/**

 * 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);

}