pilu/src/Event.hs

48 lines
1.6 KiB
Haskell

module Event (
Event(..)
, EventType(..)
) where
import CSV (Row(..))
import Control.Monad (foldM)
import Data.List (isSuffixOf, takeWhile)
import Data.Map (Map)
import qualified Data.Map as Map (delete, empty, insert, lookup, toList)
import Data.Time (Day)
import Medicine (MedicineName)
import Text.ParserCombinators.Parsec.Error (Message(..))
data EventType = Prescription | Provisioning deriving (Eq, Show)
data Event = Event {
date :: Day
, amounts :: Map MedicineName Float
, eventType :: EventType
} deriving (Show)
instance Row Event where
fromRow assoc = do
rowDate <- read <$> get "date"
(kind, ints) <- foldM addAmount (Nothing, Map.empty) . Map.toList $ Map.delete "date" assoc
maybe
(Left $ Expect "A prescription or provisioning for a medicine")
(Right . Event rowDate ints)
kind
where
get key = maybe (Left $ Expect key) Right $ Map.lookup key assoc
unexpected = Left . UnExpect . show
addAmount (evType, ints) (key, val) = do
(newEvType, amount) <- readAmount val
let newFloats = Map.insert key amount ints
case evType of
Nothing -> Right (Just newEvType, newFloats)
Just currentEvType ->
if currentEvType == newEvType then Right (evType, newFloats) else unexpected newEvType
readAmount :: String -> Either Message (EventType, Float)
readAmount [] = Left $ Expect "prescription or provisioning"
readAmount ('+':n) = Right (Provisioning, read n)
readAmount s =
if "/j" `isSuffixOf` s
then Right (Prescription, read $ takeWhile (/= '/') s)
else Left $ Expect "rate"