-- cabal-helper: Simple interface to Cabal's configuration state
-- Copyright (C) 2015-2018  Daniel Gröber <cabal-helper@dxld.at>
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

{-# LANGUAGE RecordWildCards, FlexibleContexts, ConstraintKinds,
  GeneralizedNewtypeDeriving, DeriveDataTypeable, DeriveGeneric, DeriveFunctor,
  StandaloneDeriving, NamedFieldPuns, OverloadedStrings, ViewPatterns,
  TupleSections, TypeFamilies, DataKinds, GADTs, ScopedTypeVariables,
  ImplicitParams, RankNTypes #-}

{-# OPTIONS_GHC -fno-warn-name-shadowing #-}

{-|
Module      : Distribution.Helper
License     : GPL-3
Maintainer  : cabal-helper@dxld.at
Portability : POSIX
-}

module Distribution.Helper (
  -- * Running Queries
    Query
  , runQuery

  -- * Queries against Cabal\'s on disk state

  -- ** Project queries
  , compilerVersion
  , projectUnits

  -- ** Unit queries
  , Unit -- abstract
  , UnitId -- abstract
  , UnitInfo(..)
  , unitQuery

  -- ** Convenience Queries
  , allUnits

  -- * Query environment
  , QueryEnv -- abstract
  , mkQueryEnv
  , qeReadProcess
  , qePrograms
  , qeProjectDir
  , qeDistDir

  -- * GADTs
  , DistDir(..)
  , ProjType(..)
  , ProjDir(..)

  , Programs(..)
  , defaultPrograms


  -- * Result types
  , ChComponentInfo(..)
  , ChComponentName(..)
  , ChModuleName(..)
  , ChPkgDb(..)
  , ChEntrypoint(..)
  , NeedsBuildOutput(..)

  -- * General information
  , Distribution.Helper.buildPlatform

  -- * Stuff that cabal-install really should export
  , Distribution.Helper.getSandboxPkgDb

  -- * Managing @dist/@
  , prepare
  , reconfigure
  , writeAutogenFiles

  -- * Reexports
  , module Data.Functor.Apply
  ) where

import Cabal.Plan hiding (Unit, UnitId, uDistDir)
import qualified Cabal.Plan as CP
import Control.Applicative
import Control.Monad
import Control.Monad.Trans.Maybe
import Control.Monad.IO.Class
import Control.Exception as E
import Data.Coerce
import Data.IORef
import Data.List hiding (filter)
import Data.String
import qualified Data.Text as Text
import Data.Maybe
import Data.Either
import Data.Map.Strict (Map)
import qualified Data.Map.Strict as Map
import Data.Set (Set)
import qualified Data.Set as Set
import Data.Version
import Data.Function
import Data.Functor.Apply
import System.Environment
import System.FilePath hiding ((<.>))
import System.Directory
import System.Process
import System.Posix.Types
import System.PosixCompat.Files
import Text.Printf
import Text.Show.Pretty
import Prelude

import CabalHelper.Compiletime.Compile
import qualified CabalHelper.Compiletime.Program.Stack as Stack
import CabalHelper.Compiletime.Types
import CabalHelper.Compiletime.Types.RelativePath
import CabalHelper.Shared.InterfaceTypes
import CabalHelper.Shared.Sandbox
import CabalHelper.Shared.Common

import CabalHelper.Compiletime.Compat.Version
import qualified CabalHelper.Compiletime.Compat.ProgramDb as ProgDb
    ( defaultProgramDb, programPath, lookupProgram, ghcProgram, ghcPkgProgram)
import CabalHelper.Shared.Common

import Distribution.System (buildPlatform)
import Distribution.Text (display)
import Distribution.Verbosity (silent, deafening)
--import Distribution.Package (packageName, packageVersion)
import Distribution.Simple.GHC as GHC (configure)

import qualified CabalHelper.Compiletime.Compat.ProgramDb as ProgDb
    ( defaultProgramDb, programPath, lookupProgram, ghcProgram, ghcPkgProgram)
import CabalHelper.Compiletime.Compat.Version
import CabalHelper.Shared.Common

-- | A lazy, cached, query against a package's Cabal configuration. Use
-- 'runQuery' to execute it.
newtype Query pt a = Query
    { runQuery :: QueryEnv pt -> IO a
    -- ^ @runQuery env query@. Run a 'Query' under a given 'QueryEnv.
    }

instance Functor (Query pt) where
    fmap = liftM

instance Applicative (Query pt) where
    (<*>) = ap
    pure = return

instance Monad (Query pt) where
    (Query ma) >>= amb = Query $ \qe -> ma qe >>= \a -> runQuery (amb a) qe
    return a = Query $ const $ return a

-- | @mkQueryEnv projdir distdir@. Smart constructor for 'QueryEnv'.
-- Sets fields 'qeProjectDir' and 'qeDistDir' to @projdir@ and @distdir@
-- respectively and provides sensible defaults for the other fields.
mkQueryEnv
    :: ProjDir pt
    -- ^ Path to the project directory
    -> DistDir pt
    -- ^ Path to the @dist/@ or @dist-newstyle/@ directory, called
    -- /builddir/ in Cabal terminology.
    -> IO (QueryEnv pt)
mkQueryEnv projdir distdir = do
  cr <- newIORef $ QueryCache Nothing Map.empty
  return $ QueryEnv
    { qeReadProcess = \mcwd exe args stdin ->
        readCreateProcess (proc exe args){ cwd = mcwd } stdin
    , qePrograms    = defaultPrograms
    , qeProjectDir  = projdir
    , qeDistDir     = distdir
    , qeCacheRef    = cr
    }

piProjConfModTimes :: ProjInfo pt -> ProjConfModTimes pt
piProjConfModTimes ProjInfoV1 {piV1ProjConfModTimes} =
    piV1ProjConfModTimes
piProjConfModTimes ProjInfoV2 {piV2ProjConfModTimes} =
    piV2ProjConfModTimes
piProjConfModTimes ProjInfoStack {piStackProjConfModTimes} =
    piStackProjConfModTimes

piUnits :: DistDir pt -> ProjInfo pt -> [Unit]
piUnits (DistDirV1 distdir) (ProjInfoV1 (ProjConfModTimesV1 (cabal_file, _))) =
  (:[]) $ Unit
    { uUnitId = UnitId ""
    , uPackageDir = takeDirectory cabal_file
    , uDistDir = DistDirLib distdir
    }
piUnits _ ProjInfoV2{..} =
    case lefts units of
      [] -> rights units
      us@(_:_) -> panic $
        msg ++ (concat $ map (unlines . map ("  "++) . lines . ppShow) us)
  where
    msg = "\
\plan.json doesn't contain 'dist-dir' key for the following local units:\n"
    units = catMaybes $ map takeunit $ Map.elems $ pjUnits piV2Plan
    takeunit u@CP.Unit
      { uType=UnitTypeLocal
      , uDistDir=Just distdirv1
      , uPkgSrc=Just (LocalUnpackedPackage pkgdir)
      } = Just $ Right $ Unit
          { uUnitId     = UnitId $ Text.unpack (coerce (uId u))
          , uPackageDir = pkgdir
          , uDistDir    = DistDirLib distdirv1
          }
    takeunit u@CP.Unit {uType=UnitTypeLocal} =
      Just $ Left u
    takeunit _ =
      Nothing
piUnits DistDirStack{} ProjInfoStack{..} = piStackUnits


-- | Find files relevant to the project-scope configuration. Depending on the
-- 'ProjType' this could be (for example) just a cabal file, one of the
-- @caba.project*@ files or @stack.yaml@.
--
-- The returned paths include the project-dir path.
projConfModTimes :: ProjDir pt -> IO (ProjConfModTimes pt)
projConfModTimes pd@(ProjDirV1 _) =
    ProjConfModTimesV1 <$> (getFileModTime =<< findCabalFile pd)
projConfModTimes (ProjDirV2 projdir) = do
    ex_files <- filterM doesFileExist (map (projdir </>) additional_files)
    let files = [ projdir </> "cabal.project" ] ++ ex_files
    ProjConfModTimesV2 <$> mapM getFileModTime files
  where
    additional_files =
        [ "cabal.project.local"
        , "cabal.project.freeze"
        ]
projConfModTimes (ProjDirStack projdir) = do
    ProjConfModTimesStack <$> getFileModTime (projdir </> "stack.yml")

getUnitModTimes :: Unit -> IO UnitModTimes
getUnitModTimes Unit { uDistDir=DistDirLib distdirv1, uPackageDir=pkgdir } = do
  cabal_file <- findCabalFile (ProjDirV1 pkgdir)
  cabal_file_mtime <- getFileModTime cabal_file

  let setup_config = distdirv1 </> "setup-config"
  setup_config_mtime <- getFileModTime setup_config

  return UnitModTimes
    { umtCabalFile   = cabal_file_mtime
    , umtSetupConfig = setup_config_mtime
    }


-- | The version of GHC the project is configured to use
compilerVersion       :: Query pt (String, Version)
compilerVersion = undefined

-- | List of units in a project
projectUnits          :: Query pt [Unit]
projectUnits = Query $ \qe@QueryEnv{qeDistDir} ->
  piUnits qeDistDir <$> getProjInfo qe

-- | Run a 'UnitQuery' on a given unit. To get a a unit see 'projectUnits'.
unitQuery          :: Unit -> Query pt UnitInfo
unitQuery u = Query $ \qe -> getUnitInfo qe u

-- | Get information on all units in a project.
allUnits :: (UnitInfo -> a) -> Query pt [a]
allUnits f = map f <$> (mapM unitQuery =<< projectUnits)

-- | Run @cabal configure@
reconfigure :: MonadIO m
            => (FilePath -> [String] -> String -> IO String)
            -> Programs -- ^ Program paths
            -> [String] -- ^ Command line arguments to be passed to @cabal@
            -> m ()
reconfigure readProc progs cabalOpts = do
    let progOpts =
            [ "--with-ghc=" ++ ghcProgram progs ]
            -- Only pass ghc-pkg if it was actually set otherwise we
            -- might break cabal's guessing logic
            ++ if ghcPkgProgram progs /= "ghc-pkg"
                 then [ "--with-ghc-pkg=" ++ ghcPkgProgram progs ]
                 else []
            ++ cabalOpts
    _ <- liftIO $ readProc (cabalProgram progs) ("configure":progOpts) ""
    return ()


getProjInfo :: QueryEnv pt -> IO (ProjInfo pt)
getProjInfo qe@QueryEnv{..} = do
  cache@QueryCache{qcProjInfo, qcUnitInfos} <- readIORef qeCacheRef
  proj_info <- checkUpdateProj qe qcProjInfo
  let active_units = piUnits qeDistDir proj_info
  writeIORef qeCacheRef $ cache
    { qcProjInfo  = Just proj_info
    , qcUnitInfos = discardInactiveUnitInfos active_units qcUnitInfos
    }
  return proj_info

checkUpdateProj
    :: QueryEnvI c pt
    -> Maybe (ProjInfo pt)
    -> IO (ProjInfo pt)
checkUpdateProj qe mproj_info = do
  mtime <- projConfModTimes (qeProjectDir qe)

  case mproj_info of
    Nothing -> reconf mtime
    Just proj_info
        | piProjConfModTimes proj_info /= mtime
            -> reconf mtime
        | otherwise
            -> return proj_info
  where
    reconf mtime = do
      shallowReconfigureProject qe
      readProjInfo qe mtime



getUnitInfo :: QueryEnv pt -> Unit -> IO UnitInfo
getUnitInfo qe@QueryEnv{..} unit@Unit{uDistDir} = do
  proj_info <- getProjInfo qe

  cache@QueryCache{qcUnitInfos} <- readIORef qeCacheRef
  let munit_info = Map.lookup uDistDir qcUnitInfos
  unit_info <- checkUpdateUnitInfo qe proj_info unit munit_info
  writeIORef qeCacheRef $ cache
    { qcUnitInfos = Map.insert uDistDir unit_info qcUnitInfos }
  return unit_info

checkUpdateUnitInfo
    :: QueryEnvI c pt
    -> ProjInfo pt
    -> Unit
    -> Maybe UnitInfo
    -> IO UnitInfo
checkUpdateUnitInfo qe proj_info unit munit_info = do
  unit_mtimes <- getUnitModTimes unit
  case munit_info of
    Nothing -> reconf
    Just unit_info
      | uiModTimes unit_info /= unit_mtimes
        -> reconf
      | otherwise
        -> return unit_info
  where
    reconf = do
      reconfigureUnit qe unit
      helper <- wrapper proj_info qe
      readUnitInfo qe helper unit

-- | Restrict 'UnitInfo' cache to units that are still active
discardInactiveUnitInfos
    :: [Unit]
    -> Map DistDirLib UnitInfo
    -> Map DistDirLib UnitInfo
discardInactiveUnitInfos active_units uis0 =
  restrictKeysMap uis0 $ Set.fromList $ map uDistDir active_units
  where
    restrictKeysMap :: Ord k => Map k a -> Set k -> Map k a
    restrictKeysMap m s = Map.filterWithKey (\k _ -> Set.member k s) m


-- | Regenerate project level information by calling the appropriate build
-- system (@cabal@ or @stack@).
shallowReconfigureProject :: QueryEnvI c pt -> IO ()
shallowReconfigureProject QueryEnv
  { qeProjectDir = ProjDirV1 _projdir
  , qeDistDir = DistDirV1 _distdirv1 } =
    return ()
shallowReconfigureProject QueryEnv
  { qeProjectDir = ProjDirV2 projdir
  , qeDistDir = DistDirV2 _distdirv2, .. } = do
    _ <- liftIO $ qeReadProcess (Just projdir) (cabalProgram qePrograms)
           ["v2-build", "--dry-run", "all"] ""
    return ()
shallowReconfigureProject QueryEnv
  { qeProjectDir = ProjDirStack _projdir, .. } =
    -- TODO: do we need to do anything here? Maybe package.yaml support needs to
    -- do stuff here?
    return ()

reconfigureUnit :: QueryEnvI c pt -> Unit -> IO ()
reconfigureUnit QueryEnv{qeDistDir=DistDirV1{}, ..} Unit{uPackageDir=_} = do
  return ()
reconfigureUnit QueryEnv{qeDistDir=DistDirV2{}, ..} Unit{uPackageDir=_} = do
  return ()
reconfigureUnit QueryEnv{qeDistDir=DistDirStack{}, ..} Unit{uPackageDir} = do
  _ <- liftIO $ qeReadProcess (Just uPackageDir) (stackProgram qePrograms)
         ["stack", "build", "--only-configure", "."] ""
  return ()

findCabalFile :: ProjDir 'V1 -> IO FilePath
findCabalFile (ProjDirV1 pkgdir) = do
  [cfile] <- filter isCabalFile <$> getDirectoryContents pkgdir
  return cfile

getFileModTime :: FilePath -> IO (FilePath, EpochTime)
getFileModTime f = do
  t <- modificationTime <$> getFileStatus f
  return (f, t)

readProjInfo :: QueryEnvI c pt -> ProjConfModTimes pt -> IO (ProjInfo pt)
readProjInfo qe conf_files = do
  case (qeProjectDir qe, qeDistDir qe) of
    (ProjDirV1 _projdir, DistDirV1 _) ->
      return $ ProjInfoV1 { piV1ProjConfModTimes = conf_files }
    (ProjDirV2 _projdir, DistDirV2 distdirv2) -> do
      let plan_path = distdirv2 </> "cache" </> "plan.json"
      plan_mtime <- modificationTime <$> getFileStatus plan_path
      plan <- decodePlanJson plan_path
      return $ ProjInfoV2
        { piV2ProjConfModTimes = conf_files
        , piV2Plan = plan
        , piV2PlanModTime = plan_mtime
        }
    (ProjDirStack{} , DistDirStack{}) -> do
      cabal_files <- Stack.listPackageCabalFiles qe
      units <- mapM (Stack.getUnit qe) cabal_files
      proj_paths <- Stack.projPaths qe
      return $ ProjInfoStack
        { piStackProjConfModTimes = conf_files
        , piStackUnits = units
        , piStackProjPaths = proj_paths
        }

readUnitInfo :: QueryEnvI c pt -> FilePath -> Unit -> IO UnitInfo
readUnitInfo
  qe exe unit@Unit {uUnitId=uiUnitId, uPackageDir=pkgdir, uDistDir=distdir} = do
    res <- readHelper qe exe pkgdir distdir
           [ "package-db-stack"
           , "flags"
           , "compiler-version"
           , "config-flags"
           , "non-default-config-flags"
           , "component-info"
           ]
    let [ Just (ChResponsePkgDbs         uiPackageDbStack),
          Just (ChResponseFlags          uiPackageFlags),
          Just (ChResponseVersion        comp compVer),
          Just (ChResponseFlags          uiConfigFlags),
          Just (ChResponseFlags          uiNonDefaultConfigFlags),
          Just (ChResponseComponentsInfo uiComponents)
          ] = res
        uiCompilerVersion = (comp, compVer)
    uiModTimes <- getUnitModTimes unit
    return $ UnitInfo {..}

readHelper
    :: QueryEnvI c pt
    -> FilePath
    -> FilePath
    -> DistDirLib
    -> [String]
    -> IO [Maybe ChResponse]
readHelper qe exe cabal_file distdir args = do
  out <- invokeHelper qe exe cabal_file distdir args
  let res :: [Maybe ChResponse]
      res = read out
  liftIO $ evaluate res `E.catch` \ex@ErrorCall{} -> do
      md <- lookupEnv' "CABAL_HELPER_DEBUG"
      let msg = "readHelper: exception: '" ++ show ex ++ "'"
      panicIO $ msg ++ case md of
        Nothing -> "\n  for more information set the environment variable CABAL_HELPER_DEBUG and try again"
        Just _ -> "\n  output:\n'"++ out ++"'"

invokeHelper
    :: QueryEnvI c pt
    -> FilePath
    -> FilePath
    -> DistDirLib
    -> [String]
    -> IO String
invokeHelper QueryEnv {..} exe cabal_file (DistDirLib distdir) args0 = do
  let args1 = cabal_file : distdir : args0
  evaluate =<< qeReadProcess Nothing exe args1 "" `E.catch`
    \(_ :: E.IOException) ->
      panicIO $ concat
        ["invokeHelper", ": ", exe, " "
        , intercalate " " (map show args1)
        , " failed!"
        ]

-- getPackageId :: QueryEnv pt -> IO (String, Version)
-- getPackageId QueryEnv{..}  = do
--   [cfile] <- filter isCabalFile <$> getDirectoryContents qeProjectDir
--   gpd <- readPackageDescription silent (qeProjectDir </> cfile)
--   return $ (display (packageName gpd), toDataVersion (packageVersion gpd))

-- | Make sure the appropriate helper executable for the given project is
-- installed and ready to run queries.
prepare :: QueryEnv pt -> IO ()
prepare qe = do
  proj_info <- getProjInfo qe
  void $ wrapper proj_info qe

-- | Create @cabal_macros.h@ and @Paths_\<pkg\>@ possibly other generated files
-- in the usual place.
writeAutogenFiles :: QueryEnv pt -> IO ()
writeAutogenFiles qe = do
  proj_info <- getProjInfo qe
  _exe <- wrapper proj_info qe
  undefined -- void $ invokeHelper qe exe ["write-autogen-files"]

-- | Get the path to the sandbox package-db in a project
getSandboxPkgDb
    :: String
    -- ^ Cabal build platform, i.e. @buildPlatform@
    -> Version
    -- ^ GHC version (@cProjectVersion@ is your friend)
    -> FilePath
    -- ^ Path to the project directory, i.e. a directory containing a
    -- @cabal.sandbox.config@ file
    -> IO (Maybe FilePath)
getSandboxPkgDb buildPlat ghc_ver projdir =
    CabalHelper.Shared.Sandbox.getSandboxPkgDb buildPlat ghc_ver projdir

buildPlatform :: String
buildPlatform = display Distribution.System.buildPlatform

lookupEnv' :: String -> IO (Maybe String)
lookupEnv' k = lookup k <$> getEnvironment

guessProgramPaths :: (Verbose, Progs) => (Progs => IO a) -> IO a
guessProgramPaths act = do
    let v | ?verbose  = deafening
          | otherwise = silent

        mGhcPath0    | same ghcProgram ?progs dprogs = Nothing
                     | otherwise = Just $ ghcProgram ?progs
        mGhcPkgPath0 | same ghcPkgProgram ?progs dprogs = Nothing
                     | otherwise = Just $ ghcPkgProgram ?progs

    (_compiler, _mplatform, progdb)
        <- GHC.configure
               v
               mGhcPath0
               mGhcPkgPath0
               ProgDb.defaultProgramDb
    let getProg p = ProgDb.programPath <$> ProgDb.lookupProgram p progdb
        mghcPath1    = getProg ProgDb.ghcProgram
        mghcPkgPath1 = getProg ProgDb.ghcPkgProgram

    let ?progs = ?progs
          { ghcProgram    = fromMaybe (ghcProgram ?progs) mghcPath1
          , ghcPkgProgram = fromMaybe (ghcProgram ?progs) mghcPkgPath1
          }
    act
 where
   same f o o'  = f o == f o'
   dprogs = defaultPrograms

withVerbosity :: (Verbose => a) -> IO a
withVerbosity a = do
  x <- lookup  "CABAL_HELPER_DEBUG" <$> getEnvironment
  let ?verbose =
        case x of
          Just xs | not (null xs) -> True
          _ -> False
  return a

wrapper
    :: ProjInfo pt -> QueryEnvI c pt -> IO FilePath
wrapper proj_info QueryEnv{..} = do
  join $ withVerbosity $ do
    let ?progs = qePrograms
    guessProgramPaths $ wrapper' qeProjectDir qeDistDir proj_info

wrapper'
    :: Env
    => ProjDir pt
    -> DistDir pt
    -> ProjInfo pt
    -> IO FilePath
wrapper' (ProjDirV1 projdir) (DistDirV1 distdir) _ = do
  cfgf <- canonicalizePath (distdir </> "setup-config")
  mhdr <- getCabalConfigHeader cfgf
  case mhdr of
    Nothing -> panicIO $ printf "\
\Could not read Cabal's persistent setup configuration header\n\
\- Check first line of: %s\n\
\- Maybe try: $ cabal configure" cfgf
    Just (hdrCabalVersion, _) -> do
      compileHelper' hdrCabalVersion Nothing projdir Nothing distdir
wrapper'
  (ProjDirV2 projdir)
  (DistDirV2 distdir)
  ProjInfoV2{piV2Plan=plan}
  = do
    let PlanJson {pjCabalLibVersion=Ver (makeDataVersion -> pjCabalLibVersion) }
          = plan
    compileHelper' pjCabalLibVersion
                   Nothing
                   projdir
                   (Just (plan, distdir))
                   (distdir </> "cache")
wrapper'
  (ProjDirStack projdir)
  (DistDirStack mworkdir)
  ProjInfoStack{piStackProjPaths=StackProjPaths{sppGlobalPkgDb}}
  = do
    -- Stack also just picks whatever version ghc-pkg spits out, see
    -- Stack.GhcPkg.getCabalPkgVer.
    Just (cabalVer:_) <- runMaybeT $ listCabalVersions' (Just sppGlobalPkgDb)
    let workdir = fromMaybe ".stack-work" $ unRelativePath <$> mworkdir
    compileHelper' cabalVer
                   (Just sppGlobalPkgDb)
                   projdir
                   Nothing
                   (projdir </> workdir)

compileHelper'
    :: Env
    => Version
    -> Maybe PackageDbDir
    -> FilePath
    -> Maybe (PlanJson, FilePath)
    -> FilePath
    -> IO FilePath
compileHelper' pjCabalLibVersion cabalPkgDb projdir mnewstyle distdirv1 = do
  eexe <- compileHelper pjCabalLibVersion cabalPkgDb projdir mnewstyle distdirv1
  case eexe of
    Left rv ->
      panicIO $ "compileHelper': compiling helper failed! (exit code "++ show rv
    Right exe ->
      return exe