/**

 * 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.bck2brwsr.vmzip;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

import org.apidesign.bck2brwsr.core.Exported;

import org.apidesign.bck2brwsr.core.JavaScriptBody;

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

import org.apidesign.vm4brwsr.Bck2Brwsr;

/** Conversion from classpath to load function.

 *

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

 */

@Exported

public final class ZipResources implements Bck2Brwsr.Resources {

    private final FastJar fj;

    @Exported

    public ZipResources(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");

    }

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

    private static native int length(Object arr);

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

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

    @JavaScriptBody(args = { "msg" }, body = "if (typeof console !== 'undefined') 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;

    }

    @Override

    public InputStream get(String resource) throws IOException {

        byte[] arr = findRes(resource);

        return arr == null ? null : new ByteArrayInputStream(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);

    @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();

}