/*
 *  InMemoryStrategy.java
 *  Copyright (C) 2006 Amin Ahmad           
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.ahmadsoft.postal;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;

/**
 * A retrieval strategy that loads the entire file into memory. This
 * strategy may be acceptable if you are running this library as a
 * service (e.g. a servlet-based HTTP service). It occupies roughly
 * 23 megabytes of RAM under Windows XP running Java 5.
 * 
 * @author Amin Ahmad
 */
public class InMemoryStrategy implements PostalRetrievalStrategy {
	
	private static HashMap map = new HashMap();

	/**
	 * @inheritDoc
	 */
	public void initialize(File indexFile, File dataFile) throws Exception {
		DataInputStream dis = new DataInputStream(new FileInputStream(indexFile));
		RandomAccessFile dfRan = new RandomAccessFile(dataFile, "r");
		
		int pc = 99999;
		while (99999 != (pc=dis.readInt())) {
			int loc = dis.readInt();
			
			dfRan.seek(loc);
			
			List postalCodes = new ArrayList();
			short type=0;
			while (0 != (type=dfRan.readShort())) {
				String state = dfRan.readUTF();
				String city = dfRan.readUTF();
				
				postalCodes.add(new PostalCodeEntry(pc,city,state,type));
			}

			map.put(new Integer(pc), postalCodes);
		}
		
		dis.close();
		dfRan.close();
	}

	/**
	 * @inheritDoc
	 */
	public List getCandidates(int postalCode) {
		if (map.containsKey(new Integer(postalCode))) {
			return Collections.unmodifiableList((List) map.get(new Integer(postalCode)));
		} else {
			return Arrays.asList(new PostalCodeEntry[] {});
		}
	}

	/**
	 * @inheritDoc
	 */
	public void dispose() throws Exception {
		map = null;
	}

}