//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.websocket.common;
  
  import java.nio.ByteBuffer;
  import java.nio.charset.StandardCharsets;
  import java.util.Arrays;
  
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.StringUtil;
  import org.eclipse.jetty.websocket.api.ProtocolException;
  import org.eclipse.jetty.websocket.api.extensions.Frame;
  
  /**
   * A Base Frame as seen in <a href="https://tools.ietf.org/html/rfc6455#section-5.2">RFC 6455. Sec 5.2</a>
   * 
   * <pre>
   *    0                   1                   2                   3
   *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   *   +-+-+-+-+-------+-+-------------+-------------------------------+
   *   |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
   *   |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
   *   |N|V|V|V|       |S|             |   (if payload len==126/127)   |
   *   | |1|2|3|       |K|             |                               |
   *   +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
   *   |     Extended payload length continued, if payload len == 127  |
   *   + - - - - - - - - - - - - - - - +-------------------------------+
   *   |                               |Masking-key, if MASK set to 1  |
   *   +-------------------------------+-------------------------------+
   *   | Masking-key (continued)       |          Payload Data         |
   *   +-------------------------------- - - - - - - - - - - - - - - - +
   *   :                     Payload Data continued ...                :
   *   + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
   *   |                     Payload Data continued ...                |
   *   +---------------------------------------------------------------+
   * </pre>
   */
  public class WebSocketFrame implements Frame
  {
      /** Maximum size of Control frame, per RFC 6455 */
      public static final int MAX_CONTROL_PAYLOAD = 125;
  
      public static WebSocketFrame binary()
      {
          return new WebSocketFrame(OpCode.BINARY);
      }
  
      public static WebSocketFrame binary(byte buf[])
      {
          return new WebSocketFrame(OpCode.BINARY).setPayload(buf);
      }
  
      public static WebSocketFrame ping()
      {
          return new WebSocketFrame(OpCode.PING);
      }
  
      public static WebSocketFrame pong()
      {
          return new WebSocketFrame(OpCode.PONG);
      }
  
      public static WebSocketFrame text()
      {
          return new WebSocketFrame(OpCode.TEXT);
      }
  
      public static WebSocketFrame text(String msg)
      {
          return new WebSocketFrame(OpCode.TEXT).setPayload(msg);
      }
  
      private boolean fin = true;
      private boolean rsv1 = false;
      private boolean rsv2 = false;
      private boolean rsv3 = false;
      protected byte opcode = OpCode.UNDEFINED;
      private boolean masked = false;
      private byte mask[];
      /**
       * The payload data.
       * <p>
       * It is assumed to always be in FLUSH mode (ready to read) in this object.
      */
     private ByteBuffer data;
     private int payloadLength = 0;
     /** position of start of data within a fresh payload */
     private int payloadStart = -1;
 
     private Type type;
     private boolean continuation = false;
     private int continuationIndex = 0;
 
     /**
      * Default constructor
      */
     public WebSocketFrame()
     {
         this(OpCode.UNDEFINED);
     }
 
     /**
      * Construct form opcode
      */
     public WebSocketFrame(byte opcode)
     {
         reset();
         setOpCode(opcode);
     }
 
     /**
      * Copy constructor for the websocket frame.
      * 
      * @param copy
      *            the websocket to copy.
      */
     public WebSocketFrame(Frame frame)
     {
         if (frame instanceof WebSocketFrame)
         {
             WebSocketFrame wsf = (WebSocketFrame)frame;
             copy(wsf,wsf.data);
         }
         else
         {
             // Copy manually
             fin = frame.isFin();
             rsv1 = frame.isRsv1();
             rsv2 = frame.isRsv2();
             rsv3 = frame.isRsv3();
             opcode = frame.getType().getOpCode();
             type = frame.getType();
             masked = frame.isMasked();
             mask = null;
             byte maskCopy[] = frame.getMask();
             if (maskCopy != null)
             {
                 mask = new byte[maskCopy.length];
                 System.arraycopy(maskCopy,0,mask,0,mask.length);
             }
 
             setPayload(frame.getPayload());
         }
     }
 
     /**
      * Copy constructor for the websocket frame.
      * <p>
      * Note: the underlying payload is merely a {@link ByteBuffer#slice()} of the input frame.
      * 
      * @param copy
      *            the websocket to copy.
      */
     public WebSocketFrame(WebSocketFrame copy)
     {
         copy(copy,copy.data);
     }
 
     /**
      * Copy constructor for the websocket frame, with an alternate payload.
      * <p>
      * This is especially useful for Extensions to utilize when mutating the payload.
      * 
      * @param copy
      *            the websocket to copy.
      * @param altPayload
      *            the alternate payload to use for this frame.
      */
     public WebSocketFrame(WebSocketFrame copy, ByteBuffer altPayload)
     {
         copy(copy,altPayload);
     }
 
     public void assertValid()
     {
         if (OpCode.isControlFrame(opcode))
         {
             if (getPayloadLength() > WebSocketFrame.MAX_CONTROL_PAYLOAD)
             {
                 throw new ProtocolException("Desired payload length [" + getPayloadLength() + "] exceeds maximum control payload length ["
                         + MAX_CONTROL_PAYLOAD + "]");
             }
 
             if (fin == false)
             {
                 throw new ProtocolException("Cannot have FIN==false on Control frames");
             }
 
             if (rsv1 == true)
             {
                 throw new ProtocolException("Cannot have RSV1==true on Control frames");
             }
 
             if (rsv2 == true)
             {
                 throw new ProtocolException("Cannot have RSV2==true on Control frames");
             }
 
             if (rsv3 == true)
             {
                 throw new ProtocolException("Cannot have RSV3==true on Control frames");
             }
 
             if (isContinuation())
             {
                 throw new ProtocolException("Control frames cannot be Continuations");
             }
         }
     }
 
     private final void copy(WebSocketFrame copy, ByteBuffer payload)
     {
         fin = copy.fin;
         rsv1 = copy.rsv1;
         rsv2 = copy.rsv2;
         rsv3 = copy.rsv3;
         opcode = copy.opcode;
         type = copy.type;
         masked = copy.masked;
         mask = null;
         if (copy.mask != null)
         {
             mask = new byte[copy.mask.length];
             System.arraycopy(copy.mask,0,mask,0,mask.length);
         }
         continuationIndex = copy.continuationIndex;
         continuation = copy.continuation;
 
         setPayload(payload);
     }
 
     @Override
     public boolean equals(Object obj)
     {
         if (this == obj)
         {
             return true;
         }
         if (obj == null)
         {
             return false;
         }
         if (getClass() != obj.getClass())
         {
             return false;
         }
         WebSocketFrame other = (WebSocketFrame)obj;
         if (continuation != other.continuation)
         {
             return false;
         }
         if (continuationIndex != other.continuationIndex)
         {
             return false;
         }
         if (data == null)
         {
             if (other.data != null)
             {
                 return false;
             }
         }
         else if (!data.equals(other.data))
         {
             return false;
         }
         if (fin != other.fin)
         {
             return false;
         }
         if (!Arrays.equals(mask,other.mask))
         {
             return false;
         }
         if (masked != other.masked)
         {
             return false;
         }
         if (opcode != other.opcode)
         {
             return false;
         }
         if (rsv1 != other.rsv1)
         {
             return false;
         }
         if (rsv2 != other.rsv2)
         {
             return false;
         }
         if (rsv3 != other.rsv3)
         {
             return false;
         }
         return true;
     }
 
     /**
      * The number of fragments this frame consists of.
      * <p>
      * For every {@link OpCode#CONTINUATION} opcode encountered, this increments by one.
      * <p>
      * Note: Not part of the Base Framing Protocol / header information.
      * 
      * @return the number of continuation fragments encountered.
      */
     public int getContinuationIndex()
     {
         return continuationIndex;
     }
 
     @Override
     public byte[] getMask()
     {
         if (!masked)
         {
             throw new IllegalStateException("Frame is not masked");
         }
         return mask;
     }
 
     @Override
     public final byte getOpCode()
     {
         return opcode;
     }
 
     /**
      * Get the payload ByteBuffer. possible null.
      * <p>
      * 
      * @return A {@link ByteBuffer#slice()} of the payload buffer (to prevent modification of the buffer state). Possibly null if no payload present.
      *         <p>
      *         Note: this method is exposed via the immutable {@link Frame#getPayload()} method.
      */
     @Override
     public ByteBuffer getPayload()
     {
         if (data != null)
         {
             return data;
         }
         else
         {
             return null;
         }
     }
 
     public String getPayloadAsUTF8()
     {
         if (data == null)
         {
             return null;
         }
         return BufferUtil.toUTF8String(data);
     }
 
     @Override
     public int getPayloadLength()
     {
         if (data == null)
         {
             return 0;
         }
         return payloadLength;
     }
 
     @Override
     public int getPayloadStart()
     {
         if (data == null)
         {
             return -1;
         }
         return payloadStart;
     }
 
     @Override
     public Type getType()
     {
         return type;
     }
 
     @Override
     public int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = (prime * result) + (continuation?1231:1237);
         result = (prime * result) + continuationIndex;
         result = (prime * result) + ((data == null)?0:data.hashCode());
         result = (prime * result) + (fin?1231:1237);
         result = (prime * result) + Arrays.hashCode(mask);
         result = (prime * result) + (masked?1231:1237);
         result = (prime * result) + opcode;
         result = (prime * result) + (rsv1?1231:1237);
         result = (prime * result) + (rsv2?1231:1237);
         result = (prime * result) + (rsv3?1231:1237);
         return result;
     }
 
     @Override
     public boolean hasPayload()
     {
         return ((data != null) && (payloadLength > 0));
     }
 
     @Override
     public boolean isContinuation()
     {
         return continuation;
     }
 
     public boolean isControlFrame()
     {
         return OpCode.isControlFrame(opcode);
     }
 
     public boolean isDataFrame()
     {
         return OpCode.isDataFrame(opcode);
     }
 
     @Override
     public boolean isFin()
     {
         return fin;
     }
 
     @Override
     public boolean isLast()
     {
         return fin;
     }
 
     public boolean isLastFrame()
     {
         return fin;
     }
 
     @Override
     public boolean isMasked()
     {
         return masked;
     }
 
     @Override
     public boolean isRsv1()
     {
         return rsv1;
     }
 
     @Override
     public boolean isRsv2()
     {
         return rsv2;
     }
 
     @Override
     public boolean isRsv3()
     {
         return rsv3;
     }
 
     /**
      * Get the position currently within the payload data.
      * <p>
      * Used by flow control, generator and window sizing.
      * 
      * @return the number of bytes remaining in the payload data that has not yet been written out to Network ByteBuffers.
      */
     public int position()
     {
         if (data == null)
         {
             return -1;
         }
         return data.position();
     }
 
     /**
      * Get the number of bytes remaining to write out to the Network ByteBuffer.
      * <p>
      * Used by flow control, generator and window sizing.
      * 
      * @return the number of bytes remaining in the payload data that has not yet been written out to Network ByteBuffers.
      */
     @Override
     public int remaining()
     {
         if (data == null)
         {
             return 0;
         }
         return data.remaining();
     }
 
     public void reset()
     {
         fin = true;
         rsv1 = false;
         rsv2 = false;
         rsv3 = false;
         opcode = -1;
         masked = false;
         data = null;
         payloadLength = 0;
         mask = null;
         continuationIndex = 0;
         continuation = false;
     }
 
     public Frame setContinuation(boolean continuation)
     {
         this.continuation = continuation;
         return this;
     }
 
     public Frame setContinuationIndex(int continuationIndex)
     {
         this.continuationIndex = continuationIndex;
         return this;
     }
 
     public WebSocketFrame setFin(boolean fin)
     {
         this.fin = fin;
         return this;
     }
 
     public Frame setMask(byte[] maskingKey)
     {
         this.mask = maskingKey;
         this.masked = (mask != null);
         return this;
     }
 
     public Frame setMasked(boolean mask)
     {
         this.masked = mask;
         return this;
     }
 
     public WebSocketFrame setOpCode(byte op)
     {
         this.opcode = op;
 
         if (op == OpCode.UNDEFINED)
         {
             this.type = null;
         }
         else
         {
             this.type = Frame.Type.from(op);
         }
         return this;
     }
 
     /**
      * Set the data and payload length.
      * 
      * @param buf
      *            the bytebuffer to set
      */
     public WebSocketFrame setPayload(byte buf[])
     {
         if (buf == null)
         {
             data = null;
             return this;
         }
 
         if (OpCode.isControlFrame(opcode))
         {
             if (buf.length > WebSocketFrame.MAX_CONTROL_PAYLOAD)
             {
                 throw new ProtocolException("Control Payloads can not exceed 125 bytes in length.");
             }
         }
 
         data = BufferUtil.toBuffer(buf);
         payloadStart = data.position();
         payloadLength = data.limit();
         return this;
     }
 
     /**
      * Set the data and payload length.
      * 
      * @param buf
      *            the bytebuffer to set
      */
     public WebSocketFrame setPayload(byte buf[], int offset, int len)
     {
         if (buf == null)
         {
             data = null;
             return this;
         }
 
         if (OpCode.isControlFrame(opcode))
         {
             if (len > WebSocketFrame.MAX_CONTROL_PAYLOAD)
             {
                 throw new ProtocolException("Control Payloads can not exceed 125 bytes in length.");
             }
         }
 
         data = BufferUtil.toBuffer(buf,offset,len);
         payloadStart = data.position();
         payloadLength = data.limit();
         return this;
     }
 
     /**
      * Set the data payload.
      * <p>
      * The provided buffer will be used as is, no copying of bytes performed.
      * <p>
      * The provided buffer should be flipped and ready to READ from.
      * 
      * @param buf
      *            the bytebuffer to set
      */
     public WebSocketFrame setPayload(ByteBuffer buf)
     {
         if (buf == null)
         {
             data = null;
             return this;
         }
 
         if (OpCode.isControlFrame(opcode))
         {
             if (buf.remaining() > WebSocketFrame.MAX_CONTROL_PAYLOAD)
             {
                 throw new ProtocolException("Control Payloads can not exceed 125 bytes in length. (was " + buf.remaining() + " bytes)");
             }
         }
 
         data = buf.slice();
         payloadStart = data.position();
         payloadLength = data.limit();
         return this;
     }
 
     public WebSocketFrame setPayload(String str)
     {
         setPayload(BufferUtil.toBuffer(str, StandardCharsets.UTF_8));
         return this;
     }
 
     public WebSocketFrame setRsv1(boolean rsv1)
     {
         this.rsv1 = rsv1;
         return this;
     }
 
     public WebSocketFrame setRsv2(boolean rsv2)
     {
         this.rsv2 = rsv2;
         return this;
     }
 
     public WebSocketFrame setRsv3(boolean rsv3)
     {
         this.rsv3 = rsv3;
         return this;
     }
 
     @Override
     public String toString()
     {
         StringBuilder b = new StringBuilder();
         b.append(OpCode.name(opcode));
         b.append('[');
         b.append("len=").append(payloadLength);
         b.append(",fin=").append(fin);
         b.append(",rsv=");
         b.append(rsv1?'1':'.');
         b.append(rsv2?'1':'.');
         b.append(rsv3?'1':'.');
         b.append(",masked=").append(masked);
         b.append(",continuation=").append(continuation);
         b.append(",payloadStart=").append(getPayloadStart());
         b.append(",remaining=").append(remaining());
         b.append(",position=").append(position());
         b.append(']');
         return b.toString();
     }
 }