/*

 * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.net.www.protocol.jrt;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.MalformedURLException;

import java.net.URL;

import java.security.AccessController;

import java.security.Permission;

import java.security.PrivilegedAction;

import jdk.internal.jimage.ImageLocation;

import jdk.internal.jimage.ImageReader;

import jdk.internal.jimage.ImageReaderFactory;

import jdk.internal.loader.URLClassPath;

import jdk.internal.loader.Resource;

import sun.net.www.ParseUtil;

import sun.net.www.URLConnection;

/**

 * URLConnection implementation that can be used to connect to resources

 * contained in the runtime image.

 */

public class JavaRuntimeURLConnection extends URLConnection {

    // ImageReader to access resources in jimage

    private static final ImageReader reader;

    static {

        PrivilegedAction<ImageReader> pa = ImageReaderFactory::getImageReader;

        reader = AccessController.doPrivileged(pa);

    }

    // the module and resource name in the URL

    private final String module;

    private final String name;

    // the Resource when connected

    private volatile Resource resource;

    JavaRuntimeURLConnection(URL url) throws IOException {

        super(url);

        String path = url.getPath();

        if (path.length() == 0 || path.charAt(0) != '/')

            throw new MalformedURLException(url + " missing path or /");

        if (path.length() == 1) {

            this.module = null;

            this.name = null;

        } else {

            int pos = path.indexOf('/', 1);

            if (pos == -1) {

                this.module = path.substring(1);

                this.name = null;

            } else {

                this.module = path.substring(1, pos);

                this.name = ParseUtil.decode(path.substring(pos+1));

            }

        }

    }

    /**

     * Finds a resource in a module, returning {@code null} if the resource

     * is not found.

     */

    private static Resource findResource(String module, String name) {

        if (reader != null) {

            URL url = toJrtURL(module, name);

            ImageLocation location = reader.findLocation(module, name);

            if (location != null && URLClassPath.checkURL(url) != null) {

                return new Resource() {

                    @Override

                    public String getName() {

                        return name;

                    }

                    @Override

                    public URL getURL() {

                        return url;

                    }

                    @Override

                    public URL getCodeSourceURL() {

                        return toJrtURL(module);

                    }

                    @Override

                    public InputStream getInputStream() throws IOException {

                        byte[] resource = reader.getResource(location);

                        return new ByteArrayInputStream(resource);

                    }

                    @Override

                    public int getContentLength() {

                        long size = location.getUncompressedSize();

                        return (size > Integer.MAX_VALUE) ? -1 : (int) size;

                    }

                };

            }

        }

        return null;

    }

    @Override

    public synchronized void connect() throws IOException {

        if (!connected) {

            if (name == null) {

                String s = (module == null) ? "" : module;

                throw new IOException("cannot connect to jrt:/" + s);

            }

            resource = findResource(module, name);

            if (resource == null)

                throw new IOException(module + "/" + name + " not found");

            connected = true;

        }

    }

    @Override

    public InputStream getInputStream() throws IOException {

        connect();

        return resource.getInputStream();

    }

    @Override

    public long getContentLengthLong() {

        try {

            connect();

            return resource.getContentLength();

        } catch (IOException ioe) {

            return -1L;

        }

    }

    @Override

    public int getContentLength() {

        long len = getContentLengthLong();

        return len > Integer.MAX_VALUE ? -1 : (int)len;

    }

    @Override

    public Permission getPermission() {

        return new RuntimePermission("accessSystemModules");

    }

    /**

     * Returns a jrt URL for the given module and resource name.

     */

    private static URL toJrtURL(String module, String name) {

        try {

            return new URL("jrt:/" + module + "/" + name);

        } catch (MalformedURLException e) {

            throw new InternalError(e);

        }

    }

    /**

     * Returns a jrt URL for the given module.

     */

    private static URL toJrtURL(String module) {

        try {

            return new URL("jrt:/" + module);

        } catch (MalformedURLException e) {

            throw new InternalError(e);

        }

    }

}