{-# LANGUAGE CPP #-}

-------------------------------------------------------------------------------
--
-- | Command-line parser
--
-- This is an abstract command-line parser used by both StaticFlags and
-- DynFlags.
--
-- (c) The University of Glasgow 2005
--
-------------------------------------------------------------------------------

module CmdLineParser
    (
      processArgs, OptKind(..),
      CmdLineP(..), getCmdLineState, putCmdLineState,
      Flag(..),
      errorsToGhcException,

      EwM, addErr, addWarn, getArg, getCurLoc, liftEwM, deprecate
    ) where

#include "HsVersions.h"

import Util
import Outputable
import Panic
import Bag
import SrcLoc

import Data.Function
import Data.List

import Control.Monad (liftM, ap)
import Control.Applicative (Applicative(..))


--------------------------------------------------------
--         The Flag and OptKind types
--------------------------------------------------------

data Flag m = Flag
    {   flagName    :: String,   -- Flag, without the leading "-"
        flagOptKind :: OptKind m -- What to do if we see it
    }

data OptKind m                             -- Suppose the flag is -f
    = NoArg     (EwM m ())                 -- -f all by itself
    | HasArg    (String -> EwM m ())       -- -farg or -f arg
    | SepArg    (String -> EwM m ())       -- -f arg
    | Prefix    (String -> EwM m ())       -- -farg
    | OptPrefix (String -> EwM m ())       -- -f or -farg (i.e. the arg is optional)
    | OptIntSuffix (Maybe Int -> EwM m ()) -- -f or -f=n; pass n to fn
    | IntSuffix (Int -> EwM m ())          -- -f or -f=n; pass n to fn
    | FloatSuffix (Float -> EwM m ())      -- -f or -f=n; pass n to fn
    | PassFlag  (String -> EwM m ())       -- -f; pass "-f" fn
    | AnySuffix (String -> EwM m ())       -- -f or -farg; pass entire "-farg" to fn
    | PrefixPred    (String -> Bool) (String -> EwM m ())
    | AnySuffixPred (String -> Bool) (String -> EwM m ())
    | VersionSuffix (Int -> Int -> EwM m ())
      -- -f or -f=maj.min; pass major and minor version to fn


--------------------------------------------------------
--         The EwM monad
--------------------------------------------------------

type Err   = Located String
type Warn  = Located String
type Errs  = Bag Err
type Warns = Bag Warn

-- EwM ("errors and warnings monad") is a monad
-- transformer for m that adds an (err, warn) state
newtype EwM m a = EwM { unEwM :: Located String -- Current parse arg
                              -> Errs -> Warns
                              -> m (Errs, Warns, a) }

instance Monad m => Functor (EwM m) where
    fmap = liftM

instance Monad m => Applicative (EwM m) where
    pure = return
    (<*>) = ap

instance Monad m => Monad (EwM m) where
    (EwM f) >>= k = EwM (\l e w -> do (e', w', r) <- f l e w
                                      unEwM (k r) l e' w')
    return v = EwM (\_ e w -> return (e, w, v))

setArg :: Monad m => Located String -> EwM m () -> EwM m ()
setArg l (EwM f) = EwM (\_ es ws -> f l es ws)

addErr :: Monad m => String -> EwM m ()
addErr e = EwM (\(L loc _) es ws -> return (es `snocBag` L loc e, ws, ()))

addWarn :: Monad m => String -> EwM m ()
addWarn msg = EwM (\(L loc _) es ws -> return (es, ws `snocBag` L loc msg, ()))

deprecate :: Monad m => String -> EwM m ()
deprecate s = do
    arg <- getArg
    addWarn (arg ++ " is deprecated: " ++ s)

getArg :: Monad m => EwM m String
getArg = EwM (\(L _ arg) es ws -> return (es, ws, arg))

getCurLoc :: Monad m => EwM m SrcSpan
getCurLoc = EwM (\(L loc _) es ws -> return (es, ws, loc))

liftEwM :: Monad m => m a -> EwM m a
liftEwM action = EwM (\_ es ws -> do { r <- action; return (es, ws, r) })


--------------------------------------------------------
-- A state monad for use in the command-line parser
--------------------------------------------------------

-- (CmdLineP s) typically instantiates the 'm' in (EwM m) and (OptKind m)
newtype CmdLineP s a = CmdLineP { runCmdLine :: s -> (a, s) }

instance Functor (CmdLineP s) where
    fmap = liftM

instance Applicative (CmdLineP s) where
    pure = return
    (<*>) = ap

instance Monad (CmdLineP s) where
    m >>= k = CmdLineP $ \s ->
                  let (a, s') = runCmdLine m s
                  in runCmdLine (k a) s'

    return a = CmdLineP $ \s -> (a, s)

getCmdLineState :: CmdLineP s s
getCmdLineState   = CmdLineP $ \s -> (s,s)
putCmdLineState :: s -> CmdLineP s ()
putCmdLineState s = CmdLineP $ \_ -> ((),s)


--------------------------------------------------------
--         Processing arguments
--------------------------------------------------------

processArgs :: Monad m
            => [Flag m]               -- cmdline parser spec
            -> [Located String]       -- args
            -> m ( [Located String],  -- spare args
                   [Located String],  -- errors
                   [Located String] ) -- warnings
processArgs spec args = do
    (errs, warns, spare) <- unEwM action (panic "processArgs: no arg yet")
                                  emptyBag emptyBag
    return (spare, bagToList errs, bagToList warns)
  where
    action = process args []

    -- process :: [Located String] -> [Located String] -> EwM m [Located String]
    process [] spare = return (reverse spare)

    process (locArg@(L _ ('-' : arg)) : args) spare =
        case findArg spec arg of
            Just (rest, opt_kind) ->
                case processOneArg opt_kind rest arg args of
                    Left err ->
                        let b = process args spare
                        in (setArg locArg $ addErr err) >> b

                    Right (action,rest) ->
                        let b = process rest spare
                        in (setArg locArg $ action) >> b

            Nothing -> process args (locArg : spare)

    process (arg : args) spare = process args (arg : spare)


processOneArg :: OptKind m -> String -> String -> [Located String]
              -> Either String (EwM m (), [Located String])
processOneArg opt_kind rest arg args
  = let dash_arg = '-' : arg
        rest_no_eq = dropEq rest
    in case opt_kind of
        NoArg  a -> ASSERT(null rest) Right (a, args)

        HasArg f | notNull rest_no_eq -> Right (f rest_no_eq, args)
                 | otherwise -> case args of
                                    []               -> missingArgErr dash_arg
                                    (L _ arg1:args1) -> Right (f arg1, args1)

        SepArg f -> case args of
                        []               -> unknownFlagErr dash_arg
                        (L _ arg1:args1) -> Right (f arg1, args1)

        Prefix f | notNull rest_no_eq -> Right (f rest_no_eq, args)
                 | otherwise          -> unknownFlagErr dash_arg

        PrefixPred _ f | notNull rest_no_eq -> Right (f rest_no_eq, args)
                       | otherwise          -> unknownFlagErr dash_arg

        PassFlag f  | notNull rest -> unknownFlagErr dash_arg
                    | otherwise    -> Right (f dash_arg, args)

        OptIntSuffix f | null rest                     -> Right (f Nothing,  args)
                       | Just n <- parseInt rest_no_eq -> Right (f (Just n), args)
                       | otherwise -> Left ("malformed integer argument in " ++ dash_arg)

        IntSuffix f | Just n <- parseInt rest_no_eq -> Right (f n, args)
                    | otherwise -> Left ("malformed integer argument in " ++ dash_arg)

        FloatSuffix f | Just n <- parseFloat rest_no_eq -> Right (f n, args)
                      | otherwise -> Left ("malformed float argument in " ++ dash_arg)

        OptPrefix f       -> Right (f rest_no_eq, args)
        AnySuffix f       -> Right (f dash_arg, args)
        AnySuffixPred _ f -> Right (f dash_arg, args)

        VersionSuffix f | [maj_s, min_s] <- split '.' rest_no_eq,
                          Just maj <- parseInt maj_s,
                          Just min <- parseInt min_s -> Right (f maj min, args)
                        | [maj_s] <- split '.' rest_no_eq,
                          Just maj <- parseInt maj_s -> Right (f maj 0, args)
                        | null rest_no_eq -> Right (f 1 0, args)
                        | otherwise -> Left ("malformed version argument in " ++ dash_arg)


findArg :: [Flag m] -> String -> Maybe (String, OptKind m)
findArg spec arg =
    case sortBy (compare `on` (length . fst)) -- prefer longest matching flag
           [ (removeSpaces rest, optKind)
           | flag <- spec,
             let optKind  = flagOptKind flag,
             Just rest <- [stripPrefix (flagName flag) arg],
             arg_ok optKind rest arg ]
    of
        []      -> Nothing
        (one:_) -> Just one

arg_ok :: OptKind t -> [Char] -> String -> Bool
arg_ok (NoArg           _)  rest _   = null rest
arg_ok (HasArg          _)  _    _   = True
arg_ok (SepArg          _)  rest _   = null rest
arg_ok (Prefix          _)  rest _   = notNull rest
arg_ok (PrefixPred p    _)  rest _   = notNull rest && p (dropEq rest)
arg_ok (OptIntSuffix    _)  _    _   = True
arg_ok (IntSuffix       _)  _    _   = True
arg_ok (FloatSuffix     _)  _    _   = True
arg_ok (OptPrefix       _)  _    _   = True
arg_ok (PassFlag        _)  rest _   = null rest
arg_ok (AnySuffix       _)  _    _   = True
arg_ok (AnySuffixPred p _)  _    arg = p arg
arg_ok (VersionSuffix   _)  _    _   = True

-- | Parse an Int
--
-- Looks for "433" or "=342", with no trailing gubbins
--   * n or =n      => Just n
--   * gibberish    => Nothing
parseInt :: String -> Maybe Int
parseInt s = case reads s of
                 ((n,""):_) -> Just n
                 _          -> Nothing

parseFloat :: String -> Maybe Float
parseFloat s = case reads s of
                   ((n,""):_) -> Just n
                   _          -> Nothing

-- | Discards a leading equals sign
dropEq :: String -> String
dropEq ('=' : s) = s
dropEq s         = s

unknownFlagErr :: String -> Either String a
unknownFlagErr f = Left ("unrecognised flag: " ++ f)

missingArgErr :: String -> Either String a
missingArgErr f = Left ("missing argument for flag: " ++ f)

--------------------------------------------------------
-- Utils
--------------------------------------------------------

errorsToGhcException :: [Located String] -> GhcException
errorsToGhcException errs =
    UsageError $
        intercalate "\n" [ showUserSpan True l ++ ": " ++ e | L l e <- errs ]