{-# LANGUAGE OverloadedStrings #-}

module Main
  ( main
  ) where

import System.IO (stderr)

import qualified Data.Text as T
import qualified Data.Text.IO as T

import Date (getCurrentDate)
import Birthdate (filterBirthday)
import BirthdateParser (parseBirthdates)
import Mail (mailSubject, mailBody)
import SendMail (sendMail)
import Config

birthdatePath :: FilePath
birthdatePath = "birthdates.csv"

configPath :: FilePath
configPath = "config.txt"

main :: IO ()
main = do
  eitherBirthdates <- parseBirthdates <$> T.readFile birthdatePath
  eitherConfig <- getConfig configPath
  case (eitherBirthdates, eitherConfig) of
    (Left err, _) ->
      T.hPutStr stderr $
        T.concat
          [ "Error while parsing file "
          , T.pack birthdatePath
          , ":\n"
          , err
          ]
    (_, Left err) ->
      T.hPutStr stderr $
        T.concat
          [ "Error while parsing config file "
          , T.pack birthdatePath
          , ":\n"
          , err
          ]
    (Right birthdates, Right config) -> do
      currentDate <- getCurrentDate
      let birthdays = filterBirthday currentDate birthdates
      if not (null birthdays)
        then
          sendMail
            (mailTo config)
            (mailFrom config)
            (mailSubject birthdays)
            (mailBody currentDate birthdays)
        else
          return ()