Add support for groovy rules provider, fixes #19

pom.xml

@@ -13,6 +13,7 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
+        <groovyVersion>3.0.0</groovyVersion>
         <jlineVersion>3.12.1</jlineVersion>
         <junitVersion>4.12</junitVersion>
         <logbackVersion>1.2.3</logbackVersion>
@@ -71,6 +72,11 @@
             <artifactId>jline-terminal-jansi</artifactId>
             <version>${jlineVersion}</version>
         </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy</artifactId>
+            <version>${groovyVersion}</version>
+        </dependency>
 
         <dependency>
             <groupId>junit</groupId>

src/main/java/org/jboss/fuse/mvnd/builder/DependencyGraph.java

@@ -37,6 +37,9 @@ static DependencyGraph<MavenProject> fromMaven(ProjectDependencyGraph graph, Str
 
         if (rules != null) {
             for (String rule : rules.split("\\s*;\\s*|\n")) {
+                if (rule.trim().isEmpty()) {
+                    continue;
+                }
                 String[] parts = rule.split("\\s*->\\s*|\\s+before\\s+");
                 if (parts.length != 2) {
                     throw new IllegalArgumentException("Invalid rule: " + rule);

src/main/java/org/jboss/fuse/mvnd/builder/SmartBuilder.java

@@ -1,19 +1,27 @@
 package org.jboss.fuse.mvnd.builder;
 
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.MalformedURLException;
+import java.net.URL;
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
 
 import javax.enterprise.inject.Default;
 import javax.inject.Inject;
 import javax.inject.Named;
 import javax.inject.Singleton;
 
-import com.google.common.base.Joiner;
+import groovy.lang.Binding;
+import groovy.lang.GroovyShell;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.lifecycle.internal.LifecycleModuleBuilder;
 import org.apache.maven.lifecycle.internal.ProjectBuildList;
@@ -37,6 +45,8 @@ public class SmartBuilder implements Builder {
     public static final String PROP_PROFILING = "smartbuilder.profiling";
     public static final String MVND_BUILDER_RULES = "mvnd.builder.rules";
     public static final String MVND_BUILDER_RULE = "mvnd.builder.rule";
+    public static final String MVND_BUILDER_RULES_PROVIDER_URL = "mvnd.builder.rules.provider.url";
+    public static final String MVND_BUILDER_RULES_PROVIDER_SCRIPT = "mvnd.builder.rules.provider.script";
 
     private final Logger logger = LoggerFactory.getLogger(getClass());
 
@@ -54,6 +64,58 @@ public void build(final MavenSession session, final ReactorContext reactorContex
                       ReactorBuildStatus reactorBuildStatus) throws ExecutionException, InterruptedException {
 
         List<String> list = new ArrayList<>();
+
+        String providerScript = null;
+        String providerUrl = session.getTopLevelProject().getProperties()
+                .getProperty(MVND_BUILDER_RULES_PROVIDER_URL);
+        if (providerUrl != null) {
+            URL url;
+            try {
+                url = new URL(providerUrl);
+            } catch (MalformedURLException e) {
+                try {
+                    url = new File(providerUrl).toURI().toURL();
+                } catch (MalformedURLException ex) {
+                    url = null;
+                }
+            }
+            if (url == null) {
+                throw new ExecutionException("Bad syntax for " + MVND_BUILDER_RULES_PROVIDER_URL, null);
+            }
+            try (BufferedReader r = new BufferedReader(new InputStreamReader(url.openStream()))) {
+                StringBuilder sb = new StringBuilder();
+                char[] buf = new char[8192];
+                int l;
+                while ((l = r.read(buf)) >= 0) {
+                    sb.append(buf, 0, l);
+                }
+                providerScript = sb.toString();
+            } catch (IOException e) {
+                throw new ExecutionException("Unable to read provider url " + MVND_BUILDER_RULES_PROVIDER_URL, e);
+            }
+        }
+        if (providerScript == null) {
+            providerScript = session.getTopLevelProject().getProperties()
+                    .getProperty(MVND_BUILDER_RULES_PROVIDER_SCRIPT);
+        }
+        if (providerScript != null) {
+            Binding binding = new Binding();
+            GroovyShell shell = new GroovyShell(binding);
+            binding.setProperty("session", session);
+            Object result = shell.evaluate(providerScript);
+            if (result instanceof Iterable) {
+                for (Object r : (Iterable) result) {
+                    list.add(r.toString());
+                }
+            } else if (result != null) {
+                list.add(result.toString());
+            } else {
+                throw new ExecutionException("The provider script did not return a valid string or string collection", null);
+            }
+            list.add(result.toString());
+        }
+
+
         String topRule = session.getTopLevelProject().getProperties()
                 .getProperty(MVND_BUILDER_RULES);
         if (topRule != null) {
@@ -75,7 +137,7 @@ public void build(final MavenSession session, final ReactorContext reactorContex
 
         // log overall build info
         final int degreeOfConcurrency = session.getRequest().getDegreeOfConcurrency();
-        logger.info("Task segments : " + Joiner.on(" ").join(taskSegments));
+        logger.info("Task segments : " + taskSegments.stream().map(Object::toString).collect(Collectors.joining(" ")));
         logger.info("Build maximum degree of concurrency is " + degreeOfConcurrency);
         logger.info("Total number of projects is " + graph.getProjects().count());