/*
 * 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.catalina;

import java.io.File;
import java.util.concurrent.ExecutorService;
import java.util.regex.Pattern;


/**
 * A <b>Host</b> is a Container that represents a virtual host in the Catalina servlet engine. It is useful in the
 * following types of scenarios:
 * <ul>
 * <li>You wish to use Interceptors that see every single request processed by this particular virtual host.
 * <li>You wish to run Catalina in with a standalone HTTP connector, but still want support for multiple virtual hosts.
 * </ul>
 * In general, you would not use a Host when deploying Catalina connected to a web server (such as Apache), because the
 * Connector will have utilized the web server's facilities to determine which Context (or perhaps even which Wrapper)
 * should be utilized to process this request.
 * <p>
 * The parent Container attached to a Host is generally an Engine, but may be some other implementation, or may be
 * omitted if it is not necessary.
 * <p>
 * The child containers attached to a Host are generally implementations of Context (representing an individual servlet
 * context).
 *
 * @author Craig R. McClanahan
 */
public interface Host extends Container {


    // ----------------------------------------------------- Manifest Constants


    /**
     * The ContainerEvent event type sent when a new alias is added by <code>addAlias()</code>.
     */
    String ADD_ALIAS_EVENT = "addAlias";


    /**
     * The ContainerEvent event type sent when an old alias is removed by <code>removeAlias()</code>.
     */
    String REMOVE_ALIAS_EVENT = "removeAlias";


    // ------------------------------------------------------------- Properties


    /**
     * @return the XML root for this Host. This can be an absolute pathname or a relative pathname. If null, the base
     *             path defaults to ${catalina.base}/conf/&lt;engine name&gt;/&lt;host name&gt; directory
     */
    String getXmlBase();

    /**
     * Set the Xml root for this Host. This can be an absolute pathname or a relative pathname. If null, the base path
     * defaults to ${catalina.base}/conf/&lt;engine name&gt;/&lt;host name&gt; directory
     *
     * @param xmlBase The new XML root
     */
    void setXmlBase(String xmlBase);

    /**
     * @return a default configuration path of this Host. The file will be canonical if possible.
     */
    File getConfigBaseFile();

    /**
     * @return the application root for this Host. This can be an absolute pathname, a relative pathname, or a URL.
     */
    String getAppBase();


    /**
     * @return an absolute {@link File} for the appBase of this Host. The file will be canonical if possible. There is
     *             no guarantee that the appBase exists.
     */
    File getAppBaseFile();


    /**
     * Set the application root for this Host. This can be an absolute pathname, a relative pathname, or a URL.
     *
     * @param appBase The new application root
     */
    void setAppBase(String appBase);


    /**
     * @return the value of the auto deploy flag. If true, it indicates that this host's child webapps should be
     *             discovered and automatically deployed dynamically.
     */
    boolean getAutoDeploy();


    /**
     * Set the auto deploy flag value for this host.
     *
     * @param autoDeploy The new auto deploy flag
     */
    void setAutoDeploy(boolean autoDeploy);


    /**
     * @return the Java class name of the context configuration class for new web applications.
     */
    String getConfigClass();


    /**
     * Set the Java class name of the context configuration class for new web applications.
     *
     * @param configClass The new context configuration class
     */
    void setConfigClass(String configClass);


    /**
     * @return the value of the deploy on startup flag. If true, it indicates that this host's child webapps should be
     *             discovered and automatically deployed.
     */
    boolean getDeployOnStartup();


    /**
     * Set the deploy on startup flag value for this host.
     *
     * @param deployOnStartup The new deploy on startup flag
     */
    void setDeployOnStartup(boolean deployOnStartup);


    /**
     * @return the regular expression that defines the files and directories in the host's appBase that will be ignored
     *             by the automatic deployment process.
     */
    String getDeployIgnore();


    /**
     * @return the compiled regular expression that defines the files and directories in the host's appBase that will be
     *             ignored by the automatic deployment process.
     */
    Pattern getDeployIgnorePattern();


    /**
     * Set the regular expression that defines the files and directories in the host's appBase that will be ignored by
     * the automatic deployment process.
     *
     * @param deployIgnore A regular expression matching file names
     */
    void setDeployIgnore(String deployIgnore);


    /**
     * @return the executor that is used for starting and stopping contexts. This is primarily for use by components
     *             deploying contexts that want to do this in a multithreaded manner.
     */
    ExecutorService getStartStopExecutor();


    /**
     * Returns <code>true</code> if the Host will attempt to create directories for appBase and xmlBase unless they
     * already exist.
     *
     * @return true if the Host will attempt to create directories
     */
    boolean getCreateDirs();


    /**
     * Should the Host attempt to create directories for xmlBase and appBase upon startup.
     *
     * @param createDirs The new value for this flag
     */
    void setCreateDirs(boolean createDirs);


    /**
     * @return <code>true</code> of the Host is configured to automatically undeploy old versions of applications
     *             deployed using parallel deployment. This only takes effect is {@link #getAutoDeploy()} also returns
     *             <code>true</code>.
     */
    boolean getUndeployOldVersions();


    /**
     * Set to <code>true</code> if the Host should automatically undeploy old versions of applications deployed using
     * parallel deployment. This only takes effect if {@link #getAutoDeploy()} returns <code>true</code>.
     *
     * @param undeployOldVersions The new value for this flag
     */
    void setUndeployOldVersions(boolean undeployOldVersions);


    // --------------------------------------------------------- Public Methods

    /**
     * Add an alias name that should be mapped to this same Host.
     *
     * @param alias The alias to be added
     */
    void addAlias(String alias);


    /**
     * @return the array of alias names for this Host. If none are defined, a zero length array is returned.
     */
    String[] findAliases();


    /**
     * Remove the specified alias name from the aliases for this Host.
     *
     * @param alias Alias name to be removed
     */
    void removeAlias(String alias);
}
