module Options (module Options, usageInfo)
where
import System.Console.GetOpt
import System.Environment (getEnv)
import Data.Maybe (fromMaybe)
    
import Utils


usageHeader = "Usage: hledger [OPTIONS] register|balance [MATCHARGS]"

getOptions :: [String] -> IO ([Flag], [String])
getOptions argv =
    case getOpt RequireOrder options argv of
      (o,n,[]  ) -> return (o,n)
      (_,_,errs) -> ioError (userError (concat errs ++ usageInfo usageHeader options))

options :: [OptDescr Flag]
options = [
            Option ['v'] ["version"] (NoArg Version)     "show version number"
          , Option ['f'] ["file"]    (OptArg readFileOpt "FILE") "ledger file, or - to read stdin"
          , Option ['s'] ["subtotal"] (NoArg ShowSubs)     "balance: show sub-accounts" --; register: show subtotals"
          ]

data Flag = Version | File String | ShowSubs deriving (Show,Eq)
    
readFileOpt :: Maybe String -> Flag
readFileOpt  = File . fromMaybe "stdin"
    
getFile :: Flag -> String
getFile (File s) = s
getFile _ = []

getLedgerFilePath :: [Flag] -> IO String
getLedgerFilePath opts = do
  defaultpath <- tildeExpand "~/ledger.dat"
  envordefault <- getEnv "LEDGER" `catch` \_ -> return defaultpath
  path <- tildeExpand envordefault
  return $ last $ [envordefault] ++ (filter (/= "") (map getFile opts))

-- ledger pattern args are a list of account patterns optionally followed
-- by -- and a list of description patterns
ledgerPatternArgs :: [String] -> ([String],[String])
ledgerPatternArgs args = 
    case "--" `elem` args of
      True -> ((takeWhile (/= "--") args), tail $ (dropWhile (/= "--") args))
      False -> (args,[])

getDepth :: [Flag] -> Int
getDepth opts = 
    maximum $ [1] ++ map depthval opts where
        depthval (ShowSubs) = 9999
        depthval _ = 1


-- example:
--     module Opts where
    
--     import System.Console.GetOpt
--     import Data.Maybe ( fromMaybe )
    
--     data Flag 
--      = Verbose  | Version 
--      | Input String | Output String | LibDir String
--        deriving Show
    
--     options :: [OptDescr Flag]
--     options =
--      [ Option ['v']     ["verbose"] (NoArg Verbose)       "chatty output on stderr"
--      , Option ['V','?'] ["version"] (NoArg Version)       "show version number"
--      , Option ['o']     ["output"]  (OptArg outp "FILE")  "output FILE"
--      , Option ['c']     []          (OptArg inp  "FILE")  "input FILE"
--      , Option ['L']     ["libdir"]  (ReqArg LibDir "DIR") "library directory"
--      ]
    
--     inp,outp :: Maybe String -> Flag
--     outp = Output . fromMaybe "stdout"
--     inp  = Input  . fromMaybe "stdin"
    
--     compilerOpts :: [String] -> IO ([Flag], [String])
--     compilerOpts argv = 
--        case getOpt Permute options argv of
--           (o,n,[]  ) -> return (o,n)
--           (_,_,errs) -> ioError (userError (concat errs ++ usageInfo header options))
--       where header = "Usage: ic [OPTION...] files..."