/*
 * ExtractFromGzipInTar.java
 */
package gov.noaa.eds.tryVfs;

import org.apache.commons.vfs.AllFileSelector;
import org.apache.commons.vfs.FileName;
import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystemException;
import org.apache.commons.vfs.FileSystemManager;
import org.apache.commons.vfs.FileType;
import org.apache.commons.vfs.FileTypeSelector;
import org.apache.commons.vfs.VFS;
import org.apache.commons.vfs.provider.local.LocalFile;

/**
 * Try using VFS to read the content of a compressed (gz) file inside of
 * a tar file. Extract tar file objects. If they are gzip files, decompress them.
 * Any directory structure in the tarfile is not being preserved, the contents
 * are pulled out to the same location regardless of directory hierarchy (for
 * the purposes of this example, all objects in the tar file have unique names,
 * so there are no file name conflicts).
 *
 * @author Ken Tanaka
 */
public class ExtractFromGzipInTar 
{
    FileSystemManager fsManager = null;
    static String extractDirname = "/extra/data/tryVfs";
    
    /**
     * Extract files from a tar file. If the file extracted is gzipped,
     * decompress it and remove the gzipped version.
     * @param args command line arguments are currently not used
     */
    public static void main( String[] args )
    {
        ExtractFromGzipInTar extract = new ExtractFromGzipInTar();
        
        try {
            extract.fsManager = VFS.getManager();
        } catch (FileSystemException ex) {
            throw new RuntimeException("failed to get fsManager from VFS", ex);
        }
        
        
        /* Create a tarFile FileObject to connect to the tarfile on disk */
        FileObject tarFile;
        try {
            String tarName = new String("tar:file://" + extractDirname + "/archive.tar");
            System.out.println("Resolve " + tarName);
            tarFile = extract.fsManager.resolveFile(tarName);
            
            FileName tarFileName = tarFile.getName();
            System.out.println("  Path     : " + tarFileName.getPath());
            System.out.println("  URI      : " + tarFileName.getURI());
        } catch (Exception ex) {
            throw new RuntimeException("failed to open tar file ", ex);
        }
        
        /* Work on files inside tarFile */
        FileObject[] children;
        try {
            children = tarFile.getChildren();
        } catch (FileSystemException ex) {
            throw new RuntimeException("failed to get contents of tarfile ", ex);
        }
        
        for (FileObject f : children) {
            extract.processChild(f);
        }
    } // main( String[] args )
    
    private void processChild(FileObject f) {
        try {
            if (f.getType() == FileType.FOLDER) {
                // Recursively process files in this folder
                FileObject[] children = f.getChildren();
                for (FileObject subfile : children) {
                    processChild(subfile);
                }
            } else {
                FileName fname = f.getName();
                String extractName = new String("file://" + extractDirname + "/"
                        + fname.getBaseName());
                System.out.println("Extracting " + extractName);
                LocalFile extractFile = (LocalFile) this.fsManager.resolveFile(extractName);
                
                // if the file is gzipped, decompress it
/* line  90   */          if (extractFile.getName().getExtension().equals("gz")) {
                    System.out.println("Decompressing " + extractName);
                    
                    // The uncompressed filename we seek
                    // content.txt
                    String fileName = extractFile.getName().getBaseName().replaceAll(".gz$", "");
                    
                    // Build the direct path to the uncompressed content of the 
                    // gzip file in the tar file.
                    // gz:tar:file:///archive.tar!/tardir/content.txt.gz!content.txt
/* line             100 */      String gzName = new String("gz:" + fname.getURI() + "!" + fileName);
                    FileObject gzFile = this.fsManager.resolveFile(gzName);
                    
                    // The decompressed path we want
                    String decompName = new String("file://" + extractDirname + "/" 
                            + fileName);
                    LocalFile decompFile = (LocalFile) this.fsManager.resolveFile(decompName);
                    
                    // Some debug lines
                    System.out.println("fileName   =" + fileName);
                    System.out.println("decompName =" + decompName);
                    System.out.println("gzName=" + gzName);
                    
                    // Extracting
                    decompFile.copyFrom(gzFile, new FileTypeSelector(FileType.FILE));
                } else {
                    // just extract the non-gzip file
                    extractFile.copyFrom(f, new AllFileSelector());
                }
            }
        } catch (FileSystemException ex) {
            ex.printStackTrace();
            throw new RuntimeException("Error working on tarfile object " + f.getName());
        }
    } // processChild(FileObject f)
}