package pt.iscte.ci.authentication;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import net.sourceforge.fenixedu._development.PropertiesManager;
import net.sourceforge.fenixedu.applicationTier.Servico.ExcepcaoAutenticacao;
import net.sourceforge.fenixedu.applicationTier.security.PasswordEncryptor;
import net.sourceforge.fenixedu.domain.exceptions.DomainException;

public class BlackboardUtils {

    private static final String CHECK_BLACKBOARD_SERVER;

    private static final String PASSWD = "passwd";

    private static String databaseDriver;

    private static String databaseName;

    private static String databaseUrl;

    private static String databaseUsername;

    private static String databasePassword;

    private static final String BLACKBOARD_DATABASE_DRIVER = "blackboard.database.driver";

    private static final String BLACKBOARD_DATABASE_NAME = "blackboard.database.name";

    private static final String BLACKBOARD_DATABASE_URL = "blackboard.database.url";

    private static final String BLACKBOARD_DATABASE_USERNAME = "blackboard.database.username";

    private static final String BLACKBOARD_DATABASE_PASSWORD = "blackboard.database.password";

    private static final String GET_USERNAME_AND_PASSWORD_STATEMENT;

    private static final String GET_USERNAME_STATEMENT;

    private static final String UPDATE_PASSWORD_STATEMENT;

    static {
	databaseDriver = PropertiesManager.getProperty(BLACKBOARD_DATABASE_DRIVER);
	databaseName = PropertiesManager.getProperty(BLACKBOARD_DATABASE_NAME);
	databaseUrl = PropertiesManager.getProperty(BLACKBOARD_DATABASE_URL);
	databaseUsername = PropertiesManager.getProperty(BLACKBOARD_DATABASE_USERNAME);
	databasePassword = PropertiesManager.getProperty(BLACKBOARD_DATABASE_PASSWORD);
	GET_USERNAME_AND_PASSWORD_STATEMENT = "SELECT user_id, passwd FROM " + databaseName + ".users WHERE user_id = ?";
	UPDATE_PASSWORD_STATEMENT = "UPDATE " + databaseName + ".users SET passwd = ? WHERE user_id = ?";
	GET_USERNAME_STATEMENT = "SELECT user_id FROM " + databaseName + ".users WHERE user_id = ?";
	CHECK_BLACKBOARD_SERVER = PropertiesManager.getProperty("blackboard.check.enabled");

	try {
	    Class.forName(databaseDriver);
	} catch (ClassNotFoundException e) {
	    System.out.println("ClassNotFoundException " + e);
	}
    }

    private static Connection openAndConfigureConnection() throws SQLException {
	Connection connection;
	connection = DriverManager.getConnection(databaseUrl, databaseUsername, databasePassword);
	return connection;
    }

    private static void closeConnection(final Connection connection) {
	try {
	    if (connection != null && !connection.isClosed()) {
		connection.close();
	    }
	} catch (SQLException e) {
	    e.printStackTrace();
	    throw new DomainException("error.sql.close.connection.failed", e);
	}
    }

    /**
     * 
     * @param connection
     * @param username
     *            The username whose access is to be checked.
     * @param cryptedPasswordInUpperCase
     *            The password the user has introduced in MD5 format, with all
     *            characters in uppercase.
     * @return
     * @throws SQLException
     */
    private static boolean authenticate(final Connection connection, final String username,
	    final String cryptedPasswordInUpperCase) throws SQLException {
	final PreparedStatement stm = connection.prepareStatement(GET_USERNAME_AND_PASSWORD_STATEMENT);
	stm.setString(1, username);
	final ResultSet rs = stm.executeQuery();
	if (rs.next()) {
	    final String userPassword = rs.getString(PASSWD);
	    return userPassword.equals(cryptedPasswordInUpperCase);
	}
	return false;
    }

    public static void authenticate(final String username, final String password) throws ExcepcaoAutenticacao {
	if (!checkBlackboard()) {
	    return;
	}

	Connection connection = null;
	try {
	    connection = openAndConfigureConnection();
	    if (!authenticate(connection, username, PasswordEncryptor.generatePasswordForBlackboard(password))) {
		throw new ExcepcaoAutenticacao();
	    }
	} catch (SQLException e) {
	    e.printStackTrace();
	    throw new DomainException("error.blackboard.sql.exception");
	} finally {
	    closeConnection(connection);
	}
    }

    public static void changePassword(final String username, final String newPassword) {
	if (!checkBlackboard()) {
	    return;
	}

	Connection connection = null;
	try {
	    connection = openAndConfigureConnection();
	    final PreparedStatement stm = connection.prepareStatement(UPDATE_PASSWORD_STATEMENT);
	    stm.setString(1, PasswordEncryptor.generatePasswordForBlackboard(newPassword));
	    stm.setString(2, username);
	    stm.executeUpdate();

	    System.out.println("Blackboard password changed successfully for username " + username);

	    connection.commit();

	} catch (SQLException e) {
	    e.printStackTrace();
	} finally {
	    closeConnection(connection);
	}
    }

    public static boolean isUserInBlackboard(final String username) {
	if (!checkBlackboard()) {
	    return false;
	}

	Connection connection = null;
	try {
	    connection = openAndConfigureConnection();
	    final PreparedStatement stm = connection.prepareStatement(GET_USERNAME_STATEMENT);
	    stm.setString(1, username);
	    final ResultSet rs = stm.executeQuery();
	    if (rs.next()) {
		return true;
	    }
	    return false;
	} catch (SQLException e) {
	    e.printStackTrace();
	} finally {
	    closeConnection(connection);
	}
	return false;
    }

    /**
     * 
     * @return Returns true if an access to the email server database should be
     *         performed. It returns false otherwise. This method returns the
     *         property set in the build configuration file, where one specifies
     *         if this should be enabled or not.
     */
    public static boolean checkBlackboard() {
	return CHECK_BLACKBOARD_SERVER == null || "true".equals(CHECK_BLACKBOARD_SERVER);
    }
}