/*
 * [RefreshAux.java]
 *
 * Summary: Download any stale auxiliary files.
 *
 * Copyright: (c) 2009-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.0 2007-07-18 07-18
 */
package com.mindprod.replicator;

import com.mindprod.replicatorcommon.Config;
import com.mindprod.replicatorcommon.MiniFD;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.zip.GZIPInputStream;

import static java.lang.System.*;

/**
 * Download any stale auxiliary files.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.0 2007-07-18 07-18
 * @since 2009
 */
final class RefreshAux
    {
    /**
     * check which auxiliary files are stale, and download them.
     *
     * @throws java.net.MalformedURLException if url is bad on one of files.
     */
    static void refreshAuxFiles() throws MalformedURLException
        {
        if ( !ConfigForReceiver.KEEP_ZIPS )
            {
            // if we don't keep zips to pass on, there is no need for aux files.
            return;
            }
        // Always freshly download freshness.ser
        final String freshnessFilename = ConfigForReceiver
                                                 .RECEIVER_ZIP_STAGING_DIR + File
                                                 .separatorChar + Config
                                                 .FRESHNESS_SER;
        final String freshnessURL =
                ConfigForReceiver.RECEIVER_ZIP_URL + "/" + Config.FRESHNESS_SER;
        Replicator.doing( "downloading list of most recent aux files: "
                          + freshnessURL );
        if ( !FetchZips.ft
                .download( new URL( freshnessURL ),
                        new File( freshnessFilename ), false ) )
            {
            Replicator.fatal( "Unable to download "
                              + freshnessURL
                              + " to "
                              + freshnessFilename );
            }
        MiniFD[] auxFiles = null;
        // get array of files and freshness dates
        try
            {
            final FileInputStream fis =
                    new FileInputStream( freshnessFilename );
            // stream is compressed
            final GZIPInputStream gzis =
                    new GZIPInputStream( fis, 4 * 1024 );
            final ObjectInputStream ois = new ObjectInputStream( gzis );
            final long fileSerialVersionUID = ( Long ) ois.readObject();
            if ( fileSerialVersionUID != MiniFD.serialVersionUID )
                {
                throw new IOException( "Incompatible version of "
                                       + Config
                                               .FRESHNESS_SER
                                       + " got: "
                                       + fileSerialVersionUID
                                       + " expected: "
                                       + MiniFD
                                               .serialVersionUID );
                }
            auxFiles = ( MiniFD[] ) ois.readObject();
            ois.close();
            }
        catch ( ClassNotFoundException e )
            {
            Replicator.fatal( "Corrupt: "
                              + freshnessFilename
                              + "\n"
                              + e.getMessage() );
            }
        catch ( IOException e )
            {
            Replicator.fatal( "Unable to read "
                              + freshnessFilename
                              + " file."
                              + "\n"
                              + e.getMessage() );
            }
        if ( auxFiles == null )
            {
            err.println( "unable to read " + Config.FRESHNESS_SER );
            Replicator.die();
            }
        for ( MiniFD fd : auxFiles )
            {
            String auxFilename = ConfigForReceiver
                                         .RECEIVER_ZIP_STAGING_DIR + File
                                         .separatorChar + fd.getRelativeFilename( '/' );
            String auxURL = ConfigForReceiver
                                    .RECEIVER_ZIP_URL + "/" + fd.getRelativeFilename( '/' );
            final File auxFile = new File( auxFilename );
            if ( auxFile.exists()
                 && auxFile.lastModified() >= fd.getClumping() )
                {
                // can bypass download
                continue;
                }
            Replicator.doing( "downloading: " + auxURL );
            if ( !FetchZips.ft
                    .download( new URL( auxURL ), new File( auxFilename ), false ) )
                {
                Replicator.fatal( "Unable to download auxiliary file "
                                  + auxURL
                                  + " to "
                                  + auxFilename );
                }
            } // end for
        }
    }