{-# LANGUAGE OverloadedStrings #-}

{-|
Module       : System.Posix.IO.Log
Description  : Helper methods for viewing & writing log files
Copyright    : (c) Philip Woods 2015
License      : AGPL-3
Maintainer   : elzairthesorcerer@gmail.com
Stability    : experimental
Portabiltity : Linux
-}

module System.Posix.IO.Log (
  getCurrentLog,
  writeLog
) where

import Control.Monad    (liftM)
import qualified Data.Text as DT
import qualified Data.Text.IO as DTI
import Data.Info        (ProjectInfo(..), LogInfo(..), tPathRoot)
import Data.UnixTime    (getUnixTime, UnixTime(utSeconds, utMicroSeconds))
import System.Directory (createDirectoryIfMissing, getDirectoryContents)

-- | Retrieve the contents of the most recent log file
getCurrentLog :: ProjectInfo  -- ^ The given project
              -> IO LogInfo   -- ^ Contents and metadata of log file
getCurrentLog info = do
  dir         <- return $ getLogPath info
  createDirectoryIfMissing True dir
  dirContents <- getFilteredContents dir
  case dirContents of
   Left err    -> return $ LogInfo{provider_info = provider info, repository_info = repository info, branch_info = branch info, log_info = DT.pack err}
   Right files -> do
     latest   <- return $ maximum files
     contents <- DTI.readFile $ dir ++ latest
     return $ LogInfo{provider_info = provider info, repository_info = repository info, branch_info = branch info, log_info = contents}
  where getFilteredContents dir = do
          dirContents <- liftM filterDots $ getDirectoryContents dir
          if (length dirContents) == 0
            then return $ Left $ "No logfiles in " ++ dir
            else return $ Right dirContents
        filterDots = filter (\x -> x /= "." && x /= "..")
 
-- | Write new log file
writeLog :: ProjectInfo       -- ^ The given project
         -> DT.Text           -- ^ Contents to write
         -> IO ()             -- ^ No return value
writeLog info contents = do
  logPath  <- return $ getLogPath info
  createDirectoryIfMissing True logPath
  fileName <- getFullTime
  DTI.writeFile (logPath ++ fileName) contents
  where getFullTime = do
          time     <- getUnixTime
          seconds  <- (return . fromEnum . utSeconds)      time
          useconds <- (return . fromEnum . utMicroSeconds) time
          return $ show $ seconds * 1000000 + useconds

-- | Retrieve the absolute path to the log directory for a given project
getLogPath :: ProjectInfo     -- ^ The given project
           -> FilePath        -- ^ Path to log directory for given project
getLogPath info =
  let p = provider info
      r = repository info
      b = branch info
  in DT.unpack $ DT.concat [tPathRoot, "logs/", p, "/", r, "/", b, "/"]