module Development.Shake.Derived where

import Control.Monad
import Control.Monad.IO.Class
import System.Cmd
import System.Directory
import System.Exit

import Development.Shake.Core
import Development.Shake.File
import Development.Shake.FilePath


-- | Execute a system command. This function will raise an error if the exit code is non-zero.
--   Before running 'system'' make sure you 'need' any required files.
system' :: FilePath -> [String] -> Action ()
system' path args = do
    let path2 = toNative path
    let cmd = unwords $ path2 : args
    putLoud cmd
    res <- liftIO $ rawSystem path2 args
    when (res /= ExitSuccess) $ do
        k <- currentRule
        error $ "System command failed while building " ++ show k ++ ", " ++ cmd


-- | @copyFile old new@ copies the existing file from @old@ to @new@. The @old@ file is has 'need' called on it
--   before copying the file.
copyFile' :: FilePath -> FilePath -> Action ()
copyFile' old new = need [old] >> liftIO (copyFile old new)


-- | Read a file, after calling 'need'.
readFile' :: FilePath -> Action String
readFile' x = need [x] >> liftIO (readFile x)

-- | Write a file, lifted to the 'Action' monad.
writeFile' :: FilePath -> String -> Action ()
writeFile' name x = liftIO $ writeFile name x


-- | A version of 'readFile'' which also splits the result into lines.
readFileLines :: FilePath -> Action [String]
readFileLines = fmap lines . readFile'

-- | A version of 'writeFile'' which writes out a list of lines.
writeFileLines :: FilePath -> [String] -> Action ()
writeFileLines name = writeFile' name . unlines