{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards   #-}

module Worldcup.Events (Events, Event(..), parseEvents, lookupEvent) where

import           Data.Aeson
import           Data.Aeson.Types    as AET
import           Data.HashMap.Strict as HM
import           Data.Maybe          as M
import           Prelude             as P

type Events = HashMap Int Event

data Event = Event {
    eventId   :: Int,
    eventName :: String } deriving (Show)

instance FromJSON Event where
    parseJSON = withObject "event" $ \o -> do
        eventId <- o .: "id"
        eventName <- o .: "key"
        return Event{..}

lookupEvent :: Int -> Events -> Event
lookupEvent _id es = M.fromMaybe (Event 999 "DNE") (HM.lookup _id es)

parseEvents :: Either String [Value] -> Events
parseEvents (Left x)   = error x
parseEvents (Right xs) = P.foldl reduce HM.empty xs where
    reduce acc x = case (parseEither parseJSON x :: Either String Event) of
        (Left s)  -> error s
        (Right v) -> HM.insert (eventId v) v acc