ReadStream.hs

{-# LANGUAGE OverloadedStrings #-}
--
-- Data vault for metrics
--
--
-- Copyright © 2013-2014 Anchor Systems, Pty Ltd and Others
--
-- The code in this file, and the program it is a part of, is
-- made available to you by its authors as open source software:
-- you can redistribute it and/or modify it under the terms of
-- the 3-clause SD licence.
--

module Vaultaire.Types.ReadStream
(
    ReadStream(..),
    ExtendedBurst(..),
    SimpleBurst(..),
) where

import Control.Applicative
import Control.Exception (SomeException (..))
import Data.ByteString (ByteString)
import qualified Data.ByteString as S
import Test.QuickCheck
import Vaultaire.Classes.WireFormat

newtype ExtendedBurst = ExtendedBurst { unExtendedBurst :: ByteString }
  deriving (Show, Eq)

newtype SimpleBurst = SimpleBurst { unSimpleBurst :: ByteString }
  deriving (Show, Eq)

data ReadStream = InvalidReadOrigin
                | SimpleStream { unSimpleStream :: SimpleBurst }
                | ExtendedStream { unExtendedStream :: ExtendedBurst }
                | EndOfStream
  deriving (Show, Eq)

instance WireFormat ReadStream where
    fromWire bs
        | bs == "\x00" = Right InvalidReadOrigin
        | bs == "\x01" = Right EndOfStream
        | S.take 1 bs == "\x02" =
            Right . SimpleStream . SimpleBurst $ S.drop 1 bs
        | S.take 1 bs == "\x03" =
            Right . ExtendedStream. ExtendedBurst $ S.drop 1 bs
        | otherwise = Left $ SomeException $ userError "Invalid ReadStream packet"
    toWire InvalidReadOrigin = "\x00"
    toWire EndOfStream = "\x01"
    toWire (SimpleStream (SimpleBurst bs)) = "\x02" `S.append` bs
    toWire (ExtendedStream (ExtendedBurst bs)) = "\x03" `S.append` bs

instance Arbitrary ReadStream where
    arbitrary = oneof [ return InvalidReadOrigin
                      , SimpleStream . SimpleBurst . S.pack <$> arbitrary
                      , ExtendedStream . ExtendedBurst . S.pack <$> arbitrary
                      , return EndOfStream ]