    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.Setup
    -- Copyright   :  Isaac Jones 2003-2004
    --                Duncan Coutts 2007
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- This is a big module, but not very complicated. The code is very regular
    -- and repetitive. It defines the command line interface for all the Cabal
    -- commands. For each command (like @configure@, @build@ etc) it defines a type
    -- that holds all the flags, the default set of flags and a 'CommandUI' that
    -- maps command line flags to and from the corresponding flags type.
    --
    -- All the flags types are instances of 'Monoid', see
    -- <http://www.haskell.org/pipermail/cabal-devel/2007-December/001509.html>
    -- for an explanation.
    --
    -- The types defined here get used in the front end and especially in
    -- @cabal-install@ which has to do quite a bit of manipulating sets of command
    -- line flags.
    --
    -- This is actually relatively nice, it works quite well. The main change it
    -- needs is to unify it with the code for managing sets of fields that can be
    -- read and written from files. This would allow us to save configure flags in
    -- config files.

    {- All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

        * Redistributions in binary form must reproduce the above
          copyright notice, this list of conditions and the following
          disclaimer in the documentation and/or other materials provided
          with the distribution.

        * Neither the name of Isaac Jones nor the names of other
          contributors may be used to endorse or promote products derived
          from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}

    module Distribution.Simple.Setup (

      GlobalFlags(..),   emptyGlobalFlags,   defaultGlobalFlags,   globalCommand,
      ConfigFlags(..),   emptyConfigFlags,   defaultConfigFlags,   configureCommand,
      CopyFlags(..),     emptyCopyFlags,     defaultCopyFlags,     copyCommand,
      InstallFlags(..),  emptyInstallFlags,  defaultInstallFlags,  installCommand,
      HaddockFlags(..),  emptyHaddockFlags,  defaultHaddockFlags,  haddockCommand,
      HscolourFlags(..), emptyHscolourFlags, defaultHscolourFlags, hscolourCommand,
      BuildFlags(..),    emptyBuildFlags,    defaultBuildFlags,    buildCommand,
      buildVerbose,
      CleanFlags(..),    emptyCleanFlags,    defaultCleanFlags,    cleanCommand,
      MakefileFlags(..), emptyMakefileFlags, defaultMakefileFlags, makefileCommand,
      RegisterFlags(..), emptyRegisterFlags, defaultRegisterFlags, registerCommand,
                                                                   unregisterCommand,
      SDistFlags(..),    emptySDistFlags,    defaultSDistFlags,    sdistCommand,
      TestFlags(..),     emptyTestFlags,     defaultTestFlags,     testCommand,
      CopyDest(..),
      configureArgs, configureOptions,
      installDirsOptions,

      defaultDistPref,

      Flag(..),
      toFlag,
      fromFlag,
      fromFlagOrDefault,
      flagToMaybe,
      flagToList,
      boolOpt, boolOpt', trueArg, falseArg, optionVerbosity ) where

    import Distribution.Compiler ()
    import Distribution.ReadE
    import Distribution.Text (display, Text(parse))
    import Distribution.Package ( Dependency(..) )
    import Distribution.PackageDescription
             ( FlagName(..), FlagAssignment )
    import Distribution.Simple.Command hiding (boolOpt, boolOpt')
    import qualified Distribution.Simple.Command as Command
    import Distribution.Simple.Compiler
             ( CompilerFlavor(..), defaultCompilerFlavor, PackageDB(..)
             , OptimisationLevel(..), flagToOptimisationLevel )
    import Distribution.Simple.Utils
             ( wrapLine, lowercase )
    import Distribution.Simple.Program (Program(..), ProgramConfiguration,
                                 knownPrograms,
                                 addKnownProgram, emptyProgramConfiguration,
                                 haddockProgram)
    import Distribution.Simple.InstallDirs
             ( InstallDirs(..), CopyDest(..),
               PathTemplate, toPathTemplate, fromPathTemplate )
    import Data.List (sort)
    import Data.Char (isSpace)
    import Data.Monoid (Monoid(..))
    import Distribution.Verbosity

    -- XXX Not sure where this should live
    defaultDistPref :: FilePath
    defaultDistPref = "dist"

    -- ------------------------------------------------------------
    -- * Flag type
    -- ------------------------------------------------------------

    -- | All flags are monoids, they come in two flavours:
    --
    -- 1. list flags eg
    --
    -- > --ghc-option=foo --ghc-option=bar
    --
    -- gives us all the values ["foo", "bar"]
    --
    -- 2. singular value flags, eg:
    --
    -- > --enable-foo --disable-foo
    --
    -- gives us Just False
    -- So this Flag type is for the latter singular kind of flag.
    -- Its monoid instance gives us the behaviour where it starts out as
    -- 'NoFlag' and later flags override earlier ones.
    --
    data Flag a = Flag a | NoFlag deriving (Show, Eq)

    instance Functor Flag where
      fmap f (Flag x) = Flag (f x)
      fmap _ NoFlag  = NoFlag

    instance Monoid (Flag a) where
      mempty = NoFlag
      _ `mappend` f@(Flag _) = f
      f `mappend` NoFlag    = f

    instance Bounded a => Bounded (Flag a) where
      minBound = toFlag minBound
      maxBound = toFlag maxBound

    instance Enum a => Enum (Flag a) where
      fromEnum = fromEnum . fromFlag
      toEnum   = toFlag   . toEnum
      enumFrom (Flag a) = map toFlag . enumFrom $ a
      enumFrom _        = []
      enumFromThen (Flag a) (Flag b) = toFlag `map` enumFromThen a b
      enumFromThen _        _        = []
      enumFromTo   (Flag a) (Flag b) = toFlag `map` enumFromTo a b
      enumFromTo   _        _        = []
      enumFromThenTo (Flag a) (Flag b) (Flag c) = toFlag `map` enumFromThenTo a b c
      enumFromThenTo _        _        _        = []

    toFlag :: a -> Flag a
    toFlag = Flag

    fromFlag :: Flag a -> a
    fromFlag (Flag x) = x
    fromFlag NoFlag   = error "fromFlag NoFlag. Use fromFlagOrDefault"

    fromFlagOrDefault :: a -> Flag a -> a
    fromFlagOrDefault _   (Flag x) = x
    fromFlagOrDefault def NoFlag   = def

    flagToMaybe :: Flag a -> Maybe a
    flagToMaybe (Flag x) = Just x
    flagToMaybe NoFlag   = Nothing

    flagToList :: Flag a -> [a]
    flagToList (Flag x) = [x]
    flagToList NoFlag   = []

    -- ------------------------------------------------------------
    -- * Global flags
    -- ------------------------------------------------------------

    -- In fact since individual flags types are monoids and these are just sets of
    -- flags then they are also monoids pointwise. This turns out to be really
    -- useful. The mempty is the set of empty flags and mappend allows us to
    -- override specific flags. For example we can start with default flags and
    -- override with the ones we get from a file or the command line, or both.

    -- | Flags that apply at the top level, not to any sub-command.
    data GlobalFlags = GlobalFlags {
        globalVersion        :: Flag Bool,
        globalNumericVersion :: Flag Bool
      }

    defaultGlobalFlags :: GlobalFlags
    defaultGlobalFlags  = GlobalFlags {
        globalVersion        = Flag False,
        globalNumericVersion = Flag False
      }

    globalCommand :: CommandUI GlobalFlags
    globalCommand = CommandUI {
        commandName         = "",
        commandSynopsis     = "",
        commandUsage        = \_ ->
             "This Setup program uses the Haskell Cabal Infrastructure.\n"
          ++ "See http://www.haskell.org/cabal/ for more information.\n",
        commandDescription  = Just $ \pname ->
             "For more information about a command use\n"
          ++ "  " ++ pname ++ " COMMAND --help\n\n"
          ++ "Typical steps for installing Cabal packages:\n"
          ++ concat [ "  " ++ pname ++ " " ++ x ++ "\n"
                    | x <- ["configure", "build", "install"]],
        commandDefaultFlags = defaultGlobalFlags,
        commandOptions      = \_ ->
          [option ['V'] ["version"]
             "Print version information"
             globalVersion (\v flags -> flags { globalVersion = v })
             trueArg
          ,option [] ["numeric-version"]
             "Print just the version number"
             globalNumericVersion (\v flags -> flags { globalNumericVersion = v })
             trueArg
          ]
      }

    emptyGlobalFlags :: GlobalFlags
    emptyGlobalFlags = mempty

    instance Monoid GlobalFlags where
      mempty = GlobalFlags {
        globalVersion        = mempty,
        globalNumericVersion = mempty
      }
      mappend a b = GlobalFlags {
        globalVersion        = combine globalVersion,
        globalNumericVersion = combine globalNumericVersion
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Config flags
    -- ------------------------------------------------------------

    -- | Flags to @configure@ command
    data ConfigFlags = ConfigFlags {
        --FIXME: the configPrograms is only here to pass info through to configure
        -- because the type of configure is constrained by the UserHooks.
        -- when we change UserHooks next we should pass the initial
        -- ProgramConfiguration directly and not via ConfigFlags
        configPrograms      :: ProgramConfiguration, -- ^All programs that cabal may run

        configProgramPaths  :: [(String, FilePath)], -- ^user specifed programs paths
        configProgramArgs   :: [(String, [String])], -- ^user specifed programs args
        configHcFlavor      :: Flag CompilerFlavor, -- ^The \"flavor\" of the compiler, sugh as GHC or Hugs.
        configHcPath        :: Flag FilePath, -- ^given compiler location
        configHcPkg         :: Flag FilePath, -- ^given hc-pkg location
        configVanillaLib    :: Flag Bool,     -- ^Enable vanilla library
        configProfLib       :: Flag Bool,     -- ^Enable profiling in the library
        configSharedLib     :: Flag Bool,     -- ^Build shared library
        configProfExe       :: Flag Bool,     -- ^Enable profiling in the executables.
        configConfigureArgs :: [String],      -- ^Extra arguments to @configure@
        configOptimization  :: Flag OptimisationLevel,  -- ^Enable optimization.
        configProgPrefix    :: Flag PathTemplate, -- ^Installed executable prefix.
        configProgSuffix    :: Flag PathTemplate, -- ^Installed executable suffix.
        configInstallDirs   :: InstallDirs (Flag PathTemplate), -- ^Installation paths
        configScratchDir    :: Flag FilePath,
        configExtraLibDirs  :: [FilePath],   -- ^ path to search for extra libraries
        configExtraIncludeDirs :: [FilePath],   -- ^ path to search for header files

        configDistPref :: Flag FilePath, -- ^"dist" prefix
        configVerbosity :: Flag Verbosity, -- ^verbosity level
        configUserInstall :: Flag Bool,    -- ^The --user\/--global flag
        configPackageDB :: Flag PackageDB, -- ^Which package DB to use
        configGHCiLib   :: Flag Bool,      -- ^Enable compiling library for GHCi
        configSplitObjs :: Flag Bool,      -- ^Enable -split-objs with GHC
        configStripExes :: Flag Bool,      -- ^Enable executable stripping
        configConstraints :: [Dependency], -- ^Additional constraints for
                                           -- dependencies
        configConfigurationsFlags :: FlagAssignment
      }
      deriving Show

    defaultConfigFlags :: ProgramConfiguration -> ConfigFlags
    defaultConfigFlags progConf = emptyConfigFlags {
        configPrograms     = progConf,
        configHcFlavor     = maybe NoFlag Flag defaultCompilerFlavor,
        configVanillaLib   = Flag True,
        configProfLib      = Flag False,
        configSharedLib    = Flag False,
        configProfExe      = Flag False,
        configOptimization = Flag NormalOptimisation,
        configProgPrefix   = Flag (toPathTemplate ""),
        configProgSuffix   = Flag (toPathTemplate ""),
        configDistPref     = Flag defaultDistPref,
        configVerbosity    = Flag normal,
        configUserInstall  = Flag False,           --TODO: reverse this
        configGHCiLib      = Flag True,
        configSplitObjs    = Flag False, -- takes longer, so turn off by default
        configStripExes    = Flag True
      }

    configureCommand :: ProgramConfiguration -> CommandUI ConfigFlags
    configureCommand progConf = makeCommand name shortDesc longDesc defaultFlags options
      where
        name       = "configure"
        shortDesc  = "Prepare to build the package."
        longDesc   = Just (\_ -> programFlagsDescription progConf)
        defaultFlags = defaultConfigFlags progConf
        options showOrParseArgs =
             configureOptions showOrParseArgs
          ++ programConfigurationPaths   progConf showOrParseArgs
               configProgramPaths (\v fs -> fs { configProgramPaths = v })
          ++ programConfigurationOptions progConf showOrParseArgs
               configProgramArgs (\v fs -> fs { configProgramArgs = v })

    configureOptions :: ShowOrParseArgs -> [OptionField ConfigFlags]
    configureOptions showOrParseArgs =
          [optionVerbosity configVerbosity (\v flags -> flags { configVerbosity = v })
          ,optionDistPref
             configDistPref (\d flags -> flags { configDistPref = d })
             showOrParseArgs

          ,option [] ["compiler"] "compiler"
             configHcFlavor (\v flags -> flags { configHcFlavor = v })
             (choiceOpt [ (Flag GHC, ("g", ["ghc"]), "compile with GHC")
                        , (Flag NHC, ([] , ["nhc98"]), "compile with NHC")
                        , (Flag JHC, ([] , ["jhc"]), "compile with JHC")
                        , (Flag Hugs,([] , ["hugs"]), "compile with Hugs")])

          ,option "w" ["with-compiler"]
             "give the path to a particular compiler"
             configHcPath (\v flags -> flags { configHcPath = v })
             (reqArgFlag "PATH")

          ,option "" ["with-hc-pkg"]
             "give the path to the package tool"
             configHcPkg (\v flags -> flags { configHcPkg = v })
             (reqArgFlag "PATH")
          ]
       ++ map liftInstallDirs installDirsOptions
       ++ [option "b" ["scratchdir"]
             "directory to receive the built package [dist/scratch]"
             configScratchDir (\v flags -> flags { configScratchDir = v })
             (reqArgFlag "DIR")

          ,option "" ["program-prefix"]
              "prefix to be applied to installed executables"
              configProgPrefix
              (\v flags -> flags { configProgPrefix = v })
              (reqPathTemplateArgFlag "PREFIX")

          ,option "" ["program-suffix"]
              "suffix to be applied to installed executables"
              configProgSuffix (\v flags -> flags { configProgSuffix = v } )
              (reqPathTemplateArgFlag "SUFFIX")

          ,option "" ["library-vanilla"]
             "Vanilla libraries"
             configVanillaLib (\v flags -> flags { configVanillaLib = v })
             (boolOpt [] [])

          ,option "p" ["library-profiling"]
             "Library profiling"
             configProfLib (\v flags -> flags { configProfLib = v })
             (boolOpt "p" [])

          ,option "" ["shared"]
             "Shared library"
             configSharedLib (\v flags -> flags { configSharedLib = v })
             (boolOpt [] [])

          ,option "" ["executable-profiling"]
             "Executable profiling"
             configProfExe (\v flags -> flags { configProfExe = v })
             (boolOpt [] [])
          ,multiOption "optimization"
             configOptimization (\v flags -> flags { configOptimization = v })
             [optArg' "n" (Flag . flagToOptimisationLevel)
                         (\f -> case f of
                                  Flag NoOptimisation      -> []
                                  Flag NormalOptimisation  -> [Nothing]
                                  Flag MaximumOptimisation -> [Just "2"]
                                  _                        -> [])
                     "O" ("enable-optimization": case showOrParseArgs of
                          -- Allow British English spelling:
                          ShowArgs -> []; ParseArgs -> ["enable-optimisation"])
                     "Build with optimization (n is 0--2, default is 1)",
              noArg (Flag NoOptimisation) []
                    ("disable-optimization": case showOrParseArgs of
                          -- Allow British English spelling:
                          ShowArgs -> []; ParseArgs -> ["disable-optimisation"])
                    "Build without optimization"
             ]

          ,option "" ["library-for-ghci"]
             "compile library for use with GHCi"
             configGHCiLib (\v flags -> flags { configGHCiLib = v })
             (boolOpt [] [])

          ,option "" ["split-objs"]
             "split library into smaller objects to reduce binary sizes (GHC 6.6+)"
             configSplitObjs (\v flags -> flags { configSplitObjs = v })
             (boolOpt [] [])

          ,option "" ["executable-stripping"]
             "strip executables upon installation to reduce binary sizes"
             configStripExes (\v flags -> flags { configStripExes = v })
             (boolOpt [] [])

          ,option "" ["configure-option"]
             "Extra option for configure"
             configConfigureArgs (\v flags -> flags { configConfigureArgs = v })
             (reqArg' "OPT" (\x -> [x]) id)

          ,option "" ["user-install"]
             "doing a per-user installation"
             configUserInstall (\v flags -> flags { configUserInstall = v })
             (boolOpt' ([],["user"]) ([], ["global"]))

          ,option "" ["package-db"]
             "Use a specific package database (to satisfy dependencies and register in)"
             configPackageDB (\v flags -> flags { configPackageDB = v })
             (reqArg' "PATH" (Flag . SpecificPackageDB)
                            (\f -> case f of
                                     Flag (SpecificPackageDB db) -> [db]
                                     _ -> []))

          ,option "f" ["flags"]
             "Force values for the given flags in Cabal conditionals in the .cabal file.  E.g., --flags=\"debug -usebytestrings\" forces the flag \"debug\" to true and \"usebytestrings\" to false."
             configConfigurationsFlags (\v flags -> flags { configConfigurationsFlags = v })
             (reqArg' "FLAGS" readFlagList showFlagList)

          ,option "" ["extra-include-dirs"]
             "A list of directories to search for header files"
             configExtraIncludeDirs (\v flags -> flags {configExtraIncludeDirs = v})
             (reqArg' "PATH" (\x -> [x]) id)

          ,option "" ["extra-lib-dirs"]
             "A list of directories to search for external libraries"
             configExtraLibDirs (\v flags -> flags {configExtraLibDirs = v})
             (reqArg' "PATH" (\x -> [x]) id)
          ,option "" ["constraint"]
             "A list of additional constraints on the dependencies."
             configConstraints (\v flags -> flags { configConstraints = v})
             (reqArg "DEPENDENCY"
                     (readP_to_E (const "dependency expected") ((\x -> [x]) `fmap` parse))
                     (map (\x -> display x)))
          ]
      where
        readFlagList :: String -> FlagAssignment
        readFlagList = map tagWithValue . words
          where tagWithValue ('-':fname) = (FlagName (lowercase fname), False)
                tagWithValue fname       = (FlagName (lowercase fname), True)

        showFlagList :: FlagAssignment -> [String]
        showFlagList fs = [ if not set then '-':fname else fname
                          | (FlagName fname, set) <- fs]

        liftInstallDirs =
          liftOption configInstallDirs (\v flags -> flags { configInstallDirs = v })

        reqPathTemplateArgFlag title _sf _lf d get set =
          reqArgFlag title _sf _lf d
            (fmap fromPathTemplate . get) (set . fmap toPathTemplate)

    installDirsOptions :: [OptionField (InstallDirs (Flag PathTemplate))]
    installDirsOptions =
      [ option "" ["prefix"]
          "bake this prefix in preparation of installation"
          prefix (\v flags -> flags { prefix = v })
          installDirArg

      , option "" ["bindir"]
          "installation directory for executables"
          bindir (\v flags -> flags { bindir = v })
          installDirArg

      , option "" ["libdir"]
          "installation directory for libraries"
          libdir (\v flags -> flags { libdir = v })
          installDirArg

      , option "" ["libsubdir"]
          "subdirectory of libdir in which libs are installed"
          libsubdir (\v flags -> flags { libsubdir = v })
          installDirArg

      , option "" ["libexecdir"]
          "installation directory for program executables"
          libexecdir (\v flags -> flags { libexecdir = v })
          installDirArg

      , option "" ["datadir"]
          "installation directory for read-only data"
          datadir (\v flags -> flags { datadir = v })
          installDirArg

      , option "" ["datasubdir"]
          "subdirectory of datadir in which data files are installed"
          datasubdir (\v flags -> flags { datasubdir = v })
          installDirArg

      , option "" ["docdir"]
          "installation directory for documentation"
          docdir (\v flags -> flags { docdir = v })
          installDirArg

      , option "" ["htmldir"]
          "installation directory for HTML documentation"
          htmldir (\v flags -> flags { htmldir = v })
          installDirArg

      , option "" ["haddockdir"]
          "installation directory for haddock interfaces"
          haddockdir (\v flags -> flags { haddockdir = v })
          installDirArg
      ]
      where
        installDirArg _sf _lf d get set =
          reqArgFlag "DIR" _sf _lf d
            (fmap fromPathTemplate . get) (set . fmap toPathTemplate)

    emptyConfigFlags :: ConfigFlags
    emptyConfigFlags = mempty

    instance Monoid ConfigFlags where
      mempty = ConfigFlags {
        configPrograms      = error "FIXME: remove configPrograms",
        configProgramPaths  = mempty,
        configProgramArgs   = mempty,
        configHcFlavor      = mempty,
        configHcPath        = mempty,
        configHcPkg         = mempty,
        configVanillaLib    = mempty,
        configProfLib       = mempty,
        configSharedLib     = mempty,
        configProfExe       = mempty,
        configConfigureArgs = mempty,
        configOptimization  = mempty,
        configProgPrefix    = mempty,
        configProgSuffix    = mempty,
        configInstallDirs   = mempty,
        configScratchDir    = mempty,
        configDistPref      = mempty,
        configVerbosity     = mempty,
        configUserInstall   = mempty,
        configPackageDB     = mempty,
        configGHCiLib       = mempty,
        configSplitObjs     = mempty,
        configStripExes     = mempty,
        configExtraLibDirs  = mempty,
        configConstraints   = mempty,
        configExtraIncludeDirs    = mempty,
        configConfigurationsFlags = mempty
      }
      mappend a b =  ConfigFlags {
        configPrograms      = configPrograms b,
        configProgramPaths  = combine configProgramPaths,
        configProgramArgs   = combine configProgramArgs,
        configHcFlavor      = combine configHcFlavor,
        configHcPath        = combine configHcPath,
        configHcPkg         = combine configHcPkg,
        configVanillaLib    = combine configVanillaLib,
        configProfLib       = combine configProfLib,
        configSharedLib     = combine configSharedLib,
        configProfExe       = combine configProfExe,
        configConfigureArgs = combine configConfigureArgs,
        configOptimization  = combine configOptimization,
        configProgPrefix    = combine configProgPrefix,
        configProgSuffix    = combine configProgSuffix,
        configInstallDirs   = combine configInstallDirs,
        configScratchDir    = combine configScratchDir,
        configDistPref      = combine configDistPref,
        configVerbosity     = combine configVerbosity,
        configUserInstall   = combine configUserInstall,
        configPackageDB     = combine configPackageDB,
        configGHCiLib       = combine configGHCiLib,
        configSplitObjs     = combine configSplitObjs,
        configStripExes     = combine configStripExes,
        configExtraLibDirs  = combine configExtraLibDirs,
        configConstraints   = combine configConstraints,
        configExtraIncludeDirs    = combine configExtraIncludeDirs,
        configConfigurationsFlags = combine configConfigurationsFlags
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Copy flags
    -- ------------------------------------------------------------

    -- | Flags to @copy@: (destdir, copy-prefix (backwards compat), verbosity)
    data CopyFlags = CopyFlags {
        copyDest      :: Flag CopyDest,
        copyDistPref  :: Flag FilePath,
        copyUseWrapper :: Flag Bool,
        copyInPlace    :: Flag Bool,
        copyVerbosity :: Flag Verbosity
      }
      deriving Show

    defaultCopyFlags :: CopyFlags
    defaultCopyFlags  = CopyFlags {
        copyDest      = Flag NoCopyDest,
        copyDistPref  = Flag defaultDistPref,
        copyUseWrapper = Flag False,
        copyInPlace    = Flag False,
        copyVerbosity = Flag normal
      }

    copyCommand :: CommandUI CopyFlags
    copyCommand = makeCommand name shortDesc longDesc defaultCopyFlags options
      where
        name       = "copy"
        shortDesc  = "Copy the files into the install locations."
        longDesc   = Just $ \_ ->
              "Does not call register, and allows a prefix at install time\n"
           ++ "Without the --destdir flag, configure determines location.\n"
        options showOrParseArgs =
          [optionVerbosity copyVerbosity (\v flags -> flags { copyVerbosity = v })

          ,option "" ["shell-wrappers"]
             "using shell script wrappers around executables"
             copyUseWrapper (\v flags -> flags { copyUseWrapper = v })
             (boolOpt [] [])

          ,optionDistPref
             copyDistPref (\d flags -> flags { copyDistPref = d })
             showOrParseArgs

          ,option "" ["inplace"]
             "copy the package in the install subdirectory of the dist prefix, so it can be used without being installed"
             copyInPlace (\v flags -> flags { copyInPlace = v })
             trueArg

          ,option "" ["destdir"]
             "directory to copy files to, prepended to installation directories"
             copyDest (\v flags -> flags { copyDest = v })
             (reqArg "DIR" (succeedReadE (Flag . CopyTo))
                           (\f -> case f of Flag (CopyTo p) -> [p]; _ -> []))

          ,option "" ["copy-prefix"]
             "[DEPRECATED, directory to copy files to instead of prefix]"
             copyDest (\v flags -> flags { copyDest = v })
             (reqArg' "DIR" (Flag . CopyPrefix)
                           (\f -> case f of Flag (CopyPrefix p) -> [p]; _ -> []))

          ]

    emptyCopyFlags :: CopyFlags
    emptyCopyFlags = mempty

    instance Monoid CopyFlags where
      mempty = CopyFlags {
        copyDest      = mempty,
        copyDistPref  = mempty,
        copyUseWrapper = mempty,
        copyInPlace    = mempty,
        copyVerbosity = mempty
      }
      mappend a b = CopyFlags {
        copyDest      = combine copyDest,
        copyDistPref  = combine copyDistPref,
        copyUseWrapper = combine copyUseWrapper,
        copyInPlace    = combine copyInPlace,
        copyVerbosity = combine copyVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Install flags
    -- ------------------------------------------------------------

    -- | Flags to @install@: (package db, verbosity)
    data InstallFlags = InstallFlags {
        installPackageDB :: Flag PackageDB,
        installDistPref  :: Flag FilePath,
        installUseWrapper :: Flag Bool,
        installInPlace    :: Flag Bool,
        installVerbosity :: Flag Verbosity
      }
      deriving Show

    defaultInstallFlags :: InstallFlags
    defaultInstallFlags  = InstallFlags {
        installPackageDB = NoFlag,
        installDistPref  = Flag defaultDistPref,
        installUseWrapper = Flag False,
        installInPlace    = Flag False,
        installVerbosity = Flag normal
      }

    installCommand :: CommandUI InstallFlags
    installCommand = makeCommand name shortDesc longDesc defaultInstallFlags options
      where
        name       = "install"
        shortDesc  = "Copy the files into the install locations. Run register."
        longDesc   = Just $ \_ ->
             "Unlike the copy command, install calls the register command.\n"
          ++ "If you want to install into a location that is not what was\n"
          ++ "specified in the configure step, use the copy command.\n"
        options showOrParseArgs =
          [optionVerbosity installVerbosity (\v flags -> flags { installVerbosity = v })
          ,optionDistPref
             installDistPref (\d flags -> flags { installDistPref = d })
             showOrParseArgs

          ,option "" ["inplace"]
             "install the package in the install subdirectory of the dist prefix, so it can be used without being installed"
             installInPlace (\v flags -> flags { installInPlace = v })
             trueArg

          ,option "" ["shell-wrappers"]
             "using shell script wrappers around executables"
             installUseWrapper (\v flags -> flags { installUseWrapper = v })
             (boolOpt [] [])

          ,option "" ["package-db"] ""
             installPackageDB (\v flags -> flags { installPackageDB = v })
             (choiceOpt [ (Flag UserPackageDB, ([],["user"]),
                          "upon configuration register this package in the user's local package database")
                        , (Flag GlobalPackageDB, ([],["global"]),
                          "(default) upon configuration register this package in the system-wide package database")])
          ]

    emptyInstallFlags :: InstallFlags
    emptyInstallFlags = mempty

    instance Monoid InstallFlags where
      mempty = InstallFlags{
        installPackageDB = mempty,
        installDistPref  = mempty,
        installUseWrapper = mempty,
        installInPlace    = mempty,
        installVerbosity = mempty
      }
      mappend a b = InstallFlags{
        installPackageDB = combine installPackageDB,
        installDistPref  = combine installDistPref,
        installUseWrapper = combine installUseWrapper,
        installInPlace    = combine installInPlace,
        installVerbosity = combine installVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * SDist flags
    -- ------------------------------------------------------------

    -- | Flags to @sdist@: (snapshot, verbosity)
    data SDistFlags = SDistFlags {
        sDistSnapshot  :: Flag Bool,
        sDistDistPref  :: Flag FilePath,
        sDistVerbosity :: Flag Verbosity
      }
      deriving Show

    defaultSDistFlags :: SDistFlags
    defaultSDistFlags = SDistFlags {
        sDistSnapshot  = Flag False,
        sDistDistPref  = Flag defaultDistPref,
        sDistVerbosity = Flag normal
      }

    sdistCommand :: CommandUI SDistFlags
    sdistCommand = makeCommand name shortDesc longDesc defaultSDistFlags options
      where
        name       = "sdist"
        shortDesc  = "Generate a source distribution file (.tar.gz)."
        longDesc   = Nothing
        options showOrParseArgs =
          [optionVerbosity sDistVerbosity (\v flags -> flags { sDistVerbosity = v })
          ,optionDistPref
             sDistDistPref (\d flags -> flags { sDistDistPref = d })
             showOrParseArgs

          ,option "" ["snapshot"]
             "Produce a snapshot source distribution"
             sDistSnapshot (\v flags -> flags { sDistSnapshot = v })
             trueArg
          ]

    emptySDistFlags :: SDistFlags
    emptySDistFlags = mempty

    instance Monoid SDistFlags where
      mempty = SDistFlags {
        sDistSnapshot  = mempty,
        sDistDistPref  = mempty,
        sDistVerbosity = mempty
      }
      mappend a b = SDistFlags {
        sDistSnapshot  = combine sDistSnapshot,
        sDistDistPref  = combine sDistDistPref,
        sDistVerbosity = combine sDistVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Register flags
    -- ------------------------------------------------------------

    -- | Flags to @register@ and @unregister@: (user package, gen-script,
    -- in-place, verbosity)
    data RegisterFlags = RegisterFlags {
        regPackageDB   :: Flag PackageDB,
        regGenScript   :: Flag Bool,
        regGenPkgConf  :: Flag (Maybe FilePath),
        regInPlace     :: Flag Bool,
        regDistPref    :: Flag FilePath,
        regVerbosity   :: Flag Verbosity
      }
      deriving Show

    defaultRegisterFlags :: RegisterFlags
    defaultRegisterFlags = RegisterFlags {
        regPackageDB   = NoFlag,
        regGenScript   = Flag False,
        regGenPkgConf  = NoFlag,
        regInPlace     = Flag False,
        regDistPref    = Flag defaultDistPref,
        regVerbosity   = Flag normal
      }

    registerCommand :: CommandUI RegisterFlags
    registerCommand = makeCommand name shortDesc longDesc defaultRegisterFlags options
      where
        name       = "register"
        shortDesc  = "Register this package with the compiler."
        longDesc   = Nothing
        options showOrParseArgs =
          [optionVerbosity regVerbosity (\v flags -> flags { regVerbosity = v })
          ,optionDistPref
             regDistPref (\d flags -> flags { regDistPref = d })
             showOrParseArgs

          ,option "" ["packageDB"] ""
             regPackageDB (\v flags -> flags { regPackageDB = v })
             (choiceOpt [ (Flag UserPackageDB, ([],["user"]),
                                    "upon registration, register this package in the user's local package database")
                        , (Flag GlobalPackageDB, ([],["global"]),
                                    "(default)upon registration, register this package in the system-wide package database")])

          ,option "" ["inplace"]
             "register the package in the build location, so it can be used without being installed"
             regInPlace (\v flags -> flags { regInPlace = v })
             trueArg

          ,option "" ["gen-script"]
             "instead of registering, generate a script to register later"
             regGenScript (\v flags -> flags { regGenScript = v })
             trueArg

          ,option "" ["gen-pkg-config"]
             "instead of registering, generate a package registration file"
             regGenPkgConf (\v flags -> flags { regGenPkgConf  = v })
             (optArg' "PKG" Flag flagToList)
          ]

    unregisterCommand :: CommandUI RegisterFlags
    unregisterCommand = makeCommand name shortDesc longDesc defaultRegisterFlags options
      where
        name       = "unregister"
        shortDesc  = "Unregister this package with the compiler."
        longDesc   = Nothing
        options showOrParseArgs =
          [optionVerbosity regVerbosity (\v flags -> flags { regVerbosity = v })
          ,optionDistPref
             regDistPref (\d flags -> flags { regDistPref = d })
              showOrParseArgs

          ,option "" ["user"] ""
             regPackageDB (\v flags -> flags { regPackageDB = v })
             (choiceOpt [ (Flag UserPackageDB, ([],["user"]),
                                  "unregister this package in the user's local package database")
                        , (Flag GlobalPackageDB, ([],["global"]),
                                  "(default) unregister this package in the  system-wide package database")])

          ,option "" ["gen-script"]
             "Instead of performing the unregister command, generate a script to unregister later"
             regGenScript (\v flags -> flags { regGenScript = v })
             trueArg
          ]

    emptyRegisterFlags :: RegisterFlags
    emptyRegisterFlags = mempty

    instance Monoid RegisterFlags where
      mempty = RegisterFlags {
        regPackageDB   = mempty,
        regGenScript   = mempty,
        regGenPkgConf  = mempty,
        regInPlace     = mempty,
        regDistPref    = mempty,
        regVerbosity   = mempty
      }
      mappend a b = RegisterFlags {
        regPackageDB   = combine regPackageDB,
        regGenScript   = combine regGenScript,
        regGenPkgConf  = combine regGenPkgConf,
        regInPlace     = combine regInPlace,
        regDistPref    = combine regDistPref,
        regVerbosity   = combine regVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * HsColour flags
    -- ------------------------------------------------------------

    data HscolourFlags = HscolourFlags {
        hscolourCSS         :: Flag FilePath,
        hscolourExecutables :: Flag Bool,
        hscolourDistPref    :: Flag FilePath,
        hscolourVerbosity   :: Flag Verbosity
      }
      deriving Show

    emptyHscolourFlags :: HscolourFlags
    emptyHscolourFlags = mempty

    defaultHscolourFlags :: HscolourFlags
    defaultHscolourFlags = HscolourFlags {
        hscolourCSS         = NoFlag,
        hscolourExecutables = Flag False,
        hscolourDistPref    = Flag defaultDistPref,
        hscolourVerbosity   = Flag normal
      }

    instance Monoid HscolourFlags where
      mempty = HscolourFlags {
        hscolourCSS         = mempty,
        hscolourExecutables = mempty,
        hscolourDistPref    = mempty,
        hscolourVerbosity   = mempty
      }
      mappend a b = HscolourFlags {
        hscolourCSS         = combine hscolourCSS,
        hscolourExecutables = combine hscolourExecutables,
        hscolourDistPref    = combine hscolourDistPref,
        hscolourVerbosity   = combine hscolourVerbosity
      }
        where combine field = field a `mappend` field b

    hscolourCommand :: CommandUI HscolourFlags
    hscolourCommand = makeCommand name shortDesc longDesc defaultHscolourFlags options
      where
        name       = "hscolour"
        shortDesc  = "Generate HsColour colourised code, in HTML format."
        longDesc   = Just (\_ -> "Requires hscolour.\n")
        options showOrParseArgs =
          [optionVerbosity hscolourVerbosity (\v flags -> flags { hscolourVerbosity = v })
          ,optionDistPref
             hscolourDistPref (\d flags -> flags { hscolourDistPref = d })
             showOrParseArgs

          ,option "" ["executables"]
             "Run hscolour for Executables targets"
             hscolourExecutables (\v flags -> flags { hscolourExecutables = v })
             trueArg

          ,option "" ["css"]
             "Use a cascading style sheet"
             hscolourCSS (\v flags -> flags { hscolourCSS = v })
             (reqArgFlag "PATH")
          ]

    -- ------------------------------------------------------------
    -- * Haddock flags
    -- ------------------------------------------------------------

    data HaddockFlags = HaddockFlags {
        haddockProgramPaths :: [(String, FilePath)],
        haddockProgramArgs  :: [(String, [String])],
        haddockHoogle       :: Flag Bool,
        haddockHtmlLocation :: Flag String,
        haddockExecutables  :: Flag Bool,
        haddockInternal     :: Flag Bool,
        haddockCss          :: Flag FilePath,
        haddockHscolour     :: Flag Bool,
        haddockHscolourCss  :: Flag FilePath,
        haddockDistPref     :: Flag FilePath,
        haddockVerbosity    :: Flag Verbosity
      }
      deriving Show

    defaultHaddockFlags :: HaddockFlags
    defaultHaddockFlags  = HaddockFlags {
        haddockProgramPaths = mempty,
        haddockProgramArgs  = [],
        haddockHoogle       = Flag False,
        haddockHtmlLocation = NoFlag,
        haddockExecutables  = Flag False,
        haddockInternal     = Flag False,
        haddockCss          = NoFlag,
        haddockHscolour     = Flag False,
        haddockHscolourCss  = NoFlag,
        haddockDistPref     = Flag defaultDistPref,
        haddockVerbosity    = Flag normal
      }

    haddockCommand :: CommandUI HaddockFlags
    haddockCommand = makeCommand name shortDesc longDesc defaultHaddockFlags options
      where
        name       = "haddock"
        shortDesc  = "Generate Haddock HTML documentation."
        longDesc   = Just $ \_ -> "Requires the program haddock, either version 0.x or 2.x.\n"
        options showOrParseArgs =
          [optionVerbosity haddockVerbosity (\v flags -> flags { haddockVerbosity = v })
          ,optionDistPref
             haddockDistPref (\d flags -> flags { haddockDistPref = d })
             showOrParseArgs

          ,option "" ["hoogle"]
             "Generate a hoogle database"
             haddockHoogle (\v flags -> flags { haddockHoogle = v })
             trueArg

          ,option "" ["html-location"]
             "Location of HTML documentation for pre-requisite packages"
             haddockHtmlLocation (\v flags -> flags { haddockHtmlLocation = v })
             (reqArgFlag "URL")

          ,option "" ["executables"]
             "Run haddock for Executables targets"
             haddockExecutables (\v flags -> flags { haddockExecutables = v })
             trueArg

          ,option "" ["internal"]
             "Run haddock for internal modules and include all symbols"
             haddockInternal (\v flags -> flags { haddockInternal = v })
             trueArg

          ,option "" ["css"]
             "Use PATH as the haddock stylesheet"
             haddockCss (\v flags -> flags { haddockCss = v })
             (reqArgFlag "PATH")

          ,option "" ["hyperlink-source"]
             "Hyperlink the documentation to the source code (using HsColour)"
             haddockHscolour (\v flags -> flags { haddockHscolour = v })
             trueArg

          ,option "" ["hscolour-css"]
             "Use PATH as the HsColour stylesheet"
             haddockHscolourCss (\v flags -> flags { haddockHscolourCss = v })
             (reqArgFlag "PATH")
          ]
          ++ programConfigurationPaths   progConf ParseArgs
                 haddockProgramPaths (\v flags -> flags { haddockProgramPaths = v})
          ++ programConfigurationOptions progConf ParseArgs
                 haddockProgramArgs  (\v flags -> flags { haddockProgramArgs = v})
        progConf = addKnownProgram haddockProgram
                   emptyProgramConfiguration

    emptyHaddockFlags :: HaddockFlags
    emptyHaddockFlags = mempty

    instance Monoid HaddockFlags where
      mempty = HaddockFlags {
        haddockProgramPaths = mempty,
        haddockProgramArgs  = mempty,
        haddockHoogle       = mempty,
        haddockHtmlLocation = mempty,
        haddockExecutables  = mempty,
        haddockInternal     = mempty,
        haddockCss          = mempty,
        haddockHscolour     = mempty,
        haddockHscolourCss  = mempty,
        haddockDistPref     = mempty,
        haddockVerbosity    = mempty
      }
      mappend a b = HaddockFlags {
        haddockProgramPaths = combine haddockProgramPaths,
        haddockProgramArgs  = combine haddockProgramArgs,
        haddockHoogle       = combine haddockHoogle,
        haddockHtmlLocation = combine haddockHtmlLocation,
        haddockExecutables  = combine haddockExecutables,
        haddockInternal     = combine haddockInternal,
        haddockCss          = combine haddockCss,
        haddockHscolour     = combine haddockHscolour,
        haddockHscolourCss  = combine haddockHscolourCss,
        haddockDistPref     = combine haddockDistPref,
        haddockVerbosity    = combine haddockVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Clean flags
    -- ------------------------------------------------------------

    data CleanFlags = CleanFlags {
        cleanSaveConf  :: Flag Bool,
        cleanDistPref  :: Flag FilePath,
        cleanVerbosity :: Flag Verbosity
      }
      deriving Show

    defaultCleanFlags :: CleanFlags
    defaultCleanFlags  = CleanFlags {
        cleanSaveConf  = Flag False,
        cleanDistPref  = Flag defaultDistPref,
        cleanVerbosity = Flag normal
      }

    cleanCommand :: CommandUI CleanFlags
    cleanCommand = makeCommand name shortDesc longDesc defaultCleanFlags options
      where
        name       = "clean"
        shortDesc  = "Clean up after a build."
        longDesc   = Just (\_ -> "Removes .hi, .o, preprocessed sources, etc.\n")
        options showOrParseArgs =
          [optionVerbosity cleanVerbosity (\v flags -> flags { cleanVerbosity = v })
          ,optionDistPref
             cleanDistPref (\d flags -> flags { cleanDistPref = d })
             showOrParseArgs

          ,option "s" ["save-configure"]
             "Do not remove the configuration file (dist/setup-config) during cleaning.  Saves need to reconfigure."
             cleanSaveConf (\v flags -> flags { cleanSaveConf = v })
             trueArg
          ]

    emptyCleanFlags :: CleanFlags
    emptyCleanFlags = mempty

    instance Monoid CleanFlags where
      mempty = CleanFlags {
        cleanSaveConf  = mempty,
        cleanDistPref  = mempty,
        cleanVerbosity = mempty
      }
      mappend a b = CleanFlags {
        cleanSaveConf  = combine cleanSaveConf,
        cleanDistPref  = combine cleanDistPref,
        cleanVerbosity = combine cleanVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Build flags
    -- ------------------------------------------------------------

    data BuildFlags = BuildFlags {
        buildProgramPaths :: [(String, FilePath)],
        buildProgramArgs :: [(String, [String])],
        buildDistPref    :: Flag FilePath,
        buildVerbosity   :: Flag Verbosity
      }
      deriving Show

    {-# DEPRECATED buildVerbose "Use buildVerbosity instead" #-}
    buildVerbose :: BuildFlags -> Verbosity
    buildVerbose = fromFlagOrDefault normal . buildVerbosity

    defaultBuildFlags :: BuildFlags
    defaultBuildFlags  = BuildFlags {
        buildProgramPaths = mempty,
        buildProgramArgs = [],
        buildDistPref    = Flag defaultDistPref,
        buildVerbosity   = Flag normal
      }

    buildCommand :: ProgramConfiguration -> CommandUI BuildFlags
    buildCommand progConf = makeCommand name shortDesc longDesc defaultBuildFlags options
      where
        name       = "build"
        shortDesc  = "Make this package ready for installation."
        longDesc   = Nothing
        options showOrParseArgs =
          optionVerbosity buildVerbosity (\v flags -> flags { buildVerbosity = v })
          : optionDistPref
              buildDistPref (\d flags -> flags { buildDistPref = d })
              showOrParseArgs

          : programConfigurationPaths   progConf showOrParseArgs
              buildProgramPaths (\v flags -> flags { buildProgramPaths = v})

         ++ programConfigurationOptions progConf showOrParseArgs
              buildProgramArgs (\v flags -> flags { buildProgramArgs = v})

    emptyBuildFlags :: BuildFlags
    emptyBuildFlags = mempty

    instance Monoid BuildFlags where
      mempty = BuildFlags {
        buildProgramPaths = mempty,
        buildProgramArgs = mempty,
        buildVerbosity   = mempty,
        buildDistPref    = mempty
      }
      mappend a b = BuildFlags {
        buildProgramPaths = combine buildProgramPaths,
        buildProgramArgs = combine buildProgramArgs,
        buildVerbosity   = combine buildVerbosity,
        buildDistPref    = combine buildDistPref
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Makefile flags
    -- ------------------------------------------------------------

    data MakefileFlags = MakefileFlags {
        makefileFile      :: Flag FilePath,
        makefileDistPref  :: Flag FilePath,
        makefileVerbosity :: Flag Verbosity
      }
      deriving Show

    defaultMakefileFlags :: MakefileFlags
    defaultMakefileFlags  = MakefileFlags {
        makefileFile      = NoFlag,
        makefileDistPref  = Flag defaultDistPref,
        makefileVerbosity = Flag normal
      }

    makefileCommand :: CommandUI MakefileFlags
    makefileCommand = makeCommand name shortDesc longDesc defaultMakefileFlags options
      where
        name       = "makefile"
        shortDesc  = "Generate a makefile (only for GHC libraries)."
        longDesc   = Nothing
        options showOrParseArgs =
          [optionVerbosity makefileVerbosity (\v flags -> flags { makefileVerbosity = v })
          ,optionDistPref
             makefileDistPref (\d flags -> flags { makefileDistPref = d })
             showOrParseArgs

          ,option "f" ["file"]
             "Filename to use (default: Makefile)."
             makefileFile (\f flags -> flags { makefileFile = f })
             (reqArgFlag "PATH")
          ]

    emptyMakefileFlags :: MakefileFlags
    emptyMakefileFlags  = mempty

    instance Monoid MakefileFlags where
      mempty = MakefileFlags {
        makefileFile      = mempty,
        makefileDistPref  = mempty,
        makefileVerbosity = mempty
      }
      mappend a b = MakefileFlags {
        makefileFile      = combine makefileFile,
        makefileDistPref  = combine makefileDistPref,
        makefileVerbosity = combine makefileVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Test flags
    -- ------------------------------------------------------------

    data TestFlags = TestFlags {
        testDistPref  :: Flag FilePath,
        testVerbosity :: Flag Verbosity
      }
      deriving Show

    defaultTestFlags :: TestFlags
    defaultTestFlags  = TestFlags {
        testDistPref  = Flag defaultDistPref,
        testVerbosity = Flag normal
      }

    testCommand :: CommandUI TestFlags
    testCommand = makeCommand name shortDesc longDesc defaultTestFlags options
      where
        name       = "test"
        shortDesc  = "Run the test suite, if any (configure with UserHooks)."
        longDesc   = Nothing
        options showOrParseArgs =
          [optionVerbosity testVerbosity (\v flags -> flags { testVerbosity = v })
          ,optionDistPref
             testDistPref (\d flags -> flags { testDistPref = d })
             showOrParseArgs
          ]

    emptyTestFlags :: TestFlags
    emptyTestFlags  = mempty

    instance Monoid TestFlags where
      mempty = TestFlags {
        testDistPref  = mempty,
        testVerbosity = mempty
      }
      mappend a b = TestFlags {
        testDistPref  = combine testDistPref,
        testVerbosity = combine testVerbosity
      }
        where combine field = field a `mappend` field b

    -- ------------------------------------------------------------
    -- * Shared options utils
    -- ------------------------------------------------------------

    programFlagsDescription :: ProgramConfiguration -> String
    programFlagsDescription progConf =
         "The flags --with-PROG and --PROG-option(s) can be used with"
      ++ " the following programs:"
      ++ (concatMap (\line -> "\n  " ++ unwords line) . wrapLine 77 . sort)
         [ programName prog | (prog, _) <- knownPrograms progConf ]
      ++ "\n"

    programConfigurationPaths
      :: ProgramConfiguration
      -> ShowOrParseArgs
      -> (flags -> [(String, FilePath)])
      -> ([(String, FilePath)] -> (flags -> flags))
      -> [OptionField flags]
    programConfigurationPaths progConf showOrParseArgs get set =
      case showOrParseArgs of
        -- we don't want a verbose help text list so we just show a generic one:
        ShowArgs  -> [withProgramPath "PROG"]
        ParseArgs -> map (withProgramPath . programName . fst) (knownPrograms progConf)
      where
        withProgramPath prog =
          option "" ["with-" ++ prog]
            ("give the path to " ++ prog)
            get set
            (reqArg' "PATH" (\path -> [(prog, path)])
              (\progPaths -> [ path | (prog', path) <- progPaths, prog==prog' ]))

    programConfigurationOptions
      :: ProgramConfiguration
      -> ShowOrParseArgs
      -> (flags -> [(String, [String])])
      -> ([(String, [String])] -> (flags -> flags))
      -> [OptionField flags]
    programConfigurationOptions progConf showOrParseArgs get set =
      case showOrParseArgs of
        -- we don't want a verbose help text list so we just show a generic one:
        ShowArgs  -> [programOptions  "PROG", programOption   "PROG"]
        ParseArgs -> map (programOptions . programName . fst) (knownPrograms progConf)
                  ++ map (programOption  . programName . fst) (knownPrograms progConf)
      where
        programOptions prog =
          option "" [prog ++ "-options"]
            ("give extra options to " ++ prog)
            get set
            (reqArg' "OPTS" (\args -> [(prog, splitArgs args)]) (const []))

        programOption prog =
          option "" [prog ++ "-option"]
            ("give an extra option to " ++ prog ++
             " (no need to quote options containing spaces)")
            get set
            (reqArg' "OPT" (\arg -> [(prog, [arg])])
               (\progArgs -> concat [ args | (prog', args) <- progArgs, prog==prog' ]))

    -- ------------------------------------------------------------
    -- * GetOpt Utils
    -- ------------------------------------------------------------

    boolOpt :: SFlags -> SFlags -> MkOptDescr (a -> Flag Bool) (Flag Bool -> a -> a) a
    boolOpt  = Command.boolOpt  flagToMaybe Flag

    boolOpt' :: OptFlags -> OptFlags -> MkOptDescr (a -> Flag Bool) (Flag Bool -> a -> a) a
    boolOpt' = Command.boolOpt' flagToMaybe Flag

    trueArg, falseArg :: SFlags -> LFlags -> Description -> (b -> Flag Bool) ->
                         (Flag Bool -> (b -> b)) -> OptDescr b
    trueArg  = noArg (Flag True)
    falseArg = noArg (Flag False)

    reqArgFlag :: ArgPlaceHolder -> SFlags -> LFlags -> Description ->
                  (b -> Flag String) -> (Flag String -> b -> b) -> OptDescr b
    reqArgFlag ad = reqArg ad (succeedReadE Flag) flagToList

    optionDistPref :: (flags -> Flag FilePath)
                   -> (Flag FilePath -> flags -> flags)
                   -> ShowOrParseArgs
                   -> OptionField flags
    optionDistPref get set = \showOrParseArgs ->
      option "" (distPrefFlagName showOrParseArgs)
        (   "The directory where Cabal puts generated build files "
         ++ "(default " ++ defaultDistPref ++ ")")
        get set
        (reqArgFlag "DIR")
      where
        distPrefFlagName ShowArgs  = ["builddir"]
        distPrefFlagName ParseArgs = ["builddir", "distdir", "distpref"]

    optionVerbosity :: (flags -> Flag Verbosity)
                    -> (Flag Verbosity -> flags -> flags)
                    -> OptionField flags
    optionVerbosity get set =
      option "v" ["verbose"]
        "Control verbosity (n is 0--3, default verbosity level is 1)"
        get set
        (optArg "n" (fmap Flag flagToVerbosity)
                    (Flag verbose) -- default Value if no n is given
                    (fmap (Just . showForCabal) . flagToList))

    -- ------------------------------------------------------------
    -- * Other Utils
    -- ------------------------------------------------------------

    -- | Arguments to pass to a @configure@ script, e.g. generated by
    -- @autoconf@.
    configureArgs :: Bool -> ConfigFlags -> [String]
    configureArgs bcHack flags
      = hc_flag
     ++ optFlag  "with-hc-pkg" configHcPkg
     ++ optFlag' "prefix"      prefix
     ++ optFlag' "bindir"      bindir
     ++ optFlag' "libdir"      libdir
     ++ optFlag' "libexecdir"  libexecdir
     ++ optFlag' "datadir"     datadir
     ++ configConfigureArgs flags
      where
            hc_flag = case (configHcFlavor flags, configHcPath flags) of
                            (_, Flag hc_path) -> [hc_flag_name ++ hc_path]
                            (Flag hc, NoFlag) -> [hc_flag_name ++ display hc]
                            (NoFlag,NoFlag)   -> []
            hc_flag_name
                --TODO kill off thic bc hack when defaultUserHooks is removed.
                | bcHack    = "--with-hc="
                | otherwise = "--with-compiler="
            optFlag name config_field = case config_field flags of
                            Flag p -> ["--" ++ name ++ "=" ++ p]
                            NoFlag -> []
            optFlag' name config_field = optFlag name (fmap fromPathTemplate
                                                     . config_field
                                                     . configInstallDirs)

    -- | Helper function to split a string into a list of arguments.
    -- It's supposed to handle quoted things sensibly, eg:
    --
    -- > splitArgs "--foo=\"C:\Program Files\Bar\" --baz"
    -- >   = ["--foo=C:\Program Files\Bar", "--baz"]
    --
    splitArgs :: String -> [String]
    splitArgs  = space []
      where
        space :: String -> String -> [String]
        space w []      = word w []
        space w ( c :s)
            | isSpace c = word w (space [] s)
        space w ('"':s) = string w s
        space w s       = nonstring w s

        string :: String -> String -> [String]
        string w []      = word w []
        string w ('"':s) = space w s
        string w ( c :s) = string (c:w) s

        nonstring :: String -> String -> [String]
        nonstring w  []      = word w []
        nonstring w  ('"':s) = string w s
        nonstring w  ( c :s) = space (c:w) s

        word [] s = s
        word w  s = reverse w : s

    -- The test cases kinda have to be rewritten from the ground up... :/
    --hunitTests :: [Test]
    --hunitTests =
    --    let m = [("ghc", GHC), ("nhc98", NHC), ("hugs", Hugs)]
    --        (flags, commands', unkFlags, ers)
    --               = getOpt Permute options ["configure", "foobar", "--prefix=/foo", "--ghc", "--nhc98", "--hugs", "--with-compiler=/comp", "--unknown1", "--unknown2", "--install-prefix=/foo", "--user", "--global"]
    --       in  [TestLabel "very basic option parsing" $ TestList [
    --                 "getOpt flags" ~: "failed" ~:
    --                 [Prefix "/foo", GhcFlag, NhcFlag, HugsFlag,
    --                  WithCompiler "/comp", InstPrefix "/foo", UserFlag, GlobalFlag]
    --                 ~=? flags,
    --                 "getOpt commands" ~: "failed" ~: ["configure", "foobar"] ~=? commands',
    --                 "getOpt unknown opts" ~: "failed" ~:
    --                      ["--unknown1", "--unknown2"] ~=? unkFlags,
    --                 "getOpt errors" ~: "failed" ~: [] ~=? ers],
    --
    --               TestLabel "test location of various compilers" $ TestList
    --               ["configure parsing for prefix and compiler flag" ~: "failed" ~:
    --                    (Right (ConfigCmd (Just comp, Nothing, Just "/usr/local"), []))
    --                   ~=? (parseArgs ["--prefix=/usr/local", "--"++name, "configure"])
    --                   | (name, comp) <- m],
    --
    --               TestLabel "find the package tool" $ TestList
    --               ["configure parsing for prefix comp flag, withcompiler" ~: "failed" ~:
    --                    (Right (ConfigCmd (Just comp, Just "/foo/comp", Just "/usr/local"), []))
    --                   ~=? (parseArgs ["--prefix=/usr/local", "--"++name,
    --                                   "--with-compiler=/foo/comp", "configure"])
    --                   | (name, comp) <- m],
    --
    --               TestLabel "simpler commands" $ TestList
    --               [flag ~: "failed" ~: (Right (flagCmd, [])) ~=? (parseArgs [flag])
    --                   | (flag, flagCmd) <- [("build", BuildCmd),
    --                                         ("install", InstallCmd Nothing False),
    --                                         ("sdist", SDistCmd),
    --                                         ("register", RegisterCmd False)]
    --                  ]
    --               ]

    {- Testing ideas:
       * IO to look for hugs and hugs-pkg (which hugs, etc)
       * quickCheck to test permutations of arguments
       * what other options can we over-ride with a command-line flag?
    -}