1	// joi/7/juno/LoginInterpreter.java
     2	//
     3	//
     4	// Copyright 2003 Ethan Bolker and Bill Campbell
     5	
     6	import java.util.*;
     7	
     8	/**
     9	 * Interpreter for Juno login commands.
    10	 * 
    11	 * There are so few commands that if-then-else logic is OK.
    12	 *
    13	 * @version 7
    14	 */
    15	
    16	public class LoginInterpreter 
    17	{
    18	    private static final String LOGIN_COMMANDS =
    19	        "help, register, <username>, exit";
    20	
    21	    private Juno     system;  // the Juno object
    22	    private Terminal console; // for i/o
    23	
    24	    /**
    25	     * Construct a new LoginInterpreter for interpreting
    26	     * login commands.
    27	     *
    28	     * @param system the system creating this interpreter.
    29	     * @param console the Terminal used for input and output.
    30	     */
    31	
    32	    public LoginInterpreter( Juno system, Terminal console) 
    33	    {
    34	        this.system  = system;
    35	        this.console = console;
    36	    }
    37	
    38	    /**
    39	     * Set the console for this interpreter.  Used by the
    40	     * creator of this interpreter.
    41	     *
    42	     * @param console the Terminal to be used for input and output.
    43	     */
    44	
    45	    public void setConsole( Terminal console ) 
    46	    {
    47	        this.console = console;
    48	    }
    49	
    50	    /** 
    51	     * Simulates behavior at login: prompt.
    52	     * CLI stands for "Command Line Interface".
    53	     */
    54	
    55	    public void CLILogin()  
    56	    {
    57	        welcome();
    58	        boolean moreWork = true;
    59	        while( moreWork ) { 
    60	            moreWork = interpret( console.readLine( "Juno login: " ) );
    61	        }
    62	    }
    63	
    64	    // Parse user's command line and dispatch appropriate
    65	    // semantic action.
    66	    //
    67	    // return true unless "exit" command or null inputLine.
    68	
    69	    private boolean interpret( String inputLine ) 
    70	    {
    71	        if (inputLine == null) return false;
    72	        StringTokenizer st = 
    73	            new StringTokenizer( inputLine );
    74	        if (st.countTokens() == 0) {
    75	            return true; // skip blank line
    76	        }
    77	        String visitor = st.nextToken();
    78	        if (visitor.equals( "exit" )) {      
    79	            return false;
    80	        }
    81	        if (visitor.equals( "register" )) {
    82	            register( st );
    83	        }
    84	        else if (visitor.equals( "help" )) {
    85	            help();
    86	        }
    87	        else {
    88	            User user = system.lookupUser(visitor);
    89	            new Shell( system, user, console );
    90	        }
    91	        return true;
    92	    }
    93	
    94	    // Register a new user, giving him or her a login name and a
    95	    // home directory on the system.
    96	    // 
    97	    // StringTokenizer argument contains the new user's login name
    98	    // followed by full real name.
    99	
   100	    private void register( StringTokenizer st )
   101	    {
   102	        String userName = st.nextToken();
   103	        String realName = st.nextToken("").trim();
   104	        Directory home  = new Directory( userName, null,
   105	                                        system.getUserHomes() );
   106	        User user = system.createUser( userName, home, realName );
   107	        home.setOwner( user );
   108	    }
   109	
   110	    // Display a short welcoming message, and remind users of
   111	    // available commands.
   112	
   113	    private void welcome()
   114	    {
   115	        console.println( "Welcome to " + system.getHostName() +
   116	                         " running " + system.getOS() +
   117	                         " version " + system.getVersion() );
   118	        help();
   119	    }
   120	
   121	    // Remind user of available commands.
   122	
   123	    private void help()
   124	    {
   125	        console.println( LOGIN_COMMANDS );
   126	        console.println("");
   127	    }
   128	}