/*
 ** 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.File;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * 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 $Revision$
 * @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;
    }

    /**
     * 
     */
    public void setEntryFactory(EntryFactory factory)
    {
        this.eFactory = factory;
    }

    /**
     * 
     */
    public void setBufferDebug(boolean debug)
    {
        this.buffer.setDebug(debug);
    }

    /**
     * Closes this stream. Calls the TarBuffer's close() method.
     */
    /* @Override */
    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.
     */
    /* @Override */
    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.
     */
    /* @Override */
    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.
     */
    /* @Override */
    public boolean markSupported()
    {
        return false;
    }

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

    /**
     * Since we do not support marking just yet, we do nothing.
     */
    /* @Override */
    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.
     */
    /* @Override */
    public int read() throws IOException
    {
        int num = this.read(this.oneBuf, 0, 1);
        if (num == -1)
        {
            return num;
        }

        return 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.
     */
    /* @Override */
    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.
     */
    /* @Override */
    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);
        }
    }

}