tikhomirov@51: /*
tikhomirov@51:  * Copyright (c) 2011 Artem Tikhomirov 
tikhomirov@51:  */
tikhomirov@51: package com.tmate.hgkit.fs;
tikhomirov@51: 
tikhomirov@51: import java.io.EOFException;
tikhomirov@51: import java.io.IOException;
tikhomirov@51: import java.util.zip.DataFormatException;
tikhomirov@51: import java.util.zip.Inflater;
tikhomirov@51: import java.util.zip.ZipException;
tikhomirov@51: 
tikhomirov@51: /**
tikhomirov@51:  * DataAccess counterpart for InflaterInputStream.
tikhomirov@51:  * XXX is it really needed to be subclass of FilterDataAccess? 
tikhomirov@51:  * @author artem
tikhomirov@51:  */
tikhomirov@51: public class InflaterDataAccess extends FilterDataAccess {
tikhomirov@51: 
tikhomirov@51: 	private final Inflater inflater;
tikhomirov@51: 	private final byte[] buffer;
tikhomirov@51: 	private final byte[] singleByte = new byte[1];
tikhomirov@51: 	private int decompressedPos = 0;
tikhomirov@51: 	private int decompressedLength = -1;
tikhomirov@51: 
tikhomirov@51: 	public InflaterDataAccess(DataAccess dataAccess, long offset, int length) {
tikhomirov@51: 		this(dataAccess, offset, length, new Inflater(), 512);
tikhomirov@51: 	}
tikhomirov@51: 
tikhomirov@51: 	public InflaterDataAccess(DataAccess dataAccess, long offset, int length, Inflater inflater, int bufSize) {
tikhomirov@51: 		super(dataAccess, offset, length);
tikhomirov@51: 		this.inflater = inflater;
tikhomirov@51: 		buffer = new byte[bufSize];
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public void reset() throws IOException {
tikhomirov@51: 		super.reset();
tikhomirov@51: 		inflater.reset();
tikhomirov@51: 		decompressedPos = 0;
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	protected int available() {
tikhomirov@51: 		throw new IllegalStateException("Can't tell how much uncompressed data left");
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public boolean isEmpty() {
tikhomirov@51: 		return super.available() <= 0 && inflater.finished(); // and/or inflater.getRemaining() <= 0 ?
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public long length() {
tikhomirov@51: 		if (decompressedLength != -1) {
tikhomirov@51: 			return decompressedLength;
tikhomirov@51: 		}
tikhomirov@51: 		int c = 0;
tikhomirov@51: 		try {
tikhomirov@51: 			int oldPos = decompressedPos;
tikhomirov@51: 			while (!isEmpty()) {
tikhomirov@51: 				readByte();
tikhomirov@51: 				c++;
tikhomirov@51: 			}
tikhomirov@51: 			decompressedLength = c + oldPos;
tikhomirov@51: 			reset();
tikhomirov@51: 			seek(oldPos);
tikhomirov@51: 			return decompressedLength;
tikhomirov@51: 		} catch (IOException ex) {
tikhomirov@51: 			ex.printStackTrace(); // FIXME log error
tikhomirov@51: 			decompressedLength = -1; // better luck next time?
tikhomirov@51: 			return 0;
tikhomirov@51: 		}
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public void seek(long localOffset) throws IOException {
tikhomirov@51: 		System.out.println("Seek: " + localOffset);
tikhomirov@51: 		if (localOffset < 0 /* || localOffset >= length() */) {
tikhomirov@51: 			throw new IllegalArgumentException();
tikhomirov@51: 		}
tikhomirov@51: 		if (localOffset >= decompressedPos) {
tikhomirov@51: 			skip((int) (localOffset - decompressedPos));
tikhomirov@51: 		} else {
tikhomirov@51: 			reset();
tikhomirov@51: 			skip((int) localOffset);
tikhomirov@51: 		}
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public void skip(int bytes) throws IOException {
tikhomirov@51: 		if (bytes < 0) {
tikhomirov@51: 			bytes += decompressedPos;
tikhomirov@51: 			if (bytes < 0) {
tikhomirov@51: 				throw new IOException("Underflow. Rewind past start of the slice.");
tikhomirov@51: 			}
tikhomirov@51: 			reset();
tikhomirov@51: 			// fall-through
tikhomirov@51: 		}
tikhomirov@51: 		while (!isEmpty() && bytes > 0) {
tikhomirov@51: 			readByte();
tikhomirov@51: 			bytes--;
tikhomirov@51: 		}
tikhomirov@51: 		if (bytes != 0) {
tikhomirov@51: 			throw new IOException("Underflow. Rewind past end of the slice");
tikhomirov@51: 		}
tikhomirov@51: 	}
tikhomirov@51: 
tikhomirov@51: 	@Override
tikhomirov@51: 	public byte readByte() throws IOException {
tikhomirov@51: 		readBytes(singleByte, 0, 1);
tikhomirov@51: 		return singleByte[0];
tikhomirov@51: 	}
tikhomirov@51: 
tikhomirov@51: 	@Override
tikhomirov@51: 	public void readBytes(byte[] b, int off, int len) throws IOException {
tikhomirov@51: 		try {
tikhomirov@51: 		    int n;
tikhomirov@51: 		    while (len > 0) {
tikhomirov@51: 			    while ((n = inflater.inflate(b, off, len)) == 0) {
tikhomirov@51: 					if (inflater.finished() || inflater.needsDictionary()) {
tikhomirov@51: 	                    throw new EOFException();
tikhomirov@51: 					}
tikhomirov@51: 					if (inflater.needsInput()) {
tikhomirov@51: 						// fill:
tikhomirov@51: 						int toRead = super.available();
tikhomirov@51: 						if (toRead > buffer.length) {
tikhomirov@51: 							toRead = buffer.length;
tikhomirov@51: 						}
tikhomirov@51: 						super.readBytes(buffer, 0, toRead);
tikhomirov@51: 						inflater.setInput(buffer, 0, toRead);
tikhomirov@51: 					}
tikhomirov@51: 			    }
tikhomirov@51: 				off += n;
tikhomirov@51: 				len -= n;
tikhomirov@51: 				decompressedPos += n;
tikhomirov@51: 				if (len == 0) {
tikhomirov@51: 					return; // filled
tikhomirov@51: 				}
tikhomirov@51: 		    }
tikhomirov@51: 		} catch (DataFormatException e) {
tikhomirov@51: 		    String s = e.getMessage();
tikhomirov@51: 		    throw new ZipException(s != null ? s : "Invalid ZLIB data format");
tikhomirov@51: 		}
tikhomirov@51:     }
tikhomirov@51: }