{-# LANGUAGE OverloadedStrings #-}

module AdListener
  ( listenToNewAds
  ) where

import Data.List (intersperse)
import Data.Text (Text)
import qualified Data.Text as T
import qualified Data.Text.IO as T

import Control.Concurrent (threadDelay)

import Ad (fetchResumes, fetchAds)

import Model.Ad
import Model.URL
import Model.Resume

import View.Ad (renderAds)

import Page
import Parser.Detail

import Config (Config)
import qualified Config as C

listenToNewAds :: Config -> IO ()
listenToNewAds config = do
  eitherResumes <- fetchResumes (C.url config)
  case eitherResumes of
    Left error ->
      listenError config [] error
    Right resumes ->
      let newURLs = map url resumes
      in  listenToNewAdsWithViewedURLs config newURLs

listenToNewAdsWithViewedURLs :: Config -> [URL] -> IO ()
listenToNewAdsWithViewedURLs config viewedURLs = do
  eitherResumes <- fetchResumes (C.url config)
  case eitherResumes of
    Left error ->
      listenError config viewedURLs error
    Right resumes ->
      listenToNewAdsWithResumes config viewedURLs resumes

listenToNewAdsWithResumes :: Config -> [URL] -> [Resume] -> IO ()
listenToNewAdsWithResumes config viewedURLs resumes =
  let (newURLs, newResumes) = getNewResumes viewedURLs resumes
  in  do
        eitherNewAds <- fetchAds newResumes
        case eitherNewAds of
          Left error ->
            listenError config viewedURLs error
          Right newAds ->
            do
              if not (null newAds)
                then
                  T.putStrLn (newAdsMessage newAds)
                else
                  return ()
              waitOneMinute
              listenToNewAdsWithViewedURLs config (viewedURLs ++ newURLs)

newAdsMessage :: [Ad] -> Text
newAdsMessage newAds =
  let newAdsMessage =
        T.concat
          [ "Got "
          , T.pack . show . length $ newAds
          , " new ad"
          , if length newAds > 1 then "s" else ""
          , "."
          ]
      line = T.map (\_ -> '-') newAdsMessage
  in  T.intercalate
        "\n"
        [ newAdsMessage
        , T.concat [line, "\n"]
        , renderAds newAds
        ]

listenError :: Config -> [URL] -> Text -> IO ()
listenError config viewedURLs error = do
  T.putStrLn error
  waitOneMinute
  listenToNewAdsWithViewedURLs config viewedURLs

waitOneMinute :: IO ()
waitOneMinute = threadDelay (1000 * 1000 * 60)