/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     MetaMatrix, Inc - repackaging and updates for use as a metadata store
 *******************************************************************************/
package org.teiid.internal.core.index;

import java.util.Arrays;


public class WordEntry implements Comparable<WordEntry> {
	protected char[] fWord;
	protected int fNumRefs;
	protected int[] fRefs;
	public WordEntry() {
		this(new char[0]);
	}
	public WordEntry(char[] word) {
		fWord= word;
		fNumRefs= 0;
		fRefs= new int[1];
	}
	/**
	 * Adds a reference and records the change in footprint.
	 */
	public int addRef(int fileNum) {
		if (fNumRefs > 0 && fRefs[fNumRefs - 1] == fileNum) {
			return 0;
		}
		if (fNumRefs < fRefs.length) {
			fRefs[fNumRefs++]= fileNum;
			return 0;
		} 

		// For rt.jar, 73265 word entries are created. 51997 have 1 ref, then 9438, 3738, 1980, 1214, 779, 547, 429, 371 etc.
		int newSize= fNumRefs < 4 ? 4 : fNumRefs * 2; // so will start @ 1, grow to 4, 8, 16, 32, 64 etc.
		System.arraycopy(fRefs, 0, fRefs= new int[newSize], 0, fNumRefs);
		fRefs[fNumRefs++]= fileNum;
		return (newSize - fNumRefs + 1) * 4;
	}
	/**
	 * Adds a set of references and records the change in footprint.
	 */
	public void addRefs(int[] refs) {
		int[] newRefs= new int[fNumRefs + refs.length];
		int pos1= 0;
		int pos2= 0;
		int posNew= 0;
		int compare;
		int r1= 0;
		int r2= 0;
		while (pos1 < fNumRefs || pos2 < refs.length) {
			if (pos1 >= fNumRefs) {
				r2= refs[pos2];
				compare= -1;
			} else if (pos2 >= refs.length) {
				compare= 1;
				r1= fRefs[pos1];
			} else {
				r1= fRefs[pos1];
				r2= refs[pos2];
				compare= r2 - r1;
			}
			if (compare > 0) {
				newRefs[posNew]= r1;
				posNew++;
				pos1++;
			} else {
				if (r2 != 0) {
					newRefs[posNew]= r2;
					posNew++;
				}
				pos2++;
			}
		}
		fRefs= newRefs;
		fNumRefs= posNew;
		/*for (int i = 0; i < refs.length; i++)
		addRef(refs[i]);
		int[] newRefs = new int[fNumRefs];
		System.arraycopy(fRefs, 0, newRefs, 0, fNumRefs);
		fRefs = newRefs;
		Util.sort(fRefs);*/
	}
	/**
	 * Returns the size of the wordEntry
	 */

	public int footprint() {
		return 8 + (3 * 4) + (8 + fWord.length * 2) + (8 + fRefs.length * 4);
	}
	/**
	 * Returns the number of references, e.g. the number of files this word appears in.
	 */
	public int getNumRefs() {
		return fNumRefs;
	}
	/**
	 * returns the file number in the i position in the list of references.
	 */
	public int getRef(int i) {
		if (i < fNumRefs) return fRefs[i];
		throw new IndexOutOfBoundsException();
	}
	/**
	 * Returns the references of the wordEntry (the number of the files it appears in).
	 */

	public int[] getRefs() {
		int[] result= new int[fNumRefs];
		System.arraycopy(fRefs, 0, result, 0, fNumRefs);
		return result;
	}
	/**
	 * returns the word of the wordEntry.
	 */

	public char[] getWord() {
		return fWord;
	}
	/**
	 * Changes the references of the wordEntry to match the mapping. For example,<br>
	 * if the current references are [1 3 4]<br>
	 * and mapping is [1 2 3 4 5]<br>
	 * in references 1 becomes mapping[1] = 2, 3->4, and 4->5<br>
	 * => references = [2 4 5].<br>
	 */
	public void mapRefs(int[] mappings) {
		int position= 0;
		for (int i= 0; i < fNumRefs; i++) {
			int map= mappings[fRefs[i]];
			if (map != -1 && map != 0)
				fRefs[position++]= map;
		}
		fNumRefs= position;

		//to be changed!
		System.arraycopy(fRefs, 0, (fRefs= new int[fNumRefs]), 0, fNumRefs);
		Arrays.sort(fRefs);
	}
	/**
	 * Clears the wordEntry.
	 */

	public void reset(char[] word) {
		for (int i= fNumRefs; i-- > 0;) {
			fRefs[i]= 0;
		}
		fNumRefs= 0;
		fWord= word;
	}
	public String toString() {
		return new String(fWord);
	}
	public int compareTo(WordEntry other) {
		return Util.compare(this.fWord, other.fWord);
	}
}
