/*
 *                  BioJava development code
 *
 * This code may be freely distributed and modified under the
 * terms of the GNU Lesser General Public Licence.  This should
 * be distributed with the code.  If you do not have a copy,
 * see:
 *
 *      http://www.gnu.org/copyleft/lesser.html
 *
 * Copyright for this code is held jointly by the individual
 * authors.  These should be listed in @author doc comments.
 *
 * For more information on the BioJava project and its aims,
 * or to join the biojava-l mailing list, visit the home page
 * at:
 *
 *      http://www.biojava.org/
 *
 * Created on Dec 28, 2005
 *
 */
package org.biojava.nbio.core.util;

import java.io.*;
import java.net.URL;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

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


/** A class that provides an InputStream from a File. The file can be compressed or uncompressed.
 *
 * Currently supported
 * compressions:
 * <ul>
 * <li>Gzip (extension .gz)</li>
 * <li>Zip (extension .zip) in this case a stream to the first entry in the zip file is returned </li>
 * <li>Jar (extension .jar) same as .Zip; only stream to first entry is returned </li>
 * <li>Z (extension .Z) compressed using the unix compress command </li>
 * <li>for any other extension, no compression is assumed </li>
 * </ul>
 *
 *
 * @author Andreas Prlic
 * @since 1.5
 * @version %I% %G%
 *
 */
public class InputStreamProvider {

	//private final static Logger logger = LoggerFactory.getLogger(InputStreamProvider.class);

	/**
	 * The magic number found at the start of a GZIP stream.
	 */
	public static final int GZIP_MAGIC = 0x1f8b;
	public static final String CACHE_PROPERTY = "biojava.cache.files";

	private boolean cacheRawFiles ;

	FlatFileCache cache ;
	public InputStreamProvider() {
		super();
		cacheRawFiles = false;

		String prop = System.getProperty(CACHE_PROPERTY);
		if ( prop != null && prop.equals("true")) {
			cacheRawFiles = true;
			cache = FlatFileCache.getInstance();
		}

	}

	/**
	 * Get an InputStream for given file path.
	 * The caller is responsible for closing the stream or otherwise
	 * a resource leak can occur.
	 * @param pathToFile the path of the file.
	 * @return an InputStream for the file located at the path.
	 * @throws IOException
	 */
	public InputStream getInputStream(String pathToFile)
	throws IOException
	{
		File f = new File(pathToFile);
		return getInputStream(f);
	}


	/** open the file and read the magic number from the beginning
	 * this is used to determine the compression type
	 *
	 * @param in an input stream to read from
	 * @return the magic number
	 * @throws IOException
	 */
	private int getMagicNumber(InputStream in)
	throws IOException {


		int t = in.read();
		if (t < 0) throw new EOFException("Failed to read magic number");
		int magic = (t & 0xff) << 8;
		t = in.read();
		if (t < 0) throw new EOFException("Failed to read magic number");
		magic += t & 0xff;

		return magic;
	}


	public InputStream getInputStream(URL u)
	throws IOException{

		int magic = 0;


		InputStream inStream = u.openStream();
		magic = getMagicNumber(inStream);
		inStream.close();


		if (magic == UncompressInputStream.LZW_MAGIC ) {
			// a Z compressed file
			return openCompressedURL(u);
		} else if (magic == GZIP_MAGIC ) {
			return openGZIPURL(u);
		} else if ( u.getPath().endsWith(".gz")) {
			return openGZIPURL(u);
		} else if ( u.getPath().endsWith(".Z")) {
			// unix compressed
			return openCompressedURL(u);

		} else {
			inStream = u.openStream();
			return inStream;
		}

	}


	/**
	 * Get an InputStream for the file.
	 * The caller is responsible for closing the stream or otherwise
	 * a resource leak can occur.
	 * @param f a File
	 * @return an InputStream for the file
	 * @throws IOException
	 */
	public  InputStream getInputStream(File f)
	throws IOException
	{

		// use the magic numbers to determine the compression type,
		// use file extension only as 2nd choice

		int magic = 0;


		InputStream test = getInputStreamFromFile(f);
		magic = getMagicNumber(test);
		test.close();


		InputStream inputStream = null;

		String fileName = f.getName();

		if (magic == UncompressInputStream.LZW_MAGIC ) {
			// a Z compressed file
			return openCompressedFile(f);
		}

		else if (magic == GZIP_MAGIC ) {
			return openGZIPFile(f);
		}

		else if ( fileName.endsWith(".gz")) {
			return openGZIPFile(f);
		}

		else if ( fileName.endsWith(".zip")){

			ZipFile zipfile = new ZipFile(f);

			// stream to first entry is returned ...
			ZipEntry entry;
			Enumeration<? extends ZipEntry> e = zipfile.entries();
			if ( e.hasMoreElements()){
				entry = e.nextElement();
				inputStream = zipfile.getInputStream(entry);
			} else {
				throw new IOException ("Zip file has no entries");
			}

		}

		else if ( fileName.endsWith(".jar")) {

			JarFile jarFile = new JarFile(f);

			// stream to first entry is returned
			JarEntry entry;
			Enumeration<JarEntry> e = jarFile.entries();
			if ( e.hasMoreElements()){
				entry = e.nextElement();
				inputStream = jarFile.getInputStream(entry);
			} else {
				throw new IOException ("Jar file has no entries");
			}
		}

		else if ( fileName.endsWith(".Z")) {
			// unix compressed
			return openCompressedFile(f);

		}

		else {

			// no particular extension found, assume that it is an uncompressed file
			inputStream = getInputStreamFromFile(f);
		}

		return inputStream;
	}


	/**
	 * Wrapper for new FileInputStream. if System.property biojava.cache.files is set, will try to load files from memory cache.
	 *
	 * @param f
	 * @return
	 * @throws FileNotFoundException
	 */
	private InputStream getInputStreamFromFile(File f) throws FileNotFoundException{
		InputStream stream = null;



		if ( cacheRawFiles ){
			stream = FlatFileCache.getInputStream(f.getAbsolutePath());

			if ( stream == null){
				FlatFileCache.addToCache(f.getAbsolutePath(),f);
				stream = FlatFileCache.getInputStream(f.getAbsolutePath());
			}
		}

		if ( stream == null)
			stream = new FileInputStream(f);

		return stream;
	}


	private InputStream openCompressedFile(File f)
	throws IOException{

		InputStream is           =  getInputStreamFromFile(f);
		InputStream inputStream =  new UncompressInputStream(is);
		return inputStream;
	}

	private InputStream openCompressedURL(URL u)
	throws IOException{

		InputStream is           =  u.openStream();
		InputStream inputStream =  new UncompressInputStream(is);
		return inputStream;
	}


	private InputStream openGZIPFile(File f)
	throws IOException{

		InputStream is      = getInputStreamFromFile(f);
		InputStream inputStream = new GZIPInputStream(is);
		return inputStream;
	}

	private InputStream openGZIPURL(URL u)
	throws IOException{

		InputStream is      = u.openStream();
		InputStream inputStream = new GZIPInputStream(is);
		return inputStream;
	}
}
