Make it possible to configure port names using external resources

Url could be
- regular file on file system
- any file within classpath

Resource file should be in plain text format with `new line` character as separator.
Lines starting with `#` considered commented and therefore are ignored.

Signed-off-by: Maksim Chizhov <maksim.chizhov@gmail.com>

src/it/reserve-ports-with-urls/invoker.properties

@@ -0,0 +1,2 @@
+invoker.goals = test
+invoker.buildResult = success

src/it/reserve-ports-with-urls/names1.txt

@@ -0,0 +1,4 @@
+ # Port names
+port1
+port2
+port3

src/it/reserve-ports-with-urls/names2.txt

@@ -0,0 +1,4 @@
+ # Port names
+port4
+port5
+port6

src/it/reserve-ports-with-urls/pom.xml

@@ -0,0 +1,79 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.codehaus.mojo</groupId>
+  <artifactId>build-helper-maven-plugin-reverse-port-it</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <name>build-helper-maven-plugin-reverse-port-it</name>
+
+  <build>
+    <defaultGoal>package</defaultGoal>
+    <plugins>
+      <plugin>
+        <groupId>@project.groupId@</groupId>
+        <artifactId>@project.artifactId@</artifactId>
+        <version>@project.version@</version>
+        <executions>
+          <execution>
+            <id>reserve-ports</id>
+            <phase>process-test-resources</phase>
+            <goals>
+              <goal>reserve-network-port</goal>
+            </goals>
+            <configuration>
+              <urls>
+                <url>file://${project.basedir}/names2.txt</url>
+              </urls>
+            </configuration>
+          </execution>
+          <execution>
+            <id>reserve-ports-to-files</id>
+            <phase>process-test-resources</phase>
+            <goals>
+              <goal>reserve-network-port</goal>
+            </goals>
+            <configuration>
+              <outputFile>${project.build.directory}/ports.properties</outputFile>
+              <urls>
+                <url>file://${project.basedir}/names1.txt</url>
+                <url>file://${project.basedir}/names2.txt</url>
+              </urls>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <artifactId>maven-antrun-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>mk-target-dir</id>
+            <phase>compile</phase>
+            <goals>
+              <goal>run</goal>
+            </goals>
+            <configuration>
+              <tasks>
+                <mkdir dir="${project.build.directory}" />
+              </tasks>
+            </configuration>
+          </execution>
+
+          <execution>
+            <id>echo-reserve-ports</id>
+            <phase>test</phase>
+            <goals>
+              <goal>run</goal>
+            </goals>
+            <configuration>
+              <tasks>
+                <echo>port1=${port1}</echo>
+                <echo>port2=${port2}</echo>
+                <echo>port3=${port3}</echo>
+              </tasks>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/it/reserve-ports-with-urls/verify.groovy

@@ -0,0 +1,10 @@
+File file = new File( basedir, "build.log" );
+assert file.exists();
+
+String text = file.getText("utf-8");
+
+assert text.contains("port1=")
+assert text.contains("port2=")
+assert text.contains("port3=")
+
+return true;

src/main/java/org/codehaus/mojo/buildhelper/ReserveListenerPortMojo.java

@@ -24,11 +24,17 @@
  * SOFTWARE.
  */
 
+import java.io.BufferedInputStream;
+import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.io.OutputStream;
+import java.net.MalformedURLException;
 import java.net.ServerSocket;
+import java.net.URL;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
@@ -63,12 +69,21 @@ public class ReserveListenerPortMojo
     private static final Object lock = new Object();
 
     /**
-     * A List to property names to be placed in Maven project
+     * A List to property names to be placed in Maven project. At least one of {@code #urls} or {@code #portNames} has to be specified.
      *
      * @since 1.2
      */
-    @Parameter( required = true )
-    private final String[] portNames = new String[0];
+    @Parameter
+    private String[] portNames = new String[0];
+
+    /**
+     * A List of urls to resource where list of name could be found. Can be in
+     * form of classpath:com/myproject/names.txt . At least one of {@code #urls} or {@code #portNames} has to be specified.
+     * 
+     * @since 1.11
+     */
+    @Parameter
+    private String[] urls = new String[0];
 
     /**
      * Output file to write the generated properties to. if not given, they are written to Maven project
@@ -124,6 +139,8 @@ public void execute()
             properties = new Properties();
         }
 
+        loadUrls();
+
         // Reserve the entire block of ports to guarantee we don't get the same port twice
         final List<ServerSocket> sockets = new ArrayList<ServerSocket>();
         try
@@ -231,8 +248,9 @@ private ServerSocket getServerSocket()
                 {
 
                     ServerSocket serverSocket = reservePort( port );
-                    if ( serverSocket != null )
+                    if ( serverSocket != null ) {
                         return serverSocket;
+                    }
                 }
             }
         }
@@ -241,7 +259,7 @@ private ServerSocket getServerSocket()
     private List<Integer> randomPortList()
     {
 
-        int difference = ( maxPortNumber - minPortNumber ) + 1;
+        int difference = maxPortNumber - minPortNumber + 1;
         List<Integer> portList = new ArrayList<Integer>( difference );
         List<Integer> reservedPorts = getReservedPorts();
         for ( int i = 0; i < difference; i++ )
@@ -328,4 +346,120 @@ private int findAvailablePortNumber( Integer portNumberStartingPoint, List<Integ
         }
         return candidate;
     }
+
+    private void loadUrls() throws MojoExecutionException {
+        for (String url : urls) {
+            load(new UrlResource(url));
+        }
+    }
+
+    private void load(UrlResource resource) throws MojoExecutionException {
+        if (resource.canBeOpened()) {
+            loadPortNamesFromResource(resource);
+        } else {
+            throw new MojoExecutionException("Port names could not be loaded from \"" + resource + "\"");
+        }
+    }
+
+    private void loadPortNamesFromResource(UrlResource resource) throws MojoExecutionException {
+        try {
+            if (getLog().isDebugEnabled()) {
+                getLog().debug("Loading port names from " + resource);
+            }
+            final InputStream stream = resource.getInputStream();
+
+            try {
+                BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
+                List<String> names = new ArrayList<String>();
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    line = line.trim();
+                    if (!line.isEmpty() && !line.replace(" ", "").startsWith("#")) {
+                        names.add(line);
+                    }
+                }
+                if (getLog().isDebugEnabled()) {
+                    getLog().debug("Loaded port names " + names);
+                }
+                String[] tPortNames = names.toArray(new String[portNames.length + names.size()]);
+                if (portNames.length > 0) {
+                    System.arraycopy(portNames, 0, tPortNames, names.size(), portNames.length);
+                }
+                portNames = tPortNames;
+            } finally {
+                stream.close();
+            }
+        } catch (IOException e) {
+            throw new MojoExecutionException("Error reading port names from \"" + resource + "\"", e);
+        }
+    }
+
+    private class UrlResource {
+        private static final String CLASSPATH_PREFIX = "classpath:";
+
+        private static final String SLASH_PREFIX = "/";
+
+        private final URL url;
+
+        private boolean isMissingClasspathResouce = false;
+
+        private String classpathUrl;
+
+        private InputStream stream;
+
+        public UrlResource(String url)
+                throws MojoExecutionException {
+            if (url.startsWith(CLASSPATH_PREFIX)) {
+                String resource = url.substring(CLASSPATH_PREFIX.length(), url.length());
+                if (resource.startsWith(SLASH_PREFIX)) {
+                    resource = resource.substring(1, resource.length());
+                }
+                this.url = getClass().getClassLoader().getResource(resource);
+                if (this.url == null) {
+                    if (getLog().isDebugEnabled()) {
+                        getLog().debug("Can not load classpath resouce \"" + url + "\"");
+                    }
+                    isMissingClasspathResouce = true;
+                    classpathUrl = url;
+                }
+            } else {
+                try {
+                    this.url = new URL(url);
+                } catch (MalformedURLException e) {
+                    throw new MojoExecutionException("Badly formed URL " + url + " - " + e.getMessage());
+                }
+            }
+        }
+
+        public InputStream getInputStream() throws IOException {
+            if (stream == null) {
+                stream = openStream();
+            }
+            return stream;
+        }
+
+        public boolean canBeOpened() {
+            if (isMissingClasspathResouce) {
+                return false;
+            }
+            try {
+                openStream().close();
+            } catch (IOException e) {
+                return false;
+            }
+            return true;
+        }
+
+        private InputStream openStream() throws IOException {
+            return new BufferedInputStream(url.openStream());
+        }
+
+        @Override
+        public String toString() {
+            if (!isMissingClasspathResouce) {
+                return "URL " + url.toString();
+            }
+            return classpathUrl;
+        }
+    }
 }

src/site/apt/usage.apt.vm

@@ -438,6 +438,56 @@ releasedVersion.incrementalVersion
     </plugins>
   </build>
 </project>
+-------------------
+  It is also possible to define port names via resource file(s). Resources in classpath are also supported (artifact 
+  with resource has to be defined in plugin dependencies section).
+
+  <<<portNames>>> and <<<urls>>> parameters can be combined.
+
+-------------------
+<project>
+  ...
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>build-helper-maven-plugin</artifactId>
+        <version>${project.version}</version>
+        <dependencies>
+          <dependency>
+            <artifactId>jar-with-port-names.txt</artifactId>
+            [...]
+        </dependencies>
+        <executions>
+          <execution>
+            <id>reserve-network-port</id>
+            <goals>
+              <goal>reserve-network-port</goal>
+            </goals>
+            <phase>process-resources</phase>
+            <configuration>
+              <urls>
+                <url>file://${project.basedir}/names1.txt</url>
+                <url>classpath:port-names.txt</url>
+              </urls>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+
+      [...]
+
+    </plugins>
+  </build>
+</project>
+-------------------
+  port-names.txt:
+
+-------------------
+# Selenium port name
+selenium.server.port
+# Tomcat port name
+tomcat.http.port
 -------------------
 
 * Set a property by applying a regex replacement to a value