content: {-# LANGUAGE DeriveDataTypeable #-}
  {-# LANGUAGE DeriveGeneric #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.System
  -- Copyright   :  Duncan Coutts 2007-2008
  --
  -- Maintainer  :  cabal-devel@haskell.org
  -- Portability :  portable
  --
  -- Cabal often needs to do slightly different things on specific platforms. You
  -- probably know about the 'System.Info.os' however using that is very
  -- inconvenient because it is a string and different Haskell implementations
  -- do not agree on using the same strings for the same platforms! (In
  -- particular see the controversy over \"windows\" vs \"ming32\"). So to make it
  -- more consistent and easy to use we have an 'OS' enumeration.
  --
  module Distribution.System (
    -- * Operating System
    OS(..),
    buildOS,
  
    -- * Machine Architecture
    Arch(..),
    buildArch,
  
    -- * Platform is a pair of arch and OS
    Platform(..),
    buildPlatform,
    platformFromTriple
    ) where
  
  import qualified System.Info (os, arch)
  import qualified Data.Char as Char (toLower, isAlphaNum)
  
  import Data.Binary (Binary)
  import Data.Data (Data)
  import Data.Typeable (Typeable)
  import Data.Maybe (fromMaybe, listToMaybe)
  import Distribution.Text (Text(..), display)
  import qualified Distribution.Compat.ReadP as Parse
  import GHC.Generics (Generic)
  import qualified Text.PrettyPrint as Disp
  import Text.PrettyPrint ((<>))
  
  -- | How strict to be when classifying strings into the 'OS' and 'Arch' enums.
  --
  -- The reason we have multiple ways to do the classification is because there
  -- are two situations where we need to do it.
  --
  -- For parsing OS and arch names in .cabal files we really want everyone to be
  -- referring to the same or or arch by the same name. Variety is not a virtue
  -- in this case. We don't mind about case though.
  --
  -- For the System.Info.os\/arch different Haskell implementations use different
  -- names for the same or\/arch. Also they tend to distinguish versions of an
  -- OS\/arch which we just don't care about.
  --
  -- The 'Compat' classification allows us to recognise aliases that are already
  -- in common use but it allows us to distinguish them from the canonical name
  -- which enables us to warn about such deprecated aliases.
  --
  data ClassificationStrictness = Permissive | Compat | Strict
  
  -- ------------------------------------------------------------
  -- * Operating System
  -- ------------------------------------------------------------
  
  data OS = Linux | Windows | OSX        -- tier 1 desktop OSs
          | FreeBSD | OpenBSD | NetBSD   -- other free Unix OSs
          | DragonFly
          | Solaris | AIX | HPUX | IRIX  -- ageing Unix OSs
          | HaLVM                        -- bare metal / VMs / hypervisors
          | IOS                          -- iOS
          | Ghcjs
          | OtherOS String
    deriving (Eq, Generic, Ord, Show, Read, Typeable, Data)
  
  instance Binary OS
  
  --TODO: decide how to handle Android and iOS.
  -- They are like Linux and OSX but with some differences.
  -- Should they be separate from Linux/OS X, or a subtype?
  -- e.g. should we have os(linux) && os(android) true simultaneously?
  
  knownOSs :: [OS]
  knownOSs = [Linux, Windows, OSX
             ,FreeBSD, OpenBSD, NetBSD, DragonFly
             ,Solaris, AIX, HPUX, IRIX
             ,HaLVM
             ,IOS
             ,Ghcjs]
  
  osAliases :: ClassificationStrictness -> OS -> [String]
  osAliases Permissive Windows = ["mingw32", "win32", "cygwin32"]
  osAliases Compat     Windows = ["mingw32", "win32"]
  osAliases _          OSX     = ["darwin"]
  osAliases Permissive FreeBSD = ["kfreebsdgnu"]
  osAliases Compat     FreeBSD = ["kfreebsdgnu"]
  osAliases Permissive Solaris = ["solaris2"]
  osAliases Compat     Solaris = ["solaris2"]
  osAliases _          _       = []
  
  instance Text OS where
    disp (OtherOS name) = Disp.text name
    disp other          = Disp.text (lowercase (show other))
  
    parse = fmap (classifyOS Compat) ident
  
  classifyOS :: ClassificationStrictness -> String -> OS
  classifyOS strictness s =
    fromMaybe (OtherOS s) $ lookup (lowercase s) osMap
    where
      osMap = [ (name, os)
              | os <- knownOSs
              , name <- display os : osAliases strictness os ]
  
  buildOS :: OS
  buildOS = classifyOS Permissive System.Info.os
  
  -- ------------------------------------------------------------
  -- * Machine Architecture
  -- ------------------------------------------------------------
  
  data Arch = I386  | X86_64 | PPC | PPC64 | Sparc
            | Arm   | Mips   | SH
            | IA64  | S390
            | Alpha | Hppa   | Rs6000
            | M68k  | Vax
            | JavaScript
            | OtherArch String
    deriving (Eq, Generic, Ord, Show, Read, Typeable, Data)
  
  instance Binary Arch
  
  knownArches :: [Arch]
  knownArches = [I386, X86_64, PPC, PPC64, Sparc
                ,Arm, Mips, SH
                ,IA64, S390
                ,Alpha, Hppa, Rs6000
                ,M68k, Vax
                ,JavaScript]
  
  archAliases :: ClassificationStrictness -> Arch -> [String]
  archAliases Strict _     = []
  archAliases Compat _     = []
  archAliases _      PPC   = ["powerpc"]
  archAliases _      PPC64 = ["powerpc64"]
  archAliases _      Sparc = ["sparc64", "sun4"]
  archAliases _      Mips  = ["mipsel", "mipseb"]
  archAliases _      Arm   = ["armeb", "armel"]
  archAliases _      _     = []
  
  instance Text Arch where
    disp (OtherArch name) = Disp.text name
    disp other            = Disp.text (lowercase (show other))
  
    parse = fmap (classifyArch Strict) ident
  
  classifyArch :: ClassificationStrictness -> String -> Arch
  classifyArch strictness s =
    fromMaybe (OtherArch s) $ lookup (lowercase s) archMap
    where
      archMap = [ (name, arch)
                | arch <- knownArches
                , name <- display arch : archAliases strictness arch ]
  
  buildArch :: Arch
  buildArch = classifyArch Permissive System.Info.arch
  
  -- ------------------------------------------------------------
  -- * Platform
  -- ------------------------------------------------------------
  
  data Platform = Platform Arch OS
    deriving (Eq, Generic, Ord, Show, Read, Typeable, Data)
  
  instance Binary Platform
  
  instance Text Platform where
    disp (Platform arch os) = disp arch <> Disp.char '-' <> disp os
    parse = do
      arch <- parse
      _ <- Parse.char '-'
      os   <- parse
      return (Platform arch os)
  
  -- | The platform Cabal was compiled on. In most cases,
  -- @LocalBuildInfo.hostPlatform@ should be used instead (the platform we're
  -- targeting).
  buildPlatform :: Platform
  buildPlatform = Platform buildArch buildOS
  
  -- Utils:
  
  ident :: Parse.ReadP r String
  ident = Parse.munch1 (\c -> Char.isAlphaNum c || c == '_' || c == '-')
    --TODO: probably should disallow starting with a number
  
  lowercase :: String -> String
  lowercase = map Char.toLower
  
  platformFromTriple :: String -> Maybe Platform
  platformFromTriple triple =
    fmap fst (listToMaybe $ Parse.readP_to_S parseTriple triple)
    where parseWord = Parse.munch1 (\c -> Char.isAlphaNum c || c == '_')
          parseTriple = do
            arch <- fmap (classifyArch Strict) parseWord
            _ <- Parse.char '-'
            _ <- parseWord -- Skip vendor
            _ <- Parse.char '-'
            os <- fmap (classifyOS Compat) ident -- OS may have hyphens, like
                                                 -- 'nto-qnx'
            return $ Platform arch os
  