profun/app/Main.hs

{-# LANGUAGE OverloadedStrings #-} --needed for ByteString arguments
import Network.HTTP.Simple
import System.Environment (lookupEnv)
import Plot
import Data.ByteString.UTF8 (fromString) --to convert acquired API key to ByteString


main :: IO ()
main = do
    apiKey <- getWeatherKey
    let todayRequest = apiRequestBuilder apiKey "today"
    response <- httpJSON todayRequest :: IO (Response ())
    generatePlot 20 100 25 --example
    putStrLn $ show todayRequest
    putStrLn $ show $ getResponseStatusCode response
    --apiResponse <- httpJSON "http://httpbin.org/get" :: IO (Response ()) -- specifying type as httpJSON return value is ambigious


--apiKey is stored in an env variable, not something that should be pushed onto git
getWeatherKey :: IO String
getWeatherKey = do
    result <- lookupEnv "WEATHER_API_KEY"
    case result of
        Just a -> return a
        Nothing -> error "API key not set in environmental variables!" -- exception thrown (but not handled) per project requirement

apiRequestBuilder :: String -> String -> Request
apiRequestBuilder apiKey day = 
            setRequestHost "api.weatherapi.com"
            $ setRequestPath path
            $ setRequestMethod "GET"
            $ setRequestQueryString [("q", Just "Poznan"), ("key", Just (fromString apiKey))]
            $ setRequestPort 443
            $ setRequestSecure True
            $ defaultRequest
                where path
                        | day == "yesterday" = "/v1/"
                        | day == "tomorrow" = "/v1/"
                        | otherwise = "/v1/current.json"