ -22,14 +22,20 @@
 import org.grails.forge.application.ApplicationType;
 import org.grails.forge.application.generator.GeneratorContext;
 import org.grails.forge.build.dependencies.Dependency;
-import org.grails.forge.feature.Category;
+import org.grails.forge.feature.DefaultFeature;
 import org.grails.forge.feature.Feature;
+import org.grails.forge.feature.view.GspLayout;
+import org.grails.forge.options.Options;
 
-@Singleton
-public class Sitemesh3 implements Feature {
+import java.util.Set;
 
-    public Sitemesh3() {
-    }
+/**
+ * Default GSP layout decorator, backed by SiteMesh 3 ({@code grails-sitemesh3}).
+ * Applied automatically to web applications unless another {@link GspLayout}
+ * (e.g. {@code grails-layout}) is explicitly selected.
+ */
+@Singleton
+public class Sitemesh3 extends GspLayout implements DefaultFeature {
 
     @Override
     public String getName() {
@@ -38,12 +44,18 @@ public String getName() {
 
     @Override
     public String getTitle() {
-        return "Sitemesh 3";
+        return "SiteMesh 3";
     }
 
     @Override
     public String getDescription() {
-        return "Adds support for Sitemesh3 based layouts instead of Sitemesh 2";
+        return "Adds support for SiteMesh 3 based GSP layouts";
+    }
+
+    @Override
+    public boolean shouldApply(ApplicationType applicationType, Options options, Set<Feature> selectedFeatures) {
+        return supports(applicationType) &&
+                selectedFeatures.stream().noneMatch(GspLayout.class::isInstance);
     }
 
     @Override
@@ -53,14 +65,4 @@ public void apply(GeneratorContext generatorContext) {
                 .artifactId("grails-sitemesh3")
                 .implementation());
     }
-
-    @Override
-    public boolean supports(ApplicationType applicationType) {
-        return true;
-    }
-
-    @Override
-    public String getCategory() {
-        return Category.VIEW;
-    }
 }

grails-forge/grails-forge-core/src/main/java/org/grails/forge/feature/view/GrailsLayout.java

@@ -0,0 +1,55 @@
+/*
+ *  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
+ *
+ *    https://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.grails.forge.feature.view;
+
+import jakarta.inject.Singleton;
+import org.grails.forge.application.generator.GeneratorContext;
+import org.grails.forge.build.dependencies.Dependency;
+
+/**
+ * Opt-in GSP layout decorator backed by the legacy SiteMesh 2 based
+ * {@code grails-layout} plugin. Mutually exclusive with {@code sitemesh3};
+ * selecting this feature replaces the default SiteMesh 3 decorator.
+ */
+@Singleton
+public class GrailsLayout extends GspLayout {
+
+    @Override
+    public String getName() {
+        return "grails-layout";
+    }
+
+    @Override
+    public String getTitle() {
+        return "GSP SiteMesh 2 Layouts";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Adds support for legacy SiteMesh 2 based GSP layouts (grails-layout) instead of SiteMesh 3";
+    }
+
+    @Override
+    public void apply(GeneratorContext generatorContext) {
+        generatorContext.addDependency(Dependency.builder()
+                .groupId("org.apache.grails")
+                .artifactId("grails-layout")
+                .implementation());
+    }
+}

grails-forge/grails-forge-core/src/main/java/org/grails/forge/feature/view/GspLayout.java

@@ -0,0 +1,47 @@
+/*
+ *  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
+ *
+ *    https://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.grails.forge.feature.view;
+
+import org.grails.forge.application.ApplicationType;
+import org.grails.forge.feature.Category;
+import org.grails.forge.feature.OneOfFeature;
+
+/**
+ * Common parent for the mutually exclusive GSP layout decorators: SiteMesh 3
+ * ({@code grails-sitemesh3}) and the legacy SiteMesh 2 based {@code grails-layout}.
+ * Because they share the same {@link #getFeatureClass()}, only one of them may be
+ * selected for a given application (enforced by the one-of feature validator).
+ */
+public abstract class GspLayout implements OneOfFeature {
+
+    @Override
+    public Class<?> getFeatureClass() {
+        return GspLayout.class;
+    }
+
+    @Override
+    public boolean supports(ApplicationType applicationType) {
+        return applicationType == ApplicationType.WEB || applicationType == ApplicationType.WEB_PLUGIN;
+    }
+
+    @Override
+    public String getCategory() {
+        return Category.VIEW;
+    }
+}

grails-forge/grails-forge-core/src/test/groovy/org/grails/forge/feature/view/GspLayoutSpec.groovy

@@ -0,0 +1,72 @@
+/*
+ *  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
+ *
+ *    https://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.grails.forge.feature.view
+
+import org.grails.forge.ApplicationContextSpec
+import org.grails.forge.BuildBuilder
+import org.grails.forge.application.ApplicationType
+import spock.lang.Unroll
+
+class GspLayoutSpec extends ApplicationContextSpec {
+
+    @Unroll
+    void "web #applicationType apps use SiteMesh 3 (grails-sitemesh3) by default"() {
+        when:
+        final String build = new BuildBuilder(beanContext)
+            .features(["gsp"])
+            .applicationType(applicationType)
+            .render()
+
+        then:
+        build.contains('implementation "org.apache.grails:grails-sitemesh3"')
+        !build.contains('implementation "org.apache.grails:grails-layout"')
+
+        and: "a SNAPSHOT build exposes the SiteMesh 3 snapshot repo so org.sitemesh:*-SNAPSHOT resolves"
+        build.contains("https://central.sonatype.com/repository/maven-snapshots")
+        build.contains("includeVersionByRegex('org[.]sitemesh.*'")
+
+        where:
+        applicationType << [ApplicationType.WEB, ApplicationType.WEB_PLUGIN]
+    }
+
+    void "selecting grails-layout replaces the default SiteMesh 3 decorator"() {
+        when:
+        final String build = new BuildBuilder(beanContext)
+            .features(["gsp", "grails-layout"])
+            .applicationType(ApplicationType.WEB)
+            .render()
+
+        then:
+        build.contains('implementation "org.apache.grails:grails-layout"')
+        !build.contains('implementation "org.apache.grails:grails-sitemesh3"')
+    }
+
+    void "sitemesh3 and grails-layout cannot both be selected"() {
+        when:
+        new BuildBuilder(beanContext)
+            .features(["gsp", "sitemesh3", "grails-layout"])
+            .applicationType(ApplicationType.WEB)
+            .render()
+
+        then:
+        IllegalArgumentException e = thrown()
+        e.message.contains("There can only be one of the following features selected")
+    }
+}