/*
    * Copyright 2002-2013 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.sockjs.frame;
  
  import java.nio.charset.Charset;
  
  import org.springframework.util.StringUtils;
  
  /**
   * Represents a SockJS frame. Provides factory methods to create SockJS frames.
   *
   * @author Rossen Stoyanchev
   * @since 4.0
   */
  public class SockJsFrame {
  
  	public static final Charset CHARSET = Charset.forName("UTF-8");
  
  	private static final SockJsFrame OPEN_FRAME = new SockJsFrame("o");
  
  	private static final SockJsFrame HEARTBEAT_FRAME = new SockJsFrame("h");
  
  	private static final SockJsFrame CLOSE_GO_AWAY_FRAME = closeFrame(3000, "Go away!");
  
  	private static final SockJsFrame CLOSE_ANOTHER_CONNECTION_OPEN_FRAME = closeFrame(2010, "Another connection still open");
  
  
  	private final SockJsFrameType type;
  
  	private final String content;
  
  
  	/**
  	 * Create a new instance frame with the given frame content.
  	 * @param content the content, must be a non-empty and represent a valid SockJS frame
  	 */
  	public SockJsFrame(String content) {
  		StringUtils.hasText(content);
  		if ("o".equals(content)) {
  			this.type = SockJsFrameType.OPEN;
  			this.content = content;
  		}
  		else if ("h".equals(content)) {
  			this.type = SockJsFrameType.HEARTBEAT;
  			this.content = content;
  		}
  		else if (content.charAt(0) == 'a') {
  			this.type = SockJsFrameType.MESSAGE;
  			this.content = (content.length() > 1 ? content : "a[]");
  		}
  		else if (content.charAt(0) == 'm') {
  			this.type = SockJsFrameType.MESSAGE;
  			this.content = (content.length() > 1 ? content : "null");
  		}
  		else if (content.charAt(0) == 'c') {
  			this.type = SockJsFrameType.CLOSE;
  			this.content = (content.length() > 1 ? content : "c[]");
  		}
  		else {
  			throw new IllegalArgumentException("Unexpected SockJS frame type in content=\"" + content + "\"");
  		}
  	}
  
  	public static SockJsFrame openFrame() {
  		return OPEN_FRAME;
  	}
  
  	public static SockJsFrame heartbeatFrame() {
  		return HEARTBEAT_FRAME;
  	}
  
  	public static SockJsFrame messageFrame(SockJsMessageCodec codec, String... messages) {
  		String encoded = codec.encode(messages);
  		return new SockJsFrame(encoded);
  	}
  
  	public static SockJsFrame closeFrameGoAway() {
  		return CLOSE_GO_AWAY_FRAME;
  	}
  
  	public static SockJsFrame closeFrameAnotherConnectionOpen() {
  		return CLOSE_ANOTHER_CONNECTION_OPEN_FRAME;
  	}
  
  	public static SockJsFrame closeFrame(int code, String reason) {
 		return new SockJsFrame("c[" + code + ",\"" + reason + "\"]");
 	}
 
 
 	/**
 	 * Return the SockJS frame type.
 	 */
 	public SockJsFrameType getType() {
 		return this.type;
 	}
 
 	/**
 	 * Return the SockJS frame content, never {@code null}.
 	 */
 	public String getContent() {
 		return this.content;
 	}
 
 	/**
 	 * Return the SockJS frame content as a byte array.
 	 */
 	public byte[] getContentBytes() {
 		return this.content.getBytes(CHARSET);
 	}
 
 	/**
 	 * Return data contained in a SockJS "message" and "close" frames. Otherwise
 	 * for SockJS "open" and "close" frames, which do not contain data, return
 	 * {@code null}.
 	 */
 	public String getFrameData() {
 		if (SockJsFrameType.OPEN == getType() || SockJsFrameType.HEARTBEAT == getType()) {
 			return null;
 		}
 		else {
 			return getContent().substring(1);
 		}
 	}
 
 
 	@Override
 	public boolean equals(Object other) {
 		if (this == other) {
 			return true;
 		}
 		if (!(other instanceof SockJsFrame)) {
 			return false;
 		}
 		return (this.type.equals(((SockJsFrame) other).type) && this.content.equals(((SockJsFrame) other).content));
 	}
 
 	@Override
 	public int hashCode() {
 		return this.content.hashCode();
 	}
 
 	@Override
 	public String toString() {
 		String result = this.content;
 		if (result.length() > 80) {
 			result = result.substring(0, 80) + "...(truncated)";
 		}
 		return "SockJsFrame content='" + result.replace("\n", "\\n").replace("\r", "\\r") + "'";
 	}
 
 }