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package org.tio.websocket.common;

import java.nio.ByteBuffer;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.tio.core.ChannelContext;
import org.tio.core.exception.TioDecodeException;
import org.tio.core.utils.ByteBufferUtils;

/**
 *
 * @author tanyaowu
 * 2017年7月30日 上午10:10:50
 */
public class WsServerDecoder {
	public static enum Step {
		header, remain_header, data,
	}

	private static Logger log = LoggerFactory.getLogger(WsServerDecoder.class);

	public static WsRequest decode(ByteBuffer buf, ChannelContext channelContext) throws TioDecodeException {
		//		WsSessionContext imSessionContext = (WsSessionContext) channelContext.get();
		//		List<byte[]> lastParts = imSessionContext.getLastParts();

		// 第一阶段解析
		int initPosition = buf.position();
		int readableLength = buf.limit() - initPosition;

		int headLength = WsPacket.MINIMUM_HEADER_LENGTH;

		if (readableLength < headLength) {
			return null;
		}

		byte first = buf.get();
		//		int b = first & 0xFF; //转换成32位
		boolean fin = (first & 0x80) > 0; // 得到第8位 10000000>0
		@SuppressWarnings("unused")
		int rsv = (first & 0x70) >>> 4; // 得到5、6、7 为01110000 然后右移四位为00000111
		byte opCodeByte = (byte) (first & 0x0F); // 后四位为opCode 00001111
		Opcode opcode = Opcode.valueOf(opCodeByte);
		if (opcode == Opcode.CLOSE) {
			//			Tio.remove(channelContext, "收到opcode:" + opcode);
			//			return null;
		}
		//		if (!fin) {
		//			log.error("{} 暂时不支持fin为false的请求", channelContext);
		//			Tio.remove(channelContext, "暂时不支持fin为false的请求");
		//			return null;
		//			//下面这段代码不要删除，以后若支持fin，则需要的
		//			//			if (lastParts == null) {
		//			//				lastParts = new ArrayList<>();
		//			//				imSessionContext.setLastParts(lastParts);
		//			//			}
		//		} else {
		//			imSessionContext.setLastParts(null);
		//		}

		byte second = buf.get(); // 向后读取一个字节
		boolean hasMask = (second & 0xFF) >> 7 == 1; // 用于标识PayloadData是否经过掩码处理。如果是1，Masking-key域的数据即是掩码密钥，用于解码PayloadData。客户端发出的数据帧需要进行掩码处理，所以此位是1。

		// Client data must be masked
		if (!hasMask) { // 第9为为mask,必须为1
			// throw new TioDecodeException("websocket client data must be masked");
		} else {
			headLength += 4;
		}
		int payloadLength = second & 0x7F; // 读取后7位  Payload legth，如果<126则payloadLength

		byte[] mask = null;
		if (payloadLength == 126) { // 为126读2个字节，后两个字节为payloadLength
			headLength += 2;
			if (readableLength < headLength) {
				return null;
			}
			payloadLength = ByteBufferUtils.readUB2WithBigEdian(buf);
			log.info("{} payloadLengthFlag: 126，payloadLength {}", channelContext, payloadLength);

		} else if (payloadLength == 127) { // 127读8个字节,后8个字节为payloadLength
			headLength += 8;
			if (readableLength < headLength) {
				return null;
			}

			payloadLength = (int) buf.getLong();
			log.info("{} payloadLengthFlag: 127，payloadLength {}", channelContext, payloadLength);
		}

		if (payloadLength < 0 || payloadLength > WsPacket.MAX_BODY_LENGTH) {
			throw new TioDecodeException("body length(" + payloadLength + ") is not right");
		}

		if (readableLength < headLength + payloadLength) {
			return null;
		}

		if (hasMask) {
			mask = ByteBufferUtils.readBytes(buf, 4);
		}

		// 第二阶段解析
		WsRequest websocketPacket = new WsRequest();
		websocketPacket.setWsEof(fin);
		websocketPacket.setWsHasMask(hasMask);
		websocketPacket.setWsMask(mask);
		websocketPacket.setWsOpcode(opcode);
		websocketPacket.setWsBodyLength(payloadLength);

		if (payloadLength == 0) {
			return websocketPacket;
		}

		byte[] array = ByteBufferUtils.readBytes(buf, payloadLength);
		if (hasMask) {
			for (int i = 0; i < array.length; i++) {
				array[i] = (byte) (array[i] ^ mask[i % 4]);
			}
		}

		websocketPacket.setBody(array);

		//		if (!fin) {
		//			//lastParts.add(array);
		//			log.error("payloadLength {}, lastParts size {}, array length {}", payloadLength,
		// lastParts.size(), array.length);
		//			return websocketPacket;
		//		} else {
		//			int allLength = array.length;
		//			if (lastParts != null) {
		//				for (byte[] part : lastParts) {
		//					allLength += part.length;
		//				}
		//				byte[] allByte = new byte[allLength];
		//
		//				int offset = 0;
		//				for (byte[] part : lastParts) {
		//					System.arraycopy(part, 0, allByte, offset, part.length);
		//					offset += part.length;
		//				}
		//				System.arraycopy(array, 0, allByte, offset, array.length);
		//				array = allByte;
		//			}
		//
		//			websocketPacket.setBody(array);
		//
		//			if (opcode == Opcode.BINARY) {
		//
		//			} else {
		//				try {
		//					String text = null;
		//					text = new String(array, WsPacket.CHARSET_NAME);
		//					websocketPacket.setWsBodyText(text);
		//				} catch (UnsupportedEncodingException e) {
		//					log.error(e.toString(), e);
		//				}
		//			}
		//		}

//		if (fin && opcode != null) {
//			if (opcode == Opcode.BINARY) {
//
//			} else {
//				try {
//					String text = new String(array, WsPacket.CHARSET_NAME);
//					websocketPacket.setWsBodyText(text);
//				} catch (UnsupportedEncodingException e) {
//					log.error(e.toString(), e);
//				}
//			}
//		}
		return websocketPacket;
	}

	/** @author tanyaowu 2017年2月22日 下午4:06:42 */
	public WsServerDecoder() {
	}
}
