{-# LANGUAGE OverloadedStrings #-}
module ConfigFiles where

import Data.ByteString.Lazy.Char8 as L
import System.Posix.User
import System.FilePath
import System.Directory
import System.IO
-- import System.IO.Strict
import System.IO.Error
import Control.Exception
import Control.Monad
import Todo
import Control.DeepSeq
import ByteStringOperators

type User = ByteString

configDir = ".presence"
buddyFile = "buddies"
subscriberFile = "subscribers"

buddyPath :: User -> IO String 
buddyPath user = do
    ue <- getUserEntryForName (unpack user)
    return $ (++("/"++configDir++"/"++buddyFile)) $ homeDirectory ue

subscriberPath :: User -> IO String
subscriberPath user = do
    ue <- getUserEntryForName (unpack user)
    return $ (++("/"++configDir++"/"++subscriberFile)) $ homeDirectory ue

createConfigFile tag path = do
    let dir = dropFileName path
    doesDirectoryExist dir >>= flip unless (do
            createDirectory dir 
        )
    withFile path WriteMode $ \h -> 
        L.hPutStrLn h tag

addItem item tag path =
    let doit = do
         handle (\e -> when (isDoesNotExistError e) 
                       (createConfigFile tag path >> doit))
           $ withFile path AppendMode $ \h ->
               L.hPutStrLn h item
    in doit

addBuddy :: User -> ByteString -> IO ()
addBuddy user buddy =
    buddyPath user >>= addItem buddy "<? buddies ?>"

addSubscriber :: User -> ByteString -> IO ()
addSubscriber user subscriber =
    subscriberPath user >>= addItem subscriber "<? subscribers ?>"

getConfigList path = 
  handle (\e -> if isDoesNotExistError e then (return []) else throw e)
    $ withFile path ReadMode $
        L.hGetContents 
        >=> return . Prelude.tail . L.lines 
        >=> (\a -> seq (rnf a) (return a))

getBuddies :: User -> IO [ByteString]
getBuddies user = buddyPath user >>= getConfigList

getSubscribers :: User -> IO [ByteString]
getSubscribers user = subscriberPath user >>= getConfigList