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

module Worldcup.Rounds (Rounds, Round(..), parseRounds, lookupRound) 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 Rounds = HashMap Int Round

data Round = Round {
    roundId      :: Int,
    roundEventId :: Int,
    roundName    :: Value } deriving (Show)

instance ToJSON Round where
    toJSON Round{..} = roundName

instance FromJSON Round where
    parseJSON = withObject "round" $ \o -> do
        roundId <- o .: "id"
        roundEventId <- o .: "event_id"
        roundName <- o .: "title"
        return Round{..}

parseRounds :: Either String [Value] -> Rounds
parseRounds (Left x)   = error x
parseRounds (Right xs) = P.foldl reduce HM.empty xs where
    reduce acc x = case (parseEither parseJSON x :: Either String Round) of
        (Left s)  -> error s
        (Right v) -> HM.insert (roundId v) v acc

lookupRound :: Int -> Rounds -> Round
lookupRound _id hm = M.fromMaybe (Round 999 999 "DNE") (HM.lookup _id hm)