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/*
 * Copyright (c) 2007, intarsys consulting GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *
 * - 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.
 *
 * - Neither the name of intarsys nor the names of its contributors may be used
 *   to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package de.intarsys.pdf.encoding;

import java.util.HashMap;
import java.util.Map;

import de.intarsys.pdf.cos.COSObject;

/**
 * A MappedEncoding is an explicit map from a codepoint to a character.
 * 
 * 
 * A MappedEncoding can be constructed individually (as in a DifferenceEncoding)
 * or be one of the predefined well known encodings that are implemented using
 * unique instances.
 * 
 */
public class MappedEncoding extends Encoding {
	/**
	 * The number of 1:1 mappings from character to code points.
	 * 
	 * 
	 * This is done for the first 256 bytes of character to cache the most often
	 * used chars.
	 * 
	 */
	private static final int ARRAY_MAPPING_SIZE = 256;

	/** encode characters indexes */
	private Map indexedEncoding = new HashMap();

	/** encode character names */
	private Map namedEncoding = new HashMap();

	/** encode characters performance optimization */
	private int[] fastEncoding = new int[ARRAY_MAPPING_SIZE];

	/** decode codepoints */
	private int[] indexDecoding = new int[ARRAY_MAPPING_SIZE];

	/**
	 * decode character names. This is for performance reasons as it is needed
	 * for computing a text's width.
	 */
	private String[] nameDecoding = new String[ARRAY_MAPPING_SIZE];

	{
		for (int i = 0; i < ARRAY_MAPPING_SIZE; i++) {
			fastEncoding[i] = -1;
		}
		for (int i = 0; i < indexDecoding.length; i++) {
			indexDecoding[i] = -1;
		}
		for (int i = 0; i < nameDecoding.length; i++) {
			nameDecoding[i] = GlyphNameMap.GLYPH_NOTDEF;
		}
	}

	public MappedEncoding() {
		super();
	}

	/**
	 * When constructing manually, one can define a map from
	 * codePoint to name with this method.
	 * 
	 * @param codePoint
	 *            The codePoint from 0..255 where the character should be
	 *            mapped.
	 * @param name
	 *            The name of the character to be mapped.
	 */
	public void addEncoding(int codePoint, String name) {
		int unicode = GlyphNameMap.Standard.getUnicode(name);
		defineEntry(codePoint, unicode, name);
	}

	/**
	 * Add a known complete tuple. THis is used if we do not have a name/unicode
	 * standard map (for example in symbolic fonts).
	 * 
	 * @param codePoint
	 *            The codePoint from 0..255 where the character should be
	 *            mapped.
	 * @param name
	 *            The name of the character to be mapped.
	 * @param character
	 *            The character value
	 */
	public void addEncoding(int codePoint, String name, int character) {
		defineEntry(codePoint, character, name);
	}

	@Override
	public COSObject cosGetObject() {
		return null;
	}

	/**
	 * Define an entry that establishes a relationship between codepoint,
	 * character and Adobe glyph name.
	 * 
	 * @param codepoint
	 *            The codepoint.
	 * @param character
	 *            The character.
	 * @param name
	 *            The Adobe glyph name.
	 */
	protected void defineEntry(int codepoint, int character, String name) {
		// byte/name association
		nameDecoding[codepoint] = name;
		Integer codePointInteger = new Integer(codepoint);
		namedEncoding.put(name, codePointInteger);
		// byte character association
		indexDecoding[codepoint] = character;
		indexedEncoding.put(new Integer(character), codePointInteger);
		// 
		if ((character >= 0) && (character < ARRAY_MAPPING_SIZE)) {
			fastEncoding[character] = codepoint;
		}
	}

	@Override
	public int getDecoded(int byteValue) {
		return indexDecoding[byteValue];
	}

	@Override
	public int getEncoded(int character) {
		if ((character >= 0) && (character < ARRAY_MAPPING_SIZE)) {
			return fastEncoding[character];
		} else {
			Integer ii = (Integer) indexedEncoding.get(new Integer(character));
			if (ii == null) {
				return -1;
			}
			return ii.intValue();
		}
	}

	@Override
	public int getEncoded(String name) {
		Integer codePoint = (Integer) namedEncoding.get(name);
		if (codePoint == null) {
			return -1;
		} else {
			return codePoint.intValue();
		}
	}

	@Override
	public String getGlyphName(int codePoint) {
		if ((codePoint < 0) || (codePoint > 255)) {
			return GlyphNameMap.GLYPH_NOTDEF;
		}
		return nameDecoding[codePoint];
	}

	/**
	 * The internal representation of the decoding map from codepoints to
	 * characters.
	 * 
	 * @return The internal representation of the decoding map from codepoints
	 *         to characters.
	 */
	protected int[] getIndexDecoding() {
		return indexDecoding;
	}

	/**
	 * The internal representation of the encoding map from characters to
	 * codepoints.
	 * 
	 * @return The internal representation of the encoding map from characters
	 *         to codepoints.
	 */
	protected Map getIndexedEncoding() {
		return indexedEncoding;
	}

	@Override
	public String getName() {
		return "MappedEncoding";
	}

	/**
	 * The internal representation of the decoding map from codePoint to
	 * character name.
	 * 
	 * @return The internal representation of the decoding map from codePoint to
	 *         character name.
	 */
	protected String[] getNameDecoding() {
		return nameDecoding;
	}

	/**
	 * The internal representation of the encoding map from characters names to
	 * codepoint.
	 * 
	 * @return The internal representation of the encoding map from characters
	 *         names to codepoint.
	 */
	protected Map getNamedEncoding() {
		return namedEncoding;
	}

}