/**

  * 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.ByteArrayInputStream;

 import java.io.IOException;

 import java.net.URL;

 import java.util.zip.ZipEntry;

 import java.util.zip.ZipInputStream;

 import org.apidesign.bck2brwsr.core.JavaScriptBody;

 /** Conversion from classpath to load function.

  *

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

  */

 final class Zips {

     private Zips() {

     }

     public static void init() {

     }

     public static byte[] loadFromCp(Object[] classpath, String res) throws Exception {

         for (int i = 0; i < classpath.length; i++) {

             Object c = classpath[i];

             if (c instanceof String) {

                 try {

                     String url = (String)c;

                     final Zips z = toZip(url);

                     c = classpath[i] = z;

                     final byte[] man = z.findRes("META-INF/MANIFEST.MF");

                     if (man != null) {

                         String mainClass = processClassPathAttr(man, url, classpath);

                         if (mainClass != null) {

                             Class.forName(mainClass);

                         }

                     }

                 } catch (Exception ex) {

                     classpath[i] = ex;

                     throw ex;

                 }

             }

             if (res != null && c instanceof Zips) {

                 Object checkRes = ((Zips)c).findRes(res);

                 if (checkRes instanceof byte[]) {

                     return (byte[])checkRes;

                 }

             }

         }

         return null;

     }

     @JavaScriptBody(args = { "res" }, body = "var r = this[res]; return r ? r : null;")

     private native byte[] findRes(String res);

     @JavaScriptBody(args = { "res", "arr" }, body = "this[res] = arr;")

     private native void putRes(String res, byte[] arr);

     private static Zips toZip(String path) throws IOException {

         URL u = new URL(path);

         ZipInputStream zip = new ZipInputStream(u.openStream());

         Zips z = new Zips();

         for (;;) {

             ZipEntry entry = zip.getNextEntry();

             if (entry == null) {

                 break;

             }

             byte[] arr = new byte[4096];

             int offset = 0;

             for (;;) {

                 int len = zip.read(arr, offset, arr.length - offset);

                 if (len == -1) {

                     break;

                 }

                 offset += len;

                 if (offset == arr.length) {

                     enlargeArray(arr, arr.length + 4096);

                 }

             }

             sliceArray(arr, offset);

             z.putRes(entry.getName(), arr);

         }

         return z;

     }

     private static String processClassPathAttr(final byte[] man, String url, Object[] classpath) throws IOException {

         try (ParseMan is = new ParseMan(new ByteArrayInputStream(man))) {

             String cp = is.toString();

             if (cp != null) {

                 cp = cp.trim();

                 for (int p = 0; p < cp.length();) {

                     int n = cp.indexOf(' ', p);

                     if (n == -1) {

                         n = cp.length();

                     }

                     String el = cp.substring(p, n);

                     URL u = new URL(new URL(url), el);

                     classpath = addToArray(classpath, u.toString());

                     p = n + 1;

                 }

             }

             return is.getMainClass();

         }

     }

     private static Object[] addToArray(Object[] arr, String value) {

         final int last = arr.length;

         Object[] ret = enlargeArray(arr, last + 1);

         ret[last] = value;

         return ret;

     }

     @JavaScriptBody(args = { "arr", "len" }, body = "while (arr.length < len) arr.push(null); return arr;throw('Arr: ' + arr);")

     private static native Object[] enlargeArray(Object[] arr, int len);

     @JavaScriptBody(args = { "arr", "len" }, body = "while (arr.length < len) arr.push(0);")

     private static native void enlargeArray(byte[] arr, int len);

     @JavaScriptBody(args = { "arr", "len" }, body = "arr.splice(len, arr.length - len);")

     private static native void sliceArray(byte[] arr, int len);

 }