/// <summary>
/// Decode a trie-based encoded message.
/// </summary>
/// <param name="encoded">the encoded bytes</param>
/// <returns>the decoded bytes</returns>
public byte[] Decode(byte[] encoded)
{
MemoryStream input = new MemoryStream(encoded);
MemoryStream result = new MemoryStream(encoded.Length);
IList<byte> missingAnnouncements = new List<byte>();
int b;
while ((b = input.ReadByte()) >= 0)
{
switch(b) {
case EscapeSingleCharacter:
result.WriteByte((byte)input.ReadByte());
break;
case EscapeMultipleCharacterSequence:
uint length = ByteUtils.DecodeLength(input);
while (length-- > 0 && input.Position < input.Length)
{
result.WriteByte((byte)input.ReadByte());
}
break;
//case EscapeDictionaryAnnouncement:
// byte shortForm = (byte)input.ReadByte();
// int longForm = ByteUtils.DecodeLength(input);
// HandleAnnouncement(longForm, shortForm);
// if (inverseShortcuts[shortForm] != 0)
// {
// byte[] decoded = decodingTable[inverseShortcuts[shortForm]];
// result.Write(decoded, 0, decoded.Length);
// }
// else
// {
// missingAnnouncements.Add((byte)shortForm);
// }
// break;
default:
if(inverseShortcuts[b] != 0)
{
byte[] decoded = decodingTable[(int)inverseShortcuts[b]];
result.Write(decoded, 0, decoded.Length);
}
else
{
missingAnnouncements.Add((byte)b);
}
break;
}
}
if (missingAnnouncements.Count > 0)
{
MissingInformationException mcce = new MissingInformationException();
mcce.Template = templateId;
//mcce.UserID = userId;
mcce.IDs = missingAnnouncements;
mcce.ExceptionType = EnumExceptionType.MissingAnnouncement;
throw mcce;
}
return result.ToArray();
}
/// <summary>
/// Decode the provided byte array received from the user with unique
/// identity <c>userId</c>.
/// </summary>
/// <param name="userId">the unique identity for the user</param>
/// <param name="encodedBytes">the encoded message received</param>
/// <returns></returns>
public byte[] Decode(int userId, byte[] encodedBytes)
{
log.Trace("\n>>>> DECODING <<<<<");
Stream input = TryInflating(encodedBytes);
CompressedMessagePackage cmp = new CompressedMessagePackage();
cmp.TemplateId = (short)ByteUtils.DecodeLength(input);
log.Trace(String.Format("==> Decoding with template {0}", cmp.TemplateId));
int inputValue;
while((inputValue = input.ReadByte()) != -1) {
switch ((GMCMessageKey)inputValue)
{
case GMCMessageKey.Huffed: cmp.Huffed = true; break;
case GMCMessageKey.NotHuffed: cmp.Huffed = false; break;
case GMCMessageKey.Template:
cmp.Template = DecodeTemplate(input);
if (log.IsTraceEnabled)
{
log.Trace(String.Format("TID={0}: Decoded template: {1}",
cmp.TemplateId, ByteUtils.DumpBytes(cmp.Template)));
}
break;
case GMCMessageKey.HuffmanFrequencyTable:
cmp.FrequencyTable = DecodeFrequencies(input);
log.Trace(String.Format("TID={0}: Decoded huffman frequencies", cmp.TemplateId));
break;
case GMCMessageKey.Announcements:
cmp.Announcements = DecodeAnnouncements(input);
if (log.IsTraceEnabled)
{
StringBuilder message = new StringBuilder();
message.Append(String.Format("TID={0}: Decoded {1} dictionary announcements:",
cmp.TemplateId, cmp.Announcements.Count));
foreach(KeyValuePair<uint, byte> kvp in cmp.Announcements)
{
message.Append(' ');
message.Append(kvp.Key);
message.Append("->");
message.Append(kvp.Value);
}
log.Trace(message);
}
break;
case GMCMessageKey.Message:
uint len = ByteUtils.DecodeLength(input);
cmp.Message = new byte[len];
input.Read(cmp.Message, 0, (int)len);
if (log.IsTraceEnabled)
{
log.Trace(String.Format("Decoded message: {0}",
ByteUtils.DumpBytes(cmp.Message)));
}
break;
default:
log.Trace("Invalid GMC message");
throw new MarshallingException("invalid GMC message");
}
}
GeneralMessageCompressor handler;
if (!decompressors.TryGetValue(userId, out handler))
{
if (cmp.Template == null)
{
//we haven't received any templates whatsoever from this person.
MissingInformationException mte = new MissingInformationException();
mte.Template = 0;
mte.UserID = userId;
mte.ExceptionType = EnumExceptionType.MissingTemplate;
throw mte;
}
handler = decompressors[userId] = new GeneralMessageCompressor();
}
return handler.Decode(cmp, userId);
}
/// <summary>
/// Decode the provided message using the specified template
/// </summary>
/// <param name="cmp">the message package to be decompressed</param>
/// <param name="userId">the user from which the encoded message was received</param>
/// <returns>The decoded (uncompressed) message</returns>
public byte[] Decode(CompressedMessagePackage cmp, int userId)
{
if (cmp.Template != null)
{
AddTemplate(cmp.Template, cmp.TemplateId);
}
if (cmp.TemplateId < 0 || cmp.TemplateId > compressors.Count)
{
MissingInformationException mte = new MissingInformationException();
mte.Template = cmp.TemplateId;
mte.UserID = userId;
mte.ExceptionType = EnumExceptionType.MissingTemplate;
throw mte;
}
return compressors[cmp.TemplateId].Decode(cmp);
}
