network.hs

{-# LANGUAGE OverloadedStrings #-}

module Main where

-- third-party libraries
import qualified Data.Configurator as Config
import Network.HTTP.Client
import System.IO.Streams as Streams

import Control.Concurrent
import Control.Concurrent.Thread
import Data.ByteString (ByteString)
import Data.String
import Data.Text
import System.Exit

-- Text values are unicode-aware, where as ByteStrings are dumb+fast char buffers

data Credentials = Credentials {
  email :: ByteString,
  password :: ByteString
} deriving (Eq, Show)


makeRequest :: String -> Credentials -> IO (InputStream ByteString)
makeRequest path creds = do
  conn <- openConnection "http://tacoapp.com" 80
  
  request <- buildRequest $ do
    http GET path
    setAuthorizationBasic (email creds) (password creds)
  
  sendRequest conn request emptyBody
  
  result <- receiveResponse (\resp stream -> stream)
  
  closeConnection conn
  
  return result

requestAndWrite :: String -> Credentials -> FilePath -> IO ()
requestAndWrite httpPath creds filePath = do
  stream <- makeRequest httpPath creds
  withFileAsOutput filePath (Streams.connect stream)

main :: IO ()
main = do
  cfg <- Config.load ["./myconfig.cfg"]
  mail <- Config.lookup cfg "email" -- mail has type (Maybe Text) now
  pass <- Config.lookup cfg "password" -- ditto
  
  when ((isNothing mail) || (isNothing pass)) exitFailure
  
  -- pattern-matches at this point are safe because we already checked for Nothing
  let (Just m) = mail
  let (Just p) = pass
  let creds = Credentials { email = m, password = p}
  
  task1 <- forkIO (requestAndWrite "/path1" creds "file1.txt")
  task2 <- forkIO (requestAndWrite "/path2" creds "file2.txt")
  task3 <- forkIO (requestAndWrite "/path3" creds "file3.txt")
  
  -- wait for all threads to complete
  mapM_ wait [task1, task2, task3]