/*

 ============================================================================
                   The Apache Software License, Version 1.1
 ============================================================================

 Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.

 Redistribution and use in source and binary forms, with or without modifica-
 tion, 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.

 2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

 3. The end-user documentation included with the redistribution, 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.

 4. The names "Batik" and  "Apache Software Foundation" must  not  be
    used to  endorse or promote  products derived from  this software without
    prior written permission. For written permission, please contact
    apache@apache.org.

 5. Products  derived from this software may not  be called "Apache", nor may
    "Apache" appear  in their name,  without prior written permission  of the
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 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL  THE
 APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
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 This software  consists of voluntary contributions made  by many individuals
 on  behalf of the Apache Software  Foundation. For more  information on the
 Apache Software Foundation, please see <http://www.apache.org/>.

*/

package org.apache.batik.ext.awt.image.codec.tiff;

import java.io.IOException;
import java.io.Serializable;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import org.apache.batik.ext.awt.image.codec.SeekableStream;

/**
 * A class representing an Image File Directory (IFD) from a TIFF 6.0
 * stream.  The TIFF file format is described in more detail in the
 * comments for the TIFFDescriptor class.
 *
 * <p> A TIFF IFD consists of a set of TIFFField tags.  Methods are
 * provided to query the set of tags and to obtain the raw field
 * array.  In addition, convenience methods are provided for acquiring
 * the values of tags that contain a single value that fits into a
 * byte, int, long, float, or double.
 *
 * <p> Every TIFF file is made up of one or more public IFDs that are
 * joined in a linked list, rooted in the file header.  A file may
 * also contain so-called private IFDs that are referenced from
 * tag data and do not appear in the main list.
 *
 * <p><b> This class is not a committed part of the JAI API.  It may
 * be removed or changed in future releases of JAI.</b>
 *
 * @see TIFFField
 */
public class TIFFDirectory extends Object implements Serializable {

    /** A boolean storing the endianness of the stream. */
    boolean isBigEndian;
    
    /** The number of entries in the IFD. */
    int numEntries;

    /** An array of TIFFFields. */
    TIFFField[] fields;

    /** A Hashtable indexing the fields by tag number. */
    Hashtable fieldIndex = new Hashtable();

    /** The offset of this IFD. */
    long IFDOffset = 8;

    /** The offset of the next IFD. */
    long nextIFDOffset = 0;

    /** The default constructor. */
    TIFFDirectory() {}

    private static boolean isValidEndianTag(int endian) {
        return ((endian == 0x4949) || (endian == 0x4d4d));
    }

    /**
     * Constructs a TIFFDirectory from a SeekableStream.
     * The directory parameter specifies which directory to read from
     * the linked list present in the stream; directory 0 is normally
     * read but it is possible to store multiple images in a single
     * TIFF file by maintaing multiple directories.
     *
     * @param stream a SeekableStream to read from.
     * @param directory the index of the directory to read.
     */
    public TIFFDirectory(SeekableStream stream, int directory)
        throws IOException {

        long global_save_offset = stream.getFilePointer();
        long ifd_offset;

        // Read the TIFF header
        stream.seek(0L);
        int endian = stream.readUnsignedShort();
        if (!isValidEndianTag(endian)) {
            throw new 
		IllegalArgumentException("TIFFDirectory1");
        }
        isBigEndian = (endian == 0x4d4d);

        int magic = readUnsignedShort(stream);
        if (magic != 42) {
            throw new 
		IllegalArgumentException("TIFFDirectory2");
        }

        // Get the initial ifd offset as an unsigned int (using a long)
        ifd_offset = readUnsignedInt(stream);
        
        for (int i = 0; i < directory; i++) {
            if (ifd_offset == 0L) {
                throw new 
		   IllegalArgumentException("TIFFDirectory3");
            }
            
            stream.seek(ifd_offset);
            int entries = readUnsignedShort(stream);
            stream.skip(12*entries);

            ifd_offset = readUnsignedInt(stream);
        }

        stream.seek(ifd_offset);
        initialize(stream);
        stream.seek(global_save_offset);
    }

    /**
     * Constructs a TIFFDirectory by reading a SeekableStream.
     * The ifd_offset parameter specifies the stream offset from which
     * to begin reading; this mechanism is sometimes used to store
     * private IFDs within a TIFF file that are not part of the normal
     * sequence of IFDs.
     *
     * @param stream a SeekableStream to read from.
     * @param ifd_offset the long byte offset of the directory.
     * @param directory the index of the directory to read beyond the
     *        one at the current stream offset; zero indicates the IFD
     *        at the current offset.
     */
    public TIFFDirectory(SeekableStream stream, long ifd_offset, int directory)
        throws IOException {

        long global_save_offset = stream.getFilePointer();
        stream.seek(0L);
        int endian = stream.readUnsignedShort();
        if (!isValidEndianTag(endian)) {
            throw new 
		IllegalArgumentException("TIFFDirectory1");
        }
        isBigEndian = (endian == 0x4d4d);

        // Seek to the first IFD.
        stream.seek(ifd_offset);

        // Seek to desired IFD if necessary.
        int dirNum = 0;
        while(dirNum < directory) {
            // Get the number of fields in the current IFD.
            int numEntries = readUnsignedShort(stream);

            // Skip to the next IFD offset value field.
            stream.seek(ifd_offset + 12*numEntries);

            // Read the offset to the next IFD beyond this one.
            ifd_offset = readUnsignedInt(stream);

            // Seek to the next IFD.
            stream.seek(ifd_offset);

            // Increment the directory.
            dirNum++;
        }

        initialize(stream);
        stream.seek(global_save_offset);
    }

    private static final int[] sizeOfType = {
        0, //  0 = n/a
        1, //  1 = byte
        1, //  2 = ascii
        2, //  3 = short
        4, //  4 = long
        8, //  5 = rational
        1, //  6 = sbyte
        1, //  7 = undefined
        2, //  8 = sshort
        4, //  9 = slong
        8, // 10 = srational
        4, // 11 = float
        8  // 12 = double 
    };

    private void initialize(SeekableStream stream) throws IOException {
        long nextTagOffset;
        int i, j;

        IFDOffset = stream.getFilePointer();

        numEntries = readUnsignedShort(stream);
        fields = new TIFFField[numEntries];
        
        for (i = 0; i < numEntries; i++) {
            int tag = readUnsignedShort(stream);
            int type = readUnsignedShort(stream);
            int count = (int)(readUnsignedInt(stream));
            int value = 0;
	    
            // The place to return to to read the next tag
            nextTagOffset = stream.getFilePointer() + 4;

	    try {
		// If the tag data can't fit in 4 bytes, the next 4 bytes
		// contain the starting offset of the data
		if (count*sizeOfType[type] > 4) {
		    value = (int)(readUnsignedInt(stream));
		    stream.seek(value);
		}
	    } catch (ArrayIndexOutOfBoundsException ae) {

		System.err.println(tag + " " + "TIFFDirectory4");
		// if the data type is unknown we should skip this TIFF Field
		stream.seek(nextTagOffset);
		continue;
	    }

            fieldIndex.put(new Integer(tag), new Integer(i));
            Object obj = null;

            switch (type) {
            case TIFFField.TIFF_BYTE:
            case TIFFField.TIFF_SBYTE:
            case TIFFField.TIFF_UNDEFINED:
            case TIFFField.TIFF_ASCII:
                byte[] bvalues = new byte[count];
                stream.readFully(bvalues, 0, count);

		if (type == TIFFField.TIFF_ASCII) {

		    // Can be multiple strings
		    int index = 0, prevIndex = 0;
		    Vector v = new Vector();

		    while (index < count) {
			
                        while ((index < count) && (bvalues[index++] != 0));

			// When we encountered zero, means one string has ended
			v.add(new String(bvalues, prevIndex, 
					 (index - prevIndex)) );
			prevIndex = index;
		    }

		    count = v.size();
		    String strings[] = new String[count];
		    for (int c = 0 ; c < count; c++) {
			strings[c] = (String)v.elementAt(c);
		    }

		    obj = strings;
		} else {
		    obj = bvalues;
		}

                break;

            case TIFFField.TIFF_SHORT:
                char[] cvalues = new char[count];
                for (j = 0; j < count; j++) {
		    cvalues[j] = (char)(readUnsignedShort(stream));
                }
                obj = cvalues;
                break;
                
            case TIFFField.TIFF_LONG:
                long[] lvalues = new long[count];
                for (j = 0; j < count; j++) {
                    lvalues[j] = readUnsignedInt(stream);
                }
                obj = lvalues;
                break;
                
            case TIFFField.TIFF_RATIONAL:
                long[][] llvalues = new long[count][2];
                for (j = 0; j < count; j++) {
                    llvalues[j][0] = readUnsignedInt(stream);
                    llvalues[j][1] = readUnsignedInt(stream);
                }
		obj = llvalues;
                break;
                
            case TIFFField.TIFF_SSHORT:
                short[] svalues = new short[count];
                for (j = 0; j < count; j++) {
		    svalues[j] = readShort(stream);
                }
                obj = svalues;
                break;
                
            case TIFFField.TIFF_SLONG:
                int[] ivalues = new int[count];
                for (j = 0; j < count; j++) {
                    ivalues[j] = readInt(stream);
                }
                obj = ivalues;
                break;
                
            case TIFFField.TIFF_SRATIONAL:
                int[][] iivalues = new int[count][2];
                for (j = 0; j < count; j++) {
                    iivalues[j][0] = readInt(stream);
                    iivalues[j][1] = readInt(stream);
                }
                obj = iivalues;
                break;

            case TIFFField.TIFF_FLOAT:
                float[] fvalues = new float[count];
                for (j = 0; j < count; j++) {
                    fvalues[j] = readFloat(stream);
                }
                obj = fvalues;
                break;

            case TIFFField.TIFF_DOUBLE:
                double[] dvalues = new double[count];
                for (j = 0; j < count; j++) {
                    dvalues[j] = readDouble(stream);
                }
                obj = dvalues;
                break;

            default:
                System.err.println("TIFFDirectory0");
                break;
            }

            fields[i] = new TIFFField(tag, type, count, obj);
            stream.seek(nextTagOffset);
        }

        // Read the offset of the next IFD.
        nextIFDOffset = readUnsignedInt(stream);
    }

    /** Returns the number of directory entries. */
    public int getNumEntries() {
        return numEntries;
    }

    /**
     * Returns the value of a given tag as a TIFFField,
     * or null if the tag is not present.
     */
    public TIFFField getField(int tag) {
        Integer i = (Integer)fieldIndex.get(new Integer(tag));
        if (i == null) {
            return null;
        } else {
            return fields[i.intValue()];
        }
    }

    /**
     * Returns true if a tag appears in the directory. 
     */
    public boolean isTagPresent(int tag) {
        return fieldIndex.containsKey(new Integer(tag));
    }

    /**
     * Returns an ordered array of ints indicating the tag
     * values.
     */
    public int[] getTags() {
        int[] tags = new int[fieldIndex.size()];
        Enumeration enum = fieldIndex.keys();
        int i = 0;

        while (enum.hasMoreElements()) {
            tags[i++] = ((Integer)enum.nextElement()).intValue();
        }

        return tags;
    }

    /**
     * Returns an array of TIFFFields containing all the fields
     * in this directory.
     */
    public TIFFField[] getFields() {
        return fields;
    }

    /**
     * Returns the value of a particular index of a given tag as a
     * byte.  The caller is responsible for ensuring that the tag is
     * present and has type TIFFField.TIFF_SBYTE, TIFF_BYTE, or
     * TIFF_UNDEFINED.
     */
    public byte getFieldAsByte(int tag, int index) {
        Integer i = (Integer)fieldIndex.get(new Integer(tag));
        byte [] b = (fields[i.intValue()]).getAsBytes();
        return b[index];
    }

    /**
     * Returns the value of index 0 of a given tag as a
     * byte.  The caller is responsible for ensuring that the tag is
     * present and has  type TIFFField.TIFF_SBYTE, TIFF_BYTE, or
     * TIFF_UNDEFINED.
     */
    public byte getFieldAsByte(int tag) {
        return getFieldAsByte(tag, 0);
    }

    /**
     * Returns the value of a particular index of a given tag as a
     * long.  The caller is responsible for ensuring that the tag is
     * present and has type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED,
     * TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG or TIFF_LONG.
     */
    public long getFieldAsLong(int tag, int index) {
        Integer i = (Integer)fieldIndex.get(new Integer(tag));
        return (fields[i.intValue()]).getAsLong(index);
    }

    /**
     * Returns the value of index 0 of a given tag as a
     * long.  The caller is responsible for ensuring that the tag is
     * present and has type TIFF_BYTE, TIFF_SBYTE, TIFF_UNDEFINED,
     * TIFF_SHORT, TIFF_SSHORT, TIFF_SLONG or TIFF_LONG.
     */
    public long getFieldAsLong(int tag) {
        return getFieldAsLong(tag, 0);
    }

    /**
     * Returns the value of a particular index of a given tag as a
     * float.  The caller is responsible for ensuring that the tag is
     * present and has numeric type (all but TIFF_UNDEFINED and
     * TIFF_ASCII).
     */
    public float getFieldAsFloat(int tag, int index) {
        Integer i = (Integer)fieldIndex.get(new Integer(tag));
        return fields[i.intValue()].getAsFloat(index);
    }

    /**
     * Returns the value of index 0 of a given tag as a float.  The
     * caller is responsible for ensuring that the tag is present and
     * has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).
     */
    public float getFieldAsFloat(int tag) {
        return getFieldAsFloat(tag, 0);
    }

    /**
     * Returns the value of a particular index of a given tag as a
     * double.  The caller is responsible for ensuring that the tag is
     * present and has numeric type (all but TIFF_UNDEFINED and
     * TIFF_ASCII).
     */
    public double getFieldAsDouble(int tag, int index) {
        Integer i = (Integer)fieldIndex.get(new Integer(tag));
        return fields[i.intValue()].getAsDouble(index);
    }

    /**
     * Returns the value of index 0 of a given tag as a double.  The
     * caller is responsible for ensuring that the tag is present and
     * has numeric type (all but TIFF_UNDEFINED and TIFF_ASCII).
     */
    public double getFieldAsDouble(int tag) {
        return getFieldAsDouble(tag, 0);
    }

    // Methods to read primitive data types from the stream

    private short readShort(SeekableStream stream)
        throws IOException {
        if (isBigEndian) {
            return stream.readShort();
        } else {
            return stream.readShortLE();
        }
    }

    private int readUnsignedShort(SeekableStream stream)
        throws IOException {
        if (isBigEndian) {
            return stream.readUnsignedShort();
        } else {
            return stream.readUnsignedShortLE();
        }
    }

    private int readInt(SeekableStream stream) 
        throws IOException {
        if (isBigEndian) {
            return stream.readInt();
        } else {
            return stream.readIntLE();
        }
    }

    private long readUnsignedInt(SeekableStream stream) 
        throws IOException {
        if (isBigEndian) {
            return stream.readUnsignedInt();
        } else {
            return stream.readUnsignedIntLE();
        }
    }

    private long readLong(SeekableStream stream)
        throws IOException {
        if (isBigEndian) {
            return stream.readLong();
        } else {
            return stream.readLongLE();
        }
    }

    private float readFloat(SeekableStream stream)
        throws IOException {
        if (isBigEndian) {
            return stream.readFloat();
        } else {
            return stream.readFloatLE();
        }
    }

    private double readDouble(SeekableStream stream)
        throws IOException {
        if (isBigEndian) {
            return stream.readDouble();
        } else {
            return stream.readDoubleLE();
        }
    }

    private static int readUnsignedShort(SeekableStream stream,
                                         boolean isBigEndian)
        throws IOException {
        if (isBigEndian) {
            return stream.readUnsignedShort();
        } else {
            return stream.readUnsignedShortLE();
        }
    }

    private static long readUnsignedInt(SeekableStream stream,
                                        boolean isBigEndian) 
        throws IOException {
        if (isBigEndian) {
            return stream.readUnsignedInt();
        } else {
            return stream.readUnsignedIntLE();
        }
    }

    // Utilities

    /**
     * Returns the number of image directories (subimages) stored in a
     * given TIFF file, represented by a <code>SeekableStream</code>.
     */
    public static int getNumDirectories(SeekableStream stream)
        throws IOException{
        long pointer = stream.getFilePointer(); // Save stream pointer

        stream.seek(0L);
        int endian = stream.readUnsignedShort();
        if (!isValidEndianTag(endian)) {
            throw new 
		IllegalArgumentException("TIFFDirectory1");
        }
        boolean isBigEndian = (endian == 0x4d4d);
        int magic = readUnsignedShort(stream, isBigEndian);
        if (magic != 42) {
            throw new 
		IllegalArgumentException("TIFFDirectory2");
        }
        
        stream.seek(4L);
        long offset = readUnsignedInt(stream, isBigEndian);

        int numDirectories = 0;
        while (offset != 0L) {
            ++numDirectories;

            stream.seek(offset);
            int entries = readUnsignedShort(stream, isBigEndian);
            stream.skip(12*entries);
            offset = readUnsignedInt(stream, isBigEndian);
        }
      
        stream.seek(pointer); // Reset stream pointer
        return numDirectories;
    }

    /**
     * Returns a boolean indicating whether the byte order used in the
     * the TIFF file is big-endian (i.e. whether the byte order is from  
     * the most significant to the least significant)
     */
    public boolean isBigEndian() {
	return isBigEndian;
    }

    /**
     * Returns the offset of the IFD corresponding to this
     * <code>TIFFDirectory</code>.
     */
    public long getIFDOffset() {
        return IFDOffset;
    }

    /**
     * Returns the offset of the next IFD after the IFD corresponding to this
     * <code>TIFFDirectory</code>.
     */
    public long getNextIFDOffset() {
        return nextIFDOffset;
    }
}
