-- Copyright: 2007-2012 Dino Morelli
-- License: BSD3 (see LICENSE)
-- Author: Dino Morelli <dino@ui3.info>

{-# LANGUAGE FlexibleContexts #-}

import Control.Monad
import System.Environment ( getArgs )
import System.FilePath
import System.Posix
import Text.Printf

import Photoname.Common
import Photoname.Opts ( Options (..) , parseOpts, usageText )
import Photoname.DateFormat ( buildDatePath )
import Photoname.SerialFormat ( buildSerialPath )


modeDir :: FileMode
modeDir = ownerModes       `unionFileModes`
          groupReadMode    `unionFileModes`
          groupExecuteMode


{- Take a file path to a JPEG file and use EXIF information available to
   link the file at its new location below the given basedir.
-}
createNewLink :: FilePath -> Ph ()
createNewLink oldPath = do
   opts <- ask
   newPath <- if (optOldStyle opts)
      then buildSerialPath oldPath
      else buildDatePath oldPath

   -- Check for existance of the target file
   exists <- liftIO $ fileExist newPath
   when exists $ throwError $ "Destination " ++ newPath ++ " exists!"

   -- Display what will be done
   unless (optQuiet opts) $
      liftIO $ putStrLn $ oldPath ++ " -> " ++ newPath

   unless (optNoAction opts) $ do
      -- Make the target dir
      liftIO $ makeDirectory $ takeDirectory newPath

      -- Make the new hard link
      liftIO $ createLink oldPath newPath

      -- If user has specified, remove the original link
      when (optMove opts) $
         liftIO $ removeLink oldPath

      return ()


{- Given a list of lists, make a new list where each sublist element 
   consists of the accumulation of all parts that came before it. 
   Like this:
      before: [[1], [2], [3], [4], [5]]
      after : [[1], [1,2], [1,2,3], [1,2,3,4], [1,2,3,4,5]]

   Many thanks to Betty Diegel for help with this algorithm.

   FIXME Try to rewrite this with a scan or something
-}
listAcc :: [[a]] -> [[a]]
listAcc []     = [[]]
listAcc (x:xs) = listAcc' x xs
   where
      listAcc' l (y:ys) = [l] ++ listAcc' (l ++ y) ys
      listAcc' l []     = [l]


{- Ensuring that a directory with subs exists turned out to be a painful 
   process involving making each parent dir piece by piece but not trying
   to make anything that's already there.
-}
makeDirectory :: FilePath -> IO ()
makeDirectory d =
   let makeOneDir dir = do
         exists <- fileExist dir
         unless exists $ createDirectory dir modeDir
   in  mapM_ makeOneDir $ listAcc $ splitPath d


-- Figure out and execute what the user wants based on the supplied args.
executeCommands :: Options -> [String] -> IO ()

-- User gave no files at all. Display help
executeCommands _ [] = putStrLn usageText

-- Normal program operation, process the files with the args.
executeCommands opts filePaths = do
   -- Get rid of anything not a regular file from the list of paths
   actualPaths <- filterM
      (\p -> getFileStatus p >>= return . isRegularFile) filePaths

   -- Notify user of the switches that will be in effect.
   when (optNoAction opts) $
      putStrLn "No-action mode, nothing will be changed."

   when (optMove opts) $
      putStrLn "Removing original links after new links are in place."

   -- Do the link manipulations, and report any errors.
   forM_ actualPaths $ \path -> do
      result <- runRename opts $ createNewLink path
      either (\em -> printf "** Processing %s: %s\n" path em)
         (const return ()) result


main :: IO ()
main = do
   -- Parse the arguments
   (opts, paths) <- getArgs >>= parseOpts

   -- Do the photo naming procedure
   executeCommands opts paths

   -- Perhaps we should get an ExitCode back from all this above?