package org.apidesign.vm4brwsr;

 import java.io.BufferedWriter;

 import java.io.FileWriter;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.Writer;

 import java.net.URL;

 import java.util.Arrays;

 import java.util.Enumeration;

 import java.util.HashSet;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Set;

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

  *

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

  */

 final class GenJS {

     private GenJS() {}

     public static void main(String... args) throws IOException {

         if (args.length < 2) {

             System.err.println("Usage: java -cp ... -jar ... <file_to_generate_js_code_to> java/lang/Class org/your/App ...");

             return;

         }

         Writer w = new BufferedWriter(new FileWriter(args[0]));

         List<String> classes = Arrays.asList(args).subList(1, args.length);

         compile(w, classes);

         w.close();

     }

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

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

     }

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

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

         LinkedList<String> toProcess = new LinkedList<String>(names);

         for (;;) {

             toProcess.removeAll(processed);

             if (toProcess.isEmpty()) {

                 break;

             }

             String name = toProcess.getFirst();

             processed.add(name);

             if (name.startsWith("java/")

                 && !name.equals("java/lang/Object")

                 && !name.equals("java/lang/Class")

                 && !name.equals("java/lang/Number")

                 && !name.equals("java/lang/Integer")

                 && !name.equals("java/lang/Throwable")

                 && !name.equals("java/lang/Exception")

                 && !name.equals("java/lang/RuntimeException")

                 && !name.equals("java/lang/UnsupportedOperationException")

                 && !name.equals("java/lang/String")

                 && !name.equals("java/lang/String$CaseInsensitiveComparator")

                 && !name.equals("java/lang/StringBuilder")

                 && !name.equals("java/lang/AbstractStringBuilder")

             ) {

                 continue;

             }            

             InputStream is = loadClass(name);

             if (is == null) {

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

             }

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

             try {

                 ByteCodeToJavaScript.compile(is, out, toProcess, scripts);

             } 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) {

                 InputStream emul = GenJS.class.getResourceAsStream(resource);

                 if (emul == null) {

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

                 }

                 readResource(emul, out);

             }

         }

     }

     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(String name) throws IOException {

         Enumeration<URL> en = ClassLoader.getSystemClassLoader().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();

     }

 }