import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

/**
 * This class is the main class of the "World of Zuul" application.
 * "World of Zuul" is a very simple, text based adventure game.
 *
 * This parser reads user input and tries to interpret it as an "Adventure" command.
 * Every time it is called it reads a line from the terminal and
 * tries to interpret the line as a two word command. It returns the command
 * as an object of class Command.
 *
 * The parser has a set of known command words. It checks user input against
 * the known commands, and if the input is not one of the known commands, it
 * returns a command object that is marked as an unknown command.
 *
 * @author Naufaliando
 * @version 1.0
 */
class Parser
{
    private CommandWords commands; // holds all valid command words

    public Parser()
    {
        commands = new CommandWords();
    }

    public Command getCommand()
    {
        String inputLine = ""; // will hold the full input line
        String word1;
        String word2;

        System.out.print("> "); // print prompt

        BufferedReader reader = new BufferedReader (new InputStreamReader(System.in));
        try {
            inputLine = reader.readLine();
        }
        catch (java.io.IOException exc){
            System.out.println ("There was an error during reading: " + exc.getMessage());
        }

        StringTokenizer tokenizer = new StringTokenizer(inputLine);

        if(tokenizer.hasMoreTokens())
            word1 = tokenizer.nextToken(); // get first word
        else
            word1=null;
        if(tokenizer.hasMoreTokens())
            word2 = tokenizer.nextToken(); // get second word
        else
            word2=null;

        // note: we just ignore the rest of the input line.

        // Now check whether this word is known. If so, create a command
        // with it. If not, create a "null" command (for unknown command).
        if(commands.isCommand(word1))
            return new Command(word1, word2);
        else
            return new Command(null, word2);
    }
}