1	// joi/10/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 10
    14	 */
    15	
    16	public class LoginInterpreter 
    17	    implements InterpreterInterface
    18	{
    19	    private static final String LOGIN_COMMANDS =
    20	        "help, register, <username>, exit";
    21	
    22	    private Juno system;             // the Juno object
    23	    private OutputInterface console; // where output goes
    24	
    25	    /**
    26	     * Construct a new LoginInterpreter for interpreting
    27	     * login commands.
    28	     *
    29	     * @param system the system creating this interpreter.
    30	     * @param console the Terminal used for input and output.
    31	     */
    32	
    33	    public LoginInterpreter( Juno system, OutputInterface console) 
    34	    {
    35	        this.system  = system;
    36	        this.console = console;
    37	    }
    38	
    39	    /**
    40	     * Set the console for this interpreter.  Used by the
    41	     * creator of this interpreter.
    42	     *
    43	     * @param console the Terminal to be used for input and output.
    44	     */
    45	
    46	    public void setConsole( OutputInterface console) 
    47	    {
    48	        this.console = console;
    49	    }
    50	
    51	    /** 
    52	     * Simulates behavior at login: prompt.
    53	     */
    54	
    55	    public void CLILogin()  
    56	    {
    57	        welcome();
    58	        boolean moreWork = true;
    59	        while( moreWork ) { 
    60	            moreWork = interpret(((InputInterface)console).
    61	                                 readLine( "Juno login: " ) );
    62	        }
    63	    }
    64	
    65	
    66	    /**
    67	     * Parse user's command line and dispatch appropriate
    68	     * semantic action.
    69	     *
    70	     * @param  inputLine the User's instructions.
    71	     * @return true except for "exit" command 
    72	     *         or null inputLine.
    73	     */
    74	
    75	    public boolean interpret( String inputLine ) 
    76	    {
    77	        if (inputLine == null) {
    78		    return false;
    79		}
    80	        StringTokenizer st = 
    81	            new StringTokenizer( inputLine );
    82	        if (st.countTokens() == 0) {
    83	            return true; // skip blank line
    84	        }
    85	        String visitor = st.nextToken();
    86	        if (visitor.equals( "exit" )) {      
    87	            return false;
    88	        }
    89	        if (visitor.equals( "register" )) {
    90	            register( st );
    91	        }
    92	        else if (visitor.equals( "help" )) {
    93	            help();
    94	        }
    95	        else {
    96	            String password; 
    97	            try { 
    98	                if (console.isGUI()) {
    99	                    password = st.nextToken();
   100	                }
   101	                else {;
   102	                    password = readPassword( "password: " );
   103	                }
   104	                User user = system.lookupUser(visitor);
   105	                user.matchPassword( password );
   106	                new Shell( system, user, console );
   107	            }
   108	            catch (Exception e) {
   109	
   110	                // NullPointerException if no such user,
   111	                // JunoException if password fails to match -
   112	                // message to user doesn't give away which.
   113	                // The sysadmin would probably want a log
   114	                // that did keep track.
   115	                //
   116	                // Other exceptions should be caught in shell()
   117	
   118	                console.println("sorry");
   119	            }
   120	        }
   121	        return true;
   122	    }
   123	
   124	    // Register a new user, giving him or her a login name and a
   125	    // home directory on the system.
   126	    // 
   127	    // StringTokenizer argument contains the new user's login name
   128	    // followed by full real name.
   129	
   130	    private void register( StringTokenizer line )
   131	    {
   132	        String username = "";
   133	        String password = "";
   134	        String realname = "";
   135	        try {
   136	            username = line.nextToken();
   137	            password = line.nextToken();
   138	            realname = line.nextToken("").trim();
   139	        }
   140	        catch (NoSuchElementException e) {
   141	        }
   142	
   143	        if (username.equals("") || password.equals("")
   144	            || realname.equals("") ) {
   145	            console.println(
   146	                  "please supply username, password, real name");
   147	            return;
   148	        }
   149	        User user = system.lookupUser(username);
   150	
   151	        if (user != null) {  // user already exists
   152	            console.println("sorry");
   153	            return;
   154	        }
   155	        if (badPassword( password )) {
   156	            console.println("password too easy to guess");
   157	            return;
   158	        }
   159	        Directory home = new Directory( username, null,
   160	                                        system.getUserHomes() );
   161	
   162	        user = system.createUser( username, home, password, realname );
   163	        home.setOwner( user );
   164	    }
   165	
   166	    // test to see if password is unacceptable:
   167	    //   fewer than 6 characters
   168	    //   contains only alphabetic characters
   169	
   170	    private boolean badPassword( String pwd )
   171	    {
   172	        if (pwd.length() < 6) {
   173		    return true;
   174		}
   175	        int nonAlphaCount = 0;
   176	        for (int i=0; i < pwd.length(); i++) {
   177	            if (!Character.isLetter(pwd.charAt(i))) {
   178	                nonAlphaCount++;
   179	            }
   180	        }
   181	        return (nonAlphaCount == 0);
   182	    }
   183	
   184	    // Used for reading the user's password in CLI.
   185	
   186	    private String readPassword( String prompt ) 
   187	    {
   188	        String line = 
   189	            ((InputInterface) console).readLine( prompt );
   190	        StringTokenizer st = new StringTokenizer( line );
   191	        try {
   192	            return st.nextToken();
   193	        }
   194	        catch ( NoSuchElementException e )  {}
   195	        return ""; // keeps compiler happy
   196	    }
   197	
   198	
   199	    // Display a short welcoming message, and remind users of
   200	    // available commands.
   201	
   202	    private void welcome()
   203	    {
   204	        console.println( "Welcome to " + system.getHostName() +
   205	                         " running "   + system.getOS() +
   206	                         " version "   + system.getVersion() );
   207	        help();
   208	    }
   209	
   210	    // Remind user of available commands.
   211	
   212	    private void help()
   213	    {
   214	        console.println( LOGIN_COMMANDS );
   215	        console.println("");
   216	    }
   217	}