content: {-# LANGUAGE ScopedTypeVariables #-}
  {-
  Copyright (C) 2009 John MacFarlane <jgm@berkeley.edu>
  
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  -}
  
  module Yst.CSV (readCSVFile)
  where
  import Yst.Types
  import Yst.Util
  import Text.CSV
  -- Note: ghc >= 6.12 (base >=4.2) supports unicode through iconv
  -- So we use System.IO.UTF8 only if we have an earlier version
  #if MIN_VERSION_base(4,2,0)
  #if !(MIN_VERSION_base(4,6,0))
  import Prelude hiding (catch)
  #endif
  #else
  import Prelude hiding (
    readFile
  #if !(MIN_VERSION_base(4,6,0))
  , catch
  #endif
  )
  import System.IO.UTF8
  #endif
  import Control.Exception (catch, SomeException)
  
  readCSVFile :: FilePath -> IO Node
  readCSVFile f = catch (toNode `fmap` readFile f)
                        (\(e::SomeException) -> do
                           errorExit 11 ("Error parsing " ++ f ++ ": " ++ show e)
                           return NNil)
    where toNode = csvToNode . parseCSV' f . stripBlanks . filter (/='\r')
  
  parseCSV' :: FilePath -> String -> CSV
  parseCSV' f s = case parseCSV f s of
                       Left e    -> error $ "Error parsing " ++ f ++ ": " ++ show e
                       Right c   -> c
  
  csvToNode :: CSV -> Node
  csvToNode [] = NNil
  csvToNode (fieldNames : records) =
    NList $ map (\record -> NMap $ zip fieldNames $ map fieldToNode record) records 
  
  fieldToNode :: Field -> Node
  fieldToNode s =
    case parseAsDate s of
         Nothing -> NString s
         Just d  -> NDate d
  