import javax.naming.*;
import javax.naming.directory.*;
import java.util.Hashtable;

public class LdapLogin {

  private static final String ERROR_PREFIX = "__LDAP_ERROR";

  private static String pretty_error (Exception e) {
    // Return a nicely formatted error message from the given execption.
    if (e instanceof IllegalArgumentException) {
      return ERROR_PREFIX + ": Illegal Argument {"+e.getMessage()+"} {"+e.toString()+"}";
    } 
    if (e instanceof NamingException) {
      return ERROR_PREFIX + ": Naming Exception {"+e.getMessage()+"} {"+e.toString()+"}";
    } 
    if (e instanceof ServiceUnavailableException) {
      return ERROR_PREFIX + ": Service Unavailable  {"+e.getMessage()+"} {"+e.toString()+"}";
    } 
    if (e instanceof AuthenticationException) {
      return ERROR_PREFIX + ": Invalid Authentication {"+e.getMessage()+"} {"+e.toString()+"}";
    } 
    return ERROR_PREFIX + ": Unknown Error Type {"+e.getMessage()+"} {"+e.toString()+"}";
  }

  private static DirContext login (String url, String dn, String password, String security_method) 
    throws IllegalArgumentException, NamingException {

      // Check arguments
      if (url == null || url == "") throw new IllegalArgumentException("No url specified");
      if (dn == null || dn == "") throw new IllegalArgumentException("No dn specified");
      if (password == null || password == "") throw new IllegalArgumentException("No password specified");
      if (security_method == null || security_method == "") throw new IllegalArgumentException("No security_method specified");
      
      Hashtable env = new Hashtable(11);
      env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
      env.put(Context.PROVIDER_URL, url);
      env.put(Context.SECURITY_AUTHENTICATION, security_method);
      env.put(Context.SECURITY_PRINCIPAL, dn);
      env.put(Context.SECURITY_CREDENTIALS, password);
      
      DirContext ctx = new InitialDirContext(env);
      return ctx;
  }

  public static String change_password (String url, String rootdn, String rootpw, 
                                        String security_method, String dn, String password) {

    DirContext ctx;
    BasicAttribute new_password;
    ModificationItem change;
    ModificationItem[] changes;
    
    // Set up attribute stuff for changing the password
    new_password = new BasicAttribute ("userPassword", password);
    change = new ModificationItem (DirContext.REPLACE_ATTRIBUTE, new_password);
    changes = new ModificationItem[1];
    changes[0] = change;

    try { 

      // Create initial context
      // This will throw an exception if the binding does not happen.
      ctx = login (url, rootdn, rootpw, security_method);

      // Make the change
      // This will throw an error if there's a problem
      ctx.modifyAttributes(dn, changes);
      
      // Close the context when we're done. This may throw an error.
      ctx.close();
      
    } catch (Exception e) {
      return pretty_error (e);
    }
      
    // success
    return "1";

  }
    
  public static String get_attribute (String url, String rootdn, String rootpw, 
                                      String security_method, String dn, String attribute) {
    Attribute attr;
    DirContext ctx;
    NamingEnumeration results;
    Object attr_val;
    SearchControls sc;
    SearchResult sr;
    int count;

    String[] attrIDs = { attribute };
    sc = new SearchControls (SearchControls.OBJECT_SCOPE, 0, 0, attrIDs, false, false);
      
    try { 
      
      // Create initial context
      // This will throw an exception if the binding does not happen.
      ctx = login (url, rootdn, rootpw, security_method);
      
      // Search for objects that have those matching attributes.
      // This can throw a number of errors.
      results = ctx.search(dn, "(objectclass=*)", sc);
      
      // Loop through results.  
      count = 0;
      attr_val = null;
      while (results.hasMore()) {
	count++;
	sr = (SearchResult)results.next();
	attr = sr.getAttributes().get(attribute);
	if (attr != null) {
	  attr_val = attr.get();
	}
      }

      // Close the context when we're done
      ctx.close();
      
    } catch (Exception e) {
      return pretty_error (e);
    }

    // Check the results. There should be only one match containing one attribute value.
    if (count == 0) {
      return pretty_error (new Exception ("no results"));
    }
    if (count > 1) {
      return pretty_error (new Exception ("too many results"));
    }
    if (attr_val == null) {
      return pretty_error (new Exception ("attribute not found"));
    }
    
    // success
    return attr_val.toString();
  }
  
  public static String get_dn_from_email (String url, String rootdn, String rootpw, 
                                          String basedn, String security_method, String email) {

    Attributes matchAttrs;
    DirContext ctx;
    NamingEnumeration results;
    SearchResult sr;
    String dn;
    int count;

    matchAttrs = new BasicAttributes(true);
    matchAttrs.put(new BasicAttribute("mail", email));
    
    String[] attrIDs = { "dn" };

    try { 

      // Create initial context
      // This will throw an exception if the binding does not happen.
      ctx = login (url, rootdn, rootpw, security_method);

      // Search for objects that have those matching attributes
      results = ctx.search(basedn, matchAttrs, attrIDs);

      count = 0;
      dn = new String();
      while (results.hasMore()) {
	count++;
	sr = (SearchResult)results.next();
	sr.setRelative(false);
	dn = sr.getName();
      }

      // Close the context when we're done
      ctx.close();

    } catch (Exception e) {
      return pretty_error (e);
    }

    if (count == 0) {
      return pretty_error (new Exception ("no results"));
    }
    if (count > 1) {
      return pretty_error (new Exception ("too many results"));
    }

    // success
    return dn;
    
  }

  public static String add_user (String url, String rootdn, String rootpw, String security_method, 
				 String dn, String first_name, String last_name, String email, String password) {
    DirContext ctx;
    Attributes attrs;
    Attribute objclass;
    Attribute givenName;
    Attribute sn;
    Attribute cn;
    Attribute mail;
    Attribute userPassword;

    attrs = new BasicAttributes(true);
    objclass = new BasicAttribute("objectclass");
    objclass.add("top");
    objclass.add("person");
    objclass.add("organizationalPerson");
    objclass.add("inetOrgPerson");
    givenName = new BasicAttribute("givenName");
    givenName.add(first_name);
    sn = new BasicAttribute("sn");
    sn.add(last_name);
    cn = new BasicAttribute("cn");
    cn.add(first_name + " " + last_name);
    mail = new BasicAttribute("mail");
    mail.add(email);
    userPassword = new BasicAttribute("userPassword");
    userPassword.add(password);
    attrs.put(objclass);
    attrs.put(givenName);
    attrs.put(sn);
    attrs.put(cn);
    attrs.put(mail);
    attrs.put(userPassword);
    
    try { 

      // Create initial context
      // This will throw an exception if the binding does not happen.
      ctx = login (url, rootdn, rootpw, security_method);

      // Create the new entry
      Context result = ctx.createSubcontext(dn, attrs);

      // Close the contexts when we're done
      ctx.close();
      result.close();

    } catch (Exception e) {
      return pretty_error (e);
    }

    // success
    return dn;
  }

  public static String authenticate (String url, String security_method, String dn, String password) {
    try { 
	    
      // Create initial context
      // This will throw an exception if the binding does not happen.
      DirContext ctx = login (url, dn, password, security_method);
      
      // Close the context when we're done
      ctx.close();
      
      return "1";
    } catch (Exception e) {
      return pretty_error (e);
    }
  }
}