/*
** Authored by Timothy Gerard Endres
** <mailto:time@gjt.org>  <http://www.trustice.com>
** 
** This work has been placed into the public domain.
** You may use this work in any way and for any purpose you wish.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE. 
** 
*/

package com.ice.tar;

import java.io.*;
import javax.activation.*;


/**
 * The TarInputStream reads a UNIX tar archive as an InputStream.
 * methods are provided to position at each successive entry in
 * the archive, and the read each entry as a normal input stream
 * using read().
 *
 * Kerry Menzel <kmenzel@cfl.rr.com> Contributed the code to support
 * file sizes greater than 2GB (longs versus ints).
 *
 *
 * @version $Revision: 1.9 $
 * @author Timothy Gerard Endres, <time@gjt.org>
 * @see TarBuffer
 * @see TarHeader
 * @see TarEntry
 */


public
class           TarInputStream
extends         FilterInputStream
        {
        protected boolean                       debug;
        protected boolean                       hasHitEOF;

        protected long                          entrySize;
        protected long                          entryOffset;

        protected byte[]                        oneBuf;
        protected byte[]                        readBuf;

        protected TarBuffer                     buffer;

        protected TarEntry                      currEntry;

        protected EntryFactory          eFactory;


        public
        TarInputStream( InputStream is )
                {
                this( is, TarBuffer.DEFAULT_BLKSIZE, TarBuffer.DEFAULT_RCDSIZE );
                }

        public
        TarInputStream( InputStream is, int blockSize )
                {
                this( is, blockSize, TarBuffer.DEFAULT_RCDSIZE );
                }

        public
        TarInputStream( InputStream is, int blockSize, int recordSize )
                {
                super( is );

                this.buffer = new TarBuffer( is, blockSize, recordSize );

                this.readBuf = null;
                this.oneBuf = new byte[1];
                this.debug = false;
                this.hasHitEOF = false;
                this.eFactory = null;
                }

        /**
         * Sets the debugging flag.
         *
         * @param debugF True to turn on debugging.
         */
        public void
        setDebug( boolean debugF )
                {
                this.debug = debugF;
                }

        /**
         * Sets the debugging flag.
         *
         * @param debugF True to turn on debugging.
         */
        public void
        setEntryFactory( EntryFactory factory )
                {
                this.eFactory = factory;
                }

        /**
         * Sets the debugging flag in this stream's TarBuffer.
         *
         * @param debugF True to turn on debugging.
         */
        public void
        setBufferDebug( boolean debug )
                {
                this.buffer.setDebug( debug );
                }

        /**
         * Closes this stream. Calls the TarBuffer's close() method.
         */
        public void
        close()
                throws IOException
                {
                this.buffer.close();
                }

        /**
         * Get the record size being used by this stream's TarBuffer.
         *
         * @return The TarBuffer record size.
         */
        public int
        getRecordSize()
                {
                return this.buffer.getRecordSize();
                }

        /**
         * Get the available data that can be read from the current
         * entry in the archive. This does not indicate how much data
         * is left in the entire archive, only in the current entry.
         * This value is determined from the entry's size header field
         * and the amount of data already read from the current entry.
         * 
         *
         * @return The number of available bytes for the current entry.
         */
        public int
        available()
                throws IOException
                {
                return (int)(this.entrySize - this.entryOffset);
                }

        /**
         * Skip bytes in the input buffer. This skips bytes in the
         * current entry's data, not the entire archive, and will
         * stop at the end of the current entry's data if the number
         * to skip extends beyond that point.
         *
         * @param numToSkip The number of bytes to skip.
         * @return The actual number of bytes skipped.
         */
        public long
        skip( long numToSkip )
                throws IOException
                {
                // REVIEW
                // This is horribly inefficient, but it ensures that we
                // properly skip over bytes via the TarBuffer...
                //

                byte[] skipBuf = new byte[ 8 * 1024 ];
        long num = numToSkip;
                for ( ; num > 0 ; )
                        {
                        int numRead =
                                this.read( skipBuf, 0,
                                        ( num > skipBuf.length ? skipBuf.length : (int) num ) );

                        if ( numRead == -1 )
                                break;

                        num -= numRead;
                        }

                return ( numToSkip - num );
                }

        /**
         * Since we do not support marking just yet, we return false.
         *
         * @return False.
         */
        public boolean
        markSupported()
                {
                return false;
                }

        /**
         * Since we do not support marking just yet, we do nothing.
         *
         * @param markLimit The limit to mark.
         */
        public void
        mark( int markLimit )
                {
                }

        /**
         * Since we do not support marking just yet, we do nothing.
         */
        public void
        reset()
                {
                }

        /**
         * Get the number of bytes into the current TarEntry.
         * This method returns the number of bytes that have been read
         * from the current TarEntry's data.
         *
         * @returns The current entry offset.
         */

        public long
        getEntryPosition()
                {
                return this.entryOffset;
                }

        /**
         * Get the number of bytes into the stream we are currently at.
         * This method accounts for the blocking stream that tar uses,
         * so it represents the actual position in input stream, as
         * opposed to the place where the tar archive parsing is.
         *
         * @returns The current file pointer.
         */

        public long
        getStreamPosition()
                {
                return ( buffer.getBlockSize() * buffer.getCurrentBlockNum() )
                                        + buffer.getCurrentRecordNum();
                }

        /**
         * Get the next entry in this tar archive. This will skip
         * over any remaining data in the current entry, if there
         * is one, and place the input stream at the header of the
         * next entry, and read the header and instantiate a new
         * TarEntry from the header bytes and return that entry.
         * If there are no more entries in the archive, null will
         * be returned to indicate that the end of the archive has
         * been reached.
         *
         * @return The next TarEntry in the archive, or null.
         */
        public TarEntry
        getNextEntry()
                throws IOException
                {
                if ( this.hasHitEOF )
                        return null;

                if ( this.currEntry != null )
                        {
                        long numToSkip = (this.entrySize - this.entryOffset);

                        if ( this.debug )
                        System.err.println
                                ( "TarInputStream: SKIP currENTRY '"
                                + this.currEntry.getName() + "' SZ "
                                + this.entrySize + " OFF " + this.entryOffset
                                + "  skipping " + numToSkip + " bytes" );

                        if ( numToSkip > 0 )
                                {
                                this.skip( numToSkip );
                                }

                        this.readBuf = null;
                        }

                byte[] headerBuf = this.buffer.readRecord();

                if ( headerBuf == null )
                        {
                        if ( this.debug )
                                {
                                System.err.println( "READ NULL RECORD" );
                                }

                        this.hasHitEOF = true;
                        }
                else if ( this.buffer.isEOFRecord( headerBuf ) )
                        {
                        if ( this.debug )
                                {
                                System.err.println( "READ EOF RECORD" );
                                }

                        this.hasHitEOF = true;
                        }

                if ( this.hasHitEOF )
                        {
                        this.currEntry = null;
                        }
                else
                        {
                        try {
                                if ( this.eFactory == null )
                                        {
                                        this.currEntry = new TarEntry( headerBuf );
                                        }
                                else
                                        {
                                        this.currEntry =
                                                this.eFactory.createEntry( headerBuf );
                                        }

                                if ( this.debug )
                                System.err.println
                                        ( "TarInputStream: SET CURRENTRY '"
                                                + this.currEntry.getName()
                                                + "' size = " + this.currEntry.getSize() );

                                this.entryOffset = 0;
                                this.entrySize = this.currEntry.getSize();
                                }
                        catch ( InvalidHeaderException ex )
                                {
                                this.entrySize = 0;
                                this.entryOffset = 0;
                                this.currEntry = null;
                                throw new InvalidHeaderException
                                        ( "bad header in block "
                                                + this.buffer.getCurrentBlockNum()
                                                + " record "
                                                + this.buffer.getCurrentRecordNum()
                                                + ", " + ex.getMessage() );
                                }
                        }

                return this.currEntry;
                }

        /**
         * Reads a byte from the current tar archive entry.
         *
         * This method simply calls read( byte[], int, int ).
         *
         * @return The byte read, or -1 at EOF.
         */
        public int
        read()
                throws IOException
                {
                int num = this.read( this.oneBuf, 0, 1 );
                if ( num == -1 )
                        return num;
                else
                        return (int) this.oneBuf[0];
                }

        /**
         * Reads bytes from the current tar archive entry.
         *
         * This method simply calls read( byte[], int, int ).
         *
         * @param buf The buffer into which to place bytes read.
         * @return The number of bytes read, or -1 at EOF.
         */
        public int
        read( byte[] buf )
                throws IOException
                {
                return this.read( buf, 0, buf.length );
                }

        /**
         * Reads bytes from the current tar archive entry.
         *
         * This method is aware of the boundaries of the current
         * entry in the archive and will deal with them as if they
         * were this stream's start and EOF.
         *
         * @param buf The buffer into which to place bytes read.
         * @param offset The offset at which to place bytes read.
         * @param numToRead The number of bytes to read.
         * @return The number of bytes read, or -1 at EOF.
         */
        public int
        read( byte[] buf, int offset, int numToRead )
                throws IOException
                {
                int totalRead = 0;

                if ( this.entryOffset >= this.entrySize )
                        return -1;

                if ( (numToRead + this.entryOffset) > this.entrySize )
                        {
                        numToRead = (int) (this.entrySize - this.entryOffset);
                        }

                if ( this.readBuf != null )
                        {
                        int sz = ( numToRead > this.readBuf.length )
                                                ? this.readBuf.length : numToRead;

                        System.arraycopy( this.readBuf, 0, buf, offset, sz );

                        if ( sz >= this.readBuf.length )
                                {
                                this.readBuf = null;
                                }
                        else
                                {
                                int newLen = this.readBuf.length - sz;
                                byte[] newBuf = new byte[ newLen ];
                                System.arraycopy( this.readBuf, sz, newBuf, 0, newLen );
                                this.readBuf = newBuf;
                                }

                        totalRead += sz;
                        numToRead -= sz;
                        offset += sz;
                        }

                for ( ; numToRead > 0 ; )
                        {
                        byte[] rec = this.buffer.readRecord();
                        if ( rec == null )
                                {
                                // Unexpected EOF!
                                throw new IOException
                                        ( "unexpected EOF with " + numToRead + " bytes unread" );
                                }

                        int sz = numToRead;
                        int recLen = rec.length;

                        if ( recLen > sz )
                                {
                                System.arraycopy( rec, 0, buf, offset, sz );
                                this.readBuf = new byte[ recLen - sz ];
                                System.arraycopy( rec, sz, this.readBuf, 0, recLen - sz );
                                }
                        else
                                {
                                sz = recLen;
                                System.arraycopy( rec, 0, buf, offset, recLen );
                                }

                        totalRead += sz;
                        numToRead -= sz;
                        offset += sz;
                        }

                this.entryOffset += totalRead;

                return totalRead;
                }

        /**
         * Copies the contents of the current tar archive entry directly into
         * an output stream.
         *
         * @param out The OutputStream into which to write the entry's data.
         */
        public void
        copyEntryContents( OutputStream out )
                throws IOException
                {
                byte[] buf = new byte[ 32 * 1024 ];

                for ( ; ; )
                        {
                        int numRead = this.read( buf, 0, buf.length );
                        if ( numRead == -1 )
                                break;
                        out.write( buf, 0, numRead );
                        }
                }

        /**
         * This interface is provided, with the method setEntryFactory(), to allow
         * the programmer to have their own TarEntry subclass instantiated for the
         * entries return from getNextEntry().
         */

        public
        interface       EntryFactory
                {
                public TarEntry
                        createEntry( String name );

                public TarEntry
                        createEntry( File path )
                                throws InvalidHeaderException;

                public TarEntry
                        createEntry( byte[] headerBuf )
                                throws InvalidHeaderException;
                }

        public
        class           EntryAdapter
        implements      EntryFactory
                {
                public TarEntry
                createEntry( String name )
                        {
                        return new TarEntry( name );
                        }

                public TarEntry
                createEntry( File path )
                        throws InvalidHeaderException
                        {
                        return new TarEntry( path );
                        }

                public TarEntry
                createEntry( byte[] headerBuf )
                        throws InvalidHeaderException
                        {
                        return new TarEntry( headerBuf );
                        }
                }

        }