import java.util.HashMap;
/**
 * Representations for all the valid command words for the game
 * along with a string in a particular language.
 * 
 * ---------------------------------------------------------------------------
 * The CommandWords class was merged with this one since there is really no
 * point to haveing them separate. There are many reasons to have the 
 * reverse-lookup implemented within the enum, and that was really all the
 * CommandWords class was doing.
 * ---------------------------------------------------------------------------
 * 
 * @author Michael Kolling and David J. Barnes
 * @version 2006.03.30
 * 
 * @author Modified by Charles Cusack, October 2008.
 * 
 */
public enum CommandWord
{
    // A value for each command word along with its
    // corresponding user interface string.
    GO("go"), QUIT("quit"), HELP("help"), UNKNOWN("?");
    
    // The command string.
    private String commandString;
    
    /**
     * Initialise with the corresponding command word.
     * @param commandWord The command string.
     */
    private CommandWord(String commandString)
    {
        this.commandString = commandString;
    }
    
    /**
     * @return The command word as a string.
     */
    public String toString()
    {
        return commandString;
    }
    
    
    // The following code, taken from CommandWords, allows for
    // reverse lookup.
    //
    // A mapping between a command word and the CommandWord
    // associated with it.
    private static HashMap<String, CommandWord> validCommands;
    
    // This static block is executed once--it fills the HashMap
    static { 
        validCommands = new HashMap<String, CommandWord>();
        for(CommandWord command : CommandWord.values()) {
            if(command != CommandWord.UNKNOWN) {
                validCommands.put(command.toString(), command);
            }
        }
    
    }
    
   /**
     * Find the CommandWord associated with a command word.
     * @param commandWord The word to look up.
     * @return The CommandWord correspondng to commandWord, or UNKNOWN
     *         if it is not a valid command word.
     */
    public static CommandWord getCommandWord(String commandWord)
    {
        CommandWord command = validCommands.get(commandWord);
        if(command != null) {
            return command;
        } else {
            return CommandWord.UNKNOWN;
        }
    }
    
   /**
     * Returns a String representation of all valid commands.
     */
    public static String getAllCommandWords() 
    {
        StringBuilder sb = new StringBuilder("");
        for(String command : validCommands.keySet()) {
            sb.append(command + "  ");
        }
        return sb.toString();
    }
    
    /**
     * Check whether a given String is a valid command word. 
     * @return true if it is, false if it isn't.
     */
    public boolean isCommand(String aString)
    {
        return validCommands.containsKey(aString);
    }
    
}