Add project description diff (gh-1005)

initializr-generator/src/main/java/io/spring/initializr/generator/project/MutableProjectDescription.java

@@ -61,6 +61,33 @@ public class MutableProjectDescription implements ProjectDescription {
 
 	private String baseDirectory;
 
+	public MutableProjectDescription() {
+		super();
+	}
+
+	protected MutableProjectDescription(final MutableProjectDescription source) {
+		super();
+		setPlatformVersion(source.getPlatformVersion());
+		setBuildSystem(source.getBuildSystem());
+		setPackaging(source.getPackaging());
+		setLanguage(source.getLanguage());
+		source.getRequestedDependencies().forEach(this::addDependency);
+		setGroupId(source.getGroupId());
+		setArtifactId(source.getArtifactId());
+		setVersion(source.getVersion());
+		setName(source.getName());
+		setDescription(source.getDescription());
+		setApplicationName(source.getApplicationName());
+		setPackageName(source.getPackageName());
+		setBaseDirectory(source.getBaseDirectory());
+	}
+
+	@Override
+	public MutableProjectDescription createCopy() {
+		return new MutableProjectDescription(this);
+	}
+
+	@Override
 	public Version getPlatformVersion() {
 		return this.platformVersion;
 	}
@@ -69,6 +96,7 @@ public void setPlatformVersion(Version platformVersion) {
 		this.platformVersion = platformVersion;
 	}
 
+	@Override
 	public BuildSystem getBuildSystem() {
 		return this.buildSystem;
 	}
@@ -77,6 +105,7 @@ public void setBuildSystem(BuildSystem buildSystem) {
 		this.buildSystem = buildSystem;
 	}
 
+	@Override
 	public Packaging getPackaging() {
 		return this.packaging;
 	}
@@ -85,6 +114,7 @@ public void setPackaging(Packaging packaging) {
 		this.packaging = packaging;
 	}
 
+	@Override
 	public Language getLanguage() {
 		return this.language;
 	}
@@ -101,10 +131,12 @@ public Dependency addDependency(String id, Dependency.Builder<?> builder) {
 		return addDependency(id, builder.build());
 	}
 
+	@Override
 	public Map<String, Dependency> getRequestedDependencies() {
 		return Collections.unmodifiableMap(this.requestedDependencies);
 	}
 
+	@Override
 	public String getGroupId() {
 		return this.groupId;
 	}
@@ -113,6 +145,7 @@ public void setGroupId(String groupId) {
 		this.groupId = groupId;
 	}
 
+	@Override
 	public String getArtifactId() {
 		return this.artifactId;
 	}
@@ -121,6 +154,7 @@ public void setArtifactId(String artifactId) {
 		this.artifactId = artifactId;
 	}
 
+	@Override
 	public String getVersion() {
 		return this.version;
 	}
@@ -129,6 +163,7 @@ public void setVersion(String version) {
 		this.version = version;
 	}
 
+	@Override
 	public String getName() {
 		return this.name;
 	}
@@ -137,6 +172,7 @@ public void setName(String name) {
 		this.name = name;
 	}
 
+	@Override
 	public String getDescription() {
 		return this.description;
 	}
@@ -145,6 +181,7 @@ public void setDescription(String description) {
 		this.description = description;
 	}
 
+	@Override
 	public String getApplicationName() {
 		return this.applicationName;
 	}
@@ -153,6 +190,7 @@ public void setApplicationName(String applicationName) {
 		this.applicationName = applicationName;
 	}
 
+	@Override
 	public String getPackageName() {
 		if (StringUtils.hasText(this.packageName)) {
 			return this.packageName;
@@ -167,6 +205,7 @@ public void setPackageName(String packageName) {
 		this.packageName = packageName;
 	}
 
+	@Override
 	public String getBaseDirectory() {
 		return this.baseDirectory;
 	}

initializr-generator/src/main/java/io/spring/initializr/generator/project/ProjectDescription.java

@@ -110,4 +110,15 @@ public interface ProjectDescription {
 	 */
 	String getBaseDirectory();
 
+	/**
+	 * ProjectDescription implementations should implement this to create a copy of
+	 * themselves. However, the default implementation throws
+	 * UnsupportedOperationException.
+	 * @return never
+	 * @throws UnsupportedOperationException always
+	 */
+	default ProjectDescription createCopy() {
+		throw new UnsupportedOperationException();
+	}
+
 }

initializr-generator/src/main/java/io/spring/initializr/generator/project/ProjectGenerator.java

@@ -21,6 +21,10 @@
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
+import io.spring.initializr.generator.project.diff.DefaultProjectDescriptionDiffFactory;
+import io.spring.initializr.generator.project.diff.ProjectDescriptionDiff;
+import io.spring.initializr.generator.project.diff.ProjectDescriptionDiffFactory;
+
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.ImportSelector;
@@ -119,9 +123,20 @@ public <T> T generate(ProjectDescription description, ProjectAssetGenerator<T> p
 
 	private Supplier<ProjectDescription> resolve(ProjectDescription description, ProjectGenerationContext context) {
 		return () -> {
+
 			if (description instanceof MutableProjectDescription) {
+
+				final MutableProjectDescription mutableProjectDesc = (MutableProjectDescription) description;
+
+				// Find the diff factory and use it to create and register a diff bean
+				final ProjectDescriptionDiffFactory diffFactory = context
+						.getBeanProvider(ProjectDescriptionDiffFactory.class)
+						.getIfAvailable(() -> new DefaultProjectDescriptionDiffFactory());
+				final ProjectDescriptionDiff diff = diffFactory.create(mutableProjectDesc);
+				context.registerBean(ProjectDescriptionDiff.class, () -> diff);
+
 				context.getBeanProvider(ProjectDescriptionCustomizer.class).orderedStream()
-						.forEach((customizer) -> customizer.customize((MutableProjectDescription) description));
+						.forEach((customizer) -> customizer.customize(mutableProjectDesc));
 			}
 			return description;
 		};

initializr-generator/src/main/java/io/spring/initializr/generator/project/diff/DefaultProjectDescriptionDiffFactory.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed 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 io.spring.initializr.generator.project.diff;
+
+import io.spring.initializr.generator.project.ProjectDescription;
+
+/**
+ * A default {@link ProjectDescriptionDiffFactory} implementation that creates default
+ * {@link ProjectDescriptionDiff} instances.
+ *
+ * @author Chris Bono
+ */
+public class DefaultProjectDescriptionDiffFactory implements ProjectDescriptionDiffFactory<ProjectDescription> {
+
+	@Override
+	public ProjectDescriptionDiff create(final ProjectDescription description) {
+		return new ProjectDescriptionDiff(description);
+	}
+
+}