/*
 * Copyright (c) 2007, Sun Microsystems, Inc.
 * All rights reserved.
 * 
 * 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 Sun Microsystems, Inc. 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
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 * 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. 
 */

/* Anagram Game Application */

package org.javaone.anagram.lib;

/**
 * Interface defining logic for the Anagram Game application.
 */
public abstract class WordLibrary {
    private static WordLibrary defaultLib;
    /**
     * Constructor for subclasses.
     */
    protected WordLibrary() {
    }
    
    /** Getter for the default implementation of the WordLibrary.
     * @return some default implementation of WordLibrary
     */
    public static WordLibrary getDefault() {
        if (defaultLib == null) {
            return StaticWordLibrary.DEFAULT;
        } else {
            return defaultLib;
        }
    }

    public static void setDefault(WordLibrary lib) {
        defaultLib = lib;
    }

    /**
     * Gets the word at a given index.
     * @param idx index of required word
     * @return word at that index in its natural form
     */
    public abstract String getWord(int idx);

    /**
     * Gets the word at a given index in its scrambled form.
     * @param idx index of required word
     * @return word at that index in its scrambled form
     */
    public abstract String getScrambledWord(int idx);

    /**
     * Gets the number of words in the library.
     * @return the total number of plain/scrambled word pairs in the library
     */
    public abstract int getSize();

    /**
     * Checks whether a user's guess for a word at the given index is correct.
     * @param idx index of the word guessed
     * @param userGuess the user's guess for the actual word
     * @return true if the guess was correct; false otherwise
     */
    public abstract boolean isCorrect(int idx, String userGuess);
}
