/*
 * #%L
 * Netarchivesuite - wayback
 * %%
 * Copyright (C) 2005 - 2014 The Royal Danish Library, the Danish State and University Library,
 *             the National Library of France and the Austrian National Library.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 2.1 of the
 * License, or (at your option) any later version.
 * 
 * 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 Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-2.1.html>.
 * #L%
 */

package dk.netarkivet.wayback.aggregator;

import java.io.File;
import java.util.LinkedList;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import dk.netarkivet.common.exceptions.ArgumentNotValid;
import dk.netarkivet.common.utils.Settings;
import dk.netarkivet.wayback.WaybackSettings;

/**
 * Encapsulates the functionality for sorting and merging index files. Uses the Unix sort cmd for optimized sorting and
 * file merging. Operations in this class are synchronized to avoid multiple jobs running at the same time (by the same
 * object at least).
 */
public class IndexAggregator {
    /** The logger for this class. */
    //private Log log = LogFactory.getLog(getClass().getName());
    private final Logger log = LoggerFactory.getLogger(IndexAggregator.class);

    /**
     * Generates a sorted CDX index file based on the set of unsorted CDX input files.
     * <p>
     * The operation will not run on a folder which already has a process job running.
     *
     * @param files A list of the files to aggregate
     * @param outputFile Name of the output file. In case of a empty filesNames array no outputFiles will be generated
     */
    public void sortAndMergeFiles(File[] files, File outputFile) {
        processFiles(files, outputFile, null);
    }

    /**
     * Takes a list of sorted files and merges them.
     *
     * @param files The files to merge.
     * @param outputFile The resulting file containing total sorted set of index lines found in all the provided index
     * files
     */

    public void mergeFiles(File[] files, File outputFile) {
        List<String> args = new LinkedList<String>();
        args.add("-m");
        processFiles(files, outputFile, args);
    }

    /**
     * Calls the Unix sort command with the options <code>$filesNames -o
     * $outputfile -T WaybackSettings#WAYBACK_AGGREGATOR_TEMP_DIR.
     * <p>
     * Sets the LC_ALL environment variable before making the call.
     *
     * @param files The files to merge and sort
     * @param outputFile The resulting sorted file
     * @param additionalArgs A list af extra arguments, which (if different from null) are added to the sort call.<p>
     * Note: If any of the args contain a whitespace the call will fail.
     */
    private void processFiles(File[] files, File outputFile, List<String> additionalArgs) {
        if (files.length == 0) {
            // Empty file list will cause sort to wait for further input,
            // and the call will therefore never return
            return;
        }

        Process p = null;

        try {
            List<String> inputFileList = new LinkedList<String>();
            for (int i = 0; i < files.length; i++) {
                if (files[i].exists() && files[i].isFile()) {
                    inputFileList.add(files[i].getCanonicalPath());
                } else {
                    log.warn("File " + files[i] + " doesn't exist or isn't a regular file, "
                            + "dropping from list of files to " + "sort and merge");
                }
            }
            List<String> cmd = new LinkedList<String>();
            // Prepare to run the unix sort command, see sort manual page for
            // details
            cmd.add("sort");
            cmd.addAll(inputFileList);
            cmd.add("-o");
            cmd.add(outputFile.getCanonicalPath());
            cmd.add("-T");
            cmd.add(Settings.get(WaybackSettings.WAYBACK_AGGREGATOR_TEMP_DIR));
            if (additionalArgs != null && !additionalArgs.isEmpty()) {
                for (String argument : additionalArgs) {
                    ArgumentNotValid.checkTrue(argument.indexOf(' ') == -1, "The argument '" + argument
                            + "' contains spaces, this isn't allowed ");
                }
                cmd.addAll(additionalArgs);
            }
            ProcessBuilder pb = new ProcessBuilder(cmd);
            // Reset all locale definitions
            pb.environment().put("LC_ALL", "C");
            // Run the command in the user.dir directory
            pb.directory(new File(System.getProperty("user.dir")));
            p = pb.start();
            p.waitFor();
            if (p.exitValue() != 0) {
                log.error("Failed to sort index files, sort exited with " + "return code " + p.exitValue());
            }
        } catch (Exception e) {
            log.error("Failed to aggregate indexes ", e);
        }
    }
}