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

module Worldcup.Countries (Countries, Country(..), parseCountries, lookupCountry) 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 Countries = HashMap Int Country

data Country = Country {
    countryId          :: Int,
    countryContinentId :: Int,
    countryName        :: String } deriving (Show)

instance FromJSON Country where
    parseJSON = withObject "country" $ \o -> do
        countryId <- o .: "id"
        countryContinentId <- o .: "continent_id"
        countryName <- o .: "name"
        return Country{..}

lookupCountry :: Int -> Countries -> Country
lookupCountry _id hm = M.fromMaybe (Country 999 999 "DNE") (HM.lookup _id hm)

parseCountries :: Either String [Value] -> Countries
parseCountries (Left x)   = error x
parseCountries (Right xs) = P.foldl reduce HM.empty xs where
    reduce acc x = case (parseEither parseJSON x :: Either String Country) of
        (Left s)  -> error s
        (Right v) -> HM.insert (countryId v) v acc