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diff --git a/src/Data/Tox/Message.hs b/src/Data/Tox/Message.hs
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+-- | This module assigns meaningful symbolic names to Tox message ids and
+-- classifies messages as lossy or lossless.
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE PatternSynonyms            #-}
+{-# LANGUAGE ViewPatterns               #-}
+module Data.Tox.Message where
+
+import Data.Word
+
+-- | The one-byte type code prefix that classifies a 'CryptoMessage'.
+newtype MessageID = MessageID Word8 deriving (Eq,Enum,Ord,Bounded)
+pattern Padding              = MessageID   0 -- ^ 0 padding (skipped until we hit a non zero (data id) byte)
+pattern PacketRequest        = MessageID   1 -- ^ 1 packet request packet (lossy packet)
+pattern KillPacket           = MessageID   2 -- ^ 2 connection kill packet (lossy packet)
+pattern UnspecifiedPacket003 = MessageID   3 -- ^ 3+ unspecified
+pattern PING                 = MessageID  16 -- ^ 16+  reserved for Messenger usage (lossless packets)
+-- TODO: rename to ALIVE 16
+-- SHARE_RELAYS 17
+-- FRIEND_REQUESTS 18
+pattern ONLINE               = MessageID  24 -- 1 byte
+pattern OFFLINE              = MessageID  25 -- 1 byte
+-- LOSSLESS_RANGE_SIZE 32
+pattern NICKNAME             = MessageID  48 -- up to 129 bytes
+pattern STATUSMESSAGE        = MessageID  49 -- up to 1008 bytes
+pattern USERSTATUS           = MessageID  50 -- 2 bytes
+pattern TYPING               = MessageID  51 -- 2 bytes
+-- LOSSY_RANGE_SIZE 63
+pattern MESSAGE              = MessageID  64 -- up to 1373 bytes
+pattern ACTION               = MessageID  65 -- up to 1373 bytes
+pattern MSI                  = MessageID  69
+pattern FILE_SENDREQUEST     = MessageID  80 -- 1+1+4+8+32+max255 = up to 301
+pattern FILE_CONTROL         = MessageID  81 -- 8 bytes if seek, otherwise 4
+pattern FILE_DATA            = MessageID  82 -- up to 1373
+pattern INVITE_GROUPCHAT     = MessageID  96 -- 0x60
+-- TODO: rename to INVITE_CONFERENCE 96
+pattern ONLINE_PACKET        = MessageID  97 -- 0x61
+pattern DIRECT_GROUPCHAT     = MessageID  98 -- 0x62
+-- TODO: rename to DIRECT_CONFERENCE 98
+pattern MESSAGE_GROUPCHAT    = MessageID  99 -- 0x63
+-- TODO: rename to MESSAGE_CONFERENCE 99
+-- LOSSLESS_RANGE_START 160
+pattern MessengerLossy192    = MessageID 192 -- ^ 192+ reserved for Messenger usage (lossy packets)
+pattern LOSSY_GROUPCHAT      = MessageID 199 -- 0xC7
+pattern Messenger255         = MessageID 255 -- ^ 255 reserved for Messenger usage (lossless packet)
+
+instance Show MessageID where
+    show Padding              = "Padding"
+    show PacketRequest        = "PacketRequest"
+    show KillPacket           = "KillPacket"
+    show UnspecifiedPacket003 = "UnspecifiedPacket003"
+    show PING                 = "PING"
+    show ONLINE               = "ONLINE"
+    show OFFLINE              = "OFFLINE"
+    show NICKNAME             = "NICKNAME"
+    show STATUSMESSAGE        = "STATUSMESSAGE"
+    show USERSTATUS           = "USERSTATUS"
+    show TYPING               = "TYPING"
+    show MESSAGE              = "MESSAGE"
+    show ACTION               = "ACTION"
+    show MSI                  = "MSI"
+    show FILE_SENDREQUEST     = "FILE_SENDREQUEST"
+    show FILE_CONTROL         = "FILE_CONTROL"
+    show FILE_DATA            = "FILE_DATA"
+    show INVITE_GROUPCHAT     = "INVITE_GROUPCHAT"
+    show ONLINE_PACKET        = "ONLINE_PACKET"
+    show DIRECT_GROUPCHAT     = "DIRECT_GROUPCHAT"
+    show MESSAGE_GROUPCHAT    = "MESSAGE_GROUPCHAT"
+    show MessengerLossy192    = "MessengerLossy192"
+    show LOSSY_GROUPCHAT      = "LOSSY_GROUPCHAT"
+    show Messenger255         = "Messenger255"
+    show (MessageID n)        = "MessageID " ++ show n
+
+data LossyOrLossless = Lossless | Lossy
+    deriving (Eq,Ord,Enum,Show,Bounded)
+
+-- | Classify a packet as lossy or lossless.
+lossyness :: MessageID -> LossyOrLossless
+lossyness (fromEnum -> x) | x < 3                = Lossy
+lossyness (fromEnum -> x) | {-16 <= x,-} x < 192 = Lossless
+lossyness (fromEnum -> x) | 192 <= x, x < 255    = Lossy
+lossyness (fromEnum -> 255)                      = Lossless
+
+