/**
 * @(#)ZipInputStream.java	1.43 06/07/31
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package free.utils.zip;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
import java.io.UnsupportedEncodingException;
import java.util.zip.CRC32;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;

/**
 * This class implements an input stream filter for reading files in the ZIP file format. Includes support for both compressed and uncompressed entries.
 * @author	David Connelly
 * @version	1.43, 07/31/06
 *
 * Patch to take care of the file encoding
 */
public class ZipInputStream extends InflaterInputStream implements ZipConstants  {
	private ZipEntry entry;
	private int flag;
	private CRC32 crc = new CRC32();
	private long remaining;
	private byte[] tmpbuf = new byte[512];
	private static final int STORED = ZipEntry.STORED;
	private static final int DEFLATED = ZipEntry.DEFLATED;
	private boolean closed = false;
	// this flag is set to true after EOF has reached for one entry
	private boolean entryEOF = false;



	/**
	 * Creates a new ZIP input stream.
	 * @param in the actual input stream
	 */
//	public ZipInputStream(InputStream in) {
//		super(new PushbackInputStream(in, 512), new Inflater(true), 512);
//		usesDefaultInflater = true;
//		if (in == null) {
//			throw new NullPointerException("in is null");
//		}
//	}

	public ZipInputStream(InputStream in) {
		super(new PushbackInputStream(in, 512), new Inflater(true), 512);
		if (in == null) {
			throw new NullPointerException("in is null");
		}
	}

	private void ensureOpen() throws IOException {
		if (closed) {
			throw new IOException("Stream closed");
		}
	}

	/**
	 * Reads the next ZIP file entry and positions the stream at the beginning of the entry data.
	 * @return the next ZIP file entry, or null if there are no more entries
	 * @exception ZipException if a ZIP file error has occurred
	 * @exception IOException if an I/O error has occurred
	 */
	public ZipEntry getNextEntry() throws IOException {
		ensureOpen();

		if (entry != null) {
			closeEntry();
		}

		crc.reset();
		inf.reset();

		if ((entry = readLOC()) == null) {
			return null;
		}

		if (entry.getMethod() == STORED) {
			remaining = entry.getSize();
		}

		entryEOF = false;

		return entry;
	}

	/**
	 * Closes the current ZIP entry and positions the stream for reading the next entry.
	 * @exception ZipException if a ZIP file error has occurred
	 * @exception IOException if an I/O error has occurred
	 */
	public void closeEntry() throws IOException {
		ensureOpen();

		while (read(tmpbuf, 0, tmpbuf.length) != -1) ;
		entryEOF = true;
	}

	/**
	 * Returns 0 after EOF has reached for the current entry data, otherwise always return 1.
	 * Programs should not count on this method to return the actual number of bytes that could be read without blocking.
	 * @return 1 before EOF and 0 after EOF has reached for current entry.
	 * @exception IOException if an I/O error occurs.
	 */
	public int available() throws IOException {
		ensureOpen();

		if (entryEOF) {
			return 0;
		} else {
			return 1;
		}
	}

	/**
	 * Reads from the current ZIP entry into an array of bytes. If <code>len</code> is not zero, the method blocks until some input is available; otherwise, no bytes are read and <code>0</code> is returned.
	 * @param b the buffer into which the data is read
	 * @param off the start offset in the destination array <code>b</code>
	 * @param len the maximum number of bytes read
	 * @return the actual number of bytes read, or -1 if the end of the entry is reached
	 * @exception NullPointerException If <code>b</code> is <code>null</code>.
	 * @exception IndexOutOfBoundsException If <code>off</code> is negative, <code>len</code> is negative, or <code>len</code> is greater than <code>b.length - off</code>
	 * @exception ZipException if a ZIP file error has occurred
	 * @exception IOException if an I/O error has occurred
	 */
//	public int read(byte[] b, int off, int len) throws IOException {
//		ensureOpen();
//		if (off < 0 || len < 0 || off > b.length - len) {
//			throw new IndexOutOfBoundsException();
//		} else if (len == 0) {
//			return 0;
//		}
//
//		if (entry == null) {
//			return -1;
//		}
//		switch (entry.method) {
//			case DEFLATED:
//				len = super.read(b, off, len);
//				if (len == -1) {
//					readEnd(entry);
//					entryEOF = true;
//					entry = null;
//				} else {
//					crc.update(b, off, len);
//				}
//				return len;
//			case STORED:
//				if (remaining <= 0) {
//					entryEOF = true;
//					entry = null;
//					return -1;
//				}
//				if (len > remaining) {
//					len = (int) remaining;
//				}
//				len = in.read(b, off, len);
//				if (len == -1) {
//					throw new ZipException("unexpected EOF");
//				}
//				crc.update(b, off, len);
//				remaining -= len;
//				return len;
//			default:
//				throw new ZipException("invalid compression method");
//		}
//	}

	public int read(byte[] b, int off, int len) throws IOException {
		ensureOpen();

		if (off < 0 || len < 0 || off > b.length - len) {
			throw new IndexOutOfBoundsException();
		} else if (len == 0) {
			return 0;
		}

		if (entry == null) {
			return -1;
		}
		switch (entry.getMethod()) {
			case DEFLATED:
				len = super.read(b, off, len);
				if (len == -1) {
					readEnd(entry);
					entryEOF = true;
					entry = null;
				} else {
					crc.update(b, off, len);
				}
				return len;
			case STORED:
				if (remaining <= 0) {
					entryEOF = true;
					entry = null;
					return -1;
				}
				if (len > remaining) {
					len = (int) remaining;
				}
				len = in.read(b, off, len);
				if (len == -1) {
					throw new ZipException("unexpected EOF");
				}
				crc.update(b, off, len);
				remaining -= len;
				return len;
			default:
				throw new ZipException("invalid compression method");
		}
	}

	/**
	 * Skips specified number of bytes in the current ZIP entry.
	 * @param n the number of bytes to skip
	 * @return the actual number of bytes skipped
	 * @exception ZipException if a ZIP file error has occurred
	 * @exception IOException if an I/O error has occurred
	 * @exception IllegalArgumentException if n < 0
	 */
	public long skip2(long n) throws IOException {
		if (n < 0) {
			throw new IllegalArgumentException("negative skip length");
		}

		ensureOpen();

		int max = (int) Math.min(n, Integer.MAX_VALUE);
		int total = 0;

		while (total < max) {
			int len = max - total;
			if (len > tmpbuf.length) {
				len = tmpbuf.length;
			}
			len = read(tmpbuf, 0, len);
			if (len == -1) {
				entryEOF = true;
				break;
			}
			total += len;
		}

		return total;
	}

	/**
	 * Closes this input stream and releases any system resources associated with the stream.
	 * @exception IOException if an I/O error has occurred
	 */
	public void close() throws IOException {
		if (!closed) {
			super.close();
			closed = true;
		}
	}

	private byte[] b = new byte[256];

	/**
	 * Reads local file (LOC) header for next entry.
	 */
//	private ZipEntry readLOC() throws IOException {
//		try {
//			readFully(tmpbuf, 0, LOCHDR);
//		} catch (EOFException e) {
//			return null;
//		}
//		if (get32(tmpbuf, 0) != LOCSIG) {
//			return null;
//		}
//		// get the entry name and create the ZipEntry first
//		int len = get16(tmpbuf, LOCNAM);
//		int blen = b.length;
//		if (len > blen) {
//			do
//				blen = blen * 2;
//			while (len > blen);
//			b = new byte[blen];
//		}
//		readFully(b, 0, len);
//		ZipEntry e = createZipEntry(getUTF8String(b, 0, len));
//		// now get the remaining fields for the entry
//		flag = get16(tmpbuf, LOCFLG);
//		if ((flag & 1) == 1) {
//			throw new ZipException("encrypted ZIP entry not supported");
//		}
//		e.method = get16(tmpbuf, LOCHOW);
//		e.time = get32(tmpbuf, LOCTIM);
//		if ((flag & 8) == 8) {
//			/* "Data Descriptor" present */
//			if (e.method != DEFLATED) {
//				throw new ZipException(
//						"only DEFLATED entries can have EXT descriptor");
//			}
//		} else {
//			e.crc = get32(tmpbuf, LOCCRC);
//			e.csize = get32(tmpbuf, LOCSIZ);
//			e.size = get32(tmpbuf, LOCLEN);
//		}
//		len = get16(tmpbuf, LOCEXT);
//		if (len > 0) {
//			byte[] bb = new byte[len];
//			readFully(bb, 0, len);
//			e.setExtra(bb);
//		}
//		return e;
//	}

	private ZipEntry readLOC() throws IOException {
		try {
			readFully(tmpbuf, 0, LOCHDR);
		} catch (EOFException e) {
			return null;
		}

		if (get32(tmpbuf, 0) != LOCSIG) {
			return null;
		}

		// get the entry name and create the ZipEntry first
		int len = get16(tmpbuf, LOCNAM);
		int blen = b.length;
		if (len > blen) {
			do
				blen = blen * 2;
			while (len > blen);
			b = new byte[blen];
		}

		readFully(b, 0, len);

		ZipEntry e = createZipEntry(getZipEntryName(b, 0, len));
		// now get the remaining fields for the entry
		flag = get16(tmpbuf, LOCFLG);
		if ((flag & 1) == 1) {
			throw new ZipException("encrypted ZIP entry not supported");
		}

		e.setMethod(get16(tmpbuf, LOCHOW));
		e.setTime(get32(tmpbuf, LOCTIM));
		if ((flag & 8) == 8) {
			/* "Data Descriptor" present */
			if (e.getMethod() != DEFLATED) {
				throw new ZipException("only DEFLATED entries can have EXT descriptor");
			}
		} else {
			e.setCrc(get32(tmpbuf, LOCCRC));
			e.setCompressedSize(get32(tmpbuf, LOCSIZ));
			e.setSize(get32(tmpbuf, LOCLEN));
		}

		len = get16(tmpbuf, LOCEXT);
		if (len > 0) {
			byte[] bb = new byte[len];
			readFully(bb, 0, len);
			e.setExtra(bb);
		}

		return e;
	}

	/**
	 * Fetches a UTF8-encoded String from the specified byte array.
	 */
	private static String getUTF8String(byte[] b, int off, int len) {
		// First, count the number of characters in the sequence
		int count = 0;
		int max = off + len;
		int i = off;
		while (i < max) {
			int c = b[i++] & 0xff;
			switch (c >> 4) {
			case 0:
			case 1:
			case 2:
			case 3:
			case 4:
			case 5:
			case 6:
			case 7:
				// 0xxxxxxx
				count++;
				break;
			case 12:
			case 13:
				// 110xxxxx 10xxxxxx
				if ((int) (b[i++] & 0xc0) != 0x80) {
					throw new IllegalArgumentException();
				}
				count++;
				break;
			case 14:
				// 1110xxxx 10xxxxxx 10xxxxxx
				if (((int) (b[i++] & 0xc0) != 0x80)
						|| ((int) (b[i++] & 0xc0) != 0x80)) {
					throw new IllegalArgumentException();
				}
				count++;
				break;
			default:
				// 10xxxxxx, 1111xxxx
				throw new IllegalArgumentException();
			}
		}
		if (i != max) {
			throw new IllegalArgumentException();
		}
		// Now decode the characters...
		char[] cs = new char[count];
		i = 0;
		while (off < max) {
			int c = b[off++] & 0xff;
			switch (c >> 4) {
			case 0:
			case 1:
			case 2:
			case 3:
			case 4:
			case 5:
			case 6:
			case 7:
				// 0xxxxxxx
				cs[i++] = (char) c;
				break;
			case 12:
			case 13:
				// 110xxxxx 10xxxxxx
				cs[i++] = (char) (((c & 0x1f) << 6) | (b[off++] & 0x3f));
				break;
			case 14:
				// 1110xxxx 10xxxxxx 10xxxxxx
				int t = (b[off++] & 0x3f) << 6;
				cs[i++] = (char) (((c & 0x0f) << 12) | t | (b[off++] & 0x3f));
				break;
			default:
				// 10xxxxxx, 1111xxxx
				throw new IllegalArgumentException();
			}
		}

		return new String(cs, 0, count);
	}

	private String getZipEntryName(byte[] b, int off, int len) {
		try {
			return new String(b, off, len, "ISO-8851-1");
		} catch (UnsupportedEncodingException e) {
			return new String(b, off, len);
		}
	}

	/**
	 * Creates a new <code>ZipEntry</code> object for the specified entry name.
	 * @param name the ZIP file entry name
	 * @return the ZipEntry just created
	 */
	protected ZipEntry createZipEntry(String name) {
		return new ZipEntry(name);
	}

	/**
	 * Reads end of deflated entry as well as EXT descriptor if present.
	 */
//	private void readEnd(ZipEntry e) throws IOException {
//		int n = inf.getRemaining();
//		if (n > 0) {
//			((PushbackInputStream) in).unread(buf, len - n, n);
//		}
//		if ((flag & 8) == 8) {
//			/* "Data Descriptor" present */
//			readFully(tmpbuf, 0, EXTHDR);
//			long sig = get32(tmpbuf, 0);
//			if (sig != EXTSIG) { // no EXTSIG present
//				e.crc = sig;
//				e.csize = get32(tmpbuf, EXTSIZ - EXTCRC);
//				e.size = get32(tmpbuf, EXTLEN - EXTCRC);
//				((PushbackInputStream) in).unread(tmpbuf, EXTHDR - EXTCRC - 1,
//						EXTCRC);
//			} else {
//				e.crc = get32(tmpbuf, EXTCRC);
//				e.csize = get32(tmpbuf, EXTSIZ);
//				e.size = get32(tmpbuf, EXTLEN);
//			}
//		}
//		if (e.size != inf.getBytesWritten()) {
//			throw new ZipException("invalid entry size (expected " + e.size
//					+ " but got " + inf.getBytesWritten() + " bytes)");
//		}
//		if (e.csize != inf.getBytesRead()) {
//			throw new ZipException("invalid entry compressed size (expected "
//					+ e.csize + " but got " + inf.getBytesRead() + " bytes)");
//		}
//		if (e.crc != crc.getValue()) {
//			throw new ZipException("invalid entry CRC (expected 0x"
//					+ Long.toHexString(e.crc) + " but got 0x"
//					+ Long.toHexString(crc.getValue()) + ")");
//		}
//	}

	private void readEnd(ZipEntry e) throws IOException {
		int n = inf.getRemaining();

		if (n > 0) {
			((PushbackInputStream) in).unread(buf, len - n, n);
		}

		if ((flag & 8) == 8) {
			/* "Data Descriptor" present */
			readFully(tmpbuf, 0, EXTHDR);
			long sig = get32(tmpbuf, 0);
			if (sig != EXTSIG) { // no EXTSIG present
				e.setCrc(sig);
				e.setCompressedSize(get32(tmpbuf, EXTSIZ - EXTCRC));
				e.setSize(get32(tmpbuf, EXTLEN - EXTCRC));
				((PushbackInputStream) in).unread(tmpbuf, EXTHDR - EXTCRC - 1, EXTCRC);
			} else {
				e.setCrc(get32(tmpbuf, EXTCRC));
				e.setCompressedSize(get32(tmpbuf, EXTSIZ));
				e.setSize(get32(tmpbuf, EXTLEN));
			}
		}

		if (e.getSize() != inf.getBytesWritten()) {
			throw new ZipException("invalid entry size (expected " + e.getSize() + " but got " + inf.getBytesWritten() + " bytes)");
		}

		if (e.getCompressedSize() != inf.getBytesRead()) {
			throw new ZipException("invalid entry compressed size (expected " + e.getCompressedSize() + " but got " + inf.getBytesRead() + " bytes)");
		}

		if (e.getCrc() != crc.getValue()) {
			throw new ZipException("invalid entry CRC (expected 0x" + Long.toHexString(e.getCrc()) + " but got 0x" + Long.toHexString(crc.getValue()) + ")");
		}
	}

	/**
	 * Reads bytes, blocking until all bytes are read.
	 */
	private void readFully(byte[] b, int off, int len) throws IOException {
		while (len > 0) {
			int n = in.read(b, off, len);

			if (n == -1) {
				throw new EOFException();
			}

			off += n;
			len -= n;
		}
	}

	/**
	 * Fetches unsigned 16-bit value from byte array at specified offset. The
	 * bytes are assumed to be in Intel (little-endian) byte order.
	 */
	private static final int get16(byte b[], int off) {
		return (b[off] & 0xff) | ((b[off + 1] & 0xff) << 8);
	}

	/**
	 * Fetches unsigned 32-bit value from byte array at specified offset. The
	 * bytes are assumed to be in Intel (little-endian) byte order.
	 */
	private static final long get32(byte b[], int off) {
		return get16(b, off) | ((long) get16(b, off + 2) << 16);
	}
}