package com.temp.client.foundation.pavment;

import java.util.*;

/**
 * Registry of the Default PlaceTokenCodec for encoding, and all the
 * PlaceTokenCodec(s) available for decoding.
 *
 * @author georgs
 */
public class PlaceTokenCodecRegistry {
    /******************* See Bottom of Class for Registering PlaceTokenCodec(s) *******************/

    /**
     * Encode the String (nulls are returned as "")
     *
     * @return nulls are returned as "", otherwise the Encoded String.
     */
    public static String encode( String unencoded ) {
        if ( (unencoded == null) || (unencoded.length() == 0) ) {
            return "";
        }
        return Character.toString( DEFAULT_CODEC_ID ) + DEFAULT_CODEC.encode( unencoded );
    }

    /**
     * Decode the previously "encoded" data, null or bad encoding will return
     * null.
     *
     * @return null indicates that the data was either null or contained
     * unacceptable characters for decoding.
     */
    public static String decode( String encoded ) {
        if ( encoded == null ) {
            return null;
        }
        if ( encoded.length() == 0 ) {
            return "";
        }
        PlaceTokenCodec codec = CODECS.get( encoded.charAt( 0 ) );
        return (codec != null) ? codec.decode( encoded.substring( 1 ) ) : null;
    }

    /**
     * ***************************** Maintain the order of the following *******************************
     */
    private static final Map<Character, PlaceTokenCodec> CODECS = new HashMap<Character, PlaceTokenCodec>();
    private static char DEFAULT_CODEC_ID;
    private static PlaceTokenCodec DEFAULT_CODEC;

    private static void register( char chr, PlaceTokenCodec codec ) {
        CODECS.put( DEFAULT_CODEC_ID = chr, DEFAULT_CODEC = codec );
    }

    static { // Last One registered is the Default!
        register( '0', new PlaceTokenCodecCharacterDeltaWithRandomStart() );
        register( '1', new PlaceTokenCodecCharacterDeltaWithRandomStartWitAdjustment() );
    }
}