{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}

module Hhp.CabalApi (
    getCompilerOptions
  , parseCabalFile
  , cabalAllBuildInfo
  , cabalDependPackages
  , cabalSourceDirs
  , cabalAllTargets
  ) where

import Distribution.Compiler (unknownCompilerInfo, AbiTag(NoAbiTag))
import Distribution.ModuleName (ModuleName,toFilePath)
import Distribution.Package (Dependency(Dependency))
import qualified Distribution.Package as C
import Distribution.PackageDescription (PackageDescription, BuildInfo, TestSuite, TestSuiteInterface(..), Executable)
import qualified Distribution.PackageDescription as P
import Distribution.Simple.Compiler (CompilerId(..), CompilerFlavor(..))
import Distribution.Simple.Program (ghcProgram)
import Distribution.Simple.Program.Types (programName, programFindVersion)
import Distribution.System (buildPlatform)
import Distribution.Text (display)
import Distribution.Verbosity (silent)
import Distribution.Version (Version)
import Distribution.PackageDescription.Configuration (finalizePD)
import Distribution.PackageDescription.Parsec (readGenericPackageDescription)
import Distribution.Types.ComponentRequestedSpec (defaultComponentRequestedSpec)
import Distribution.Types.Flag (mkFlagAssignment, mkFlagName)
import Distribution.Types.PackageName (unPackageName)
#if MIN_VERSION_Cabal(3,6,0)
import Distribution.Utils.Path (getSymbolicPath, SymbolicPath)
#endif

import GHC.Utils.Monad (liftIO)

import Control.Exception (throwIO)
import Control.Monad (filterM)
import Data.Maybe (maybeToList, mapMaybe)
import Data.Set (fromList, toList)
import System.Directory (doesFileExist)
import System.Environment (lookupEnv)
import System.FilePath (dropExtension, takeFileName, (</>))

import Hhp.Types
import Hhp.GhcPkg

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

-- | Getting necessary 'CompilerOptions' from three information sources.
getCompilerOptions :: [GHCOption]
                   -> Cradle
                   -> PackageDescription
                   -> IO CompilerOptions
getCompilerOptions ghcopts cradle pkgDesc = do
    gopts <- getGHCOptions ghcopts cradle rdir $ head buildInfos
    dbPkgs <- ghcPkgListEx (cradlePkgDbStack cradle)
    return $ CompilerOptions gopts idirs (depPkgs dbPkgs)
  where
    wdir       = cradleCurrentDir cradle
    rdir       = cradleRootDir    cradle
    Just cfile = cradleCabalFile  cradle
    thisPkg    = dropExtension $ takeFileName cfile
    buildInfos = cabalAllBuildInfo pkgDesc
    idirs      = includeDirectories rdir wdir $ cabalSourceDirs buildInfos
    depPkgs ps = attachPackageIds ps
                   $ removeThem (problematicPackages ++ [thisPkg])
                   $ cabalDependPackages buildInfos

----------------------------------------------------------------
-- Dependent packages

removeThem :: [PackageBaseName] -> [PackageBaseName] -> [PackageBaseName]
removeThem badpkgs = filter (`notElem` badpkgs)

problematicPackages :: [PackageBaseName]
problematicPackages = [
    "base-compat" -- providing "Prelude"
  ]

attachPackageIds :: [Package] -> [PackageBaseName] -> [Package]
attachPackageIds pkgs = mapMaybe (`lookup3` pkgs)

lookup3 :: Eq a => a -> [(a,b,c)] -> Maybe (a,b,c)
lookup3 _ [] = Nothing
lookup3 k (t@(a,_,_):ls)
    | k == a = Just t
    | otherwise = lookup3 k ls

----------------------------------------------------------------
-- Include directories for modules

cabalBuildDirs :: [FilePath]
cabalBuildDirs = ["dist/build", "dist/build/autogen"]

includeDirectories :: FilePath -> FilePath -> [FilePath] -> [FilePath]
includeDirectories cdir wdir dirs = uniqueAndSort (extdirs ++ [cdir,wdir])
  where
    extdirs = map expand $ dirs ++ cabalBuildDirs
    expand "."    = cdir
    expand subdir = cdir </> subdir

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

-- | Parsing a cabal file and returns 'PackageDescription'.
--   'IOException' is thrown if parsing fails.
parseCabalFile :: FilePath -> IO PackageDescription
parseCabalFile file = do
    cid <- getGHCId
    let cid' = unknownCompilerInfo cid NoAbiTag
    epgd <- readGenericPackageDescription silent file
    flags <- getFlags
    case toPkgDesc cid' flags epgd of
        Left deps    -> throwIO $ userError $ show deps ++ " are not installed"
        Right (pd,_) -> if nullPkg pd
                        then throwIO $ userError $ file ++ " is broken"
                        else return pd
  where
    envFlags = do
      let parseF []      = []
          parseF ccs@(c:cs)
            | c == '-'   = [(mkFlagName cs, False)]
            | otherwise  = [(mkFlagName ccs, True)]
      maybe [] (concatMap parseF . words) `fmap` lookupEnv "HHP_CABAL_FLAGS"
    getFlags = mkFlagAssignment <$> envFlags
    nullPkg pd = unPackageName (C.pkgName (P.package pd)) == ""
    toPkgDesc cid flags = finalizePD flags defaultComponentRequestedSpec (const True) buildPlatform cid []

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

getGHCOptions :: [GHCOption] -> Cradle -> FilePath -> BuildInfo -> IO [GHCOption]
getGHCOptions ghcopts cradle rdir binfo = do
    cabalCpp <- cabalCppOptions rdir
    let cpps = map ("-optP" ++) $ P.cppOptions binfo ++ cabalCpp
    return $ ghcopts ++ pkgDb ++ exts ++ [lang] ++ libs ++ libDirs ++ cpps
  where
    pkgDb = ghcDbStackOpts $ cradlePkgDbStack cradle
    lang = maybe "-XHaskell98" (("-X" ++) . display) $ P.defaultLanguage binfo
    libDirs = map ("-L" ++) $ P.extraLibDirs binfo
    exts = map (("-X" ++) . display) $ P.usedExtensions binfo
    libs = map ("-l" ++) $ P.extraLibs binfo

cabalCppOptions :: FilePath -> IO [String]
cabalCppOptions dir = do
    exist <- doesFileExist cabalMacro
    return $ if exist then
        ["-include", cabalMacro]
      else
        []
  where
    cabalMacro = dir </> "dist/build/autogen/cabal_macros.h"

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

-- | Extracting all 'BuildInfo' for libraries, executables, and tests.
cabalAllBuildInfo :: PackageDescription -> [BuildInfo]
cabalAllBuildInfo pd = libBI ++ subBI ++ execBI ++ testBI ++ benchBI
  where
    libBI   = map P.libBuildInfo       $ maybeToList $ P.library pd
    subBI   = map P.libBuildInfo       $ P.subLibraries pd
    execBI  = map P.buildInfo          $ P.executables pd
    testBI  = map P.testBuildInfo      $ P.testSuites pd
    benchBI = map P.benchmarkBuildInfo $ P.benchmarks pd

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

-- | Extracting package names of dependency.
cabalDependPackages :: [BuildInfo] -> [PackageBaseName]
cabalDependPackages bis = uniqueAndSort pkgs
  where
    pkgs = map getDependencyPackageName $ concatMap P.targetBuildDepends bis
    getDependencyPackageName (Dependency pkg _ _) = unPackageName pkg

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

-- | Extracting include directories for modules.
cabalSourceDirs :: [BuildInfo] -> [IncludeDir]
cabalSourceDirs bis = uniqueAndSort $ concatMap (map toPath . P.hsSourceDirs) bis

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

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

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

getGHCId :: IO CompilerId
getGHCId = CompilerId GHC <$> getGHC

getGHC :: IO Version
getGHC = do
    mv <- programFindVersion ghcProgram silent (programName ghcProgram)
    case mv of
        Nothing -> throwIO $ userError "ghc not found"
        Just v  -> return v

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

-- | Extracting all 'Module' 'FilePath's for libraries, executables,
-- tests and benchmarks.
cabalAllTargets :: PackageDescription -> IO ([String],[String],[String],[String])
cabalAllTargets pd = do
    exeTargets  <- mapM getExecutableTarget $ P.executables pd
    testTargets <- mapM getTestTarget $ P.testSuites pd
    return (libTargets,concat exeTargets,concat testTargets,benchTargets)
  where
    lib = maybe [] P.explicitLibModules $ P.library pd

    libTargets = map toModuleString lib
    benchTargets = map toModuleString $ concatMap P.benchmarkModules $ P.benchmarks  pd
    toModuleString :: ModuleName -> String
    toModuleString mn = fromFilePath $ toFilePath mn

    fromFilePath :: FilePath -> String
    fromFilePath fp = map (\c -> if c=='/' then '.' else c) fp

    getTestTarget :: TestSuite -> IO [String]
    getTestTarget ts =
       case P.testInterface ts of
        (TestSuiteExeV10 _ filePath) -> do
          let maybeTests = [toPath p </> e | p <- P.hsSourceDirs $ P.testBuildInfo ts, e <- [filePath]]
          liftIO $ filterM doesFileExist maybeTests
        (TestSuiteLibV09 _ moduleName) -> return [toModuleString moduleName]
        (TestSuiteUnsupported _)       -> return []

    getExecutableTarget :: Executable -> IO [String]
    getExecutableTarget exe = do
      let maybeExes = [toPath p </> e | p <- P.hsSourceDirs $ P.buildInfo exe, e <- [P.modulePath exe]]
      liftIO $ filterM doesFileExist maybeExes

#if MIN_VERSION_Cabal(3,6,0)
toPath :: SymbolicPath from to -> FilePath
toPath = getSymbolicPath
#else
toPath :: String -> String
toPath = id
#endif