-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Simple
-- Copyright   :  Isaac Jones 2003-2005
-- License     :  BSD3
--
-- Maintainer  :  cabal-devel@haskell.org
-- Portability :  portable
--
-- This is the command line front end to the Simple build system. When given
-- the parsed command-line args and package information, is able to perform
-- basic commands like configure, build, install, register, etc.
--
-- This module exports the main functions that Setup.hs scripts use. It
-- re-exports the 'UserHooks' type, the standard entry points like
-- 'defaultMain' and 'defaultMainWithHooks' and the predefined sets of
-- 'UserHooks' that custom @Setup.hs@ scripts can extend to add their own
-- behaviour.
--
-- This module isn't called \"Simple\" because it's simple.  Far from
-- it.  It's called \"Simple\" because it does complicated things to
-- simple software.
--
-- The original idea was that there could be different build systems that all
-- presented the same compatible command line interfaces. There is still a
-- "Distribution.Make" system but in practice no packages use it.

{-
Work around this warning:
libraries/Cabal/Distribution/Simple.hs:78:0:
    Warning: In the use of `runTests'
             (imported from Distribution.Simple.UserHooks):
             Deprecated: "Please use the new testing interface instead!"
-}
{-# OPTIONS_GHC -fno-warn-deprecations #-}

module Distribution.Simple (
        module Distribution.Package,
        module Distribution.Version,
        module Distribution.License,
        module Distribution.Simple.Compiler,
        module Language.Haskell.Extension,
        -- * Simple interface
        defaultMain, defaultMainNoRead, defaultMainArgs,
        -- * Customization
        UserHooks(..), Args,
        defaultMainWithHooks, defaultMainWithHooksArgs,
        -- ** Standard sets of hooks
        simpleUserHooks,
        autoconfUserHooks,
        defaultUserHooks, emptyUserHooks,
        -- ** Utils
        defaultHookedPackageDesc
  ) where

-- local
import Distribution.Simple.Compiler hiding (Flag)
import Distribution.Simple.UserHooks
import Distribution.Package --must not specify imports, since we're exporting module.
import Distribution.PackageDescription
         ( PackageDescription(..), GenericPackageDescription, Executable(..)
         , updatePackageDescription, hasLibs
         , HookedBuildInfo, emptyHookedBuildInfo )
import Distribution.PackageDescription.Parse
         ( readPackageDescription, readHookedBuildInfo )
import Distribution.PackageDescription.Configuration
         ( flattenPackageDescription )
import Distribution.Simple.Program
         ( defaultProgramConfiguration, addKnownPrograms, builtinPrograms
         , restoreProgramConfiguration, reconfigurePrograms )
import Distribution.Simple.PreProcess (knownSuffixHandlers, PPSuffixHandler)
import Distribution.Simple.Setup
import Distribution.Simple.Command

import Distribution.Simple.Build        ( build, repl )
import Distribution.Simple.SrcDist      ( sdist )
import Distribution.Simple.Register
         ( register, unregister )

import Distribution.Simple.Configure
         ( getPersistBuildConfig, maybeGetPersistBuildConfig
         , writePersistBuildConfig, checkPersistBuildConfigOutdated
         , configure, checkForeignDeps, findDistPrefOrDefault )

import Distribution.Simple.LocalBuildInfo ( LocalBuildInfo(..) )
import Distribution.Simple.Bench (bench)
import Distribution.Simple.BuildPaths ( srcPref)
import Distribution.Simple.Test (test)
import Distribution.Simple.Install (install)
import Distribution.Simple.Haddock (haddock, hscolour)
import Distribution.Simple.Utils
         (die, notice, info, warn, setupMessage, chattyTry,
          defaultPackageDesc, defaultHookedPackageDesc,
          rawSystemExitWithEnv, cabalVersion, topHandler )
import Distribution.System
         ( OS(..), buildOS )
import Distribution.Verbosity
import Language.Haskell.Extension
import Distribution.Version
import Distribution.License
import Distribution.Text
         ( display )

-- Base
import System.Environment(getArgs, getProgName)
import System.Directory(removeFile, doesFileExist,
                        doesDirectoryExist, removeDirectoryRecursive)
import System.Exit       (exitWith,ExitCode(..))
import System.IO.Error   (isDoesNotExistError)
import Control.Exception (throwIO)
import Distribution.Compat.Environment (getEnvironment)
import Distribution.Compat.Exception (catchIO)

import Control.Monad   (when)
import Data.Foldable   (traverse_)
import Data.List       (intercalate, unionBy, nub, (\\))

-- | A simple implementation of @main@ for a Cabal setup script.
-- It reads the package description file using IO, and performs the
-- action specified on the command line.
defaultMain :: IO ()
defaultMain = getArgs >>= defaultMainHelper simpleUserHooks

-- | A version of 'defaultMain' that is passed the command line
-- arguments, rather than getting them from the environment.
defaultMainArgs :: [String] -> IO ()
defaultMainArgs = defaultMainHelper simpleUserHooks

-- | A customizable version of 'defaultMain'.
defaultMainWithHooks :: UserHooks -> IO ()
defaultMainWithHooks hooks = getArgs >>= defaultMainHelper hooks

-- | A customizable version of 'defaultMain' that also takes the command
-- line arguments.
defaultMainWithHooksArgs :: UserHooks -> [String] -> IO ()
defaultMainWithHooksArgs = defaultMainHelper

-- | Like 'defaultMain', but accepts the package description as input
-- rather than using IO to read it.
defaultMainNoRead :: GenericPackageDescription -> IO ()
defaultMainNoRead pkg_descr =
  getArgs >>=
  defaultMainHelper simpleUserHooks { readDesc = return (Just pkg_descr) }

defaultMainHelper :: UserHooks -> Args -> IO ()
defaultMainHelper hooks args = topHandler $
  case commandsRun (globalCommand commands) commands args of
    CommandHelp   help                 -> printHelp help
    CommandList   opts                 -> printOptionsList opts
    CommandErrors errs                 -> printErrors errs
    CommandReadyToGo (flags, commandParse)  ->
      case commandParse of
        _ | fromFlag (globalVersion flags)        -> printVersion
          | fromFlag (globalNumericVersion flags) -> printNumericVersion
        CommandHelp     help           -> printHelp help
        CommandList     opts           -> printOptionsList opts
        CommandErrors   errs           -> printErrors errs
        CommandReadyToGo action        -> action

  where
    printHelp help = getProgName >>= putStr . help
    printOptionsList = putStr . unlines
    printErrors errs = do
      putStr (intercalate "\n" errs)
      exitWith (ExitFailure 1)
    printNumericVersion = putStrLn $ display cabalVersion
    printVersion        = putStrLn $ "Cabal library version "
                                  ++ display cabalVersion

    progs = addKnownPrograms (hookedPrograms hooks) defaultProgramConfiguration
    commands =
      [configureCommand progs `commandAddAction` \fs as ->
                                                 configureAction    hooks fs as >> return ()
      ,buildCommand     progs `commandAddAction` buildAction        hooks
      ,replCommand      progs `commandAddAction` replAction         hooks
      ,installCommand         `commandAddAction` installAction      hooks
      ,copyCommand            `commandAddAction` copyAction         hooks
      ,haddockCommand         `commandAddAction` haddockAction      hooks
      ,cleanCommand           `commandAddAction` cleanAction        hooks
      ,sdistCommand           `commandAddAction` sdistAction        hooks
      ,hscolourCommand        `commandAddAction` hscolourAction     hooks
      ,registerCommand        `commandAddAction` registerAction     hooks
      ,unregisterCommand      `commandAddAction` unregisterAction   hooks
      ,testCommand            `commandAddAction` testAction         hooks
      ,benchmarkCommand       `commandAddAction` benchAction        hooks
      ]

-- | Combine the preprocessors in the given hooks with the
-- preprocessors built into cabal.
allSuffixHandlers :: UserHooks
                  -> [PPSuffixHandler]
allSuffixHandlers hooks
    = overridesPP (hookedPreProcessors hooks) knownSuffixHandlers
    where
      overridesPP :: [PPSuffixHandler] -> [PPSuffixHandler] -> [PPSuffixHandler]
      overridesPP = unionBy (\x y -> fst x == fst y)

configureAction :: UserHooks -> ConfigFlags -> Args -> IO LocalBuildInfo
configureAction hooks flags args = do
    distPref <- findDistPrefOrDefault (configDistPref flags)
    let flags' = flags { configDistPref = toFlag distPref }
    pbi <- preConf hooks args flags'

    (mb_pd_file, pkg_descr0) <- confPkgDescr

    --get_pkg_descr (configVerbosity flags')
    --let pkg_descr = updatePackageDescription pbi pkg_descr0
    let epkg_descr = (pkg_descr0, pbi)

    --(warns, ers) <- sanityCheckPackage pkg_descr
    --errorOut (configVerbosity flags') warns ers

    localbuildinfo0 <- confHook hooks epkg_descr flags'

    -- remember the .cabal filename if we know it
    -- and all the extra command line args
    let localbuildinfo = localbuildinfo0 {
                           pkgDescrFile = mb_pd_file,
                           extraConfigArgs = args
                         }
    writePersistBuildConfig distPref localbuildinfo

    let pkg_descr = localPkgDescr localbuildinfo
    postConf hooks args flags' pkg_descr localbuildinfo
    return localbuildinfo
  where
    verbosity = fromFlag (configVerbosity flags)
    confPkgDescr :: IO (Maybe FilePath, GenericPackageDescription)
    confPkgDescr = do
        mdescr <- readDesc hooks
        case mdescr of
          Just descr -> return (Nothing, descr)
          Nothing -> do
              pdfile <- defaultPackageDesc verbosity
              descr  <- readPackageDescription verbosity pdfile
              return (Just pdfile, descr)

buildAction :: UserHooks -> BuildFlags -> Args -> IO ()
buildAction hooks flags args = do
  distPref <- findDistPrefOrDefault (buildDistPref flags)
  let verbosity = fromFlag $ buildVerbosity flags
      flags' = flags { buildDistPref = toFlag distPref }

  lbi <- getBuildConfig hooks verbosity distPref
  progs <- reconfigurePrograms verbosity
             (buildProgramPaths flags')
             (buildProgramArgs flags')
             (withPrograms lbi)

  hookedAction preBuild buildHook postBuild
               (return lbi { withPrograms = progs })
               hooks flags' { buildArgs = args } args

replAction :: UserHooks -> ReplFlags -> Args -> IO ()
replAction hooks flags args = do
  distPref <- findDistPrefOrDefault (replDistPref flags)
  let verbosity = fromFlag $ replVerbosity flags
      flags' = flags { replDistPref = toFlag distPref }

  lbi <- getBuildConfig hooks verbosity distPref
  progs <- reconfigurePrograms verbosity
             (replProgramPaths flags')
             (replProgramArgs flags')
             (withPrograms lbi)

  pbi <- preRepl hooks args flags'
  let lbi' = lbi { withPrograms = progs }
      pkg_descr0 = localPkgDescr lbi'
      pkg_descr = updatePackageDescription pbi pkg_descr0
  replHook hooks pkg_descr lbi' hooks flags' args
  postRepl hooks args flags' pkg_descr lbi'

hscolourAction :: UserHooks -> HscolourFlags -> Args -> IO ()
hscolourAction hooks flags args = do
    distPref <- findDistPrefOrDefault (hscolourDistPref flags)
    let verbosity = fromFlag $ hscolourVerbosity flags
        flags' = flags { hscolourDistPref = toFlag distPref }
    hookedAction preHscolour hscolourHook postHscolour
                 (getBuildConfig hooks verbosity distPref)
                 hooks flags' args

haddockAction :: UserHooks -> HaddockFlags -> Args -> IO ()
haddockAction hooks flags args = do
  distPref <- findDistPrefOrDefault (haddockDistPref flags)
  let verbosity = fromFlag $ haddockVerbosity flags
      flags' = flags { haddockDistPref = toFlag distPref }

  lbi <- getBuildConfig hooks verbosity distPref
  progs <- reconfigurePrograms verbosity
             (haddockProgramPaths flags')
             (haddockProgramArgs flags')
             (withPrograms lbi)

  hookedAction preHaddock haddockHook postHaddock
               (return lbi { withPrograms = progs })
               hooks flags' args

cleanAction :: UserHooks -> CleanFlags -> Args -> IO ()
cleanAction hooks flags args = do
    distPref <- findDistPrefOrDefault (cleanDistPref flags)
    let flags' = flags { cleanDistPref = toFlag distPref }

    pbi <- preClean hooks args flags'

    pdfile <- defaultPackageDesc verbosity
    ppd <- readPackageDescription verbosity pdfile
    let pkg_descr0 = flattenPackageDescription ppd
    -- We don't sanity check for clean as an error
    -- here would prevent cleaning:
    --sanityCheckHookedBuildInfo pkg_descr0 pbi
    let pkg_descr = updatePackageDescription pbi pkg_descr0

    cleanHook hooks pkg_descr () hooks flags'
    postClean hooks args flags' pkg_descr ()
  where
    verbosity = fromFlag (cleanVerbosity flags)

copyAction :: UserHooks -> CopyFlags -> Args -> IO ()
copyAction hooks flags args = do
    distPref <- findDistPrefOrDefault (copyDistPref flags)
    let verbosity = fromFlag $ copyVerbosity flags
        flags' = flags { copyDistPref = toFlag distPref }
    hookedAction preCopy copyHook postCopy
                 (getBuildConfig hooks verbosity distPref)
                 hooks flags' args

installAction :: UserHooks -> InstallFlags -> Args -> IO ()
installAction hooks flags args = do
    distPref <- findDistPrefOrDefault (installDistPref flags)
    let verbosity = fromFlag $ installVerbosity flags
        flags' = flags { installDistPref = toFlag distPref }
    hookedAction preInst instHook postInst
                 (getBuildConfig hooks verbosity distPref)
                 hooks flags' args

sdistAction :: UserHooks -> SDistFlags -> Args -> IO ()
sdistAction hooks flags args = do
    distPref <- findDistPrefOrDefault (sDistDistPref flags)
    let flags' = flags { sDistDistPref = toFlag distPref }
    pbi <- preSDist hooks args flags'

    mlbi <- maybeGetPersistBuildConfig distPref
    pdfile <- defaultPackageDesc verbosity
    ppd <- readPackageDescription verbosity pdfile
    let pkg_descr0 = flattenPackageDescription ppd
    sanityCheckHookedBuildInfo pkg_descr0 pbi
    let pkg_descr = updatePackageDescription pbi pkg_descr0

    sDistHook hooks pkg_descr mlbi hooks flags'
    postSDist hooks args flags' pkg_descr mlbi
  where
    verbosity = fromFlag (sDistVerbosity flags)

testAction :: UserHooks -> TestFlags -> Args -> IO ()
testAction hooks flags args = do
    distPref <- findDistPrefOrDefault (testDistPref flags)
    let verbosity = fromFlag $ testVerbosity flags
        flags' = flags { testDistPref = toFlag distPref }

    localBuildInfo <- getBuildConfig hooks verbosity distPref
    let pkg_descr = localPkgDescr localBuildInfo
    -- It is safe to do 'runTests' before the new test handler because the
    -- default action is a no-op and if the package uses the old test interface
    -- the new handler will find no tests.
    runTests hooks args False pkg_descr localBuildInfo
    hookedActionWithArgs preTest testHook postTest
            (getBuildConfig hooks verbosity distPref)
            hooks flags' args

benchAction :: UserHooks -> BenchmarkFlags -> Args -> IO ()
benchAction hooks flags args = do
    distPref <- findDistPrefOrDefault (benchmarkDistPref flags)
    let verbosity = fromFlag $ benchmarkVerbosity flags
        flags' = flags { benchmarkDistPref = toFlag distPref }
    hookedActionWithArgs preBench benchHook postBench
            (getBuildConfig hooks verbosity distPref)
            hooks flags' args

registerAction :: UserHooks -> RegisterFlags -> Args -> IO ()
registerAction hooks flags args = do
    distPref <- findDistPrefOrDefault (regDistPref flags)
    let verbosity = fromFlag $ regVerbosity flags
        flags' = flags { regDistPref = toFlag distPref }
    hookedAction preReg regHook postReg
                 (getBuildConfig hooks verbosity distPref)
                 hooks flags' args

unregisterAction :: UserHooks -> RegisterFlags -> Args -> IO ()
unregisterAction hooks flags args = do
    distPref <- findDistPrefOrDefault (regDistPref flags)
    let verbosity = fromFlag $ regVerbosity flags
        flags' = flags { regDistPref = toFlag distPref }
    hookedAction preUnreg unregHook postUnreg
                 (getBuildConfig hooks verbosity distPref)
                 hooks flags' args

hookedAction :: (UserHooks -> Args -> flags -> IO HookedBuildInfo)
        -> (UserHooks -> PackageDescription -> LocalBuildInfo
                      -> UserHooks -> flags -> IO ())
        -> (UserHooks -> Args -> flags -> PackageDescription
                      -> LocalBuildInfo -> IO ())
        -> IO LocalBuildInfo
        -> UserHooks -> flags -> Args -> IO ()
hookedAction pre_hook cmd_hook =
    hookedActionWithArgs pre_hook (\h _ pd lbi uh flags -> cmd_hook h pd lbi uh flags)

hookedActionWithArgs :: (UserHooks -> Args -> flags -> IO HookedBuildInfo)
        -> (UserHooks -> Args -> PackageDescription -> LocalBuildInfo
                      -> UserHooks -> flags -> IO ())
        -> (UserHooks -> Args -> flags -> PackageDescription
                      -> LocalBuildInfo -> IO ())
        -> IO LocalBuildInfo
        -> UserHooks -> flags -> Args -> IO ()
hookedActionWithArgs pre_hook cmd_hook post_hook get_build_config hooks flags args = do
   pbi <- pre_hook hooks args flags
   localbuildinfo <- get_build_config
   let pkg_descr0 = localPkgDescr localbuildinfo
   --pkg_descr0 <- get_pkg_descr (get_verbose flags)
   sanityCheckHookedBuildInfo pkg_descr0 pbi
   let pkg_descr = updatePackageDescription pbi pkg_descr0
   -- TODO: should we write the modified package descr back to the
   -- localbuildinfo?
   cmd_hook hooks args pkg_descr localbuildinfo hooks flags
   post_hook hooks args flags pkg_descr localbuildinfo

sanityCheckHookedBuildInfo :: PackageDescription -> HookedBuildInfo -> IO ()
sanityCheckHookedBuildInfo PackageDescription { library = Nothing } (Just _,_)
    = die $ "The buildinfo contains info for a library, "
         ++ "but the package does not have a library."

sanityCheckHookedBuildInfo pkg_descr (_, hookExes)
    | not (null nonExistant)
    = die $ "The buildinfo contains info for an executable called '"
         ++ head nonExistant ++ "' but the package does not have a "
         ++ "executable with that name."
  where
    pkgExeNames  = nub (map exeName (executables pkg_descr))
    hookExeNames = nub (map fst hookExes)
    nonExistant  = hookExeNames \\ pkgExeNames

sanityCheckHookedBuildInfo _ _ = return ()


getBuildConfig :: UserHooks -> Verbosity -> FilePath -> IO LocalBuildInfo
getBuildConfig hooks verbosity distPref = do
  lbi_wo_programs <- getPersistBuildConfig distPref
  -- Restore info about unconfigured programs, since it is not serialized
  let lbi = lbi_wo_programs {
    withPrograms = restoreProgramConfiguration
                     (builtinPrograms ++ hookedPrograms hooks)
                     (withPrograms lbi_wo_programs)
  }

  case pkgDescrFile lbi of
    Nothing -> return lbi
    Just pkg_descr_file -> do
      outdated <- checkPersistBuildConfigOutdated distPref pkg_descr_file
      if outdated
        then reconfigure pkg_descr_file lbi
        else return lbi

  where
    reconfigure :: FilePath -> LocalBuildInfo -> IO LocalBuildInfo
    reconfigure pkg_descr_file lbi = do
      notice verbosity $ pkg_descr_file ++ " has been changed. "
                      ++ "Re-configuring with most recently used options. "
                      ++ "If this fails, please run configure manually.\n"
      let cFlags = configFlags lbi
      let cFlags' = cFlags {
            -- Since the list of unconfigured programs is not serialized,
            -- restore it to the same value as normally used at the beginning
            -- of a configure run:
            configPrograms = restoreProgramConfiguration
                               (builtinPrograms ++ hookedPrograms hooks)
                               (configPrograms cFlags),

            -- Use the current, not saved verbosity level:
            configVerbosity = Flag verbosity
          }
      configureAction hooks cFlags' (extraConfigArgs lbi)


-- --------------------------------------------------------------------------
-- Cleaning

clean :: PackageDescription -> CleanFlags -> IO ()
clean pkg_descr flags = do
    let distPref = fromFlagOrDefault defaultDistPref $ cleanDistPref flags
    notice verbosity "cleaning..."

    maybeConfig <- if fromFlag (cleanSaveConf flags)
                     then maybeGetPersistBuildConfig distPref
                     else return Nothing

    -- remove the whole dist/ directory rather than tracking exactly what files
    -- we created in there.
    chattyTry "removing dist/" $ do
      exists <- doesDirectoryExist distPref
      when exists (removeDirectoryRecursive distPref)

    -- Any extra files the user wants to remove
    mapM_ removeFileOrDirectory (extraTmpFiles pkg_descr)

    -- If the user wanted to save the config, write it back
    traverse_ (writePersistBuildConfig distPref) maybeConfig

  where
        removeFileOrDirectory :: FilePath -> IO ()
        removeFileOrDirectory fname = do
            isDir <- doesDirectoryExist fname
            isFile <- doesFileExist fname
            if isDir then removeDirectoryRecursive fname
              else when isFile $ removeFile fname
        verbosity = fromFlag (cleanVerbosity flags)

-- --------------------------------------------------------------------------
-- Default hooks

-- | Hooks that correspond to a plain instantiation of the
-- \"simple\" build system
simpleUserHooks :: UserHooks
simpleUserHooks =
    emptyUserHooks {
       confHook  = configure,
       postConf  = finalChecks,
       buildHook = defaultBuildHook,
       replHook  = defaultReplHook,
       copyHook  = \desc lbi _ f -> install desc lbi f, -- has correct 'copy' behavior with params
       testHook  = defaultTestHook,
       benchHook = defaultBenchHook,
       instHook  = defaultInstallHook,
       sDistHook = \p l h f -> sdist p l f srcPref (allSuffixHandlers h),
       cleanHook = \p _ _ f -> clean p f,
       hscolourHook = \p l h f -> hscolour p l (allSuffixHandlers h) f,
       haddockHook  = \p l h f -> haddock  p l (allSuffixHandlers h) f,
       regHook   = defaultRegHook,
       unregHook = \p l _ f -> unregister p l f
      }
  where
    finalChecks _args flags pkg_descr lbi =
      checkForeignDeps pkg_descr lbi (lessVerbose verbosity)
      where
        verbosity = fromFlag (configVerbosity flags)

-- | Basic autoconf 'UserHooks':
--
-- * 'postConf' runs @.\/configure@, if present.
--
-- * the pre-hooks 'preBuild', 'preClean', 'preCopy', 'preInst',
--   'preReg' and 'preUnreg' read additional build information from
--   /package/@.buildinfo@, if present.
--
-- Thus @configure@ can use local system information to generate
-- /package/@.buildinfo@ and possibly other files.

{-# DEPRECATED defaultUserHooks
     "Use simpleUserHooks or autoconfUserHooks, unless you need Cabal-1.2\n             compatibility in which case you must stick with defaultUserHooks" #-}
defaultUserHooks :: UserHooks
defaultUserHooks = autoconfUserHooks {
          confHook = \pkg flags -> do
                       let verbosity = fromFlag (configVerbosity flags)
                       warn verbosity
                         "defaultUserHooks in Setup script is deprecated."
                       confHook autoconfUserHooks pkg flags,
          postConf = oldCompatPostConf
    }
    -- This is the annoying old version that only runs configure if it exists.
    -- It's here for compatibility with existing Setup.hs scripts. See:
    -- https://github.com/haskell/cabal/issues/158
    where oldCompatPostConf args flags pkg_descr lbi
              = do let verbosity = fromFlag (configVerbosity flags)
                   noExtraFlags args
                   confExists <- doesFileExist "configure"
                   when confExists $
                       runConfigureScript verbosity
                         backwardsCompatHack flags lbi

                   pbi <- getHookedBuildInfo verbosity
                   sanityCheckHookedBuildInfo pkg_descr pbi
                   let pkg_descr' = updatePackageDescription pbi pkg_descr
                   postConf simpleUserHooks args flags pkg_descr' lbi

          backwardsCompatHack = True

autoconfUserHooks :: UserHooks
autoconfUserHooks
    = simpleUserHooks
      {
       postConf    = defaultPostConf,
       preBuild    = \_ flags ->
                       -- not using 'readHook' here because 'build' takes
                       -- extra args
                       getHookedBuildInfo $ fromFlag $ buildVerbosity flags,
       preClean    = readHook cleanVerbosity,
       preCopy     = readHook copyVerbosity,
       preInst     = readHook installVerbosity,
       preHscolour = readHook hscolourVerbosity,
       preHaddock  = readHook haddockVerbosity,
       preReg      = readHook regVerbosity,
       preUnreg    = readHook regVerbosity
      }
    where defaultPostConf :: Args -> ConfigFlags -> PackageDescription -> LocalBuildInfo -> IO ()
          defaultPostConf args flags pkg_descr lbi
              = do let verbosity = fromFlag (configVerbosity flags)
                   noExtraFlags args
                   confExists <- doesFileExist "configure"
                   if confExists
                     then runConfigureScript verbosity
                            backwardsCompatHack flags lbi
                     else die "configure script not found."

                   pbi <- getHookedBuildInfo verbosity
                   sanityCheckHookedBuildInfo pkg_descr pbi
                   let pkg_descr' = updatePackageDescription pbi pkg_descr
                   postConf simpleUserHooks args flags pkg_descr' lbi

          backwardsCompatHack = False

          readHook :: (a -> Flag Verbosity) -> Args -> a -> IO HookedBuildInfo
          readHook get_verbosity a flags = do
              noExtraFlags a
              getHookedBuildInfo verbosity
            where
              verbosity = fromFlag (get_verbosity flags)

runConfigureScript :: Verbosity -> Bool -> ConfigFlags -> LocalBuildInfo
                   -> IO ()
runConfigureScript verbosity backwardsCompatHack flags lbi = do

  env <- getEnvironment
  let programConfig = withPrograms lbi
  (ccProg, ccFlags) <- configureCCompiler verbosity programConfig
  -- The C compiler's compilation and linker flags (e.g.
  -- "C compiler flags" and "Gcc Linker flags" from GHC) have already
  -- been merged into ccFlags, so we set both CFLAGS and LDFLAGS
  -- to ccFlags
  -- We don't try and tell configure which ld to use, as we don't have
  -- a way to pass its flags too
  let env' = appendToEnvironment ("CFLAGS",  unwords ccFlags)
             env
      args' = args ++ ["--with-gcc=" ++ ccProg]
  handleNoWindowsSH $
    rawSystemExitWithEnv verbosity "sh" args' env'

  where
    args = "./configure" : configureArgs backwardsCompatHack flags

    appendToEnvironment (key, val) [] = [(key, val)]
    appendToEnvironment (key, val) (kv@(k, v) : rest)
     | key == k  = (key, v ++ " " ++ val) : rest
     | otherwise = kv : appendToEnvironment (key, val) rest

    handleNoWindowsSH action
      | buildOS /= Windows
      = action

      | otherwise
      = action
          `catchIO` \ioe -> if isDoesNotExistError ioe
                              then die notFoundMsg
                              else throwIO ioe

    notFoundMsg = "The package has a './configure' script. This requires a "
               ++ "Unix compatibility toolchain such as MinGW+MSYS or Cygwin."

getHookedBuildInfo :: Verbosity -> IO HookedBuildInfo
getHookedBuildInfo verbosity = do
  maybe_infoFile <- defaultHookedPackageDesc
  case maybe_infoFile of
    Nothing       -> return emptyHookedBuildInfo
    Just infoFile -> do
      info verbosity $ "Reading parameters from " ++ infoFile
      readHookedBuildInfo verbosity infoFile

defaultTestHook :: Args -> PackageDescription -> LocalBuildInfo
                -> UserHooks -> TestFlags -> IO ()
defaultTestHook args pkg_descr localbuildinfo _ flags =
    test args pkg_descr localbuildinfo flags

defaultBenchHook :: Args -> PackageDescription -> LocalBuildInfo
                 -> UserHooks -> BenchmarkFlags -> IO ()
defaultBenchHook args pkg_descr localbuildinfo _ flags =
    bench args pkg_descr localbuildinfo flags

defaultInstallHook :: PackageDescription -> LocalBuildInfo
                   -> UserHooks -> InstallFlags -> IO ()
defaultInstallHook pkg_descr localbuildinfo _ flags = do
  let copyFlags = defaultCopyFlags {
                      copyDistPref   = installDistPref flags,
                      copyDest       = toFlag NoCopyDest,
                      copyVerbosity  = installVerbosity flags
                  }
  install pkg_descr localbuildinfo copyFlags
  let registerFlags = defaultRegisterFlags {
                          regDistPref  = installDistPref flags,
                          regInPlace   = installInPlace flags,
                          regPackageDB = installPackageDB flags,
                          regVerbosity = installVerbosity flags
                      }
  when (hasLibs pkg_descr) $ register pkg_descr localbuildinfo registerFlags

defaultBuildHook :: PackageDescription -> LocalBuildInfo
        -> UserHooks -> BuildFlags -> IO ()
defaultBuildHook pkg_descr localbuildinfo hooks flags =
  build pkg_descr localbuildinfo flags (allSuffixHandlers hooks)

defaultReplHook :: PackageDescription -> LocalBuildInfo
        -> UserHooks -> ReplFlags -> [String] -> IO ()
defaultReplHook pkg_descr localbuildinfo hooks flags args =
  repl pkg_descr localbuildinfo flags (allSuffixHandlers hooks) args

defaultRegHook :: PackageDescription -> LocalBuildInfo
        -> UserHooks -> RegisterFlags -> IO ()
defaultRegHook pkg_descr localbuildinfo _ flags =
    if hasLibs pkg_descr
    then register pkg_descr localbuildinfo flags
    else setupMessage verbosity
           "Package contains no library to register:" (packageId pkg_descr)
  where verbosity = fromFlag (regVerbosity flags)