/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed 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.springframework.web.socket;

import java.io.Closeable;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.security.Principal;
import java.util.List;
import java.util.Map;

import org.springframework.http.HttpHeaders;
import org.springframework.lang.Nullable;

/**
 * A WebSocket session abstraction. Allows sending messages over a WebSocket
 * connection and closing it.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public interface WebSocketSession extends Closeable {

	/**
	 * Return a unique session identifier.
	 */
	String getId();

	/**
	 * Return the URI used to open the WebSocket connection.
	 */
	@Nullable
	URI getUri();

	/**
	 * Return the headers used in the handshake request (never {@code null}).
	 */
	HttpHeaders getHandshakeHeaders();

	/**
	 * Return the map with attributes associated with the WebSocket session.
	 * <p>On the server side the map can be populated initially through a
	 * {@link org.springframework.web.socket.server.HandshakeInterceptor
	 * HandshakeInterceptor}. On the client side the map can be populated via
	 * {@link org.springframework.web.socket.client.WebSocketClient
	 * WebSocketClient} handshake methods.
	 * @return a Map with the session attributes (never {@code null})
	 */
	Map<String, Object> getAttributes();

	/**
	 * Return a {@link java.security.Principal} instance containing the name
	 * of the authenticated user.
	 * <p>If the user has not been authenticated, the method returns <code>null</code>.
	 */
	@Nullable
	Principal getPrincipal();

	/**
	 * Return the address on which the request was received.
	 */
	@Nullable
	InetSocketAddress getLocalAddress();

	/**
	 * Return the address of the remote client.
	 */
	@Nullable
	InetSocketAddress getRemoteAddress();

	/**
	 * Return the negotiated sub-protocol.
	 * @return the protocol identifier, or {@code null} if no protocol
	 * was specified or negotiated successfully
	 */
	@Nullable
	String getAcceptedProtocol();

	/**
	 * Configure the maximum size for an incoming text message.
	 */
	void setTextMessageSizeLimit(int messageSizeLimit);

	/**
	 * Get the configured maximum size for an incoming text message.
	 */
	int getTextMessageSizeLimit();

	/**
	 * Configure the maximum size for an incoming binary message.
	 */
	void setBinaryMessageSizeLimit(int messageSizeLimit);

	/**
	 * Get the configured maximum size for an incoming binary message.
	 */
	int getBinaryMessageSizeLimit();

	/**
	 * Determine the negotiated extensions.
	 * @return the list of extensions, or an empty list if no extension
	 * was specified or negotiated successfully
	 */
	List<WebSocketExtension> getExtensions();

	/**
	 * Send a WebSocket message: either {@link TextMessage} or {@link BinaryMessage}.
	 *
	 * <p><strong>Note:</strong> The underlying standard WebSocket session (JSR-356) does
	 * not allow concurrent sending. Therefore sending must be synchronized. To ensure
	 * that, one option is to wrap the {@code WebSocketSession} with the
	 * {@link org.springframework.web.socket.handler.ConcurrentWebSocketSessionDecorator
	 * ConcurrentWebSocketSessionDecorator}.
	 * @see org.springframework.web.socket.handler.ConcurrentWebSocketSessionDecorator
	 */
	void sendMessage(WebSocketMessage<?> message) throws IOException;

	/**
	 * Return whether the connection is still open.
	 */
	boolean isOpen();

	/**
	 * Close the WebSocket connection with status 1000, i.e. equivalent to:
	 * <pre class="code">
	 * session.close(CloseStatus.NORMAL);
	 * </pre>
	 */
	@Override
	void close() throws IOException;

	/**
	 * Close the WebSocket connection with the given close status.
	 */
	void close(CloseStatus status) throws IOException;

}
