feat: OpenApi-generation from within eclipse (#509) (#1332)

* feat: OpenApi-generation from within eclipse (#509)

* Added life-cycle-mapping for recognition by M2E
* Make BuildContext injectable by M2E in oder to detect if json-source
has been modified and a regeneration is required.

* core: fix indentation problems, remove commented code

modules/openapi-generator-maven-plugin/pom.xml

@@ -15,6 +15,11 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
     <dependencies>
+        <dependency>
+            <groupId>org.sonatype.plexus</groupId>
+            <artifactId>plexus-build-api</artifactId>
+            <version>0.0.7</version>
+        </dependency>
         <dependency>
             <groupId>org.apache.maven</groupId>
             <artifactId>maven-core</artifactId>

modules/openapi-generator-maven-plugin/src/main/java/org/openapitools/codegen/plugin/CodeGenMojo.java

@@ -42,6 +42,7 @@ import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.plugins.annotations.Parameter;
+import org.apache.maven.plugins.annotations.Component;
 import org.apache.maven.project.MavenProject;
 
 import org.openapitools.codegen.CliOption;
@@ -50,6 +51,8 @@ import org.openapitools.codegen.CodegenConfig;
 import org.openapitools.codegen.CodegenConstants;
 import org.openapitools.codegen.DefaultGenerator;
 import org.openapitools.codegen.config.CodegenConfigurator;
+import org.sonatype.plexus.build.incremental.BuildContext;
+import org.sonatype.plexus.build.incremental.DefaultBuildContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -61,6 +64,13 @@ public class CodeGenMojo extends AbstractMojo {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(CodeGenMojo.class);
 
+    /**
+     * The build context is only avail when running from within eclipse.
+     * It is used to update the eclipse-m2e-layer when the plugin is executed inside the IDE.
+     */
+    @Component
+    private BuildContext buildContext = new DefaultBuildContext();
+
     @Parameter(name="validateSpec", required = false, defaultValue = "true")
     private Boolean validateSpec;
 
@@ -329,19 +339,35 @@ public class CodeGenMojo extends AbstractMojo {
     @Parameter(readonly = true, required = true, defaultValue = "${project}")
     private MavenProject project;
 
-
+    public void setBuildContext(BuildContext buildContext) {
+        this.buildContext = buildContext;
+    }
 
     @Override
     public void execute() throws MojoExecutionException {
+        File inputSpecFile = new File(inputSpec);
+        addCompileSourceRootIfConfigured();
 
+        try {
             if (skip) {
                 getLog().info("Code generation is skipped.");
-            // Even when no new sources are generated, the existing ones should
-            // still be compiled if needed.
-            addCompileSourceRootIfConfigured();
                 return;
             }
 
+            if (buildContext != null) {
+                if (buildContext.isIncremental()) {
+                    if (inputSpec != null) {
+                        if (inputSpecFile.exists()) {
+                            if (!buildContext.hasDelta(inputSpecFile)) {
+                                getLog().info(
+                                        "Code generation is skipped in delta-build because source-json was not modified.");
+                                return;
+                            }
+                        }
+                    }
+                }
+            }
+
             // attempt to read from config file
             CodegenConfigurator configurator = CodegenConfigurator.fromFile(configurationFile);
 
@@ -388,17 +414,18 @@ public class CodeGenMojo extends AbstractMojo {
                 // check if generatorName & language are set together, inform user this needs to be updated to prevent future issues.
                 if (isNotEmpty(language)) {
                     LOGGER.warn("The 'language' option is deprecated and was replaced by 'generatorName'. Both can not be set together");
-                throw new MojoExecutionException("Illegal configuration: 'language' and  'generatorName' can not be set both, remove 'language' from your configuration");
+                    throw new MojoExecutionException(
+                            "Illegal configuration: 'language' and  'generatorName' can not be set both, remove 'language' from your configuration");
                 }
             } else if (isNotEmpty(language)) {
-            LOGGER.warn("The 'language' option is deprecated and may reference language names only in the next major release (4.0). Please use 'generatorName' instead.");
+                LOGGER.warn(
+                        "The 'language' option is deprecated and may reference language names only in the next major release (4.0). Please use 'generatorName' instead.");
                 configurator.setGeneratorName(language);
             } else {
                 LOGGER.error("A generator name (generatorName) is required.");
                 throw new MojoExecutionException("The generator requires 'generatorName'. Refer to documentation for a list of options.");
             }
 
-
             configurator.setOutputDir(output.getAbsolutePath());
 
             if (isNotEmpty(auth)) {
@@ -523,7 +550,8 @@ public class CodeGenMojo extends AbstractMojo {
             }
 
             // Apply Language Specific Primitives
-        if (languageSpecificPrimitives != null && (configOptions == null || !configOptions.containsKey("language-specific-primitives"))) {
+            if (languageSpecificPrimitives != null
+                    && (configOptions == null || !configOptions.containsKey("language-specific-primitives"))) {
                 applyLanguageSpecificPrimitivesCsvList(languageSpecificPrimitives, configurator);
             }
 
@@ -573,22 +601,25 @@ public class CodeGenMojo extends AbstractMojo {
                 return;
             }
             adjustAdditionalProperties(config);
-        try {
             new DefaultGenerator().opts(input).generate();
+
+            if (buildContext != null) {
+                buildContext.refresh(new File(getCompileSourceRoot()));
+            }
         } catch (Exception e) {
             // Maven logs exceptions thrown by plugins only if invoked with -e
             // I find it annoying to jump through hoops to get basic diagnostic information,
             // so let's log it in any case:
+            if (buildContext != null) {
+                buildContext.addError(inputSpecFile, 0, 0, "unexpected error in Open-API generation", e);
+            }
             getLog().error(e);
             throw new MojoExecutionException(
                     "Code generation failed. See above for the full exception.");
         }
-
-        addCompileSourceRootIfConfigured();
     }
     
-    private void addCompileSourceRootIfConfigured() {
+    private String getCompileSourceRoot() {
-        if (addCompileSourceRoot) {
         final Object sourceFolderObject =
                 configOptions == null ? null : configOptions
                         .get(CodegenConstants.SOURCE_FOLDER);
@@ -596,7 +627,12 @@ public class CodeGenMojo extends AbstractMojo {
                 sourceFolderObject == null ? "src/main/java" : sourceFolderObject.toString();
 
         String sourceJavaFolder = output.toString() + "/" + sourceFolder;
-            project.addCompileSourceRoot(sourceJavaFolder);
+        return sourceJavaFolder;
+    }
+
+    private void addCompileSourceRootIfConfigured() {
+        if (addCompileSourceRoot) {
+            project.addCompileSourceRoot(getCompileSourceRoot());
         }
 
         // Reset all environment variables to their original value. This prevents unexpected

modules/openapi-generator-maven-plugin/src/main/resources/META-INF/m2e/lifecycle-mapping-metadata.xml

@@ -0,0 +1,17 @@
+<lifecycleMappingMetadata>
+  <pluginExecutions>
+    <pluginExecution>
+      <pluginExecutionFilter>
+        <goals>
+          <goal>generate</goal>
+        </goals>
+      </pluginExecutionFilter>
+      <action>
+        <execute>
+          <runOnIncremental>true</runOnIncremental>
+          <runOnConfiguration>true</runOnConfiguration>
+        </execute>
+      </action>
+    </pluginExecution>
+  </pluginExecutions>
+</lifecycleMappingMetadata>