exchange.hs

okcoin :: Exchange
okcoin = Exchange 
    { exchageName = OkCoin
    , fetchTicker = fetchOkCoinTicker
    }

fetchOkCoinTicker :: IO Ticker
fetchOkCoinTicker = do
    r <- Wreq.asJSON =<< Wreq.get tickerUrl
    let OkCoinTicker{..} = r ^. responseBody
    return Ticker { tBid    = octnBid octTicker
                  , tAsk    = octnAsk octTicker
                  , tLast   = octnLast octTicker
                  , tVolume = octnVolume octTicker
                  }
  where tickerUrl = "https://www.okcoin.com/api/v1/ticker.do?symbol=btc_usd"

data OkCoinTicker = OkCoinTicker 
    { octdate   :: Float
    , octTicker :: OkCoinTickerNested
    }

instance Aeson.FromJSON OkCoinTicker where
    parseJSON = Aeson.withObject "OkCoinTicker" $ \o ->
        OkCoinTicker <$> 
            (o .: "date" >>= parseFloat) <$>
             o .: "ticker"

data OkCoinTickerNested = OkCoinTickerNested 
    { octnBid    :: Float
    , octnAsk    :: Float
    , octnLast   :: Float
    , octnVolume :: Float
    }

instance Aeson.FromJSON OkCoinTickerNested where
    parseJSON = Aeson.withObject "OkCoinTickerNested" $ \o ->
        OkCoinTickerNested <$> 
            (o' .: "buy"    >>= parseFloat) <*>
            (o' .: "ask"    >>= parseFloat) <*>
            (o' .: "last"   >>= parseFloat) <*>
            (o' .: "volume" >>= parseFloat)
            

kraken :: Exchange
kraken = Exchange
    { exchageName = Kraken
    , fetchTicker = fetchKrakenTicker
    }

fetchOkCoinTicker :: IO Ticker
fetchOkCoinTicker = do
    r <- Wreq.asJSON =<< W.get tickerUrl
    let KrakenTicker{..} = r ^. responseBody
    --
    return Ticker { tBid    = ktBid
                  , tAsk    = ktAsk
                  , tLast   = ktLast
                  , tVolume = ktVolume
                  }
  where tickerUrl = "https://api.kraken.com/0/public/AssetPairs?pair=xbtusd"

data KrakenTicker = KrakenTicker 
    { ktError  :: [String]
    , kfResult :: KrakenTickerResult
    }

instance Aeson.FromJSON KrakenTicker where
    parseJSON = Aeson.withObject "KrakenTicker" $ \o ->
        KrakenTicker <$> 
            (o .: "error" >>= parseFloat) <$>
             o .: "result"

newtype KrakenTickerResult = KrakenTickerResult KrakenTickerPair

instance Aeson.FromJSON KrakenTickerResult

data KrakenTickerPair = KrakenTickerPair
    { ktpAsk       :: (Float, Float, Float) -- ask array(<price>, <whole lot volume>, <lot volume>)
    , ktpBid       :: (Float, Float, Float) -- bid array(<price>, <whole lot volume>, <lot volume>)
    , ktpLast      :: (Float, Float)        -- last trade closed array(<price>, <lot volume>)
    , ktpVolume    :: (Float, Float)        -- volume array(<today>, <last 24 hours>)
    , ktpAverage   :: (Float, Float)        -- volume weighted average price array(<today>, <last 24 hours>)
    , ktpNumTrades :: (Int, Int)            -- number of trades array(<today>, <last 24 hours>)
    , ktpLow       :: (Float, Float)        -- low array(<today>, <last 24 hours>)
    , ktpHigh      :: (Float, Float)        -- high array(<today>, <last 24 hours>)
    , ktpOpen      :: Float                 -- today's opening price
    }

instance Aeson.FromJSON KrakenTickerPair where
    parseJSON = Aeson.withObject "KrakenTickerPair" $ \o ->
        KrakenTickerPair <$> 
            (o .: "a" >>= parseFloatTriple) <*>
            (o .: "b" >>= parseFloatTriple) <*>
            (o .: "c" >>= parseFloatPair) <*>
            (o .: "v" >>= parseFloatPair) <*>
            (o .: "p" >>= parseFloatPair) <*>
             o .: "t"                     <*>
            (o .: "l" >>= parseFloatPair) <*>
            (o .: "h" >>= parseFloatPair) <*>
            (o .: "o" >>= parseFloat) <*>