/**

  * 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.vm4brwsr;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.Collections;

 import java.util.Enumeration;

 import java.util.HashMap;

 import java.util.Iterator;

 import java.util.LinkedHashSet;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Map;

 /** Generator of JavaScript from bytecode of classes on classpath of the VM.

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  */

 final class GenJS {

     private GenJS() {}

     static void compile(Appendable out, String... names) throws IOException {

         compile(out, Arrays.asList(names));

     }

     static void compile(Appendable out, List<String> names) throws IOException {

         compile(GenJS.class.getClassLoader(), out, names);

     }

     static void compile(ClassLoader l, Appendable out, List<String> names) throws IOException {

         final Map<String,String> processed = new HashMap<String, String>();

         for (String baseClass : names) {

             LinkedHashSet<String> toProcess = new LinkedHashSet<String>() {

                 @Override

                 public boolean add(String e) {

                     if (processed.containsKey(e)) {

                         return false;

                     }

                     return super.add(e);

                 }

             };

             toProcess.add(baseClass);

             for (;;) {

                 String name = null;

                 Iterator<String> it = toProcess.iterator();

                 while (it.hasNext() && name == null) {

                     String n = it.next();

                     if (processed.get(n) != null) {

                         continue;

                     }

                     name = n;

                 }

                 if (name == null) {

                     break;

                 }

                 if (name.startsWith("sun/")) {

                     processed.put(name, "");

                     continue;

                 }            

                 InputStream is = loadClass(l, name);

                 if (is == null) {

                     throw new IOException("Can't find class " + name); 

                 }

                 LinkedList<String> scripts = new LinkedList<String>();

                 try {

                     String initCode = ByteCodeToJavaScript.compile(is, out, toProcess, scripts);

                     processed.put(name, initCode == null ? "" : initCode);

                 } catch (RuntimeException ex) {

                     if (out instanceof CharSequence) {

                         CharSequence seq = (CharSequence)out;

                         int lastBlock = seq.length();

                         while (lastBlock-- > 0) {

                             if (seq.charAt(lastBlock) == '{') {

                                 break;

                             }

                         }

                         throw new IOException("Error while compiling " + name + "\n" 

                             + seq.subSequence(lastBlock + 1, seq.length()), ex

                         );

                     } else {

                         throw new IOException("Error while compiling " + name + "\n" 

                             + out, ex

                         );

                     }

                 }

                 for (String resource : scripts) {

                     while (resource.startsWith("/")) {

                         resource = resource.substring(1);

                     }

                     InputStream emul = l.getResourceAsStream(resource);

                     if (emul == null) {

                         throw new IOException("Can't find " + resource);

                     }

                     readResource(emul, out);

                 }

             }

             List<String> toInit = new ArrayList<String>(toProcess);

             Collections.reverse(toInit);

             for (String clazz : toInit) {

                 String initCode = processed.get(clazz);

                 if (initCode != null && !initCode.isEmpty()) {

                     out.append(initCode).append("\n");

                     processed.put(clazz, "");

                 }

             }

         }

     }

     private static void readResource(InputStream emul, Appendable out) throws IOException {

         try {

             int state = 0;

             for (;;) {

                 int ch = emul.read();

                 if (ch == -1) {

                     break;

                 }

                 if (ch < 0 || ch > 255) {

                     throw new IOException("Invalid char in emulation " + ch);

                 }

                 switch (state) {

                     case 0: 

                         if (ch == '/') {

                             state = 1;

                         } else {

                             out.append((char)ch);

                         }

                         break;

                     case 1:

                         if (ch == '*') {

                             state = 2;

                         } else {

                             out.append('/').append((char)ch);

                             state = 0;

                         }

                         break;

                     case 2:

                         if (ch == '*') {

                             state = 3;

                         }

                         break;

                     case 3:

                         if (ch == '/') {

                             state = 0;

                         } else {

                             state = 2;

                         }

                         break;

                 }

             }

         } finally {

             emul.close();

         }

     }

     private static InputStream loadClass(ClassLoader l, String name) throws IOException {

         Enumeration<URL> en = l.getResources(name + ".class");

         URL u = null;

         while (en.hasMoreElements()) {

             u = en.nextElement();

         }

         if (u == null) {

             throw new IOException("Can't find " + name);

         }

         return u.openStream();

     }

     static String toString(String name) throws IOException {

         StringBuilder sb = new StringBuilder();

         compile(sb, name);

         return sb.toString().toString();

     }

 }