package eu.openaire.urls_worker.util;

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

import java.io.*;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;


public class FilesZipper
{
    private static final Logger logger = LoggerFactory.getLogger(FilesZipper.class);


    public static File zipMultipleFilesAndGetZip(long assignmentsCounter, int zipBatchCounter, List<String> filesToZip, String baseDirectory)
    {
        File zipFile = null;
        ZipOutputStream zos = null;
        try {
            String zipFilename = baseDirectory + "assignments_" + assignmentsCounter + "_full-texts_" + zipBatchCounter + ".zip";
            // For example: assignments_2_full-texts_4.zip    | where < 4 > is referred to the 4th batch of files requested by the controller.
            zipFile = new File(zipFilename);
            zos = new ZipOutputStream(new FileOutputStream(zipFile));

            // Iterate over the given full-texts and add them to the zip.
            for ( String file : filesToZip )
            {
                zipAFile(file, zos, baseDirectory);
            }
        } catch (Exception e) {
            logger.error("", e);
            return null;
        } finally {
            try {
                if ( zos != null )
                    zos.close();
            } catch (IOException e) {
                logger.error(e.getMessage(), e);
            }
        }
        return zipFile;
    }


    private static boolean zipAFile(String fileName, ZipOutputStream zos, String baseDir)
    {
        final int BUFFER = 1048576; // 1 MB
        byte[] data = new byte[BUFFER];
        BufferedInputStream bis = null;
        String fullFileName = baseDir + fileName;
        try {
            FileInputStream fis = new FileInputStream(fullFileName);
            bis = new BufferedInputStream(fis, BUFFER);
            zos.putNextEntry(new ZipEntry(fileName));
            int count;
            while ( (count = bis.read(data, 0, BUFFER)) != -1 ) {
                zos.write(data, 0, count);
            }
            zos.closeEntry();   // close the entry here (not the ZipOutputStream)
        } catch (FileNotFoundException fnfe) {
            logger.error("Error zipping file: " + fullFileName, fnfe.getMessage());
            return false;
        } catch (Exception e) {
            if ( ! e.getMessage().contains("duplicate") )
                logger.error("Error zipping file: " + fullFileName, e);
            return false;
        } finally {
            try {
                if ( bis != null )
                    bis.close();
            } catch (IOException e) {
                logger.error(e.getMessage(), e);
            }
        }
        return true;
    }

}