//
   //  ========================================================================
   //  Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.jspc.plugin;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.FileFilter;
  import java.io.FileReader;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.jasper.JspC;
  import org.apache.jasper.servlet.JspCServletContext;
  import org.apache.jasper.servlet.TldScanner;
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.plugin.AbstractMojo;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.MojoFailureException;
  import org.apache.maven.project.MavenProject;
  import org.apache.tomcat.JarScanner;
  import org.apache.tomcat.util.scan.StandardJarScanner;
  import org.codehaus.plexus.util.FileUtils;
  import org.codehaus.plexus.util.StringUtils;
  import org.eclipse.jetty.util.IO;
  import org.eclipse.jetty.util.resource.Resource;
  
  /**
   * This goal will compile jsps for a webapp so that they can be included in a
   * war.
   * <p>
   * At runtime, the plugin will use the jspc compiler to precompile jsps and tags.
   * </p>
   * <p>
   * Note that the same java compiler will be used as for on-the-fly compiled
   * jsps, which will be the Eclipse java compiler.
   * <p>
   * See <a
   * href="https://www.eclipse.org/jetty/documentation/current/jetty-jspc-maven-plugin.html">Usage
   * Guide</a> for instructions on using this plugin.
   * </p>
   * @goal jspc
   * @phase process-classes
   * @requiresDependencyResolution compile+runtime
   * @description Runs jspc compiler to produce .java and .class files
   */
  public class JspcMojo extends AbstractMojo
  {
      public static final String END_OF_WEBAPP = "</web-app>";
      public static final String PRECOMPILED_FLAG = "org.eclipse.jetty.jsp.precompiled";
  
  
      /**
       * JettyJspC
       *
       * Add some extra setters to standard JspC class to help configure it
       * for running in maven.
       * 
       * TODO move all setters on the plugin onto this jspc class instead.
       */
      public static class JettyJspC extends JspC
      {
     
          private boolean scanAll;
          
          public void setClassLoader (ClassLoader loader)
          {
              this.loader = loader;
          }
          
         public void setScanAllDirectories (boolean scanAll)
         {
             this.scanAll = scanAll;
         }
        
        public boolean getScanAllDirectories ()
        {
            return this.scanAll;
        }
        
 
         @Override
         protected TldScanner newTldScanner(JspCServletContext context, boolean namespaceAware, boolean validate, boolean blockExternal)
         {            
             if (context != null && context.getAttribute(JarScanner.class.getName()) == null) 
             {
                 StandardJarScanner jarScanner = new StandardJarScanner();             
                 jarScanner.setScanAllDirectories(getScanAllDirectories());
                 context.setAttribute(JarScanner.class.getName(), jarScanner);
             }
                 
             return super.newTldScanner(context, namespaceAware, validate, blockExternal);
         }      
     }
     
     
     /**
      * Whether or not to include dependencies on the plugin's classpath with &lt;scope&gt;provided&lt;/scope&gt;
      * Use WITH CAUTION as you may wind up with duplicate jars/classes.
      * 
      * @since jetty-7.6.3
      * @parameter  default-value="false"
      */
     private boolean useProvidedScope;
     
     /**
      * The artifacts for the project.
      * 
      * @since jetty-7.6.3
      * @parameter default-value="${project.artifacts}"
      * @readonly
      */
     private Set projectArtifacts;
     
     
     /**
      * The maven project.
      * 
      * @parameter default-value="${project}"
      * @required
      * @readonly
      */
     private MavenProject project;
 
     
 
     /**
      * The artifacts for the plugin itself.
      * 
      * @parameter default-value="${plugin.artifacts}"
      * @readonly
      */
     private List pluginArtifacts;
     
     
     /**
      * File into which to generate the &lt;servlet&gt; and
      * &lt;servlet-mapping&gt; tags for the compiled jsps
      * 
      * @parameter default-value="${basedir}/target/webfrag.xml"
      */
     private String webXmlFragment;
 
     /**
      * Optional. A marker string in the src web.xml file which indicates where
      * to merge in the generated web.xml fragment. Note that the marker string
      * will NOT be preserved during the insertion. Can be left blank, in which
      * case the generated fragment is inserted just before the &lt;/web-app&gt;
      * line
      * 
      * @parameter
      */
     private String insertionMarker;
 
     /**
      * Merge the generated fragment file with the web.xml from
      * webAppSourceDirectory. The merged file will go into the same directory as
      * the webXmlFragment.
      * 
      * @parameter default-value="true"
      */
     private boolean mergeFragment;
 
     /**
      * The destination directory into which to put the compiled jsps.
      * 
      * @parameter default-value="${project.build.outputDirectory}"
      */
     private String generatedClasses;
 
     /**
      * Controls whether or not .java files generated during compilation will be
      * preserved.
      * 
      * @parameter default-value="false"
      */
     private boolean keepSources;
 
 
     /**
      * Root directory for all html/jsp etc files
      * 
      * @parameter default-value="${basedir}/src/main/webapp"
      * 
      */
     private String webAppSourceDirectory;
     
    
     
     /**
      * Location of web.xml. Defaults to src/main/webapp/web.xml.
      * @parameter default-value="${basedir}/src/main/webapp/WEB-INF/web.xml"
      */
     private String webXml;
 
 
     /**
      * The comma separated list of patterns for file extensions to be processed. By default
      * will include all .jsp and .jspx files.
      * 
      * @parameter default-value="**\/*.jsp, **\/*.jspx"
      */
     private String includes;
 
     /**
      * The comma separated list of file name patters to exclude from compilation.
      * 
      * @parameter default_value="**\/.svn\/**";
      */
     private String excludes;
 
     /**
      * The location of the compiled classes for the webapp
      * 
      * @parameter default-value="${project.build.outputDirectory}"
      */
     private File classesDirectory;
 
     
     /**
      * Patterns of jars on the system path that contain tlds. Use | to separate each pattern.
      * 
      * @parameter default-value=".*taglibs[^/]*\.jar|.*jstl[^/]*\.jar$
      */
     private String tldJarNamePatterns;
     
     
     /**
      * 
      * The JspC instance being used to compile the jsps.
      * 
      * @parameter
      */
     private JettyJspC jspc;
 
 
     /**
      * Whether dirs on the classpath should be scanned as well as jars.
      * True by default. This allows for scanning for tlds of dependent projects that
      * are in the reactor as unassembled jars.
      * 
      * @parameter default-value=true
      */
     private boolean scanAllDirectories;
     
 
     public void execute() throws MojoExecutionException, MojoFailureException
     {
         if (getLog().isDebugEnabled())
         {
 
             getLog().info("webAppSourceDirectory=" + webAppSourceDirectory);
             getLog().info("generatedClasses=" + generatedClasses);
             getLog().info("webXmlFragment=" + webXmlFragment);
             getLog().info("webXml="+webXml);
             getLog().info("insertionMarker="+ (insertionMarker == null || insertionMarker.equals("") ? END_OF_WEBAPP : insertionMarker));
             getLog().info("keepSources=" + keepSources);
             getLog().info("mergeFragment=" + mergeFragment);            
         }
         try
         {
             prepare();
             compile();
             cleanupSrcs();
             mergeWebXml();
         }
         catch (Exception e)
         {
             throw new MojoExecutionException("Failure processing jsps", e);
         }
     }
 
     public void compile() throws Exception
     {
         ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();
 
         //set up the classpath of the webapp
         List<URL> webAppUrls = setUpWebAppClassPath();
         
         //set up the classpath of the container (ie jetty and jsp jars)
         Set<URL> pluginJars = getPluginJars();
         Set<URL> providedJars = getProvidedScopeJars(pluginJars);
  
 
         //Make a classloader so provided jars will be on the classpath
         List<URL> sysUrls = new ArrayList<URL>();      
         sysUrls.addAll(providedJars);     
         URLClassLoader sysClassLoader = new URLClassLoader((URL[])sysUrls.toArray(new URL[0]), currentClassLoader);
       
         //make a classloader with the webapp classpath
         URLClassLoader webAppClassLoader = new URLClassLoader((URL[]) webAppUrls.toArray(new URL[0]), sysClassLoader);
         StringBuffer webAppClassPath = new StringBuffer();
 
         for (int i = 0; i < webAppUrls.size(); i++)
         {
             if (getLog().isDebugEnabled())
                 getLog().debug("webappclassloader contains: " + webAppUrls.get(i));                
             webAppClassPath.append(new File(webAppUrls.get(i).toURI()).getCanonicalPath());
             if (getLog().isDebugEnabled())
                 getLog().debug("added to classpath: " + ((URL) webAppUrls.get(i)).getFile());
             if (i+1<webAppUrls.size())
                 webAppClassPath.append(System.getProperty("path.separator"));
         }
         
         //Interpose a fake classloader as the webapp class loader. This is because the Apache JspC class
         //uses a TldScanner which ignores jars outside of the WEB-INF/lib path on the webapp classloader.
         //It will, however, look at all jars on the parents of the webapp classloader.
         URLClassLoader fakeWebAppClassLoader = new URLClassLoader(new URL[0], webAppClassLoader);
         Thread.currentThread().setContextClassLoader(fakeWebAppClassLoader);
   
         if (jspc == null)
             jspc = new JettyJspC();
         
 
         jspc.setWebXmlFragment(webXmlFragment);
         jspc.setUriroot(webAppSourceDirectory);     
         jspc.setOutputDir(generatedClasses);
         jspc.setClassLoader(fakeWebAppClassLoader);
         jspc.setScanAllDirectories(scanAllDirectories);
         jspc.setCompile(true);
 
         // JspC#setExtensions() does not exist, so 
         // always set concrete list of files that will be processed.
         String jspFiles = getJspFiles(webAppSourceDirectory);
        
         try
         {
             if (jspFiles == null | jspFiles.equals(""))
             {
                 getLog().info("No files selected to precompile");
             }
             else
             {
                 getLog().info("Compiling "+jspFiles+" from includes="+includes+" excludes="+excludes);
                 jspc.setJspFiles(jspFiles);
                 jspc.execute();
             }
         }
         finally
         {
 
             Thread.currentThread().setContextClassLoader(currentClassLoader);
         }
     }
 
     private String getJspFiles(String webAppSourceDirectory)
     throws Exception
     {
         List fileNames =  FileUtils.getFileNames(new File(webAppSourceDirectory),includes, excludes, false);
         return StringUtils.join(fileNames.toArray(new String[0]), ",");
 
     }
 
     /**
      * Until Jasper supports the option to generate the srcs in a different dir
      * than the classes, this is the best we can do.
      * 
      * @throws Exception if unable to clean srcs
      */
     public void cleanupSrcs() throws Exception
     {
         // delete the .java files - depending on keepGenerated setting
         if (!keepSources)
         {
             File generatedClassesDir = new File(generatedClasses);
 
             if(generatedClassesDir.exists() && generatedClassesDir.isDirectory())
             {
                 delete(generatedClassesDir, new FileFilter()
                 {
                     public boolean accept(File f)
                     {
                         return f.isDirectory() || f.getName().endsWith(".java");
                     }                
                 });
             }
         }
     }
     
     static void delete(File dir, FileFilter filter)
     {
         File[] files = dir.listFiles(filter);
         if (files != null)
         {
             for(File f: files)
             {
                 if(f.isDirectory())
                     delete(f, filter);
                 else
                     f.delete();
             }
         }
     }
 
     /**
      * Take the web fragment and put it inside a copy of the web.xml.
      * 
      * You can specify the insertion point by specifying the string in the
      * insertionMarker configuration entry.
      * 
      * If you dont specify the insertionMarker, then the fragment will be
      * inserted at the end of the file just before the &lt;/webapp&gt;
      * 
      * @throws Exception if unable to merge the web xml
      */
     public void mergeWebXml() throws Exception
     {
         if (mergeFragment)
         {
             // open the src web.xml
             File webXml = getWebXmlFile();
            
             if (!webXml.exists())
             {
                 getLog().info(webXml.toString() + " does not exist, cannot merge with generated fragment");
                 return;
             }
 
             File fragmentWebXml = new File(webXmlFragment);         
             File mergedWebXml = new File(fragmentWebXml.getParentFile(), "web.xml");
 
             try (BufferedReader webXmlReader = new BufferedReader(new FileReader(webXml));
                  PrintWriter mergedWebXmlWriter = new PrintWriter(new FileWriter(mergedWebXml))) 
             {
 
                 if (!fragmentWebXml.exists())
                 {
                     getLog().info("No fragment web.xml file generated");
                     //just copy existing web.xml to expected position
                     IO.copy(webXmlReader, mergedWebXmlWriter);
                 }
                 else
                 {
                     // read up to the insertion marker or the </webapp> if there is no
                     // marker
                     boolean atInsertPoint = false;
                     boolean atEOF = false;
                     String marker = (insertionMarker == null
                             || insertionMarker.equals("") ? END_OF_WEBAPP : insertionMarker);
                     while (!atInsertPoint && !atEOF)
                     {
                         String line = webXmlReader.readLine();
                         if (line == null)
                             atEOF = true;
                         else if (line.indexOf(marker) >= 0)
                         {
                             atInsertPoint = true;
                         }
                         else
                         {
                             mergedWebXmlWriter.println(line);
                         }
                     }
 
                     if (atEOF && !atInsertPoint)
                         throw new IllegalStateException("web.xml does not contain insertionMarker "+insertionMarker);
 
                     //put in a context init-param to flag that the contents have been precompiled
                     mergedWebXmlWriter.println("<context-param><param-name>"+PRECOMPILED_FLAG+"</param-name><param-value>true</param-value></context-param>");
 
 
                     // put in the generated fragment
                     try (BufferedReader fragmentWebXmlReader = 
                             new BufferedReader(new FileReader(fragmentWebXml))) 
                     {
                         IO.copy(fragmentWebXmlReader, mergedWebXmlWriter);
 
                         // if we inserted just before the </web-app>, put it back in
                         if (marker.equals(END_OF_WEBAPP))
                             mergedWebXmlWriter.println(END_OF_WEBAPP);
 
                         // copy in the rest of the original web.xml file
                         IO.copy(webXmlReader, mergedWebXmlWriter);
                     }
                 }
             }
         }
     }
 
     private void prepare() throws Exception
     {
         // For some reason JspC doesn't like it if the dir doesn't
         // already exist and refuses to create the web.xml fragment
         File generatedSourceDirectoryFile = new File(generatedClasses);
         if (!generatedSourceDirectoryFile.exists())
             generatedSourceDirectoryFile.mkdirs();
     }
 
     /**
      * Set up the execution classpath for Jasper.
      * 
      * Put everything in the classesDirectory and all of the dependencies on the
      * classpath.
      * 
      * @returns a list of the urls of the dependencies
      * @throws Exception
      */
     private List<URL> setUpWebAppClassPath() throws Exception
     {
         //add any classes from the webapp
         List<URL> urls = new ArrayList<URL>();
         String classesDir = classesDirectory.getCanonicalPath();
         classesDir = classesDir + (classesDir.endsWith(File.pathSeparator) ? "" : File.separator);
         urls.add(Resource.toURL(new File(classesDir)));
 
         if (getLog().isDebugEnabled())
             getLog().debug("Adding to classpath classes dir: " + classesDir);
 
         //add the dependencies of the webapp (which will form WEB-INF/lib)
         for (Iterator<Artifact> iter = project.getArtifacts().iterator(); iter.hasNext();)
         {
             Artifact artifact = (Artifact)iter.next();
 
             // Include runtime and compile time libraries
             if (!Artifact.SCOPE_TEST.equals(artifact.getScope()) && !Artifact.SCOPE_PROVIDED.equals(artifact.getScope()))
             {
                 String filePath = artifact.getFile().getCanonicalPath();
                 if (getLog().isDebugEnabled())
                     getLog().debug("Adding to classpath dependency file: " + filePath);
 
                 urls.add(Resource.toURL(artifact.getFile()));
             }
         }
         return urls;
     }
     
     
     
     /**
      * @return
      * @throws MalformedURLException
      */
     private Set<URL> getPluginJars () throws MalformedURLException
     {
         HashSet<URL> pluginJars = new HashSet<>();
         for (Iterator<Artifact> iter = pluginArtifacts.iterator(); iter.hasNext(); )
         {
             Artifact pluginArtifact = iter.next();
             if ("jar".equalsIgnoreCase(pluginArtifact.getType()))
             {
                 if (getLog().isDebugEnabled()) { getLog().debug("Adding plugin artifact "+pluginArtifact);}
                 pluginJars.add(pluginArtifact.getFile().toURI().toURL());
             }
         }
         
         return pluginJars;
     }
     
     
     
     /**
      * @param pluginJars
      * @return
      * @throws MalformedURLException
      */
     private Set<URL>  getProvidedScopeJars (Set<URL> pluginJars) throws MalformedURLException
     {
         if (!useProvidedScope)
             return Collections.emptySet();
         
         HashSet<URL> providedJars = new HashSet<>();
         
         for ( Iterator<Artifact> iter = projectArtifacts.iterator(); iter.hasNext(); )
         {                   
             Artifact artifact = iter.next();
             if (Artifact.SCOPE_PROVIDED.equals(artifact.getScope()))
             {
                 //test to see if the provided artifact was amongst the plugin artifacts
                 URL jar = artifact.getFile().toURI().toURL();
                 if (!pluginJars.contains(jar))
                 {
                     providedJars.add(jar);
                     if (getLog().isDebugEnabled()) { getLog().debug("Adding provided artifact: "+artifact);}
                 }  
                 else
                 {
                     if (getLog().isDebugEnabled()) { getLog().debug("Skipping provided artifact: "+artifact);}
                 }
             }
         }
         return providedJars;
     }
 
     
     
     private File getWebXmlFile ()
     throws IOException
     {
         File file = null;
         File baseDir = project.getBasedir().getCanonicalFile();
         File defaultWebAppSrcDir = new File (baseDir, "src/main/webapp").getCanonicalFile();
         File webAppSrcDir = new File (webAppSourceDirectory).getCanonicalFile();
         File defaultWebXml = new File (defaultWebAppSrcDir, "web.xml").getCanonicalFile();
         
         //If the web.xml has been changed from the default, try that
         File webXmlFile = new File (webXml).getCanonicalFile();
         if (webXmlFile.compareTo(defaultWebXml) != 0)
         {
             file = new File (webXml);
             return file;
         }
         
         //If the web app src directory has not been changed from the default, use whatever
         //is set for the web.xml location
         file = new File (webAppSrcDir, "web.xml");
         return file;
     }
 }