/**

  * 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.io.InputStream;

 import java.net.URL;

 import org.apidesign.bck2brwsr.core.JavaScriptBody;

 import org.apidesign.bck2brwsr.emul.zip.FastJar;

 /** Conversion from classpath to load function.

  *

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

  */

 final class Zips {

     private final FastJar fj;

     private Zips(String path, byte[] zipData) throws IOException {

         long bef = timeNow();

         fj = new FastJar(zipData);

         for (FastJar.Entry e : fj.list()) {

             putRes(e.name, e);

         }

         log("Iterating thru " + path + " took " + (timeNow() - bef) + "ms");

     }

     public static void init() {

     }

     @JavaScriptBody(args = { "arr" }, body = "return arr.length;")

     private static native int length(Object arr);

     @JavaScriptBody(args = { "arr", "index" }, body = "return arr[index];")

     private static native Object at(Object arr, int index);

     @JavaScriptBody(args = { "arr", "index", "value" }, body = "arr[index] = value; return value;")

     private static native Object set(Object arr, int index, Object value);

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

     throws IOException, ClassNotFoundException {

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

             Object c = at(classpath, i);

             if (c instanceof String) {

                 try {

                     String url = (String)c;

                     final Zips z = toZip(url);

                     c = set(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 (IOException ex) {

                     set(classpath, i, ex);

                     log("Cannot load " + c + " - " + ex.getClass().getName() + ":" + ex.getMessage());

                 }

             }

             if (res != null) {

                 byte[] checkRes;

                 if (c instanceof Zips) {

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

                 } else {

                     checkRes = callFunction(c, res);

                 }

                 if (checkRes != null) {

                     return checkRes;

                 }

             }

         }

         return null;

     }

     @JavaScriptBody(args = { "fn", "res" }, body = 

         "if (typeof fn === 'function') return fn(res);\n"

       + "return null;"

     )

     private static native byte[] callFunction(Object fn, String res);

     @JavaScriptBody(args = { "msg" }, body = "if (console) console.log(msg.toString());")

     private static native void log(String msg);

     private byte[] findRes(String res) throws IOException {

         Object arr = findResImpl(res);

         if (arr instanceof FastJar.Entry) {

             long bef = timeNow();

             InputStream zip = fj.getInputStream((FastJar.Entry)arr);

             arr = readFully(new byte[512], zip);

             putRes(res, arr);

             log("Reading " + res + " took " + (timeNow() - bef) + "ms");

         }

         return (byte[]) arr;

     }

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

     private native Object findResImpl(String res);

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

     private native void putRes(String res, Object arr);

     private static Zips toZip(String path) throws IOException {

         URL u = new URL(path);

         byte[] zipData = (byte[]) u.getContent(new Class[] { byte[].class });

         return new Zips(path, zipData);

     }

     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 = length(arr);

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

         set(ret, last, value);

         return ret;

     }

     @JavaScriptBody(args = { "arr", "len" }, body = "while (arr.length < len) arr.push(null); return 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 enlargeBytes(byte[] arr, int len);

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

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

     private static Object readFully(byte[] arr, InputStream zip) throws IOException {

         int offset = 0;

         for (;;) {

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

             if (len == -1) {

                 break;

             }

             offset += len;

             if (offset == arr.length) {

                 enlargeBytes(arr, arr.length + 4096);

             }

         }

         sliceArray(arr, offset);

         return arr;

     }

     private static long timeNow() {

         double time = m();

         if (time >= 0) {

             return (long)time;

         }

         return org.apidesign.bck2brwsr.emul.lang.System.currentTimeMillis();

     }

     @JavaScriptBody(args = {}, body = 

         "if (typeof window.performance === 'undefined') return -1;\n"

       + "if (typeof window.performance.now === 'undefined') return -1;\n"

       + "return window.performance.now();"

     )

     private static native double m();

 }