/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2000 The Apache Software Foundation.  All rights
 *  reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
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 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
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 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
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package org.apache.poi.hpsf;

import java.io.*;
import java.util.*;
import org.apache.poi.hpsf.wellknown.*;
import org.apache.poi.poifs.filesystem.*;
import org.apache.poi.util.LittleEndian;

/**
 * <p>Represents a property set in the Horrible Property Set Format
 * (HPSF). These are usually metadata of a Microsoft Office
 * document.</p>
 *
 * <p>An application that wants to access these metadata should create
 * an instance of this class or one of its subclasses by calling the
 * factory method {@link PropertySetFactory#create} and then retrieve
 * the information its needs by calling appropriate methods.</p>
 *
 * <p>{@link PropertySetFactory#create} does its work by calling one
 * of the constructors {@link PropertySet#PropertySet(InputStream)} or
 * {@link PropertySet#PropertySet(byte[])}. If the constructor's
 * argument is not in the Horrible Property Set Format, i.e. not a
 * property set stream, or if any other error occurs, an appropriate
 * exception is thrown.</p>
 *
 * <p>A {@link PropertySet} has a list of {@link Section}s, and each
 * {@link Section} has a {@link Property} array. Use {@link
 * #getSections} to retrieve the {@link Section}s, then call {@link
 * Section#getProperties} for each {@link Section} to get hold of the
 * {@link Property} arrays.</p> Since the vast majority of {@link
 * PropertySet}s contains only a single {@link Section}, the
 * convenience method {@link #getProperties} returns the properties of
 * a {@link PropertySet}'s {@link Section} (throwing a {@link
 * NoSingleSectionException} if the {@link PropertySet} contains more
 * (or less) than exactly one {@link Section}).</p>
 *
 * @author Rainer Klute (klute@rainer-klute.de)
 * @author Drew Varner (Drew.Varner hanginIn sc.edu)
 * @version $Id$
 * @since 2002-02-09
 */
public class PropertySet
{

    /**
     * <p>The "byteOrder" field must equal this value.</p>
     */
    final static byte[] BYTE_ORDER_ASSERTION =
	new byte[]{(byte) 0xFE, (byte) 0xFF};

    /**
     * <p>The "format" field must equal this value.</p>
     */
    final static byte[] FORMAT_ASSERTION =
	new byte[]{(byte) 0x00, (byte) 0x00};

    /**
     * <p>Specifies this {@link PropertySet}'s byte order. See the
     * HPFS documentation for details!</p>
     */
    private int byteOrder;

    /**
     * <p>Returns the property set stream's low-level "byte order"
     * field. It is always <tt>0xFFFE</tt> .</p>
     *
     * @return The property set stream's low-level "byte order" field.
     */
    public int getByteOrder()
    {
        return byteOrder;
    }



    /**
     * <p>Specifies this {@link PropertySet}'s format. See the HPFS
     * documentation for details!</p>
     */
    private int format;

    /**
     * <p>Returns the property set stream's low-level "format"
     * field. It is always <tt>0x0000</tt> .</p>
     *
     * @return The property set stream's low-level "format" field.
     */
    public int getFormat()
    {
        return format;
    }


 
    /**
     * <p>Specifies the version of the operating system that created
     * this {@link PropertySet}. See the HPFS documentation for
     * details!</p>
     */
    private long osVersion;

    /**
     * <p>Returns the property set stream's low-level "OS version"
     * field.</p>
     *
     * @return The property set stream's low-level "OS version" field.
     */
    public long getOSVersion()
    {
        return osVersion;
    }



    /**
     * <p>Specifies this {@link PropertySet}'s "classID" field. See
     * the HPFS documentation for details!</p>
     */
    private ClassID classID;

    /**
     * <p>Returns the property set stream's low-level "class ID"
     * field.</p>
     *
     * @return The property set stream's low-level "class ID" field.
     */
    public ClassID getClassID()
    {
        return classID;
    }



    /**
     * <p>The number of sections in this {@link PropertySet}.</p>
     */
    private long sectionCount;


    /**
     * <p>Returns the number of {@link Section}s in the property
     * set.</p>
     *
     * @return The number of {@link Section}s in the property set.
     */
    public long getSectionCount()
    {
        return sectionCount;
    }



    /**
     * <p>The sections in this {@link PropertySet}.</p>
     */
    private List sections;


    /**
     * <p>Returns the {@link Section}s in the property set.</p>
     *
     * @return The {@link Section}s in the property set.
     */
    public List getSections()
    {
        return sections;
    }



    /**
     * <p>Creates an empty (uninitialized) {@link PropertySet}.</p>
     *
     * <p><strong>Please note:</strong> For the time being this
     * constructor is protected since it is used for internal purposes
     * only, but expect it to become public once the property set's
     * writing functionality is implemented.</p>
     */
    protected PropertySet()
    {}



    /**
     * <p>Creates a {@link PropertySet} instance from an {@link
     * InputStream} in the Horrible Property Set Format.</p>
     *
     * <p>The constructor reads the first few bytes from the stream
     * and determines whether it is really a property set stream. If
     * it is, it parses the rest of the stream. If it is not, it
     * resets the stream to its beginning in order to let other
     * components mess around with the data and throws an
     * exception.</p>
     *
     * @param stream Holds the data making out the property set
     * stream.
     * @throws MarkUnsupportedException if the stream does not support
     * the {@link InputStream#markSupported} method.
     * @throws IOException if the {@link InputStream} cannot not be
     * accessed as needed.
     */
    public PropertySet(final InputStream stream)
	throws NoPropertySetStreamException, MarkUnsupportedException,
	       IOException
    {
        if (isPropertySetStream(stream))
	{
            final int avail = stream.available();
            final byte[] buffer = new byte[avail];
            stream.read(buffer, 0, buffer.length);
            init(buffer, 0, buffer.length);
        }
	else
            throw new NoPropertySetStreamException();
    }



    /**
     * <p>Creates a {@link PropertySet} instance from a byte array
     * that represents a stream in the Horrible Property Set
     * Format.</p>
     *
     * @param stream The byte array holding the stream data.
     * @param offset The offset in <var>stream</var> where the stream
     * data begin. If the stream data begin with the first byte in the
     * array, the <var>offset</var> is 0.
     * @param length The length of the stream data.
     * @throws NoPropertySetStreamException if the byte array is not a
     * property set stream.
     */
    public PropertySet(final byte[] stream, final int offset, final int length)
	throws NoPropertySetStreamException
    {
        if (isPropertySetStream(stream, offset, length))
            init(stream, offset, length);
	else
            throw new NoPropertySetStreamException();
    }



    /**
     * <p>Creates a {@link PropertySet} instance from a byte array
     * that represents a stream in the Horrible Property Set
     * Format.</p>
     *
     * @param stream The byte array holding the stream data. The
     * complete byte array contents is the stream data.
     * @throws NoPropertySetStreamException if the byte array is not a
     * property set stream.
     */
    public PropertySet(final byte[] stream) throws NoPropertySetStreamException
    {
        this(stream, 0, stream.length);
    }



    /**
     * <p>Checks whether an {@link InputStream} is in the Horrible
     * Property Set Format.</p>
     *
     * @param stream The {@link InputStream} to check. In order to
     * perform the check, the method reads the first bytes from the
     * stream. After reading, the stream is reset to the position it
     * had before reading. The {@link InputStream} must support the
     * {@link InputStream#mark} method.
     * @return <code>true</code> if the stream is a property set
     * stream, else <code>false</code>.
     * @throws MarkUnsupportedException if the {@link InputStream}
     * does not support the {@link InputStream#mark} method.
     */
    public static boolean isPropertySetStream(final InputStream stream)
	throws MarkUnsupportedException, IOException
    {
        /*
         * Read at most this many bytes.
         */
        final int BUFFER_SIZE = 50;

        /*
         * Mark the current position in the stream so that we can
         * reset to this position if the stream does not contain a
         * property set.
         */
        if (!stream.markSupported())
            throw new MarkUnsupportedException(stream.getClass().getName());
	stream.mark(BUFFER_SIZE);

        /*
         * Read a couple of bytes from the stream.
         */
        final byte[] buffer = new byte[BUFFER_SIZE];
        final int bytes =
	    stream.read(buffer, 0,
			Math.min(buffer.length, stream.available()));
        final boolean isPropertySetStream =
	    isPropertySetStream(buffer, 0, bytes);
        stream.reset();
        return isPropertySetStream;
    }



    /**
     * <p>Checks whether a byte array is in the Horrible Property Set
     * Format.</p>
     *
     * @param src The byte array to check.
     * @param offset The offset in the byte array.
     * @param length The significant number of bytes in the byte
     * array. Only this number of bytes will be checked.
     * @return <code>true</code> if the byte array is a property set
     * stream, <code>false</code> if not.
     */
    public static boolean isPropertySetStream(final byte[] src, int offset,
					      final int length)
    {
        /*
         * Read the header fields of the stream. They must always be
         * there.
         */
        final int byteOrder = LittleEndian.getUShort(src, offset);
        offset += LittleEndian.SHORT_SIZE;
        byte[] temp = new byte[LittleEndian.SHORT_SIZE];
        LittleEndian.putShort(temp,(short)byteOrder);
        if (!Util.equal(temp, BYTE_ORDER_ASSERTION))
            return false;
	final int format = LittleEndian.getUShort(src, offset);
        offset += LittleEndian.SHORT_SIZE;
        temp = new byte[LittleEndian.SHORT_SIZE];
        LittleEndian.putShort(temp,(short)format);
        if (!Util.equal(temp, FORMAT_ASSERTION))
            return false;
	final long osVersion = LittleEndian.getUInt(src, offset);
        offset += LittleEndian.INT_SIZE;
        final ClassID classID = new ClassID(src, offset);
        offset += ClassID.LENGTH;
        final long sectionCount = LittleEndian.getUInt(src, offset);
        offset += LittleEndian.INT_SIZE;
        if (sectionCount < 1)
            return false;
	return true;
    }



    /**
     * <p>Initializes this {@link PropertySet} instance from a byte
     * array. The method assumes that it has been checked already that
     * the byte array indeed represents a property set stream. It does
     * no more checks on its own.</p>
     *
     * @param src Byte array containing the property set stream
     * @param offset The property set stream starts at this offset
     * from the beginning of <var>src</src>
     * @param length Length of the property set stream.
     */
    private void init(final byte[] src, int offset, final int length)
    {
        /*
         * Read the stream's header fields.
         */
        byteOrder = LittleEndian.getUShort(src, offset);
        offset += LittleEndian.SHORT_SIZE;
        format = LittleEndian.getUShort(src, offset);
        offset += LittleEndian.SHORT_SIZE;
        osVersion = LittleEndian.getUInt(src, offset);
        offset += LittleEndian.INT_SIZE;
        classID = new ClassID(src, offset);
        offset += ClassID.LENGTH;
        sectionCount = LittleEndian.getUInt(src, offset);
        offset += LittleEndian.INT_SIZE;

        /*
         * Read the sections, which are following the header. They
         * start with an array of section descriptions. Each one
         * consists of a format ID telling what the section contains
         * and an offset telling how many bytes from the start of the
         * stream the section begins.
         */
        /*
         * Most property sets have only one section. The Document
         * Summary Information stream has 2. Everything else is a rare
         * exception and is no longer fostered by Microsoft.
         */
        sections = new ArrayList(2);

        /*
         * Loop over the section descriptor array. Each descriptor
         * consists of a ClassID and a DWord, and we have to increment
         * "offset" accordingly.
         */
        for (int i = 0; i < sectionCount; i++)
	{
            final Section s = new Section(src, offset);
            offset += ClassID.LENGTH + LittleEndian.INT_SIZE;
            sections.add(s);
        }
    }



    /**
     * <p>Checks whether this {@link PropertySet} represents a Summary
     * Information.</p>
     *
     * @return <code>true</code> if this {@link PropertySet}
     * represents a Summary Information, else <code>false</code>.
     */
    public boolean isSummaryInformation()
    {
        return Util.equal(((Section) sections.get(0)).getFormatID().getBytes(),
			  SectionIDMap.SUMMARY_INFORMATION_ID);
    }



    /**
     * <p>Checks whether this {@link PropertySet} is a Document
     * Summary Information.</p>
     *
     * @return <code>true</code> if this {@link PropertySet}
     * represents a Document Summary Information, else <code>false</code>.
     */
    public boolean isDocumentSummaryInformation()
    {
        return Util.equal(((Section) sections.get(0)).getFormatID().getBytes(),
			  SectionIDMap.DOCUMENT_SUMMARY_INFORMATION_ID);
    }



    /**
     * <p>Convenience method returning the {@link Property} array
     * contained in this property set. It is a shortcut for getting
     * the {@link PropertySet}'s {@link Section}s list and then
     * getting the {@link Property} array from the first {@link
     * Section}. However, it can only be used if the {@link
     * PropertySet} contains exactly one {@link Section}, so check
     * {@link #getSectionCount} first!</p>
     *
     * @return The properties of the only {@link Section} of this
     * {@link PropertySet}.
     * @throws NoSingleSectionException if the {@link PropertySet} has
     * more or less than one {@link Section}.
     */
    public Property[] getProperties()
	throws NoSingleSectionException
    {
        return getSingleSection().getProperties();
    }



    /**
     * <p>Convenience method returning the value of the property with
     * the specified ID. If the property is not available,
     * <code>null</code> is returned and a subsequent call to {@link
     * #wasNull} will return <code>true</code> .</p>
     *
     * @param id The property ID
     * @return The property value
     * @throws NoSingleSectionException if the {@link PropertySet} has
     * more or less than one {@link Section}.
     */
    protected Object getProperty(final int id) throws NoSingleSectionException
    {
        return getSingleSection().getProperty(id);
    }



    /**
     * <p>Convenience method returning the value of a boolean property
     * with the specified ID. If the property is not available,
     * <code>false</code> is returned. A subsequent call to {@link
     * #wasNull} will return <code>true</code> to let the caller
     * distinguish that case from a real property value of
     * <code>false</code>.</p>
     *
     * @param id The property ID
     * @return The property value
     * @throws NoSingleSectionException if the {@link PropertySet} has
     * more or less than one {@link Section}.
     */
    protected boolean getPropertyBooleanValue(final int id)
	throws NoSingleSectionException
    {
        return getSingleSection().getPropertyBooleanValue(id);
    }



    /**
     * <p>Convenience method returning the value of the numeric
     * property with the specified ID. If the property is not
     * available, 0 is returned. A subsequent call to {@link #wasNull}
     * will return <code>true</code> to let the caller distinguish
     * that case from a real property value of 0.</p>
     *
     * @param id The property ID
     * @return The propertyIntValue value
     * @throws NoSingleSectionException if the {@link PropertySet} has
     * more or less than one {@link Section}.
     */
    protected int getPropertyIntValue(final int id)
	throws NoSingleSectionException
    {
        return getSingleSection().getPropertyIntValue(id);
    }



    /**
     * <p>Checks whether the property which the last call to {@link
     * #getPropertyIntValue} or {@link #getProperty} tried to access
     * was available or not. This information might be important for
     * callers of {@link #getPropertyIntValue} since the latter
     * returns 0 if the property does not exist. Using {@link
     * #wasNull}, the caller can distiguish this case from a
     * property's real value of 0.</p>
     *
     * @return <code>true</code> if the last call to {@link
     * #getPropertyIntValue} or {@link #getProperty} tried to access a
     * property that was not available, else <code>false</code>.
     * @throws NoSingleSectionException if the {@link PropertySet} has
     * more than one {@link Section}.
     */
    public boolean wasNull() throws NoSingleSectionException
    {
        return getSingleSection().wasNull();
    }



    /**
     * <p>If the {@link PropertySet} has only a single section this
     * method returns it.</p>
     *
     *@return The singleSection value
     *@throws NoSingleSectionException if the {@link PropertySet} has
     *more or less than exactly one {@link Section}.
     */
    public Section getSingleSection()
    {
        if (sectionCount != 1)
	    throw new NoSingleSectionException
		("Property set contains " + sectionCount + " sections.");
	return ((Section) sections.get(0));
    }

}