package com.aurea.maven.plugins.util;

 import java.io.BufferedWriter;

 import java.io.File;

 import java.io.FileInputStream;

 import java.io.FileWriter;

 import java.io.IOException;

 import java.util.Properties;

 import org.apache.maven.project.MavenProject;

 import org.apache.velocity.Template;

 import org.apache.velocity.VelocityContext;

 import org.apache.velocity.app.Velocity;

 public class VelocityRunner {

   private static VelocityRunner instance = null; 

   private VelocityContext context = null;

   private MavenProject project = null;

   private File outputDirectory = null;

   private VelocityRunner(MavenProject project) {

     try {

       Velocity.init();

       context = new VelocityContext();

       this.project = project;

       Velocity.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, project.getBasedir());

     } catch (Exception e) {

       // do nothing 

     }

   }

   public static VelocityRunner getInstance(MavenProject project) {

     if (instance == null) {

       instance = new VelocityRunner(project);

     }

     return instance;

   }

   public static VelocityRunner getInstance() throws Exception {

     if (instance == null) 

       throw new Exception("VelocityRunner not initialized.");

     return instance;

   }

   public void setOutputDirectory(String outputDirName) {

     outputDirectory = new File(project.getBuild().getDirectory(), outputDirName);

   }

   public void addProperties(String prefix, String propFileName) {

     Properties props = new Properties();

     if (propFileName != null) {

       File propFile = new File(project.getBasedir() + "/" + propFileName);

       if (propFile.exists() && propFile.canRead()) {

         try {

           props.load(new FileInputStream(propFile));

         } catch (Exception e) {

           // do nothing 

         }

       }

     }

     addProperty(prefix, props);

   }

   public void addProperty(String key, Object value) {

     context.put(key, value);

   }

   public void run(String tplFile, String outFileName) throws Exception {

     if (!outputDirectory.exists()) {

       outputDirectory.mkdirs();

     }

     BufferedWriter out = null;

     try {

       Template template = Velocity.getTemplate(tplFile);

       File outFile = new File(outputDirectory.getAbsoluteFile(),  outFileName);

       outFile.getParentFile().mkdirs();

       out = new BufferedWriter(new FileWriter(outFile));

       template.merge(context, out);

     } catch (Exception e) {

       throw new Exception("Template generation failed ...");

     } finally {

       try {

         if (out != null) {

           out.flush();

           out.close();

         }

       } catch (IOException ioe) {

         // do nothing 

       }

     }

   }

 }