/**

 * 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.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) {

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

            Object c = classpath[i];

            if (c instanceof String) {

                try {

                    c = classpath[i] = toZip((String)c);

                } catch (IOException ex) {

                    classpath[i] = ex;

                }

            }

            if (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;

    }

    @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);

}