-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Simple.Build.Macros
-- Copyright   :  Simon Marlow 2008
--
-- Maintainer  :  cabal-devel@haskell.org
-- Portability :  portable
--
-- Generate cabal_macros.h - CPP macros for package version testing
--
-- When using CPP you get
--
-- > VERSION_<package>
-- > MIN_VERSION_<package>(A,B,C)
--
-- for each /package/ in @build-depends@, which is true if the version of
-- /package/ in use is @>= A.B.C@, using the normal ordering on version
-- numbers.
--
-- TODO Figure out what to do about backpack and internal libraries. It is very
-- suspecious that this stuff works with munged package identifiers
module Distribution.Simple.Build.Macros (
    generateCabalMacrosHeader,
    generatePackageVersionMacros,
  ) where

import Prelude ()
import Distribution.Compat.Prelude

import Distribution.Version
import Distribution.PackageDescription
import Distribution.Simple.LocalBuildInfo
import Distribution.Simple.Program.Db
import Distribution.Simple.Program.Types
import Distribution.Types.MungedPackageId
import Distribution.Types.MungedPackageName
import Distribution.Pretty

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

-- | The contents of the @cabal_macros.h@ for the given configured package.
--
generateCabalMacrosHeader :: PackageDescription -> LocalBuildInfo -> ComponentLocalBuildInfo -> String
generateCabalMacrosHeader pkg_descr lbi clbi = Z.render Z.Z
    { Z.zPackages        = map mkZPackage $ package pkg_descr : map getPid (componentPackageDeps clbi)
    , Z.zTools           =
        [ Z.ZTool
            { Z.ztoolName    = programId prog
            , Z.ztoolVersion = ver
            , Z.ztoolX       = major1
            , Z.ztoolY       = major2
            , Z.ztoolZ       = minor
            }
        | prog <- configuredPrograms $ withPrograms lbi
        , ver <- maybeToList (programVersion prog)
        , let (major1,major2,minor) = majorMinor ver
        ]
    , Z.zPackageKey      = case clbi of
        LibComponentLocalBuildInfo{} -> componentCompatPackageKey clbi
        _                            -> ""
    , Z.zComponentId     = prettyShow (componentComponentId clbi)
    , Z.zPackageVersion  = pkgVersion (package pkg_descr)
    , Z.zNotNull         = not . null
    , Z.zManglePkgName   = map fixchar . unPackageName
    , Z.zMangleStr       = map fixchar
    }
  where
    getPid (_, MungedPackageId (MungedPackageName pn _) v) =
       -- NB: Drop the library name! We're just reporting package versions.
       -- This would have to be revisited if you are allowed to depend
       -- on different versions of the same package
        PackageIdentifier pn v

-- | Helper function that generates just the @VERSION_pkg@ and @MIN_VERSION_pkg@
-- macros for a list of package ids (usually used with the specific deps of
-- a configured package).
--
generatePackageVersionMacros :: Version -> [PackageId] -> String
generatePackageVersionMacros ver pkgids = Z.render Z.Z
    { Z.zPackages        = map mkZPackage pkgids
    , Z.zTools           = []
    , Z.zPackageKey      = ""
    , Z.zComponentId     = ""
    , Z.zPackageVersion  = ver
    , Z.zNotNull         = not . null
    , Z.zManglePkgName   = map fixchar . unPackageName
    , Z.zMangleStr       = map fixchar
    }

mkZPackage :: PackageId -> Z.ZPackage
mkZPackage (PackageIdentifier name ver) = Z.ZPackage
    { Z.zpkgName    = name
    , Z.zpkgVersion = ver
    , Z.zpkgX       = major1
    , Z.zpkgY       = major2
    , Z.zpkgZ       = minor
    }
  where
    (major1,major2,minor) = majorMinor ver

majorMinor :: Version -> (String, String, String)
majorMinor ver = case map show (versionNumbers ver) of
        []        -> ("0", "0", "0")
        [x]       -> (x,   "0", "0")
        [x,y]     -> (x,   y,   "0")
        (x:y:z:_) -> (x,   y,   z)

fixchar :: Char -> Char
fixchar '-' = '_'
fixchar c   = c
