Cryptsy/API/Public/MarketData/New.hs

   1 {-# LANGUAGE ViewPatterns #-}
   2 module Cryptsy.API.Public.MarketData.New
   3         ( GMarketData(..), MarketData
   4         , withComponents, withMarket
   5         , getMarketData, marketData
   6         )
   7 where
   8
   9 -- aeson
  10 import Data.Aeson ( FromJSON(..), Value(Object), Object, withObject )
  11 import Data.Aeson.Types (Parser, Result(..), parse)
  12
  13 -- base
  14 import Data.Function ( ($) )
  15 import Data.Functor ( fmap, (<$>) )
  16 import Data.Maybe (Maybe(..))
  17 import Data.Traversable (mapM)
  18 import Prelude ( Show, String )
  19
  20 -- either
  21 import Control.Monad.Trans.Either (left, right)
  22
  23 -- text
  24 import Data.Text (Text, pack)
  25
  26 -- unordered-containers
  27 import           Data.HashMap.Strict (HashMap)
  28 import qualified Data.HashMap.Strict as HM (lookup)
  29
  30 -- this pacakge
  31 import           Cryptsy.API.Public
  32 import           Cryptsy.API.Public.SingleMarket           ( GSingleMarket )
  33
  34 marketdatav2URL :: String
  35 marketdatav2URL = "http://pubapi.cryptsy.com/api.php?method=marketdatav2"
  36
  37 newtype GMarketData p q dt t =
  38         MarketData { markets :: (HashMap Text (GSingleMarket p q dt t)) }
  39         deriving Show
  40 type MarketData = GMarketData Text Text Text Text
  41
  42 instance (FromJSON p, FromJSON q, FromJSON dt, FromJSON t) =>
  43         FromJSON (GMarketData p q dt t)
  44  where
  45         parseJSON = withObject "markets" $ withComponents parseJSON
  46
  47 -- |Build parser for multiple markets from parser for single market.
  48 withComponents :: (Value -> Parser (GSingleMarket p q dt t)) -- ^ market parser
  49                -> Object -> Parser (GMarketData p q dt t)
  50 withComponents parseMarket = fmap MarketData <$> mapM parseMarket
  51
  52 -- |Build parser for multiple markets from parser for single market object.
  53 withMarket :: (Object -> Parser (GSingleMarket p q dt t)) -- ^ market parser
  54            -> Object -> Parser (GMarketData p q dt t)
  55 withMarket parseMarket = withComponents (withObject "market" parseMarket)
  56
  57 {-|
  58 "Raw" request, does not convert the JSON value, but simply returns the JSON
  59 value bound to the "return" key from the response body.
  60 -}
  61 getMarketData :: PubCryptsy Value
  62 getMarketData = pubCryptsy marketdatav2URL
  63
  64 marketsKey :: Text
  65 marketsKey = pack "markets"
  66
  67 {-|
  68 "Cooked" request, extracts the JSON object bound to the "market" key of the
  69 object boudn to the "return" key and converts it.
  70 -}
  71 marketData :: (Object -> Parser (GMarketData p q dt t)) -- ^ market data parser
  72              -> PubCryptsy (GMarketData p q dt t)
  73 marketData parseMarkets = do
  74         ret <- getMarketData
  75         mkts <- case ret of
  76                 Object (HM.lookup marketsKey -> Just m) -> right m
  77                 _ -> left $ FailParseReturn ret "Missing 'markets' key."
  78         case parse (withObject "markets" parseMarkets) mkts of
  79                 Error err -> left $ FailParseReturn ret err
  80                 Success v -> right v