{-# LANGUAGE OverloadedStrings #-}
module Horizon.Gen.Nix.Writers (
   writeOverlay
 , writeMakePackageSet
 , writeCabal2Nix
 , writeDerivation
 , writeHaskellPackage
 , writeHaskellPackages
 ) where

import           Cabal2nix                               (Options, cabal2nix')
import           Control.Lens                            ((%~), (&))
import           Control.Monad                           (forM_, unless)
import           Data.Map                                (keys, toList)
import qualified Data.Text                               as T
import           Distribution.Compiler                   (CompilerId)
import           Distribution.Nixpkgs.Haskell.Derivation (Derivation,
                                                          benchmarkDepends,
                                                          testDepends)
import           Horizon.Gen.Nix.Cabal2Nix.Options       (haskellPackageToCabal2NixOptions)
import           Horizon.Gen.Nix.Pretty                  (prettyDerivation)
import           Horizon.Spec                            (HaskellPackage,
                                                          Modifiers,
                                                          Name (MkName),
                                                          Overlay (MkOverlay),
                                                          OverlayFile (MkOverlayFile),
                                                          PackageList (MkPackageList),
                                                          PackageSet (MkPackageSet),
                                                          PackageSetFile (MkPackageSetFile),
                                                          PackagesDir (MkPackagesDir),
                                                          fromName,
                                                          fromPackageList,
                                                          includeBenchmarks,
                                                          includeTests,
                                                          modifiers)
import           Path                                    (File, Path,
                                                          parseRelFile,
                                                          toFilePath, (</>))
import           Path.Dhall                              ()
import           System.Directory                        (createDirectoryIfMissing,
                                                          doesFileExist)
import           System.IO                               (IOMode (WriteMode),
                                                          hPutStrLn, stderr,
                                                          stdout, withFile)
import           System.IO.Silently                      (hSilence)
import           Text.PrettyPrint.HughesPJClass          (render)


writeOverlay :: PackagesDir -> OverlayFile -> Overlay -> IO ()
writeOverlay (MkPackagesDir d) (MkOverlayFile f) (MkOverlay (MkPackageSet _ (MkPackageList xs))) = withFile (toFilePath f) WriteMode $ \h -> do
  hPutStrLn h "{ pkgs, ... }:"
  hPutStrLn h ""
  hPutStrLn h "final: prev: with pkgs.haskell.lib; {"
  forM_ (keys xs) $ \x -> do
    y <- parseRelFile $ T.unpack $ fromName x <> ".nix"
    hPutStrLn h ("  " <> T.unpack (fromName x) <> " = final.callPackage (./" <> toFilePath (d </> y) <> ") { };")
    hPutStrLn h ""
  hPutStrLn h "}"

writeMakePackageSet :: PackagesDir -> PackageSetFile -> PackageSet -> IO ()
writeMakePackageSet (MkPackagesDir d) (MkPackageSetFile f) (MkPackageSet _ (MkPackageList xs)) = withFile (toFilePath f) WriteMode $ \h -> do
  hPutStrLn h "{ pkgs, lib, callPackage, ... }:"
  hPutStrLn h ""
  hPutStrLn h "self: with pkgs.haskell.lib; {"
  forM_ (keys xs) $ \x -> do
    y <- parseRelFile $ T.unpack $ fromName x <> ".nix"
    hPutStrLn h ("  " <> T.unpack (fromName x) <> " = self.callPackage (./" <> toFilePath (d </> y) <> ") { };")
    hPutStrLn h ""
  hPutStrLn h "}"

applyModifiersToDerivation :: Modifiers -> Derivation -> Derivation
applyModifiersToDerivation ms drv = drv & testDepends %~ (\x -> if includeTests ms then x else mempty)
                                        & benchmarkDepends %~ (\x -> if includeBenchmarks ms then x else mempty)

writeCabal2Nix :: Path b File -> Modifiers -> Options -> IO ()
writeCabal2Nix f ms opts = do
  putStrLn $ "Fetching " <> toFilePath f
  x <- hSilence [stdout, stderr] . cabal2nix' $ opts
  either (print . render) (writeDerivation f . applyModifiersToDerivation ms) x

writeDerivation :: Path b File -> Derivation -> IO ()
writeDerivation f = writeFile (toFilePath f) . show . prettyDerivation

writeHaskellPackage :: PackagesDir -> CompilerId -> Name -> HaskellPackage -> IO ()
writeHaskellPackage (MkPackagesDir d) c (MkName f) y = do
  let o = haskellPackageToCabal2NixOptions c y
  createDirectoryIfMissing True (toFilePath d)
  f' <- parseRelFile  $ T.unpack (f <> ".nix")
  let j = d </> f'
  q  <- doesFileExist $ toFilePath j
  unless q $ writeCabal2Nix j (modifiers y) o

writeHaskellPackages :: PackagesDir -> CompilerId -> PackageList -> IO ()
writeHaskellPackages d c = mapM_ (uncurry $ writeHaskellPackage d c) . toList . fromPackageList