/**

 * 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 = "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();

}