/**

  * Back 2 Browser Bytecode Translator

  * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, version 2 of the License.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. Look for COPYING file in the top folder.

  * If not, see http://opensource.org/licenses/GPL-2.0.

  */

 package org.apidesign.bck2brwsr.aot;

 import java.io.BufferedReader;

 import java.io.File;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.net.URL;

 import java.util.ArrayList;

 import java.util.Enumeration;

 import java.util.HashSet;

 import java.util.List;

 import java.util.Set;

 import java.util.jar.JarEntry;

 import java.util.jar.JarFile;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import java.util.zip.ZipEntry;

 import org.apidesign.vm4brwsr.Bck2Brwsr;

 /** Utilities to process JAR files and set a compiler

  * up 

  *

  * @author Jaroslav Tulach

  */

 public final class Bck2BrwsrJars {

     private static final Logger LOG = Logger.getLogger(Bck2BrwsrJars.class.getName());

     private Bck2BrwsrJars() {

     }

     /** Creates new compiler pre-configured from the content of 

      * provided JAR file. The compiler will compile all classes.

      * The system understands OSGi manifest entries and will export

      * all packages that are exported in the JAR file. The system

      * also recognizes META-INF/services and makes sure the file names

      * are not mangled.

      * 

      * @param c the compiler to {@link Bck2Brwsr#addClasses(java.lang.String...) add classes},

      *    {@link Bck2Brwsr#addResources(java.lang.String...) add resources} and

      *    {@link Bck2Brwsr#addExported(java.lang.String...) exported objects} to.

      *    Can be <code>null</code> - in such case an 

      *    {@link Bck2Brwsr#newCompiler() empty compiler} is constructed.

      * @param jar the file to process

      * @return newly configured compiler

      * @throws IOException if something goes wrong

      */

     public static Bck2Brwsr configureFrom(Bck2Brwsr c, File jar) throws IOException {

         final JarFile jf = new JarFile(jar);

         List<String> classes = new ArrayList<>();

         List<String> resources = new ArrayList<>();

         Set<String> exported = new HashSet<>();

         listJAR(jf, classes, resources, exported);

         class JarRes extends EmulationResources implements Bck2Brwsr.Resources {

             @Override

             public InputStream get(String resource) throws IOException {

                 InputStream is = jf.getInputStream(new ZipEntry(resource));

                 return is == null ? super.get(resource) : is;

             }

         }

         return Bck2Brwsr.newCompiler()

             .library(true)

             .addClasses(classes.toArray(new String[classes.size()]))

             .addExported(exported.toArray(new String[exported.size()]))

             .addResources(resources.toArray(new String[resources.size()]))

             .resources(new JarRes());

     }

     private static void listJAR(

         JarFile j, List<String> classes,

         List<String> resources, Set<String> keep

     ) throws IOException {

         Enumeration<JarEntry> en = j.entries();

         while (en.hasMoreElements()) {

             JarEntry e = en.nextElement();

             final String n = e.getName();

             if (n.endsWith("/")) {

                 continue;

             }

             if (n.startsWith("META-INF/maven/")) {

                 continue;

             }

             int last = n.lastIndexOf('/');

             String pkg = n.substring(0, last + 1);

             if (pkg.startsWith("java/")) {

                 keep.add(pkg);

             }

             if (n.endsWith(".class")) {

                 classes.add(n.substring(0, n.length() - 6));

             } else {

                 resources.add(n);

                 if (n.startsWith("META-INF/services/") && keep != null) {

                     BufferedReader r = new BufferedReader(new InputStreamReader(j.getInputStream(e)));

                     for (;;) {

                         String l = r.readLine();

                         if (l == null) {

                             break;

                         }

                         if (l.startsWith("#")) {

                             continue;

                         }

                         keep.add(l.replace('.', '/'));

                     }

                 }

             }

         }

         String exp = j.getManifest().getMainAttributes().getValue("Export-Package");

         if (exp != null && keep != null) {

             for (String def : exp.split(",")) {

                 for (String sep : def.split(";")) {

                     keep.add(sep.replace('.', '/') + "/");

                     break;

                 }

             }

         }

     }

     static class EmulationResources implements Bck2Brwsr.Resources {

         @Override

         public InputStream get(String name) throws IOException {

             Enumeration<URL> en = Bck2BrwsrJars.class.getClassLoader().getResources(name);

             URL u = null;

             while (en.hasMoreElements()) {

                 u = en.nextElement();

             }

             if (u == null) {

                 LOG.log(Level.WARNING, "Cannot find {0}", name);

                 return null;

             }

             if (u.toExternalForm().contains("/rt.jar!")) {

                 LOG.log(Level.WARNING, "{0}No bootdelegation for ", name);

                 return null;

             }

             return u.openStream();

         }

     }

 }