/* CachedJarFileCallback.java
   Copyright (C) 2011 Red Hat, Inc.
   Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.

This file is part of IcedTea.

IcedTea 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.

IcedTea 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
IcedTea; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is making a
combined work based on this library. Thus, the terms and conditions of the GNU
General Public License cover the whole combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent modules, and
to copy and distribute the resulting executable under terms of your choice,
provided that you also meet, for each linked independent module, the terms and
conditions of the license of that module. An independent module is a module
which is not derived from or based on this library. If you modify this library,
you may extend this exception to your version of the library, but you are not
obligated to do so. If you do not wish to do so, delete this exception
statement from your version.
*/

package net.sourceforge.jnlp.runtime;

import net.adoptopenjdk.icedteaweb.http.CloseableConnection;
import net.adoptopenjdk.icedteaweb.http.ConnectionFactory;
import net.adoptopenjdk.icedteaweb.logging.Logger;
import net.adoptopenjdk.icedteaweb.logging.LoggerFactory;
import net.sourceforge.jnlp.util.JarFile;
import net.sourceforge.jnlp.util.UrlKey;
import net.sourceforge.jnlp.util.UrlUtils;
import sun.net.www.protocol.jar.URLJarFile;
import sun.net.www.protocol.jar.URLJarFileCallBack;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.jar.Attributes;

/**
 * Invoked by URLJarFile to get a JarFile corresponding to a URL.
 *
 * Large parts of this class are based on JarFileFactory and URLJarFile.
 */
public final class CachedJarFileCallback implements URLJarFileCallBack {

    private final static Logger LOG = LoggerFactory.getLogger(CachedJarFileCallback.class);

    private static final CachedJarFileCallback INSTANCE = new CachedJarFileCallback();

    public synchronized static CachedJarFileCallback getInstance() {
        return INSTANCE;
    }

    /* our managed cache */
    private final Map<UrlKey, URL> mapping;

    private CachedJarFileCallback() {
        mapping = new ConcurrentHashMap<>();
    }

    public void addMapping(URL remoteUrl, URL localUrl) {
        LOG.debug("CachedJarFileCallback.addMapping : {} -> {} ", remoteUrl, localUrl);
        mapping.put(new UrlKey(remoteUrl), localUrl);
    }

    @Override
    public java.util.jar.JarFile retrieve(URL url) throws IOException {
        URL localUrl = mapping.get(new UrlKey(url));
        if (localUrl == null) {
            if (url.getRef() != null) {
                url = new URL(url.toString().substring(0, url.toString().lastIndexOf(url.getRef()) - 1));
                localUrl = mapping.get(new UrlKey(url));
            }
        }

        if (localUrl == null) {
            LOG.info("CachedJarFileCallback.retrieve : could not find mapping for {} - falling back to downloading without caching", url);
            /*
             * If the jar url is not known, treat it as it would be treated in
             * general by URLJarFile.
             */
            return cacheJarFile(url);
        }

        if (UrlUtils.isLocalFile(localUrl)) {
            // if it is known to us, just return the cached file
            java.util.jar.JarFile returnFile = new JarFile(UrlUtils.decodeUrlQuietly(localUrl).getPath()).getNative();

            try {
                // Blank out the class-path because:
                // 1) Web Start does not support it
                // 2) For the plug-in, we want to cache files from class-path so we do it manually
                returnFile.getManifest().getMainAttributes().putValue(Attributes.Name.CLASS_PATH.toString(), "");

                LOG.debug("Class-Path attribute cleared for Cached Jar {}", returnFile.getName());

            } catch (NullPointerException npe) {
                // Discard NPE here. Maybe there was no manifest, maybe there were no attributes, etc.
            }

            return returnFile;
        } else {
            // throw new IllegalStateException("a non-local file in cache");
            return null;
        }

    }

    /*
     * This method is a copy of URLJarFile.retrieve() without the callback check.
     */
    private  java.util.jar.JarFile cacheJarFile(URL url) throws IOException {
        java.util.jar.JarFile result = null;

        final int BUF_SIZE = 2048;

        try (CloseableConnection conn = ConnectionFactory.openConnection(url)) {
            /* get the stream before asserting privileges */
            final InputStream in = conn.getInputStream();

            result =
                    AccessController.doPrivileged(new PrivilegedExceptionAction<java.util.jar.JarFile>() {
                        @Override
                        public java.util.jar.JarFile run() throws IOException {
                            OutputStream out = null;
                            File tmpFile = null;
                            try {
                                tmpFile = File.createTempFile("jar_cache", null);
                                tmpFile.deleteOnExit();
                                out = new FileOutputStream(tmpFile);
                                int read = 0;
                                byte[] buf = new byte[BUF_SIZE];
                                while ((read = in.read(buf)) != -1) {
                                    out.write(buf, 0, read);
                                }
                                out.close();
                                out = null;
                                return new URLJarFile(tmpFile, null);
                            } catch (IOException e) {
                                if (tmpFile != null) {
                                    tmpFile.delete();
                                }
                                throw e;
                            } finally {
                                if (in != null) {
                                    in.close();
                                }
                                if (out != null) {
                                    out.close();
                                }
                            }
                        }
                    });
        } catch (PrivilegedActionException pae) {
            throw (IOException) pae.getException();
        }

        return result;
    }

}
