    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.Build
    -- Copyright   :  Isaac Jones 2003-2005,
    --                Ross Paterson 2006,
    --                Duncan Coutts 2007-2008
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- This is the entry point to actually building the modules in a package. It
    -- doesn't actually do much itself, most of the work is delegated to
    -- compiler-specific actions. It does do some non-compiler specific bits like
    -- running pre-processors.
    --

    {- Copyright (c) 2003-2005, Isaac Jones
    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.Build (
        build,

        initialBuildSteps,
        writeAutogenFiles,
      ) where

    import qualified Distribution.Simple.GHC  as GHC
    import qualified Distribution.Simple.JHC  as JHC
    import qualified Distribution.Simple.LHC  as LHC
    import qualified Distribution.Simple.NHC  as NHC
    import qualified Distribution.Simple.Hugs as Hugs
    import qualified Distribution.Simple.UHC  as UHC

    import qualified Distribution.Simple.Build.Macros      as Build.Macros
    import qualified Distribution.Simple.Build.PathsModule as Build.PathsModule

    import Distribution.Package
             ( Package(..), PackageName(..), PackageIdentifier(..)
             , thisPackageVersion )
    import Distribution.Simple.Compiler
             ( CompilerFlavor(..), compilerFlavor, PackageDB(..) )
    import Distribution.PackageDescription
             ( PackageDescription(..), BuildInfo(..), Library(..), Executable(..)
             , TestSuite(..), TestSuiteInterface(..) )
    import qualified Distribution.InstalledPackageInfo as IPI
    import qualified Distribution.ModuleName as ModuleName

    import Distribution.Simple.Setup
             ( BuildFlags(..), fromFlag )
    import Distribution.Simple.PreProcess
             ( preprocessSources, PPSuffixHandler )
    import Distribution.Simple.LocalBuildInfo
             ( LocalBuildInfo(compiler, buildDir, withPackageDB)
             , ComponentLocalBuildInfo(..), withLibLBI, withExeLBI
             , inplacePackageId, withTestLBI )
    import Distribution.Simple.BuildPaths
             ( autogenModulesDir, autogenModuleName, cppHeaderName )
    import Distribution.Simple.Register
             ( registerPackage, inplaceInstalledPackageInfo )
    import Distribution.Simple.Test ( stubFilePath, stubName )
    import Distribution.Simple.Utils
             ( createDirectoryIfMissingVerbose, rewriteFile
             , die, info, setupMessage )

    import Distribution.Verbosity
             ( Verbosity )
    import Distribution.Text
             ( display )

    import Data.Maybe
             ( maybeToList )
    import Control.Monad
             ( unless )
    import System.FilePath
             ( (</>), (<.>) )
    import System.Directory
             ( getCurrentDirectory )

    -- -----------------------------------------------------------------------------
    -- |Build the libraries and executables in this package.

    build    :: PackageDescription  -- ^mostly information from the .cabal file
             -> LocalBuildInfo -- ^Configuration information
             -> BuildFlags -- ^Flags that the user passed to build
             -> [ PPSuffixHandler ] -- ^preprocessors to run before compiling
             -> IO ()
    build pkg_descr lbi flags suffixes = do
      let distPref  = fromFlag (buildDistPref flags)
          verbosity = fromFlag (buildVerbosity flags)
      initialBuildSteps distPref pkg_descr lbi verbosity suffixes
      setupMessage verbosity "Building" (packageId pkg_descr)

      internalPackageDB <- createInternalPackageDB distPref

      withLibLBI pkg_descr lbi $ \lib clbi -> do
        info verbosity "Building library..."
        buildLib verbosity pkg_descr lbi lib clbi

        -- Register the library in-place, so exes can depend
        -- on internally defined libraries.
        pwd <- getCurrentDirectory
        let installedPkgInfo =
              (inplaceInstalledPackageInfo pwd distPref pkg_descr lib lbi clbi) {
                -- The inplace registration uses the "-inplace" suffix,
                -- not an ABI hash.
                IPI.installedPackageId = inplacePackageId (packageId installedPkgInfo)
              }
        registerPackage verbosity
          installedPkgInfo pkg_descr lbi True -- True meaning inplace
          (withPackageDB lbi ++ [internalPackageDB])

      -- Use the internal package db for the exes.
      let lbi' = lbi { withPackageDB = withPackageDB lbi ++ [internalPackageDB] }

      withExeLBI pkg_descr lbi' $ \exe clbi -> do
        info verbosity $ "Building executable " ++ exeName exe ++ "..."
        buildExe verbosity pkg_descr lbi' exe clbi

      withTestLBI pkg_descr lbi' $ \test clbi ->
        case testInterface test of
            TestSuiteExeV10 _ f -> do
                let exe = Executable
                        { exeName = testName test
                        , modulePath = f
                        , buildInfo = testBuildInfo test
                        }
                info verbosity $ "Building test suite " ++ testName test ++ "..."
                buildExe verbosity pkg_descr lbi' exe clbi
            TestSuiteLibV09 _ m -> do
                pwd <- getCurrentDirectory
                let lib = Library
                        { exposedModules = [ m ]
                        , libExposed = True
                        , libBuildInfo = testBuildInfo test
                        }
                    pkg = pkg_descr
                        { package = (package pkg_descr)
                            { pkgName = PackageName $ testName test
                            }
                        , buildDepends = targetBuildDepends $ testBuildInfo test
                        , executables = []
                        , testSuites = []
                        , library = Just lib
                        }
                    ipi = (inplaceInstalledPackageInfo
                        pwd distPref pkg lib lbi clbi)
                        { IPI.installedPackageId = inplacePackageId $ packageId ipi
                        }
                    testDir = buildDir lbi' </> stubName test
                        </> stubName test ++ "-tmp"
                    testLibDep = thisPackageVersion $ package pkg
                    exe = Executable
                        { exeName = stubName test
                        , modulePath = stubFilePath test
                        , buildInfo = (testBuildInfo test)
                            { hsSourceDirs = [ testDir ]
                            , targetBuildDepends = testLibDep
                                : (targetBuildDepends $ testBuildInfo test)
                            }
                        }
                    -- | The stub executable needs a new 'ComponentLocalBuildInfo'
                    -- that exposes the relevant test suite library.
                    exeClbi = clbi
                        { componentPackageDeps =
                            (IPI.installedPackageId ipi, packageId ipi)
                            : (filter (\(_, x) -> let PackageName name = pkgName x in name == "Cabal" || name == "base")
                                $ componentPackageDeps clbi)
                        }
                info verbosity $ "Building test suite " ++ testName test ++ "..."
                buildLib verbosity pkg lbi' lib clbi
                registerPackage verbosity ipi pkg lbi' True $ withPackageDB lbi'
                buildExe verbosity pkg_descr lbi' exe exeClbi
            TestSuiteUnsupported tt -> die $ "No support for building test suite "
                                          ++ "type " ++ display tt

    -- | Initialize a new package db file for libraries defined
    -- internally to the package.
    createInternalPackageDB :: FilePath -> IO PackageDB
    createInternalPackageDB distPref = do
        let dbFile = distPref </> "package.conf.inplace"
            packageDB = SpecificPackageDB dbFile
        writeFile dbFile "[]"
        return packageDB

    -- TODO: build separate libs in separate dirs so that we can build
    -- multiple libs, e.g. for 'LibTest' library-style testsuites
    buildLib :: Verbosity -> PackageDescription -> LocalBuildInfo
                          -> Library            -> ComponentLocalBuildInfo -> IO ()
    buildLib verbosity pkg_descr lbi lib clbi =
      case compilerFlavor (compiler lbi) of
        GHC  -> GHC.buildLib  verbosity pkg_descr lbi lib clbi
        JHC  -> JHC.buildLib  verbosity pkg_descr lbi lib clbi
        LHC  -> LHC.buildLib  verbosity pkg_descr lbi lib clbi
        Hugs -> Hugs.buildLib verbosity pkg_descr lbi lib clbi
        NHC  -> NHC.buildLib  verbosity pkg_descr lbi lib clbi
        UHC  -> UHC.buildLib  verbosity pkg_descr lbi lib clbi
        _    -> die "Building is not supported with this compiler."

    buildExe :: Verbosity -> PackageDescription -> LocalBuildInfo
                          -> Executable         -> ComponentLocalBuildInfo -> IO ()
    buildExe verbosity pkg_descr lbi exe clbi =
      case compilerFlavor (compiler lbi) of
        GHC  -> GHC.buildExe  verbosity pkg_descr lbi exe clbi
        JHC  -> JHC.buildExe  verbosity pkg_descr lbi exe clbi
        LHC  -> LHC.buildExe  verbosity pkg_descr lbi exe clbi
        Hugs -> Hugs.buildExe verbosity pkg_descr lbi exe clbi
        NHC  -> NHC.buildExe  verbosity pkg_descr lbi exe clbi
        UHC  -> UHC.buildExe  verbosity pkg_descr lbi exe clbi
        _    -> die "Building is not supported with this compiler."

    initialBuildSteps :: FilePath -- ^"dist" prefix
                      -> PackageDescription  -- ^mostly information from the .cabal file
                      -> LocalBuildInfo -- ^Configuration information
                      -> Verbosity -- ^The verbosity to use
                      -> [ PPSuffixHandler ] -- ^preprocessors to run before compiling
                      -> IO ()
    initialBuildSteps _distPref pkg_descr lbi verbosity suffixes = do
      -- check that there's something to build
      let buildInfos =
              map libBuildInfo (maybeToList (library pkg_descr)) ++
              map buildInfo (executables pkg_descr)
      unless (any buildable buildInfos) $ do
        let name = display (packageId pkg_descr)
        die ("Package " ++ name ++ " can't be built on this system.")

      createDirectoryIfMissingVerbose verbosity True (buildDir lbi)

      writeAutogenFiles verbosity pkg_descr lbi

      preprocessSources pkg_descr lbi False verbosity suffixes

    -- | Generate and write out the Paths_<pkg>.hs and cabal_macros.h files
    --
    writeAutogenFiles :: Verbosity
                      -> PackageDescription
                      -> LocalBuildInfo
                      -> IO ()
    writeAutogenFiles verbosity pkg lbi = do
      createDirectoryIfMissingVerbose verbosity True (autogenModulesDir lbi)

      let pathsModulePath = autogenModulesDir lbi
                        </> ModuleName.toFilePath (autogenModuleName pkg) <.> "hs"
      rewriteFile pathsModulePath (Build.PathsModule.generate pkg lbi)

      let cppHeaderPath = autogenModulesDir lbi </> cppHeaderName
      rewriteFile cppHeaderPath (Build.Macros.generate pkg lbi)