import java.util.*;

/**
 * Represents one user's account information.
 * @author Marty Stepp
 * @version 2010-02-08, CSE 403 Spring 2010
 */
public class Account {
    private String name;
    private String password;
    
    /** 
     * Constructs a new account with the given name and password.
     * @throws NullException if name or password is null.
     * @throws IllegalArgumentException if password is <= 6 letters or has
     *                                  fewer than 3 unique letters.
     */
    public Account(String name, String password) {
        ensureNotNull(name);
        this.name = name;
        setPassword(password);
    }
    
    /**
     * Returns this account's name.
     */
    public String getName() {
        return name;
    }
    
    /**
     * Returns this account's password.
     */
    public String getPassword() {
        return password;
    }
    
    /**
     * Sets this account to use the given password.
     * @throws NullException if password is null.
     * @throws IllegalArgumentException if password is <= 6 letters or has
     *                                  fewer than 3 unique letters.
     */
    public void setPassword(String password) {
        ensureNotNull(password);
        if (!validPassword(password)) {
            throw new IllegalArgumentException("bogus password: " + password);
        }
        this.password = password;
    }
    
    // returns true if the given password meets the criteria:
    // length at least 6, and at least 3 unique letters.
    private boolean validPassword(String password) {
        Set<String> uniqChars = new HashSet<String>(Arrays.asList(password.split("")));
        return password.length() >= 6 && 
                uniqChars.size() - 1 >= 3;
    }
    
    // Throws a NullPointerException if o is null.
    private void ensureNotNull(Object o) {
        if (o == null) {
            throw new NullPointerException();
        }
    }
}