/**

  * 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.HashMap;

 import java.util.HashSet;

 import java.util.List;

 import java.util.Map;

 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.

  *

  * @since 0.9

  * @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 class 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);

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

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

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

         class JarRes extends EmulationResources implements Bck2Brwsr.Resources {

             JarRes() {

                 super(classes);

             }

             @Override

             public InputStream get(String resource) throws IOException {

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

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

             }

         }

         JarRes jarRes = new JarRes();

         listJAR(jf, jarRes, resources, exported);

         String cp = jf.getManifest().getMainAttributes().getValue("Class-Path"); // NOI18N

         String[] classpath = cp == null ? new String[0] : cp.split(" ");

         if (c == null) {

             c = Bck2Brwsr.newCompiler();

         }

         return c

             .library(classpath)

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

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

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

             .resources(jarRes);

     }

     private static void listJAR(

         JarFile j, EmulationResources 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.addClassResource(n);

             } 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 byte[] readFrom(InputStream is) throws IOException {

         int expLen = is.available();

         if (expLen < 1) {

             expLen = 1;

         }

         byte[] arr = new byte[expLen];

         int pos = 0;

         for (;;) {

             int read = is.read(arr, pos, arr.length - pos);

             if (read == -1) {

                 break;

             }

             pos += read;

             if (pos == arr.length) {

                 byte[] tmp = new byte[arr.length * 2];

                 System.arraycopy(arr, 0, tmp, 0, arr.length);

                 arr = tmp;

             }

         }

         if (pos != arr.length) {

             byte[] tmp = new byte[pos];

             System.arraycopy(arr, 0, tmp, 0, pos);

             arr = tmp;

         }

         return arr;

     }

     static class EmulationResources implements Bck2Brwsr.Resources {

         private final List<String> classes;

         private final Map<String,byte[]> converted = new HashMap<>();

         private final BytecodeProcessor proc;

         protected EmulationResources(List<String> classes) {

             this.classes = classes;

             BytecodeProcessor p;

             try {

                 Class<?> bpClass = Class.forName("org.apidesign.bck2brwsr.aot.RetroLambda");

                 p = (BytecodeProcessor) bpClass.newInstance();

             } catch (Throwable t) {

                 p = null;

             }

             this.proc = p;

         }

         @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();

         }

         private void addClassResource(String n) throws IOException {

             if (proc != null) {

                 try (InputStream is = this.get(n)) {

                     Map<String, byte[]> conv = proc.process(n, readFrom(is), this);

                     if (conv != null) {

                         if (!conv.containsKey(n)) {

                             throw new IOException("Cannot find " + n + " among " + conv);

                         }

                         converted.putAll(conv);

                         return;

                     }

                 }

             }

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

         }

     }

 }