flatten-bom

A new mojo that helps you to maintain (and synchronize) with
published (but bloated) BOMs.

mvn toolbox:flatten-bom -Dbom=g:a:v

And outputs flat BOM.

Optionally, you can specify -Dgav=g:a:v and output a BOM POM
with provided coordinates.

Author: cstamas

shared/src/main/java/eu/maveniverse/maven/toolbox/shared/ToolboxCommando.java

@@ -337,6 +337,11 @@ Result<List<List<Artifact>>> treeFind(
      */
     Result<Model> effectiveModel(ReactorLocator reactorLocator) throws Exception;
 
+    /**
+     * Returns the effective model flattened BOM. Works only for "loaded" BOMs naturally, so it has to be installed or deployed..
+     */
+    Result<Model> flattenBOM(Artifact artifact, ResolutionRoot resolutionRoot) throws Exception;
+
     // Search API related commands: they target one single RemoteRepository
 
     /**

shared/src/main/java/eu/maveniverse/maven/toolbox/shared/internal/ToolboxCommandoImpl.java

@@ -43,6 +43,7 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -68,7 +69,9 @@
 import java.util.function.BiFunction;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
+import org.apache.maven.model.DependencyManagement;
 import org.apache.maven.model.Model;
+import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
 import org.apache.maven.model.io.xpp3.MavenXpp3Writer;
 import org.apache.maven.search.api.MAVEN;
 import org.apache.maven.search.api.SearchBackend;
@@ -963,31 +966,60 @@ public Result<CollectResult> projectDependencyTree(ReactorLocator reactorLocator
         return Result.success(collectResult);
     }
 
-    @Override
-    public Result<Model> effectiveModel(ResolutionRoot resolutionRoot) throws Exception {
+    protected void tellModel(String title, Model model) throws IOException {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        MavenXpp3Writer mavenXpp3Writer = new MavenXpp3Writer();
+        mavenXpp3Writer.write(baos, model);
+        output.doTell(
+                title != null && !title.trim().isEmpty() ? title + "\n{}" : "{}",
+                baos.toString(StandardCharsets.UTF_8));
+    }
+
+    protected Result<Model> doEffectiveModel(boolean tell, ResolutionRoot resolutionRoot) throws Exception {
         if (!resolutionRoot.isLoad()) {
             throw new IllegalArgumentException("only loaded roots can be shown as effective model");
         }
         ModelResponse response = toolboxResolver.readModel(resolutionRoot.getArtifact());
-
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        MavenXpp3Writer mavenXpp3Writer = new MavenXpp3Writer();
-        mavenXpp3Writer.write(baos, response.getEffectiveModel());
-        output.doTell("Effective model:\n{}", baos.toString(StandardCharsets.UTF_8));
-
+        if (tell) {
+            tellModel("Effective model:", response.getEffectiveModel());
+        }
         return Result.success(response.getEffectiveModel());
     }
 
+    @Override
+    public Result<Model> effectiveModel(ResolutionRoot resolutionRoot) throws Exception {
+        return doEffectiveModel(true, resolutionRoot);
+    }
+
     @Override
     public Result<Model> effectiveModel(ReactorLocator reactorLocator) throws Exception {
         requireNonNull(reactorLocator);
         Result<Model> result = Result.success(reactorLocator.getCurrentProject().effectiveModel());
+        tellModel("Effective model:", result.getData().orElseThrow());
+        return result;
+    }
 
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        MavenXpp3Writer mavenXpp3Writer = new MavenXpp3Writer();
-        mavenXpp3Writer.write(baos, result.getData().orElseThrow());
-        output.doTell("Effective model:\n{}", baos.toString(StandardCharsets.UTF_8));
-
+    @Override
+    public Result<Model> flattenBOM(Artifact artifact, ResolutionRoot resolutionRoot) throws Exception {
+        requireNonNull(artifact);
+        requireNonNull(resolutionRoot);
+        Result<Model> result = doEffectiveModel(false, resolutionRoot);
+        if (result.isSuccess()) {
+            Model resultModel = new MavenXpp3Reader()
+                    .read(new StringReader(PomSuppliers.empty400(
+                            artifact.getGroupId(), artifact.getArtifactId(), artifact.getVersion())));
+            resultModel.setDependencyManagement(new DependencyManagement());
+
+            Model bomModel = result.getData().orElseThrow();
+            if (bomModel.getDependencyManagement() != null) {
+                for (org.apache.maven.model.Dependency dependency :
+                        bomModel.getDependencyManagement().getDependencies()) {
+                    resultModel.getDependencyManagement().addDependency(dependency);
+                }
+            }
+            tellModel("Flattened BOM:", resultModel);
+            return Result.success(resultModel);
+        }
         return result;
     }
 

toolbox/src/main/java/eu/maveniverse/maven/toolbox/plugin/gav/GavFlattenBomMojo.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2023-2024 Maveniverse Org.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+package eu.maveniverse.maven.toolbox.plugin.gav;
+
+import eu.maveniverse.maven.toolbox.plugin.GavMojoSupport;
+import eu.maveniverse.maven.toolbox.shared.Result;
+import eu.maveniverse.maven.toolbox.shared.ToolboxCommando;
+import org.apache.maven.model.Model;
+import org.apache.maven.plugins.annotations.Mojo;
+import org.apache.maven.plugins.annotations.Parameter;
+import org.eclipse.aether.artifact.DefaultArtifact;
+import picocli.CommandLine;
+
+/**
+ * Flattens a BOM.
+ */
+@CommandLine.Command(name = "flatten-bom", description = "Flattens a BOM")
+@Mojo(name = "gav-flatten-bom", requiresProject = false, threadSafe = true)
+public class GavFlattenBomMojo extends GavMojoSupport {
+    /**
+     * The GAV to emit flattened BOM with.
+     */
+    @CommandLine.Parameters(
+            index = "0",
+            defaultValue = "org.acme:acme:1.0",
+            description = "The GAV to emit flattened BOM with")
+    @Parameter(property = "gav", defaultValue = "org.acme:acme:1.0")
+    private String gav;
+
+    /**
+     * The GAV of BOM to flatten.
+     */
+    @CommandLine.Parameters(index = "0", description = "The GAV of BOM to flatten")
+    @Parameter(property = "bom", required = true)
+    private String bom;
+
+    @Override
+    protected Result<Model> doExecute() throws Exception {
+        ToolboxCommando toolboxCommando = getToolboxCommando();
+        return toolboxCommando.flattenBOM(new DefaultArtifact(gav), toolboxCommando.loadGav(bom));
+    }
+}