{-# LANGUAGE OverloadedStrings #-}

module CabalApi (
    fromCabalFile
  , cabalParseFile
  , cabalBuildInfo
  , cabalAllDependPackages
  , cabalAllExtentions
  , getGHCVersion
  ) where

import Control.Applicative
import Control.Exception (throwIO)
import Data.List (intercalate)
import Data.Maybe (fromJust, maybeToList, mapMaybe)
import Data.Set (fromList, toList)
import Distribution.Package (Dependency(Dependency), PackageName(PackageName))
import Distribution.PackageDescription
import Distribution.PackageDescription.Parse (readPackageDescription)
import Distribution.Simple.Program (ghcProgram)
import Distribution.Simple.Program.Types (programName, programFindVersion)
import Distribution.Text (display)
import Distribution.Verbosity (silent)
import Distribution.Version (versionBranch)
import Language.Haskell.Extension (Extension(..))
import System.FilePath
import Types

----------------------------------------------------------------

fromCabalFile :: [GHCOption]
              -> Cradle
              -> IO ([GHCOption],[IncludeDir],[Package],[LangExt])
fromCabalFile ghcOptions cradle =
    cookInfo ghcOptions cradle <$> cabalParseFile cfile
  where
    Just cfile = cradleCabalFile  cradle

cookInfo :: [String] -> Cradle -> GenericPackageDescription
            -> ([GHCOption],[IncludeDir],[Package],[LangExt])
cookInfo ghcOptions cradle cabal = (gopts,idirs,depPkgs,hdrExts)
  where
    owdir      = cradleCurrentDir cradle
    Just cdir  = cradleCabalDir   cradle
    Just cfile = cradleCabalFile  cradle
    binfo      = cabalBuildInfo cabal
    gopts      = getGHCOptions ghcOptions binfo
    idirs      = includeDirectroies cdir owdir $ hsSourceDirs binfo
    depPkgs    = removeMe cfile $ cabalAllDependPackages cabal
    hdrExts    = cabalAllExtentions cabal

removeMe :: FilePath -> [String] -> [String]
removeMe cabalfile = filter (/= me)
  where
    me = dropExtension $ takeFileName cabalfile

----------------------------------------------------------------

cabalParseFile :: FilePath -> IO GenericPackageDescription
cabalParseFile = readPackageDescription silent

----------------------------------------------------------------

getGHCOptions :: [String] -> BuildInfo -> [String]
getGHCOptions ghcOptions binfo = ghcOptions ++ exts ++ [lang] ++ libs ++ libDirs
  where
    exts = map (("-X" ++) . display) $ usedExtensions binfo
    lang = maybe "-XHaskell98" (("-X" ++) . display) $ defaultLanguage binfo
    libs = map ("-l" ++) $ extraLibs binfo
    libDirs = map ("-L" ++) $ extraLibDirs binfo

----------------------------------------------------------------

-- Causes error, catched in the upper function.
cabalBuildInfo :: GenericPackageDescription -> BuildInfo
cabalBuildInfo pd = fromJust $ fromLibrary pd <|> fromExecutable pd
  where
    fromLibrary c     = libBuildInfo . condTreeData <$> condLibrary c
    fromExecutable c  = buildInfo . condTreeData . snd <$> toMaybe (condExecutables c)
    toMaybe []    = Nothing
    toMaybe (x:_) = Just x

----------------------------------------------------------------

cabalAllDependPackages :: GenericPackageDescription -> [Package]
cabalAllDependPackages pd = uniqueAndSort pkgs
  where
    pkgs = map getDependencyPackageName $ cabalAllDependency pd

cabalAllDependency :: GenericPackageDescription -> [Dependency]
cabalAllDependency = fromPackageDescription getDeps getDeps getDeps getDeps
  where
    getDeps :: [Tree a] -> [Dependency]
    getDeps = concatMap condTreeConstraints

getDependencyPackageName :: Dependency -> Package
getDependencyPackageName (Dependency (PackageName nm) _) = nm

----------------------------------------------------------------

cabalAllExtentions :: GenericPackageDescription -> [LangExt]
cabalAllExtentions pd = uniqueAndSort exts
  where
    buildInfos = cabalAllBuildInfos pd
    eexts = concatMap oldExtensions buildInfos
         ++ concatMap defaultExtensions buildInfos
    exts  = mapMaybe getExtensionName eexts

getExtensionName :: Extension -> Maybe LangExt
getExtensionName (EnableExtension nm) = Just (display nm)
getExtensionName _                    = Nothing

----------------------------------------------------------------

cabalAllBuildInfos :: GenericPackageDescription -> [BuildInfo]
cabalAllBuildInfos = fromPackageDescription f1 f2 f3 f4
  where
    f1 = map (libBuildInfo       . condTreeData)
    f2 = map (buildInfo          . condTreeData)
    f3 = map (testBuildInfo      . condTreeData)
    f4 = map (benchmarkBuildInfo . condTreeData)

----------------------------------------------------------------

type Tree = CondTree ConfVar [Dependency]

fromPackageDescription :: ([Tree Library]    -> [a])
                       -> ([Tree Executable] -> [a])
                       -> ([Tree TestSuite]  -> [a])
                       -> ([Tree Benchmark]  -> [a])
                       -> GenericPackageDescription
                       -> [a]
fromPackageDescription f1 f2 f3 f4 pd = lib ++ exe ++ tests ++ bench
  where
    lib   = f1 . maybeToList . condLibrary $ pd
    exe   = f2 . map snd . condExecutables $ pd
    tests = f3 . map snd . condTestSuites  $ pd
    bench = f4 . map snd . condBenchmarks  $ pd

----------------------------------------------------------------

includeDirectroies :: String -> String -> [FilePath] -> [String]
includeDirectroies cdir owdir []   = uniqueAndSort [cdir,owdir]
includeDirectroies cdir owdir dirs = uniqueAndSort (map (cdir </>) dirs ++ [owdir])

----------------------------------------------------------------

uniqueAndSort :: [String] -> [String]
uniqueAndSort = toList . fromList

----------------------------------------------------------------

getGHCVersion :: IO (String, Int)
getGHCVersion = ghcVer >>= toTupple
  where
    ghcVer = programFindVersion ghcProgram silent (programName ghcProgram)
    toTupple Nothing  = throwIO $ userError "ghc not found"
    toTupple (Just v)
      | length vs < 2 = return (verstr, 0)
      | otherwise     = return (verstr, ver)
      where
        vs = versionBranch v
        ver = (vs !! 0) * 100 + (vs !! 1)
        verstr = intercalate "." . map show $ vs