{-# LANGUAGE DeriveAnyClass        #-}
{-# LANGUAGE DeriveGeneric         #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE OverloadedStrings     #-}
{-# LANGUAGE ScopedTypeVariables   #-}
{-# LANGUAGE TypeApplications      #-}

module HaskellWorks.CabalCache.Core
  ( PackageInfo(..),
    Tagged(..),
    Presence(..),
    getPackages,
    relativePaths,
    loadPlan,
    mkCompilerContext,
  ) where

import Control.DeepSeq                  (NFData)
import Control.Lens                     ((<&>), (&), (^.))
import Control.Monad.Catch              (MonadCatch(..))
import Control.Monad.Except             (ExceptT, forM, MonadIO(..), MonadError(..))
import Data.Aeson                       (eitherDecode)
import Data.Bifunctor                   (first)
import Data.Bool                        (bool)
import Data.Generics.Product.Any        (the)
import Data.Text                        (Text)
import GHC.Generics                     (Generic)
import HaskellWorks.CabalCache.Error    (DecodeError(..))
import HaskellWorks.CabalCache.Show     (tshow)
import System.FilePath                  ((<.>), (</>))

import qualified Control.Monad.Oops             as OO
import qualified Data.ByteString.Lazy           as LBS
import qualified Data.List                      as L
import qualified Data.Text                      as T
import qualified HaskellWorks.CabalCache.IO.Tar as IO
import qualified HaskellWorks.CabalCache.Types  as Z
import qualified System.Directory               as IO
import qualified System.Info                    as I
import qualified System.Process                 as IO

{- HLINT ignore "Monoid law, left identity" -}

type PackageDir = FilePath
type ConfPath   = FilePath
type Library    = FilePath

data Presence   = Present | Absent deriving (Eq, Show, NFData, Generic)

data Tagged a t = Tagged
  { value :: a
  , tag   :: t
  } deriving (Eq, Show, Generic, NFData)

data PackageInfo = PackageInfo
  { compilerId  :: Z.CompilerId
  , packageId   :: Z.PackageId
  , packageName :: Z.PackageName
  , packageDir  :: PackageDir
  , confPath    :: Tagged ConfPath Presence
  , libs        :: [Library]
  } deriving (Show, Eq, Generic, NFData)

(<||>) :: Monad m => ExceptT e m a -> ExceptT e m a -> ExceptT e m a
(<||>) f g = f `catchError` const g

isPosix :: Bool
isPosix = I.os /= "mingw32"
{-# NOINLINE isPosix #-}

exeExt :: String
exeExt
  | isPosix = ""
  | otherwise = ".exe"

withExeExt :: FilePath -> FilePath
withExeExt = (<.> exeExt)

withExeExt' :: Text -> Text
withExeExt' = T.pack . withExeExt . T.unpack

findExecutable :: ()
  => MonadIO f
  => MonadError (OO.Variant e) f
  => e `OO.CouldBe` Text
  => Text
  -> f Text
findExecutable exe = fmap T.pack $
  liftIO (IO.findExecutable (T.unpack exe)) >>= OO.hoistMaybe (exe <> " is not in path")

runGhcPkg :: ()
  => MonadCatch m
  => MonadIO m
  => MonadError (OO.Variant e) m
  => e `OO.CouldBe` Text
  => Text
  -> [Text]
  -> m Text
runGhcPkg cmdExe args = catch (liftIO $ T.pack <$> IO.readProcess (T.unpack cmdExe) (fmap T.unpack args) "") $
  \(e :: IOError) -> OO.throw $ "Unable to run " <> cmdExe <> " " <> T.unwords args <> ": " <> tshow e

verifyGhcPkgVersion :: ()
  => MonadError (OO.Variant e) m
  => MonadIO m
  => MonadCatch m
  => e `OO.CouldBe` Text
  => Text
  -> Text
  -> m Text
verifyGhcPkgVersion version cmdExe = do
  stdout <- runGhcPkg cmdExe ["--version"]
  if T.isSuffixOf (" " <> version) (mconcat (L.take 1 (T.lines stdout)))
    then return cmdExe
    else OO.throw $ cmdExe <> " is not of version " <> version

mkCompilerContext :: ()
  => MonadIO m
  => MonadCatch m
  => e `OO.CouldBe` Text
  => Z.PlanJson
  -> ExceptT (OO.Variant e) m Z.CompilerContext
mkCompilerContext plan = do
  compilerVersion <- T.stripPrefix "ghc-" (plan ^. the @"compilerId")
    & OO.hoistMaybe @Text "No compiler version available in plan"
  let versionedGhcPkgCmd = "ghc-pkg-" <> compilerVersion
  ghcPkgCmdPath <-
          (findExecutable (withExeExt' versionedGhcPkgCmd)  >>= verifyGhcPkgVersion compilerVersion)
    <||>  (findExecutable (withExeExt' "ghc-pkg"         )  >>= verifyGhcPkgVersion compilerVersion)
  return (Z.CompilerContext [T.unpack ghcPkgCmdPath])

relativePaths :: FilePath -> PackageInfo -> [IO.TarGroup]
relativePaths basePath pInfo =
  [ IO.TarGroup basePath $ mempty
      <> (pInfo ^. the @"libs")
      <> [packageDir pInfo]
  , IO.TarGroup basePath $ mempty
      <> ([pInfo ^. the @"confPath"] & filter ((== Present) . (^. the @"tag")) <&> (^. the @"value"))
  ]

getPackages :: FilePath -> Z.PlanJson -> IO [PackageInfo]
getPackages basePath planJson = forM packages (mkPackageInfo basePath compilerId')
  where compilerId' :: Text
        compilerId' = planJson ^. the @"compilerId"
        packages :: [Z.Package]
        packages = planJson ^. the @"installPlan"

loadPlan :: ()
  => MonadIO m
  => MonadError (OO.Variant e) m
  => e `OO.CouldBe` DecodeError
  => FilePath
  -> m Z.PlanJson
loadPlan resolvedBuildPath = do
  lbs <- liftIO (LBS.readFile (resolvedBuildPath </> "cache" </> "plan.json"))
  a <- OO.hoistEither $ first (DecodeError . T.pack) (eitherDecode lbs)
  pure do a :: Z.PlanJson

-------------------------------------------------------------------------------
mkPackageInfo :: FilePath -> Z.CompilerId -> Z.Package -> IO PackageInfo
mkPackageInfo basePath cid pkg = do
  let pid               = pkg ^. the @"id"
  let compilerPath      = basePath </> T.unpack cid
  let relativeConfPath  = T.unpack cid </> "package.db" </> T.unpack pid <.> ".conf"
  let absoluteConfPath  = basePath </> relativeConfPath
  let libPath           = compilerPath </> "lib"
  let relativeLibPath   = T.unpack cid </> "lib"
  let libPrefix         = "libHS" <> pid
  absoluteConfPathExists <- IO.doesFileExist absoluteConfPath
  libFiles <- getLibFiles relativeLibPath libPath libPrefix
  return PackageInfo
    { compilerId  = cid
    , packageId   = pid
    , packageName = pkg ^. the @"name"
    , packageDir  = T.unpack cid </> T.unpack pid
    , confPath    = Tagged relativeConfPath (bool Absent Present absoluteConfPathExists)
    , libs        = libFiles
    }

getLibFiles :: FilePath -> FilePath -> Text -> IO [Library]
getLibFiles relativeLibPath libPath libPrefix = do
  libExists <- IO.doesDirectoryExist libPath
  if libExists
     then fmap (relativeLibPath </>) . filter (L.isPrefixOf (T.unpack libPrefix)) <$> IO.listDirectory libPath
     else pure []