/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.guacamole.environment;

import java.io.File;
import java.util.Map;
import org.apache.guacamole.GuacamoleException;
import org.apache.guacamole.properties.BooleanGuacamoleProperty;
import org.apache.guacamole.properties.GuacamoleProperty;
import org.apache.guacamole.properties.IntegerGuacamoleProperty;
import org.apache.guacamole.properties.StringGuacamoleProperty;
import org.apache.guacamole.protocols.ProtocolInfo;

/**
 * The environment of an arbitrary Guacamole instance, describing available
 * protocols, configuration parameters, and the GUACAMOLE_HOME directory.
 *
 * @author Michael Jumper
 */
public interface Environment {

    /**
     * The hostname of the server where guacd (the Guacamole proxy server) is
     * running.
     */
    public static final StringGuacamoleProperty GUACD_HOSTNAME = new StringGuacamoleProperty() {

        @Override
        public String getName() { return "guacd-hostname"; }

    };

    /**
     * The port that guacd (the Guacamole proxy server) is listening on.
     */
    public static final IntegerGuacamoleProperty GUACD_PORT = new IntegerGuacamoleProperty() {

        @Override
        public String getName() { return "guacd-port"; }

    };

    /**
     * Whether guacd requires SSL/TLS on connections.
     */
    public static final BooleanGuacamoleProperty GUACD_SSL = new BooleanGuacamoleProperty() {

        @Override
        public String getName() { return "guacd-ssl"; }

    };

    /**
     * Returns the Guacamole home directory as determined when this Environment
     * object was created. The Guacamole home directory is found by checking, in
     * order: the guacamole.home system property, the GUACAMOLE_HOME environment
     * variable, and finally the .guacamole directory in the home directory of
     * the user running the servlet container.
     *
     * @return The File representing the Guacamole home directory, which may
     *         or may not exist, and may turn out to not be a directory.
     */
    public File getGuacamoleHome();

    /**
     * Returns a map of all available protocols, where each key is the name of
     * that protocol as would be passed to guacd during connection.
     *
     * @return A map of all available protocols.
     */
    public Map<String, ProtocolInfo> getProtocols();

    /**
     * Returns the protocol having the given name. The name must be the
     * protocol name as would be passed to guacd during connection.
     *
     * @param name The name of the protocol.
     * @return The protocol having the given name, or null if no such
     *         protocol is registered.
     */
    public ProtocolInfo getProtocol(String name);

    /**
     * Given a GuacamoleProperty, parses and returns the value set for that
     * property in guacamole.properties, if any.
     *
     * @param <Type> The type that the given property is parsed into.
     * @param property The property to read from guacamole.properties.
     * @return The parsed value of the property as read from
     *         guacamole.properties.
     * @throws GuacamoleException If an error occurs while parsing the value
     *                            for the given property in
     *                            guacamole.properties.
     */
    public <Type> Type getProperty(GuacamoleProperty<Type> property)
            throws GuacamoleException;

    /**
     * Given a GuacamoleProperty, parses and returns the value set for that
     * property in guacamole.properties, if any. If no value is found, the
     * provided default value is returned.
     *
     * @param <Type> The type that the given property is parsed into.
     * @param property The property to read from guacamole.properties.
     * @param defaultValue The value to return if no value was given in
     *                     guacamole.properties.
     * @return The parsed value of the property as read from
     *         guacamole.properties, or the provided default value if no value
     *         was found.
     * @throws GuacamoleException If an error occurs while parsing the value
     *                            for the given property in
     *                            guacamole.properties.
     */
    public <Type> Type getProperty(GuacamoleProperty<Type> property,
            Type defaultValue) throws GuacamoleException;

    /**
     * Given a GuacamoleProperty, parses and returns the value set for that
     * property in guacamole.properties. An exception is thrown if the value
     * is not provided.
     *
     * @param <Type> The type that the given property is parsed into.
     * @param property The property to read from guacamole.properties.
     * @return The parsed value of the property as read from
     *         guacamole.properties.
     * @throws GuacamoleException If an error occurs while parsing the value
     *                            for the given property in
     *                            guacamole.properties, or if the property is
     *                            not specified.
     */
    public <Type> Type getRequiredProperty(GuacamoleProperty<Type> property)
            throws GuacamoleException;

}
