/*
 * Copyright (c) 2010, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.websockets;

import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.glassfish.grizzly.http.HttpRequestPacket;
import org.glassfish.grizzly.http.util.Header;

Abstract server-side WebSocket application, which will handle application WebSockets events. 
Author:
Alexey Stashok/**
 * Abstract server-side {@link WebSocket} application, which will handle application {@link WebSocket}s events.
 *
 * @author Alexey Stashok
 */
public abstract class WebSocketApplication extends WebSocketAdapter {

    /*
     * WebSockets registered with this application.
     */
    private final ConcurrentMap<WebSocket, Boolean> sockets = new ConcurrentHashMap<>();

    private final List<Extension> supportedExtensions = new ArrayList<>(2);
    private final List<String> supportedProtocols = new ArrayList<>(2);

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

    
Factory method to create new WebSocket instances. Developers may wish to override this to return customized WebSocket implementations. 
Params:
handler – the ProtocolHandler to use with the newly created WebSocket.
listeners – the WebSocketListeners to associate with the new WebSocket.
Returns:
a new WebSocket instance.
Deprecated:
Use createSocket(ProtocolHandler, HttpRequestPacket, WebSocketListener...)/**
     * Factory method to create new {@link WebSocket} instances. Developers may wish to override this to return customized
     * {@link WebSocket} implementations.
     *
     * @param handler the {@link ProtocolHandler} to use with the newly created {@link WebSocket}.
     * 
     * @param listeners the {@link WebSocketListener}s to associate with the new {@link WebSocket}.
     * 
     * @return a new {@link WebSocket} instance.
     *
     * @deprecated Use
     * {@link WebSocketApplication#createSocket(ProtocolHandler, org.glassfish.grizzly.http.HttpRequestPacket, WebSocketListener...)}
     */
    @Deprecated
    public WebSocket createSocket(ProtocolHandler handler, WebSocketListener... listeners) {
        return createSocket(handler, null, listeners);
    }

    
Factory method to create new WebSocket instances. Developers may wish to override this to return customized WebSocket implementations. 
Params:
handler – the ProtocolHandler to use with the newly created WebSocket.
requestPacket – the HttpRequestPacket that triggered the creation of the WebSocket connection.
listeners – the WebSocketListeners to associate with the new WebSocket.
Returns:
/**
     * Factory method to create new {@link WebSocket} instances. Developers may wish to override this to return customized
     * {@link WebSocket} implementations.
     * 
     * @param handler the {@link ProtocolHandler} to use with the newly created {@link WebSocket}.
     * @param requestPacket the {@link HttpRequestPacket} that triggered the creation of the {@link WebSocket} connection.
     * @param listeners the {@link WebSocketListener}s to associate with the new {@link WebSocket}.
     * @return
     */
    public WebSocket createSocket(final ProtocolHandler handler, final HttpRequestPacket requestPacket, final WebSocketListener... listeners) {
        return new DefaultWebSocket(handler, requestPacket, listeners);

    }

    
When a WebSocket.onClose(DataFrame) is invoked, the WebSocket will be unassociated with this application and closed. If this method is overridden, the overriding method must call remove(WebSocket). This is necessary to ensure WebSocket instances are not leaked nor are message operations against closed sockets are performed. 
Params:
socket – the WebSocket being closed.
frame – the closing frame./**
     * When a {@link WebSocket#onClose(DataFrame)} is invoked, the {@link WebSocket} will be unassociated with this
     * application and closed.
     *
     * If this method is overridden, the overriding method <em>must</em> call {@link #remove(WebSocket)}. This is necessary
     * to ensure WebSocket instances are not leaked nor are message operations against closed sockets are performed.
     *
     * @param socket the {@link WebSocket} being closed.
     * @param frame the closing frame.
     */
    @Override
    public void onClose(WebSocket socket, DataFrame frame) {
        remove(socket);
        socket.close();
    }

    
When a new WebSocket connection is made to this application, the WebSocket will be associated with this application. If this method is overridden, the overriding method must call add(WebSocket). This is necessary to ensure bulk message sending via facilities such as Broadcaster function properly. 
Params:
socket – the new WebSocket connection./**
     * When a new {@link WebSocket} connection is made to this application, the {@link WebSocket} will be associated with
     * this application.
     *
     * If this method is overridden, the overriding method <em>must</em> call {@link #add(WebSocket)}. This is necessary to
     * ensure bulk message sending via facilities such as {@link Broadcaster} function properly.
     *
     * @param socket the new {@link WebSocket} connection.
     */
    @Override
    public void onConnect(WebSocket socket) {
        add(socket);
    }

    
Invoked during the handshake if the client has advertised extensions it may use and one or more extensions intersect with those returned by getSupportedExtensions(). The Extensions passed to this method will include any extension parameters included by the client. It's up to this method to re-order and or adjust any parameter values within the list. This method must not add any extensions that weren't originally in the list, but it is acceptable to remove one or all extensions if for some reason they can't be supported. If not overridden, the List will be sent as-is back to the client. 
Params:
extensions – the intersection of extensions between client and application.
Since:
2.3/**
     * Invoked during the handshake if the client has advertised extensions it may use and one or more extensions intersect
     * with those returned by {@link #getSupportedExtensions()}.
     *
     * The {@link Extension}s passed to this method will include any extension parameters included by the client. It's up to
     * this method to re-order and or adjust any parameter values within the list. This method must not add any extensions
     * that weren't originally in the list, but it is acceptable to remove one or all extensions if for some reason they
     * can't be supported.
     *
     * If not overridden, the List will be sent as-is back to the client.
     *
     * @param extensions the intersection of extensions between client and application.
     *
     * @since 2.3
     */
    public void onExtensionNegotiation(List<Extension> extensions) {
    }

    
Checks protocol specific information can and should be upgraded.
The default implementation will check for the presence of the Upgrade header with a value of
WebSocket. If present, isApplicationRequest(HttpRequestPacket) will be invoked to determine if the request is a valid websocket request. 
Returns:
true if the request should be upgraded to a WebSocket connection/**
     * Checks protocol specific information can and should be upgraded.
     *
     * The default implementation will check for the presence of the <code>Upgrade</code> header with a value of
     * <code>WebSocket</code>. If present, {@link #isApplicationRequest(org.glassfish.grizzly.http.HttpRequestPacket)} will
     * be invoked to determine if the request is a valid websocket request.
     *
     * @return <code>true</code> if the request should be upgraded to a WebSocket connection
     */
    public final boolean upgrade(HttpRequestPacket request) {
        return "WebSocket".equalsIgnoreCase(request.getHeader(Header.Upgrade)) && isApplicationRequest(request);
    }

    
Checks application specific criteria to determine if this application can process the request as a WebSocket
connection.
Params:
request – the incoming HTTP request.
Returns:
true if this application can service this request
Deprecated:
URI mapping shouldn't be intrinsic to the application. WebSocketApplications should be registered using WebSocketEngine.register(String, String, WebSocketApplication) using standard Servlet url-pattern rules./**
     * Checks application specific criteria to determine if this application can process the request as a WebSocket
     * connection.
     *
     * @param request the incoming HTTP request.
     * @return <code>true</code> if this application can service this request
     * <p/>
     * @deprecated URI mapping shouldn't be intrinsic to the application. WebSocketApplications should be registered using
     * {@link WebSocketEngine#register(String, String, WebSocketApplication)} using standard Servlet url-pattern rules.
     */
    @Deprecated
    public boolean isApplicationRequest(HttpRequestPacket request) {
        return false;
    }

    
Return the websocket extensions supported by this WebSocketApplication. The Extensions added to this List should not include any Parameters as they will be ignored. This is used exclusively for matching the requested extensions. 
Returns:
the websocket extensions supported by this WebSocketApplication./**
     * Return the websocket extensions supported by this <code>WebSocketApplication</code>. The {@link Extension}s added to
     * this {@link List} should not include any {@link Extension.Parameter}s as they will be ignored. This is used
     * exclusively for matching the requested extensions.
     *
     * @return the websocket extensions supported by this <code>WebSocketApplication</code>.
     */
    public List<Extension> getSupportedExtensions() {
        return supportedExtensions;
    }

    
Params:
subProtocol – 
Returns:
/**
     *
     *
     * @param subProtocol
     * @return
     */
    public List<String> getSupportedProtocols(List<String> subProtocol) {
        return supportedProtocols;
    }

    // ------------------------------------------------------- Protected Methods

    
Returns a set of WebSockets, registered with the application. The returned set is unmodifiable, the possible modifications may cause exceptions. 
Returns:
a set of WebSockets, registered with the application./**
     * Returns a set of {@link WebSocket}s, registered with the application. The returned set is unmodifiable, the possible
     * modifications may cause exceptions.
     *
     * @return a set of {@link WebSocket}s, registered with the application.
     */
    protected Set<WebSocket> getWebSockets() {
        return sockets.keySet();
    }

    
Associates the specified WebSocket with this application. 
Params:
socket – the WebSocket to associate with this application.
Returns:
true if the socket was successfully associated, otherwise returns false./**
     * Associates the specified {@link WebSocket} with this application.
     *
     * @param socket the {@link WebSocket} to associate with this application.
     *
     * @return <code>true</code> if the socket was successfully associated, otherwise returns <code>false</code>.
     */
    protected boolean add(WebSocket socket) {
        return sockets.put(socket, Boolean.TRUE) == null;
    }

    
Unassociates the specified WebSocket with this application. 
Params:
socket – the WebSocket to unassociate with this application.
Returns:
true if the socket was successfully unassociated, otherwise returns false./**
     * Unassociates the specified {@link WebSocket} with this application.
     *
     * @param socket the {@link WebSocket} to unassociate with this application.
     * 
     * @return <code>true</code> if the socket was successfully unassociated, otherwise returns <code>false</code>.
     */
    public boolean remove(WebSocket socket) {
        return sockets.remove(socket) != null;
    }

    
This method will be called, when initial WebSocket handshake process has been completed, but allows the application to perform further negotiation/validation. 
Throws:
HandshakeException – error occurred during the handshake./**
     * This method will be called, when initial {@link WebSocket} handshake process has been completed, but allows the
     * application to perform further negotiation/validation.
     *
     * @throws HandshakeException error occurred during the handshake.
     */
    protected void handshake(HandShake handshake) throws HandshakeException {
    }

    
This method will be invoked if an unexpected exception is caught by the WebSocket runtime.
Params:
webSocket – the websocket being processed at the time the exception occurred.
t – the unexpected exception.
Returns:
true if the WebSocket should be closed otherwise false./**
     * This method will be invoked if an unexpected exception is caught by the WebSocket runtime.
     *
     * @param webSocket the websocket being processed at the time the exception occurred.
     * @param t the unexpected exception.
     *
     * @return <code>true</code> if the WebSocket should be closed otherwise <code>false</code>.
     */
    protected boolean onError(final WebSocket webSocket, final Throwable t) {
        return true;
    }

}