    {-# LANGUAGE DeriveDataTypeable #-}
    {-# LANGUAGE DeriveGeneric #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.PackageDescription
    -- Copyright   :  Isaac Jones 2003-2005
    -- License     :  BSD3
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- This defines the data structure for the @.cabal@ file format. There are
    -- several parts to this structure. It has top level info and then 'Library',
    -- 'Executable', 'TestSuite', and 'Benchmark' sections each of which have
    -- associated 'BuildInfo' data that's used to build the library, exe, test, or
    -- benchmark.  To further complicate things there is both a 'PackageDescription'
    -- and a 'GenericPackageDescription'. This distinction relates to cabal
    -- configurations. When we initially read a @.cabal@ file we get a
    -- 'GenericPackageDescription' which has all the conditional sections.
    -- Before actually building a package we have to decide
    -- on each conditional. Once we've done that we get a 'PackageDescription'.
    -- It was done this way initially to avoid breaking too much stuff when the
    -- feature was introduced. It could probably do with being rationalised at some
    -- point to make it simpler.

    module Distribution.PackageDescription (
            -- * Package descriptions
            PackageDescription(..),
            emptyPackageDescription,
            specVersion,
            descCabalVersion,
            BuildType(..),
            knownBuildTypes,

            -- ** Renaming
            ModuleRenaming(..),
            defaultRenaming,
            lookupRenaming,

            -- ** Libraries
            Library(..),
            ModuleReexport(..),
            emptyLibrary,
            withLib,
            hasLibs,
            libModules,

            -- ** Executables
            Executable(..),
            emptyExecutable,
            withExe,
            hasExes,
            exeModules,

            -- * Tests
            TestSuite(..),
            TestSuiteInterface(..),
            TestType(..),
            testType,
            knownTestTypes,
            emptyTestSuite,
            hasTests,
            withTest,
            testModules,
            enabledTests,

            -- * Benchmarks
            Benchmark(..),
            BenchmarkInterface(..),
            BenchmarkType(..),
            benchmarkType,
            knownBenchmarkTypes,
            emptyBenchmark,
            hasBenchmarks,
            withBenchmark,
            benchmarkModules,
            enabledBenchmarks,

            -- * Build information
            BuildInfo(..),
            emptyBuildInfo,
            allBuildInfo,
            allLanguages,
            allExtensions,
            usedExtensions,
            hcOptions,
            hcProfOptions,
            hcSharedOptions,

            -- ** Supplementary build information
            HookedBuildInfo,
            emptyHookedBuildInfo,
            updatePackageDescription,

            -- * package configuration
            GenericPackageDescription(..),
            Flag(..), FlagName(..), FlagAssignment,
            CondTree(..), ConfVar(..), Condition(..),
            cNot, cAnd, cOr,

            -- * Source repositories
            SourceRepo(..),
            RepoKind(..),
            RepoType(..),
            knownRepoTypes,

            -- * Custom setup build information
            SetupBuildInfo(..),
      ) where

    import Distribution.Compat.Binary
    import qualified Distribution.Compat.Semigroup as Semi ((<>))
    import Distribution.Compat.Semigroup as Semi (Monoid(..), Semigroup, gmempty)
    import qualified Distribution.Compat.ReadP as Parse
    import Distribution.Compat.ReadP   ((<++))
    import Distribution.Package
    import Distribution.ModuleName
    import Distribution.Version
    import Distribution.License
    import Distribution.Compiler
    import Distribution.System
    import Distribution.Text
    import Language.Haskell.Extension

    import Data.Data                  (Data)
    import Data.Foldable              (traverse_)
    import Data.List                  (nub, intercalate)
    import Data.Maybe                 (fromMaybe, maybeToList)
    import Data.Foldable as Fold      (Foldable(foldMap))
    import Data.Traversable as Trav   (Traversable(traverse))
    import Data.Typeable               ( Typeable )
    import Control.Applicative as AP   (Alternative(..), Applicative(..))
    import Control.Monad               (MonadPlus(mplus,mzero), ap)
    import GHC.Generics                (Generic)
    import Text.PrettyPrint as Disp
    import qualified Data.Char as Char (isAlphaNum, isDigit, toLower)
    import qualified Data.Map as Map
    import Data.Map                    (Map)

    -- -----------------------------------------------------------------------------
    -- The PackageDescription type

    -- | This data type is the internal representation of the file @pkg.cabal@.
    -- It contains two kinds of information about the package: information
    -- which is needed for all packages, such as the package name and version, and
    -- information which is needed for the simple build system only, such as
    -- the compiler options and library name.
    --
    data PackageDescription
        =  PackageDescription {
            -- the following are required by all packages:
            package        :: PackageIdentifier,
            license        :: License,
            licenseFiles   :: [FilePath],
            copyright      :: String,
            maintainer     :: String,
            author         :: String,
            stability      :: String,
            testedWith     :: [(CompilerFlavor,VersionRange)],
            homepage       :: String,
            pkgUrl         :: String,
            bugReports     :: String,
            sourceRepos    :: [SourceRepo],
            synopsis       :: String, -- ^A one-line summary of this package
            description    :: String, -- ^A more verbose description of this package
            category       :: String,
            customFieldsPD :: [(String,String)], -- ^Custom fields starting
                                                 -- with x-, stored in a
                                                 -- simple assoc-list.

            -- | YOU PROBABLY DON'T WANT TO USE THIS FIELD. This field is
            -- special! Depending on how far along processing the
            -- PackageDescription we are, the contents of this field are
            -- either nonsense, or the collected dependencies of *all* the
            -- components in this package.  buildDepends is initialized by
            -- 'finalizePackageDescription' and 'flattenPackageDescription';
            -- prior to that, dependency info is stored in the 'CondTree'
            -- built around a 'GenericPackageDescription'.  When this
            -- resolution is done, dependency info is written to the inner
            -- 'BuildInfo' and this field.  This is all horrible, and #2066
            -- tracks progress to get rid of this field.
            buildDepends   :: [Dependency],
            -- | The version of the Cabal spec that this package description uses.
            -- For historical reasons this is specified with a version range but
            -- only ranges of the form @>= v@ make sense. We are in the process of
            -- transitioning to specifying just a single version, not a range.
            specVersionRaw :: Either Version VersionRange,
            buildType      :: Maybe BuildType,
            setupBuildInfo :: Maybe SetupBuildInfo,
            -- components
            library        :: Maybe Library,
            executables    :: [Executable],
            testSuites     :: [TestSuite],
            benchmarks     :: [Benchmark],
            dataFiles      :: [FilePath],
            dataDir        :: FilePath,
            extraSrcFiles  :: [FilePath],
            extraTmpFiles  :: [FilePath],
            extraDocFiles  :: [FilePath]
        }
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary PackageDescription

    instance Package PackageDescription where
      packageId = package

    -- | The version of the Cabal spec that this package should be interpreted
    -- against.
    --
    -- Historically we used a version range but we are switching to using a single
    -- version. Currently we accept either. This function converts into a single
    -- version by ignoring upper bounds in the version range.
    --
    specVersion :: PackageDescription -> Version
    specVersion pkg = case specVersionRaw pkg of
      Left  version      -> version
      Right versionRange -> case asVersionIntervals versionRange of
                              []                            -> Version [0] []
                              ((LowerBound version _, _):_) -> version

    -- | The range of versions of the Cabal tools that this package is intended to
    -- work with.
    --
    -- This function is deprecated and should not be used for new purposes, only to
    -- support old packages that rely on the old interpretation.
    --
    descCabalVersion :: PackageDescription -> VersionRange
    descCabalVersion pkg = case specVersionRaw pkg of
      Left  version      -> orLaterVersion version
      Right versionRange -> versionRange
    {-# DEPRECATED descCabalVersion "Use specVersion instead" #-}

    emptyPackageDescription :: PackageDescription
    emptyPackageDescription
        =  PackageDescription {
                          package      = PackageIdentifier (PackageName "")
                                                           (Version [] []),
                          license      = UnspecifiedLicense,
                          licenseFiles = [],
                          specVersionRaw = Right anyVersion,
                          buildType    = Nothing,
                          copyright    = "",
                          maintainer   = "",
                          author       = "",
                          stability    = "",
                          testedWith   = [],
                          buildDepends = [],
                          homepage     = "",
                          pkgUrl       = "",
                          bugReports   = "",
                          sourceRepos  = [],
                          synopsis     = "",
                          description  = "",
                          category     = "",
                          customFieldsPD = [],
                          setupBuildInfo = Nothing,
                          library      = Nothing,
                          executables  = [],
                          testSuites   = [],
                          benchmarks   = [],
                          dataFiles    = [],
                          dataDir      = "",
                          extraSrcFiles = [],
                          extraTmpFiles = [],
                          extraDocFiles = []
                         }

    -- | The type of build system used by this package.
    data BuildType
      = Simple      -- ^ calls @Distribution.Simple.defaultMain@
      | Configure   -- ^ calls @Distribution.Simple.defaultMainWithHooks defaultUserHooks@,
                    -- which invokes @configure@ to generate additional build
                    -- information used by later phases.
      | Make        -- ^ calls @Distribution.Make.defaultMain@
      | Custom      -- ^ uses user-supplied @Setup.hs@ or @Setup.lhs@ (default)
      | UnknownBuildType String
                    -- ^ a package that uses an unknown build type cannot actually
                    --   be built. Doing it this way rather than just giving a
                    --   parse error means we get better error messages and allows
                    --   you to inspect the rest of the package description.
                    deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary BuildType

    knownBuildTypes :: [BuildType]
    knownBuildTypes = [Simple, Configure, Make, Custom]

    instance Text BuildType where
      disp (UnknownBuildType other) = Disp.text other
      disp other                    = Disp.text (show other)

      parse = do
        name <- Parse.munch1 Char.isAlphaNum
        return $ case name of
          "Simple"    -> Simple
          "Configure" -> Configure
          "Custom"    -> Custom
          "Make"      -> Make
          _           -> UnknownBuildType name

    -- ---------------------------------------------------------------------------
    -- The SetupBuildInfo type

    -- One can see this as a very cut-down version of BuildInfo below.
    -- To keep things simple for tools that compile Setup.hs we limit the
    -- options authors can specify to just Haskell package dependencies.

    data SetupBuildInfo = SetupBuildInfo {
            setupDepends        :: [Dependency],
            defaultSetupDepends :: Bool
            -- ^ Is this a default 'custom-setup' section added by the cabal-install
            -- code (as opposed to user-provided)? This field is only used
            -- internally, and doesn't correspond to anything in the .cabal
            -- file. See #3199.
        }
        deriving (Generic, Show, Eq, Read, Typeable, Data)

    instance Binary SetupBuildInfo

    instance Semi.Monoid SetupBuildInfo where
      mempty  = SetupBuildInfo [] False
      mappend = (Semi.<>)

    instance Semigroup SetupBuildInfo where
      a <> b = SetupBuildInfo (setupDepends a Semi.<> setupDepends b)
               (defaultSetupDepends a || defaultSetupDepends b)

    -- ---------------------------------------------------------------------------
    -- Module renaming

    -- | Renaming applied to the modules provided by a package.
    -- The boolean indicates whether or not to also include all of the
    -- original names of modules.  Thus, @ModuleRenaming False []@ is
    -- "don't expose any modules, and @ModuleRenaming True [("Data.Bool", "Bool")]@
    -- is, "expose all modules, but also expose @Data.Bool@ as @Bool@".
    --
    data ModuleRenaming = ModuleRenaming Bool [(ModuleName, ModuleName)]
        deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

    defaultRenaming :: ModuleRenaming
    defaultRenaming = ModuleRenaming True []

    lookupRenaming :: Package pkg => pkg -> Map PackageName ModuleRenaming -> ModuleRenaming
    lookupRenaming = Map.findWithDefault defaultRenaming . packageName

    instance Binary ModuleRenaming where

    instance Monoid ModuleRenaming where
        mempty = ModuleRenaming False []
        mappend = (Semi.<>)

    instance Semigroup ModuleRenaming where
        ModuleRenaming b rns <> ModuleRenaming b' rns'
            = ModuleRenaming (b || b') (rns ++ rns') -- ToDo: dedupe?

    -- NB: parentheses are mandatory, because later we may extend this syntax
    -- to allow "hiding (A, B)" or other modifier words.
    instance Text ModuleRenaming where
      disp (ModuleRenaming True []) = Disp.empty
      disp (ModuleRenaming b vs) = (if b then text "with" else Disp.empty) <+> dispRns
        where dispRns = Disp.parens
                             (Disp.hsep
                                (Disp.punctuate Disp.comma (map dispEntry vs)))
              dispEntry (orig, new)
                | orig == new = disp orig
                | otherwise = disp orig <+> text "as" <+> disp new

      parse = do Parse.string "with" >> Parse.skipSpaces
                 fmap (ModuleRenaming True) parseRns
             <++ fmap (ModuleRenaming False) parseRns
             <++ return (ModuleRenaming True [])
        where parseRns = do
                 rns <- Parse.between (Parse.char '(') (Parse.char ')') parseList
                 Parse.skipSpaces
                 return rns
              parseList =
                Parse.sepBy parseEntry (Parse.char ',' >> Parse.skipSpaces)
              parseEntry :: Parse.ReadP r (ModuleName, ModuleName)
              parseEntry = do
                orig <- parse
                Parse.skipSpaces
                (do _ <- Parse.string "as"
                    Parse.skipSpaces
                    new <- parse
                    Parse.skipSpaces
                    return (orig, new)
                 <++
                    return (orig, orig))

    -- ---------------------------------------------------------------------------
    -- The Library type

    data Library = Library {
            exposedModules    :: [ModuleName],
            reexportedModules :: [ModuleReexport],
            requiredSignatures:: [ModuleName], -- ^ What sigs need implementations?
            exposedSignatures:: [ModuleName], -- ^ What sigs are visible to users?
            libExposed        :: Bool, -- ^ Is the lib to be exposed by default?
            libBuildInfo      :: BuildInfo
        }
        deriving (Generic, Show, Eq, Read, Typeable, Data)

    instance Binary Library

    instance Monoid Library where
      mempty = Library {
        exposedModules = mempty,
        reexportedModules = mempty,
        requiredSignatures = mempty,
        exposedSignatures = mempty,
        libExposed     = True,
        libBuildInfo   = mempty
      }
      mappend = (Semi.<>)

    instance Semigroup Library where
      a <> b = Library {
        exposedModules = combine exposedModules,
        reexportedModules = combine reexportedModules,
        requiredSignatures = combine requiredSignatures,
        exposedSignatures = combine exposedSignatures,
        libExposed     = libExposed a && libExposed b, -- so False propagates
        libBuildInfo   = combine libBuildInfo
      }
        where combine field = field a `mappend` field b

    emptyLibrary :: Library
    emptyLibrary = mempty

    -- |does this package have any libraries?
    hasLibs :: PackageDescription -> Bool
    hasLibs p = maybe False (buildable . libBuildInfo) (library p)

    -- |'Maybe' version of 'hasLibs'
    maybeHasLibs :: PackageDescription -> Maybe Library
    maybeHasLibs p =
       library p >>= \lib -> if buildable (libBuildInfo lib)
                               then Just lib
                               else Nothing

    -- |If the package description has a library section, call the given
    --  function with the library build info as argument.
    withLib :: PackageDescription -> (Library -> IO ()) -> IO ()
    withLib pkg_descr f =
       traverse_ f (maybeHasLibs pkg_descr)

    -- | Get all the module names from the library (exposed and internal modules)
    -- which need to be compiled.  (This does not include reexports, which
    -- do not need to be compiled.)
    libModules :: Library -> [ModuleName]
    libModules lib = exposedModules lib
                  ++ otherModules (libBuildInfo lib)
                  ++ exposedSignatures lib
                  ++ requiredSignatures lib

    -- -----------------------------------------------------------------------------
    -- Module re-exports

    data ModuleReexport = ModuleReexport {
           moduleReexportOriginalPackage :: Maybe PackageName,
           moduleReexportOriginalName    :: ModuleName,
           moduleReexportName            :: ModuleName
        }
        deriving (Eq, Generic, Read, Show, Typeable, Data)

    instance Binary ModuleReexport

    instance Text ModuleReexport where
        disp (ModuleReexport mpkgname origname newname) =
              maybe Disp.empty (\pkgname -> disp pkgname <> Disp.char ':') mpkgname
           <> disp origname
          <+> if newname == origname
                then Disp.empty
                else Disp.text "as" <+> disp newname

        parse = do
          mpkgname <- Parse.option Nothing $ do
                        pkgname <- parse
                        _       <- Parse.char ':'
                        return (Just pkgname)
          origname <- parse
          newname  <- Parse.option origname $ do
                        Parse.skipSpaces
                        _ <- Parse.string "as"
                        Parse.skipSpaces
                        parse
          return (ModuleReexport mpkgname origname newname)

    -- ---------------------------------------------------------------------------
    -- The Executable type

    data Executable = Executable {
            exeName    :: String,
            modulePath :: FilePath,
            buildInfo  :: BuildInfo
        }
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary Executable

    instance Monoid Executable where
      mempty = gmempty
      mappend = (Semi.<>)

    instance Semigroup Executable where
      a <> b = Executable{
        exeName    = combine' exeName,
        modulePath = combine modulePath,
        buildInfo  = combine buildInfo
      }
        where combine field = field a `mappend` field b
              combine' field = case (field a, field b) of
                          ("","") -> ""
                          ("", x) -> x
                          (x, "") -> x
                          (x, y) -> error $ "Ambiguous values for executable field: '"
                                      ++ x ++ "' and '" ++ y ++ "'"

    emptyExecutable :: Executable
    emptyExecutable = mempty

    -- |does this package have any executables?
    hasExes :: PackageDescription -> Bool
    hasExes p = any (buildable . buildInfo) (executables p)

    -- | Perform the action on each buildable 'Executable' in the package
    -- description.
    withExe :: PackageDescription -> (Executable -> IO ()) -> IO ()
    withExe pkg_descr f =
      sequence_ [f exe | exe <- executables pkg_descr, buildable (buildInfo exe)]

    -- | Get all the module names from an exe
    exeModules :: Executable -> [ModuleName]
    exeModules exe = otherModules (buildInfo exe)

    -- ---------------------------------------------------------------------------
    -- The TestSuite type

    -- | A \"test-suite\" stanza in a cabal file.
    --
    data TestSuite = TestSuite {
            testName      :: String,
            testInterface :: TestSuiteInterface,
            testBuildInfo :: BuildInfo,
            testEnabled   :: Bool
            -- TODO: By having a 'testEnabled' field in the PackageDescription, we
            -- are mixing build status information (i.e., arguments to 'configure')
            -- with static package description information. This is undesirable, but
            -- a better solution is waiting on the next overhaul to the
            -- GenericPackageDescription -> PackageDescription resolution process.
        }
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary TestSuite

    -- | The test suite interfaces that are currently defined. Each test suite must
    -- specify which interface it supports.
    --
    -- More interfaces may be defined in future, either new revisions or totally
    -- new interfaces.
    --
    data TestSuiteInterface =

         -- | Test interface \"exitcode-stdio-1.0\". The test-suite takes the form
         -- of an executable. It returns a zero exit code for success, non-zero for
         -- failure. The stdout and stderr channels may be logged. It takes no
         -- command line parameters and nothing on stdin.
         --
         TestSuiteExeV10 Version FilePath

         -- | Test interface \"detailed-0.9\". The test-suite takes the form of a
         -- library containing a designated module that exports \"tests :: [Test]\".
         --
       | TestSuiteLibV09 Version ModuleName

         -- | A test suite that does not conform to one of the above interfaces for
         -- the given reason (e.g. unknown test type).
         --
       | TestSuiteUnsupported TestType
       deriving (Eq, Generic, Read, Show, Typeable, Data)

    instance Binary TestSuiteInterface

    instance Monoid TestSuite where
        mempty = TestSuite {
            testName      = mempty,
            testInterface = mempty,
            testBuildInfo = mempty,
            testEnabled   = False
        }
        mappend = (Semi.<>)

    instance Semigroup TestSuite where
        a <> b = TestSuite {
            testName      = combine' testName,
            testInterface = combine  testInterface,
            testBuildInfo = combine  testBuildInfo,
            testEnabled   = testEnabled a || testEnabled b
        }
            where combine   field = field a `mappend` field b
                  combine' f = case (f a, f b) of
                            ("", x) -> x
                            (x, "") -> x
                            (x, y) -> error "Ambiguous values for test field: '"
                                ++ x ++ "' and '" ++ y ++ "'"

    instance Monoid TestSuiteInterface where
        mempty  =  TestSuiteUnsupported (TestTypeUnknown mempty (Version [] []))
        mappend = (Semi.<>)

    instance Semigroup TestSuiteInterface where
        a <> (TestSuiteUnsupported _) = a
        _ <> b                        = b

    emptyTestSuite :: TestSuite
    emptyTestSuite = mempty

    -- | Does this package have any test suites?
    hasTests :: PackageDescription -> Bool
    hasTests = any (buildable . testBuildInfo) . testSuites

    -- | Get all the enabled test suites from a package.
    enabledTests :: PackageDescription -> [TestSuite]
    enabledTests = filter testEnabled . testSuites

    -- | Perform an action on each buildable 'TestSuite' in a package.
    withTest :: PackageDescription -> (TestSuite -> IO ()) -> IO ()
    withTest pkg_descr f =
        mapM_ f $ filter (buildable . testBuildInfo) $ enabledTests pkg_descr

    -- | Get all the module names from a test suite.
    testModules :: TestSuite -> [ModuleName]
    testModules test = (case testInterface test of
                         TestSuiteLibV09 _ m -> [m]
                         _                   -> [])
                    ++ otherModules (testBuildInfo test)

    -- | The \"test-type\" field in the test suite stanza.
    --
    data TestType = TestTypeExe Version     -- ^ \"type: exitcode-stdio-x.y\"
                  | TestTypeLib Version     -- ^ \"type: detailed-x.y\"
                  | TestTypeUnknown String Version -- ^ Some unknown test type e.g. \"type: foo\"
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary TestType

    knownTestTypes :: [TestType]
    knownTestTypes = [ TestTypeExe (Version [1,0] [])
                     , TestTypeLib (Version [0,9] []) ]

    stdParse :: Text ver => (ver -> String -> res) -> Parse.ReadP r res
    stdParse f = do
      cs   <- Parse.sepBy1 component (Parse.char '-')
      _    <- Parse.char '-'
      ver  <- parse
      let name = intercalate "-" cs
      return $! f ver (lowercase name)
      where
        component = do
          cs <- Parse.munch1 Char.isAlphaNum
          if all Char.isDigit cs then Parse.pfail else return cs
          -- each component must contain an alphabetic character, to avoid
          -- ambiguity in identifiers like foo-1 (the 1 is the version number).

    instance Text TestType where
      disp (TestTypeExe ver)          = text "exitcode-stdio-" <> disp ver
      disp (TestTypeLib ver)          = text "detailed-"       <> disp ver
      disp (TestTypeUnknown name ver) = text name <> char '-' <> disp ver

      parse = stdParse $ \ver name -> case name of
        "exitcode-stdio" -> TestTypeExe ver
        "detailed"       -> TestTypeLib ver
        _                -> TestTypeUnknown name ver

    testType :: TestSuite -> TestType
    testType test = case testInterface test of
      TestSuiteExeV10 ver _         -> TestTypeExe ver
      TestSuiteLibV09 ver _         -> TestTypeLib ver
      TestSuiteUnsupported testtype -> testtype

    -- ---------------------------------------------------------------------------
    -- The Benchmark type

    -- | A \"benchmark\" stanza in a cabal file.
    --
    data Benchmark = Benchmark {
            benchmarkName      :: String,
            benchmarkInterface :: BenchmarkInterface,
            benchmarkBuildInfo :: BuildInfo,
            benchmarkEnabled   :: Bool
            -- TODO: See TODO for 'testEnabled'.
        }
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary Benchmark

    -- | The benchmark interfaces that are currently defined. Each
    -- benchmark must specify which interface it supports.
    --
    -- More interfaces may be defined in future, either new revisions or
    -- totally new interfaces.
    --
    data BenchmarkInterface =

         -- | Benchmark interface \"exitcode-stdio-1.0\". The benchmark
         -- takes the form of an executable. It returns a zero exit code
         -- for success, non-zero for failure. The stdout and stderr
         -- channels may be logged. It takes no command line parameters
         -- and nothing on stdin.
         --
         BenchmarkExeV10 Version FilePath

         -- | A benchmark that does not conform to one of the above
         -- interfaces for the given reason (e.g. unknown benchmark type).
         --
       | BenchmarkUnsupported BenchmarkType
       deriving (Eq, Generic, Read, Show, Typeable, Data)

    instance Binary BenchmarkInterface

    instance Monoid Benchmark where
        mempty = Benchmark {
            benchmarkName      = mempty,
            benchmarkInterface = mempty,
            benchmarkBuildInfo = mempty,
            benchmarkEnabled   = False
        }
        mappend = (Semi.<>)

    instance Semigroup Benchmark where
        a <> b = Benchmark {
            benchmarkName      = combine' benchmarkName,
            benchmarkInterface = combine  benchmarkInterface,
            benchmarkBuildInfo = combine  benchmarkBuildInfo,
            benchmarkEnabled   = benchmarkEnabled a || benchmarkEnabled b
        }
            where combine   field = field a `mappend` field b
                  combine' f = case (f a, f b) of
                            ("", x) -> x
                            (x, "") -> x
                            (x, y) -> error "Ambiguous values for benchmark field: '"
                                ++ x ++ "' and '" ++ y ++ "'"

    instance Monoid BenchmarkInterface where
        mempty  =  BenchmarkUnsupported (BenchmarkTypeUnknown mempty (Version [] []))
        mappend = (Semi.<>)

    instance Semigroup BenchmarkInterface where
        a <> (BenchmarkUnsupported _) = a
        _ <> b                        = b

    emptyBenchmark :: Benchmark
    emptyBenchmark = mempty

    -- | Does this package have any benchmarks?
    hasBenchmarks :: PackageDescription -> Bool
    hasBenchmarks = any (buildable . benchmarkBuildInfo) . benchmarks

    -- | Get all the enabled benchmarks from a package.
    enabledBenchmarks :: PackageDescription -> [Benchmark]
    enabledBenchmarks = filter benchmarkEnabled . benchmarks

    -- | Perform an action on each buildable 'Benchmark' in a package.
    withBenchmark :: PackageDescription -> (Benchmark -> IO ()) -> IO ()
    withBenchmark pkg_descr f =
        mapM_ f $ filter (buildable . benchmarkBuildInfo) $ enabledBenchmarks pkg_descr

    -- | Get all the module names from a benchmark.
    benchmarkModules :: Benchmark -> [ModuleName]
    benchmarkModules benchmark = otherModules (benchmarkBuildInfo benchmark)

    -- | The \"benchmark-type\" field in the benchmark stanza.
    --
    data BenchmarkType = BenchmarkTypeExe Version
                         -- ^ \"type: exitcode-stdio-x.y\"
                       | BenchmarkTypeUnknown String Version
                         -- ^ Some unknown benchmark type e.g. \"type: foo\"
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary BenchmarkType

    knownBenchmarkTypes :: [BenchmarkType]
    knownBenchmarkTypes = [ BenchmarkTypeExe (Version [1,0] []) ]

    instance Text BenchmarkType where
      disp (BenchmarkTypeExe ver)          = text "exitcode-stdio-" <> disp ver
      disp (BenchmarkTypeUnknown name ver) = text name <> char '-' <> disp ver

      parse = stdParse $ \ver name -> case name of
        "exitcode-stdio" -> BenchmarkTypeExe ver
        _                -> BenchmarkTypeUnknown name ver

    benchmarkType :: Benchmark -> BenchmarkType
    benchmarkType benchmark = case benchmarkInterface benchmark of
      BenchmarkExeV10 ver _              -> BenchmarkTypeExe ver
      BenchmarkUnsupported benchmarktype -> benchmarktype

    -- ---------------------------------------------------------------------------
    -- The BuildInfo type

    -- Consider refactoring into executable and library versions.
    data BuildInfo = BuildInfo {
            buildable         :: Bool,      -- ^ component is buildable here
            buildTools        :: [Dependency], -- ^ tools needed to build this bit
            cppOptions        :: [String],  -- ^ options for pre-processing Haskell code
            ccOptions         :: [String],  -- ^ options for C compiler
            ldOptions         :: [String],  -- ^ options for linker
            pkgconfigDepends  :: [Dependency], -- ^ pkg-config packages that are used
            frameworks        :: [String], -- ^support frameworks for Mac OS X
            extraFrameworkDirs:: [String], -- ^ extra locations to find frameworks.
            cSources          :: [FilePath],
            jsSources         :: [FilePath],
            hsSourceDirs      :: [FilePath], -- ^ where to look for the Haskell module hierarchy
            otherModules      :: [ModuleName], -- ^ non-exposed or non-main modules

            defaultLanguage   :: Maybe Language,-- ^ language used when not explicitly specified
            otherLanguages    :: [Language],    -- ^ other languages used within the package
            defaultExtensions :: [Extension],   -- ^ language extensions used by all modules
            otherExtensions   :: [Extension],   -- ^ other language extensions used within the package
            oldExtensions     :: [Extension],   -- ^ the old extensions field, treated same as 'defaultExtensions'

            extraLibs         :: [String], -- ^ what libraries to link with when compiling a program that uses your package
            extraGHCiLibs     :: [String], -- ^ if present, overrides extraLibs when package is loaded with GHCi.
            extraLibDirs      :: [String],
            includeDirs       :: [FilePath], -- ^directories to find .h files
            includes          :: [FilePath], -- ^ The .h files to be found in includeDirs
            installIncludes   :: [FilePath], -- ^ .h files to install with the package
            options           :: [(CompilerFlavor,[String])],
            profOptions       :: [(CompilerFlavor,[String])],
            sharedOptions     :: [(CompilerFlavor,[String])],
            customFieldsBI    :: [(String,String)], -- ^Custom fields starting
                                                    -- with x-, stored in a
                                                    -- simple assoc-list.
            targetBuildDepends :: [Dependency], -- ^ Dependencies specific to a library or executable target
            targetBuildRenaming :: Map PackageName ModuleRenaming
        }
        deriving (Generic, Show, Read, Eq, Typeable, Data)

    instance Binary BuildInfo

    instance Monoid BuildInfo where
      mempty = BuildInfo {
        buildable           = True,
        buildTools          = [],
        cppOptions          = [],
        ccOptions           = [],
        ldOptions           = [],
        pkgconfigDepends    = [],
        frameworks          = [],
        extraFrameworkDirs  = [],
        cSources            = [],
        jsSources           = [],
        hsSourceDirs        = [],
        otherModules        = [],
        defaultLanguage     = Nothing,
        otherLanguages      = [],
        defaultExtensions   = [],
        otherExtensions     = [],
        oldExtensions       = [],
        extraLibs           = [],
        extraGHCiLibs       = [],
        extraLibDirs        = [],
        includeDirs         = [],
        includes            = [],
        installIncludes     = [],
        options             = [],
        profOptions         = [],
        sharedOptions       = [],
        customFieldsBI      = [],
        targetBuildDepends  = [],
        targetBuildRenaming = Map.empty
      }
      mappend = (Semi.<>)

    instance Semigroup BuildInfo where
      a <> b = BuildInfo {
        buildable           = buildable a && buildable b,
        buildTools          = combine    buildTools,
        cppOptions          = combine    cppOptions,
        ccOptions           = combine    ccOptions,
        ldOptions           = combine    ldOptions,
        pkgconfigDepends    = combine    pkgconfigDepends,
        frameworks          = combineNub frameworks,
        extraFrameworkDirs  = combineNub extraFrameworkDirs,
        cSources            = combineNub cSources,
        jsSources           = combineNub jsSources,
        hsSourceDirs        = combineNub hsSourceDirs,
        otherModules        = combineNub otherModules,
        defaultLanguage     = combineMby defaultLanguage,
        otherLanguages      = combineNub otherLanguages,
        defaultExtensions   = combineNub defaultExtensions,
        otherExtensions     = combineNub otherExtensions,
        oldExtensions       = combineNub oldExtensions,
        extraLibs           = combine    extraLibs,
        extraGHCiLibs       = combine    extraGHCiLibs,
        extraLibDirs        = combineNub extraLibDirs,
        includeDirs         = combineNub includeDirs,
        includes            = combineNub includes,
        installIncludes     = combineNub installIncludes,
        options             = combine    options,
        profOptions         = combine    profOptions,
        sharedOptions       = combine    sharedOptions,
        customFieldsBI      = combine    customFieldsBI,
        targetBuildDepends  = combineNub targetBuildDepends,
        targetBuildRenaming = combineMap targetBuildRenaming
      }
        where
          combine    field = field a `mappend` field b
          combineNub field = nub (combine field)
          combineMby field = field b `mplus` field a
          combineMap field = Map.unionWith mappend (field a) (field b)

    emptyBuildInfo :: BuildInfo
    emptyBuildInfo = mempty

    -- | The 'BuildInfo' for the library (if there is one and it's buildable), and
    -- all buildable executables, test suites and benchmarks.  Useful for gathering
    -- dependencies.
    allBuildInfo :: PackageDescription -> [BuildInfo]
    allBuildInfo pkg_descr = [ bi | Just lib <- [library pkg_descr]
                                  , let bi = libBuildInfo lib
                                  , buildable bi ]
                          ++ [ bi | exe <- executables pkg_descr
                                  , let bi = buildInfo exe
                                  , buildable bi ]
                          ++ [ bi | tst <- testSuites pkg_descr
                                  , let bi = testBuildInfo tst
                                  , buildable bi
                                  , testEnabled tst ]
                          ++ [ bi | tst <- benchmarks pkg_descr
                                  , let bi = benchmarkBuildInfo tst
                                  , buildable bi
                                  , benchmarkEnabled tst ]
      --FIXME: many of the places where this is used, we actually want to look at
      --       unbuildable bits too, probably need separate functions

    -- | The 'Language's used by this component
    --
    allLanguages :: BuildInfo -> [Language]
    allLanguages bi = maybeToList (defaultLanguage bi)
                   ++ otherLanguages bi

    -- | The 'Extension's that are used somewhere by this component
    --
    allExtensions :: BuildInfo -> [Extension]
    allExtensions bi = usedExtensions bi
                    ++ otherExtensions bi

    -- | The 'Extensions' that are used by all modules in this component
    --
    usedExtensions :: BuildInfo -> [Extension]
    usedExtensions bi = oldExtensions bi
                     ++ defaultExtensions bi

    type HookedBuildInfo = (Maybe BuildInfo, [(String, BuildInfo)])

    emptyHookedBuildInfo :: HookedBuildInfo
    emptyHookedBuildInfo = (Nothing, [])

    -- |Select options for a particular Haskell compiler.
    hcOptions :: CompilerFlavor -> BuildInfo -> [String]
    hcOptions = lookupHcOptions options

    hcProfOptions :: CompilerFlavor -> BuildInfo -> [String]
    hcProfOptions = lookupHcOptions profOptions

    hcSharedOptions :: CompilerFlavor -> BuildInfo -> [String]
    hcSharedOptions = lookupHcOptions sharedOptions

    lookupHcOptions :: (BuildInfo -> [(CompilerFlavor,[String])])
                    -> CompilerFlavor -> BuildInfo -> [String]
    lookupHcOptions f hc bi = [ opt | (hc',opts) <- f bi
                              , hc' == hc
                              , opt <- opts ]

    -- ------------------------------------------------------------
    -- * Source repos
    -- ------------------------------------------------------------

    -- | Information about the source revision control system for a package.
    --
    -- When specifying a repo it is useful to know the meaning or intention of the
    -- information as doing so enables automation. There are two obvious common
    -- purposes: one is to find the repo for the latest development version, the
    -- other is to find the repo for this specific release. The 'ReopKind'
    -- specifies which one we mean (or another custom one).
    --
    -- A package can specify one or the other kind or both. Most will specify just
    -- a head repo but some may want to specify a repo to reconstruct the sources
    -- for this package release.
    --
    -- The required information is the 'RepoType' which tells us if it's using
    -- 'Darcs', 'Git' for example. The 'repoLocation' and other details are
    -- interpreted according to the repo type.
    --
    data SourceRepo = SourceRepo {
      -- | The kind of repo. This field is required.
      repoKind     :: RepoKind,

      -- | The type of the source repository system for this repo, eg 'Darcs' or
      -- 'Git'. This field is required.
      repoType     :: Maybe RepoType,

      -- | The location of the repository. For most 'RepoType's this is a URL.
      -- This field is required.
      repoLocation :: Maybe String,

      -- | 'CVS' can put multiple \"modules\" on one server and requires a
      -- module name in addition to the location to identify a particular repo.
      -- Logically this is part of the location but unfortunately has to be
      -- specified separately. This field is required for the 'CVS' 'RepoType' and
      -- should not be given otherwise.
      repoModule   :: Maybe String,

      -- | The name or identifier of the branch, if any. Many source control
      -- systems have the notion of multiple branches in a repo that exist in the
      -- same location. For example 'Git' and 'CVS' use this while systems like
      -- 'Darcs' use different locations for different branches. This field is
      -- optional but should be used if necessary to identify the sources,
      -- especially for the 'RepoThis' repo kind.
      repoBranch   :: Maybe String,

      -- | The tag identify a particular state of the repository. This should be
      -- given for the 'RepoThis' repo kind and not for 'RepoHead' kind.
      --
      repoTag      :: Maybe String,

      -- | Some repositories contain multiple projects in different subdirectories
      -- This field specifies the subdirectory where this packages sources can be
      -- found, eg the subdirectory containing the @.cabal@ file. It is interpreted
      -- relative to the root of the repository. This field is optional. If not
      -- given the default is \".\" ie no subdirectory.
      repoSubdir   :: Maybe FilePath
    }
      deriving (Eq, Generic, Read, Show, Typeable, Data)

    instance Binary SourceRepo

    -- | What this repo info is for, what it represents.
    --
    data RepoKind =
        -- | The repository for the \"head\" or development version of the project.
        -- This repo is where we should track the latest development activity or
        -- the usual repo people should get to contribute patches.
        RepoHead

        -- | The repository containing the sources for this exact package version
        -- or release. For this kind of repo a tag should be given to give enough
        -- information to re-create the exact sources.
      | RepoThis

      | RepoKindUnknown String
      deriving (Eq, Generic, Ord, Read, Show, Typeable, Data)

    instance Binary RepoKind

    -- | An enumeration of common source control systems. The fields used in the
    -- 'SourceRepo' depend on the type of repo. The tools and methods used to
    -- obtain and track the repo depend on the repo type.
    --
    data RepoType = Darcs | Git | SVN | CVS
                  | Mercurial | GnuArch | Bazaar | Monotone
                  | OtherRepoType String
      deriving (Eq, Generic, Ord, Read, Show, Typeable, Data)

    instance Binary RepoType

    knownRepoTypes :: [RepoType]
    knownRepoTypes = [Darcs, Git, SVN, CVS
                     ,Mercurial, GnuArch, Bazaar, Monotone]

    repoTypeAliases :: RepoType -> [String]
    repoTypeAliases Bazaar    = ["bzr"]
    repoTypeAliases Mercurial = ["hg"]
    repoTypeAliases GnuArch   = ["arch"]
    repoTypeAliases _         = []

    instance Text RepoKind where
      disp RepoHead                = Disp.text "head"
      disp RepoThis                = Disp.text "this"
      disp (RepoKindUnknown other) = Disp.text other

      parse = do
        name <- ident
        return $ case lowercase name of
          "head" -> RepoHead
          "this" -> RepoThis
          _      -> RepoKindUnknown name

    instance Text RepoType where
      disp (OtherRepoType other) = Disp.text other
      disp other                 = Disp.text (lowercase (show other))
      parse = fmap classifyRepoType ident

    classifyRepoType :: String -> RepoType
    classifyRepoType s =
      fromMaybe (OtherRepoType s) $ lookup (lowercase s) repoTypeMap
      where
        repoTypeMap = [ (name, repoType')
                      | repoType' <- knownRepoTypes
                      , name <- display repoType' : repoTypeAliases repoType' ]

    ident :: Parse.ReadP r String
    ident = Parse.munch1 (\c -> Char.isAlphaNum c || c == '_' || c == '-')

    lowercase :: String -> String
    lowercase = map Char.toLower

    -- ------------------------------------------------------------
    -- * Utils
    -- ------------------------------------------------------------

    updatePackageDescription :: HookedBuildInfo -> PackageDescription -> PackageDescription
    updatePackageDescription (mb_lib_bi, exe_bi) p
        = p{ executables = updateExecutables exe_bi    (executables p)
           , library     = updateLibrary     mb_lib_bi (library     p)
           }
        where
          updateLibrary :: Maybe BuildInfo -> Maybe Library -> Maybe Library
          updateLibrary (Just bi) (Just lib) = Just (lib{libBuildInfo = bi `mappend` libBuildInfo lib})
          updateLibrary Nothing   mb_lib     = mb_lib
          updateLibrary (Just _)  Nothing    = Nothing

          updateExecutables :: [(String, BuildInfo)] -- ^[(exeName, new buildinfo)]
                            -> [Executable]          -- ^list of executables to update
                            -> [Executable]          -- ^list with exeNames updated
          updateExecutables exe_bi' executables' = foldr updateExecutable executables' exe_bi'

          updateExecutable :: (String, BuildInfo) -- ^(exeName, new buildinfo)
                           -> [Executable]        -- ^list of executables to update
                           -> [Executable]        -- ^list with exeName updated
          updateExecutable _                 []         = []
          updateExecutable exe_bi'@(name,bi) (exe:exes)
            | exeName exe == name = exe{buildInfo = bi `mappend` buildInfo exe} : exes
            | otherwise           = exe : updateExecutable exe_bi' exes

    -- ---------------------------------------------------------------------------
    -- The GenericPackageDescription type

    data GenericPackageDescription =
        GenericPackageDescription {
            packageDescription :: PackageDescription,
            genPackageFlags       :: [Flag],
            condLibrary        :: Maybe (CondTree ConfVar [Dependency] Library),
            condExecutables    :: [(String, CondTree ConfVar [Dependency] Executable)],
            condTestSuites     :: [(String, CondTree ConfVar [Dependency] TestSuite)],
            condBenchmarks     :: [(String, CondTree ConfVar [Dependency] Benchmark)]
          }
        deriving (Show, Eq, Typeable, Data, Generic)

    instance Package GenericPackageDescription where
      packageId = packageId . packageDescription

    instance Binary GenericPackageDescription

    -- | A flag can represent a feature to be included, or a way of linking
    --   a target against its dependencies, or in fact whatever you can think of.
    data Flag = MkFlag
        { flagName        :: FlagName
        , flagDescription :: String
        , flagDefault     :: Bool
        , flagManual      :: Bool
        }
        deriving (Show, Eq, Typeable, Data, Generic)

    instance Binary Flag

    -- | A 'FlagName' is the name of a user-defined configuration flag
    newtype FlagName = FlagName String
        deriving (Eq, Generic, Ord, Show, Read, Typeable, Data)

    instance Binary FlagName

    -- | A 'FlagAssignment' is a total or partial mapping of 'FlagName's to
    -- 'Bool' flag values. It represents the flags chosen by the user or
    -- discovered during configuration. For example @--flags=foo --flags=-bar@
    -- becomes @[("foo", True), ("bar", False)]@
    --
    type FlagAssignment = [(FlagName, Bool)]

    -- | A @ConfVar@ represents the variable type used.
    data ConfVar = OS OS
                 | Arch Arch
                 | Flag FlagName
                 | Impl CompilerFlavor VersionRange
        deriving (Eq, Show, Typeable, Data, Generic)

    instance Binary ConfVar

    -- | A boolean expression parameterized over the variable type used.
    data Condition c = Var c
                     | Lit Bool
                     | CNot (Condition c)
                     | COr (Condition c) (Condition c)
                     | CAnd (Condition c) (Condition c)
        deriving (Show, Eq, Typeable, Data, Generic)

    -- | Boolean negation of a 'Condition' value.
    cNot :: Condition a -> Condition a
    cNot (Lit b)  = Lit (not b)
    cNot (CNot c) = c
    cNot c        = CNot c

    -- | Boolean AND of two 'Condtion' values.
    cAnd :: Condition a -> Condition a -> Condition a
    cAnd (Lit False) _           = Lit False
    cAnd _           (Lit False) = Lit False
    cAnd (Lit True)  x           = x
    cAnd x           (Lit True)  = x
    cAnd x           y           = CAnd x y

    -- | Boolean OR of two 'Condition' values.
    cOr :: Eq v => Condition v -> Condition v -> Condition v
    cOr  (Lit True)  _           = Lit True
    cOr  _           (Lit True)  = Lit True
    cOr  (Lit False) x           = x
    cOr  x           (Lit False) = x
    cOr  c           (CNot d)
      | c == d                   = Lit True
    cOr  (CNot c)    d
      | c == d                   = Lit True
    cOr  x           y           = COr x y

    instance Functor Condition where
      f `fmap` Var c    = Var (f c)
      _ `fmap` Lit c    = Lit c
      f `fmap` CNot c   = CNot (fmap f c)
      f `fmap` COr c d  = COr  (fmap f c) (fmap f d)
      f `fmap` CAnd c d = CAnd (fmap f c) (fmap f d)

    instance Foldable Condition where
      f `foldMap` Var c    = f c
      _ `foldMap` Lit _    = mempty
      f `foldMap` CNot c   = Fold.foldMap f c
      f `foldMap` COr c d  = foldMap f c `mappend` foldMap f d
      f `foldMap` CAnd c d = foldMap f c `mappend` foldMap f d

    instance Traversable Condition where
      f `traverse` Var c    = Var `fmap` f c
      _ `traverse` Lit c    = pure $ Lit c
      f `traverse` CNot c   = CNot `fmap` Trav.traverse f c
      f `traverse` COr c d  = COr  `fmap` traverse f c <*> traverse f d
      f `traverse` CAnd c d = CAnd `fmap` traverse f c <*> traverse f d

    instance Applicative Condition where
      pure  = Var
      (<*>) = ap

    instance Monad Condition where
      return = AP.pure
      -- Terminating cases
      (>>=) (Lit x) _ = Lit x
      (>>=) (Var x) f = f x
      -- Recursing cases
      (>>=) (CNot  x  ) f = CNot (x >>= f)
      (>>=) (COr   x y) f = COr  (x >>= f) (y >>= f)
      (>>=) (CAnd  x y) f = CAnd (x >>= f) (y >>= f)

    instance Monoid (Condition a) where
      mempty = Lit False
      mappend = (Semi.<>)

    instance Semigroup (Condition a) where
      (<>) = COr

    instance Alternative Condition where
      empty = mempty
      (<|>) = mappend

    instance MonadPlus Condition where
      mzero = mempty
      mplus = mappend

    instance Binary c => Binary (Condition c)

    data CondTree v c a = CondNode
        { condTreeData        :: a
        , condTreeConstraints :: c
        , condTreeComponents  :: [( Condition v
                                  , CondTree v c a
                                  , Maybe (CondTree v c a))]
        }
        deriving (Show, Eq, Typeable, Data, Generic)

    instance (Binary v, Binary c, Binary a) => Binary (CondTree v c a)