{-# LANGUAGE PatternSynonyms #-}

-- |
-- Module      :  Distribution.Client.Get
-- Copyright   :  (c) Andrea Vezzosi 2008
--                    Duncan Coutts 2011
--                    John Millikin 2012
-- License     :  BSD-like
--
-- Maintainer  :  cabal-devel@haskell.org
-- Stability   :  provisional
-- Portability :  portable
--
-- The 'cabal get' command.
module Distribution.Client.Get
  ( get

    -- * Cloning 'SourceRepo's

    -- | Mainly exported for testing purposes
  , clonePackagesFromSourceRepo
  , ClonePackageException (..)
  ) where

import Distribution.Client.Compat.Prelude hiding (get)
import Distribution.Client.Types.SourceRepo (SourceRepoProxy, SourceRepositoryPackage (..), srpToProxy)
import Distribution.Compat.Directory
  ( listDirectory
  )
import Distribution.Package
  ( PackageId
  , packageId
  , packageName
  )
import qualified Distribution.PackageDescription as PD
import Distribution.Simple.Program
  ( programName
  )
import Distribution.Simple.Setup
  ( flagToMaybe
  , fromFlag
  , fromFlagOrDefault
  , pattern NoFlag
  )
import Distribution.Simple.Utils
  ( dieWithException
  , info
  , notice
  , warn
  , writeFileAtomic
  )
import Distribution.Types.SourceRepo (RepoKind (..))
import Prelude ()

import Distribution.Client.Dependency
import Distribution.Client.FetchUtils
import Distribution.Client.IndexUtils
  ( ActiveRepos
  , TotalIndexState
  , getSourcePackagesAtIndexState
  )
import Distribution.Client.Setup
  ( GetFlags (..)
  , GlobalFlags (..)
  , RepoContext (..)
  )
import qualified Distribution.Client.Tar as Tar (extractTarGzFile)
import Distribution.Client.Targets
import Distribution.Client.Types
import Distribution.Client.VCS
import Distribution.PackageDescription.PrettyPrint
  ( writeGenericPackageDescription
  )
import Distribution.Solver.Types.SourcePackage

import Control.Monad (mapM_)
import qualified Data.Map as Map
import Distribution.Client.Errors
import Distribution.Utils.NubList
  ( fromNubList
  )
import System.Directory
  ( createDirectoryIfMissing
  , doesDirectoryExist
  , doesFileExist
  )
import System.FilePath
  ( addTrailingPathSeparator
  , (<.>)
  , (</>)
  )

-- | Entry point for the 'cabal get' command.
get
  :: Verbosity
  -> RepoContext
  -> GlobalFlags
  -> GetFlags
  -> [UserTarget]
  -> IO ()
get verbosity _ _ _ [] =
  notice verbosity "No packages requested. Nothing to do."
get verbosity repoCtxt globalFlags getFlags userTargets = do
  let useSourceRepo = case getSourceRepository getFlags of
        NoFlag -> False
        _ -> True

  unless useSourceRepo $
    traverse_ (checkTarget verbosity) userTargets

  let idxState :: Maybe TotalIndexState
      idxState = flagToMaybe $ getIndexState getFlags

      activeRepos :: Maybe ActiveRepos
      activeRepos = flagToMaybe $ getActiveRepos getFlags

  (sourcePkgDb, _, _) <- getSourcePackagesAtIndexState verbosity repoCtxt idxState activeRepos

  pkgSpecifiers <-
    resolveUserTargets
      verbosity
      repoCtxt
      (packageIndex sourcePkgDb)
      userTargets

  pkgs <-
    either (dieWithException verbosity . PkgSpecifierException . map show) return $
      resolveWithoutDependencies
        (resolverParams sourcePkgDb pkgSpecifiers)

  unless (null prefix) $
    createDirectoryIfMissing True prefix

  if onlyPkgDescr
    then do
      when useSourceRepo $
        warn verbosity $
          "Ignoring --source-repository for --only-package-description"

      mapM_ (unpackOnlyPkgDescr verbosity prefix) pkgs
    else
      if useSourceRepo
        then clone pkgs
        else unpack pkgs
  where
    resolverParams :: SourcePackageDb -> [PackageSpecifier UnresolvedSourcePackage] -> DepResolverParams
    resolverParams sourcePkgDb pkgSpecifiers =
      -- TODO: add command-line constraint and preference args for unpack
      standardInstallPolicy mempty sourcePkgDb pkgSpecifiers

    onlyPkgDescr = fromFlagOrDefault False (getOnlyPkgDescr getFlags)

    prefix :: String
    prefix = fromFlagOrDefault "" (getDestDir getFlags)

    clone :: [UnresolvedSourcePackage] -> IO ()
    clone =
      clonePackagesFromSourceRepo verbosity prefix kind (fromNubList $ globalProgPathExtra globalFlags)
        . map (\pkg -> (packageId pkg, packageSourceRepos pkg))
      where
        kind :: Maybe RepoKind
        kind = fromFlag . getSourceRepository $ getFlags
        packageSourceRepos :: SourcePackage loc -> [PD.SourceRepo]
        packageSourceRepos =
          PD.sourceRepos
            . PD.packageDescription
            . srcpkgDescription

    unpack :: [UnresolvedSourcePackage] -> IO ()
    unpack pkgs = do
      for_ pkgs $ \pkg -> do
        location <- fetchPackage verbosity repoCtxt (srcpkgSource pkg)
        let pkgid = packageId pkg
            descOverride
              | usePristine = Nothing
              | otherwise = srcpkgDescrOverride pkg
        case location of
          LocalTarballPackage tarballPath ->
            unpackPackage verbosity prefix pkgid descOverride tarballPath
          RemoteTarballPackage _tarballURL tarballPath ->
            unpackPackage verbosity prefix pkgid descOverride tarballPath
          RepoTarballPackage _repo _pkgid tarballPath ->
            unpackPackage verbosity prefix pkgid descOverride tarballPath
          RemoteSourceRepoPackage _repo _ ->
            dieWithException verbosity UnpackGet
          LocalUnpackedPackage _ ->
            error "Distribution.Client.Get.unpack: the impossible happened."
      where
        usePristine :: Bool
        usePristine = fromFlagOrDefault False (getPristine getFlags)

checkTarget :: Verbosity -> UserTarget -> IO ()
checkTarget verbosity target = case target of
  UserTargetLocalDir dir -> dieWithException verbosity $ NotTarballDir dir
  UserTargetLocalCabalFile file -> dieWithException verbosity $ NotTarballDir file
  _ -> return ()

{-where
    notTarball t =
      "The 'get' command is for tarball packages. "
        ++ "The target '"
        ++ t
        ++ "' is not a tarball."
-}
-- ------------------------------------------------------------

-- * Unpacking the source tarball

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

unpackPackage
  :: Verbosity
  -> FilePath
  -> PackageId
  -> PackageDescriptionOverride
  -> FilePath
  -> IO ()
unpackPackage verbosity prefix pkgid descOverride pkgPath = do
  let pkgdirname = prettyShow pkgid
      pkgdir = prefix </> pkgdirname
      pkgdir' = addTrailingPathSeparator pkgdir
      emptyDirectory directory = null <$> listDirectory directory
  existsDir <- doesDirectoryExist pkgdir
  when existsDir $ do
    isEmpty <- emptyDirectory pkgdir
    unless isEmpty $
      dieWithException verbosity $
        DirectoryAlreadyExists pkgdir'
  existsFile <- doesFileExist pkgdir
  when existsFile $
    dieWithException verbosity $
      FileExists pkgdir
  notice verbosity $ "Unpacking to " ++ pkgdir'
  Tar.extractTarGzFile prefix pkgdirname pkgPath

  case descOverride of
    Nothing -> return ()
    Just pkgtxt -> do
      let descFilePath = pkgdir </> prettyShow (packageName pkgid) <.> "cabal"
      info verbosity $
        "Updating "
          ++ descFilePath
          ++ " with the latest revision from the index."
      writeFileAtomic descFilePath pkgtxt

-- | Write a @pkgId.cabal@ file with the package description to the destination
-- directory, unless one already exists.
unpackOnlyPkgDescr :: Verbosity -> FilePath -> UnresolvedSourcePackage -> IO ()
unpackOnlyPkgDescr verbosity dstDir pkg = do
  let pkgFile = dstDir </> prettyShow (packageId pkg) <.> "cabal"
  existsFile <- doesFileExist pkgFile
  when existsFile $
    dieWithException verbosity $
      FileAlreadyExists pkgFile
  existsDir <- doesDirectoryExist (addTrailingPathSeparator pkgFile)
  when existsDir $
    dieWithException verbosity $
      DirectoryExists pkgFile
  notice verbosity $ "Writing package description to " ++ pkgFile
  case srcpkgDescrOverride pkg of
    Just pkgTxt -> writeFileAtomic pkgFile pkgTxt
    Nothing ->
      writeGenericPackageDescription pkgFile (srcpkgDescription pkg)

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

-- * Cloning packages from their declared source repositories

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

data ClonePackageException
  = ClonePackageNoSourceRepos PackageId
  | ClonePackageNoSourceReposOfKind PackageId (Maybe RepoKind)
  | ClonePackageNoRepoType PackageId PD.SourceRepo
  | ClonePackageUnsupportedRepoType PackageId SourceRepoProxy RepoType
  | ClonePackageNoRepoLocation PackageId PD.SourceRepo
  | ClonePackageDestinationExists PackageId FilePath Bool
  | ClonePackageFailedWithExitCode PackageId SourceRepoProxy String ExitCode
  deriving (Show, Eq)

instance Exception ClonePackageException where
  displayException (ClonePackageNoSourceRepos pkgid) =
    "Cannot fetch a source repository for package "
      ++ prettyShow pkgid
      ++ ". The package does not specify any source repositories."
  displayException (ClonePackageNoSourceReposOfKind pkgid repoKind) =
    "Cannot fetch a source repository for package "
      ++ prettyShow pkgid
      ++ ". The package does not specify a source repository of the requested "
      ++ "kind"
      ++ maybe "." (\k -> " (kind " ++ prettyShow k ++ ").") repoKind
  displayException (ClonePackageNoRepoType pkgid _repo) =
    "Cannot fetch the source repository for package "
      ++ prettyShow pkgid
      ++ ". The package's description specifies a source repository but does "
      ++ "not specify the repository 'type' field (e.g. git, darcs or hg)."
  displayException (ClonePackageUnsupportedRepoType pkgid _ repoType) =
    "Cannot fetch the source repository for package "
      ++ prettyShow pkgid
      ++ ". The repository type '"
      ++ prettyShow repoType
      ++ "' is not yet supported."
  displayException (ClonePackageNoRepoLocation pkgid _repo) =
    "Cannot fetch the source repository for package "
      ++ prettyShow pkgid
      ++ ". The package's description specifies a source repository but does "
      ++ "not specify the repository 'location' field (i.e. the URL)."
  displayException (ClonePackageDestinationExists pkgid dest isdir) =
    "Not fetching the source repository for package "
      ++ prettyShow pkgid
      ++ ". "
      ++ if isdir
        then "The destination directory " ++ dest ++ " already exists."
        else "A file " ++ dest ++ " is in the way."
  displayException
    ( ClonePackageFailedWithExitCode
        pkgid
        repo
        vcsprogname
        exitcode
      ) =
      "Failed to fetch the source repository for package "
        ++ prettyShow pkgid
        ++ ", repository location "
        ++ srpLocation repo
        ++ " ("
        ++ vcsprogname
        ++ " failed with "
        ++ show exitcode
        ++ ")."

-- | Given a bunch of package ids and their corresponding available
-- 'SourceRepo's, pick a single 'SourceRepo' for each one and clone into
-- new subdirs of the given directory.
clonePackagesFromSourceRepo
  :: Verbosity
  -> FilePath
  -- ^ destination dir prefix
  -> Maybe RepoKind
  -- ^ preferred 'RepoKind'
  -> [FilePath]
  -- ^ Extra prog paths
  -> [(PackageId, [PD.SourceRepo])]
  -- ^ the packages and their
  -- available 'SourceRepo's
  -> IO ()
clonePackagesFromSourceRepo
  verbosity
  destDirPrefix
  preferredRepoKind
  progPaths
  pkgrepos = do
    -- Do a bunch of checks and collect the required info
    pkgrepos' <- traverse preCloneChecks pkgrepos

    -- Configure the VCS drivers for all the repository types we may need
    vcss <-
      configureVCSs verbosity progPaths $
        Map.fromList
          [ (vcsRepoType vcs, vcs)
          | (_, _, vcs, _) <- pkgrepos'
          ]

    -- Now execute all the required commands for each repo
    sequence_
      [ cloneSourceRepo verbosity vcs' repo destDir
        `catch` \exitcode ->
          throwIO
            ( ClonePackageFailedWithExitCode
                pkgid
                (srpToProxy repo)
                (programName (vcsProgram vcs))
                exitcode
            )
      | (pkgid, repo, vcs, destDir) <- pkgrepos'
      , let vcs' = Map.findWithDefault (error $ "Cannot configure " ++ prettyShow (vcsRepoType vcs)) (vcsRepoType vcs) vcss
      ]
    where
      preCloneChecks
        :: (PackageId, [PD.SourceRepo])
        -> IO (PackageId, SourceRepositoryPackage Maybe, VCS Program, FilePath)
      preCloneChecks (pkgid, repos) = do
        repo <- case selectPackageSourceRepo preferredRepoKind repos of
          Just repo -> return repo
          Nothing | null repos -> throwIO (ClonePackageNoSourceRepos pkgid)
          Nothing ->
            throwIO
              ( ClonePackageNoSourceReposOfKind
                  pkgid
                  preferredRepoKind
              )

        (repo', vcs) <- case validatePDSourceRepo repo of
          Right (repo', _, _, vcs) -> return (repo', vcs)
          Left SourceRepoRepoTypeUnspecified ->
            throwIO (ClonePackageNoRepoType pkgid repo)
          Left (SourceRepoRepoTypeUnsupported repo' repoType) ->
            throwIO (ClonePackageUnsupportedRepoType pkgid repo' repoType)
          Left SourceRepoLocationUnspecified ->
            throwIO (ClonePackageNoRepoLocation pkgid repo)

        let destDir :: FilePath
            destDir = destDirPrefix </> prettyShow (packageName pkgid)
        destDirExists <- doesDirectoryExist destDir
        destFileExists <- doesFileExist destDir
        when (destDirExists || destFileExists) $
          throwIO (ClonePackageDestinationExists pkgid destDir destDirExists)

        return (pkgid, repo', vcs, destDir)

-------------------------------------------------------------------------------
-- Selecting
-------------------------------------------------------------------------------

-- | Pick the 'SourceRepo' to use to get the package sources from.
--
-- Note that this does /not/ depend on what 'VCS' drivers we are able to
-- successfully configure. It is based only on the 'SourceRepo's declared
-- in the package, and optionally on a preferred 'RepoKind'.
selectPackageSourceRepo
  :: Maybe RepoKind
  -> [PD.SourceRepo]
  -> Maybe PD.SourceRepo
selectPackageSourceRepo preferredRepoKind =
  listToMaybe
    -- Sort repositories by kind, from This to Head to Unknown. Repositories
    -- with equivalent kinds are selected based on the order they appear in
    -- the Cabal description file.
    . sortBy (comparing thisFirst)
    -- If the user has specified the repo kind, filter out the repositories
    -- they're not interested in.
    . filter (\repo -> maybe True (PD.repoKind repo ==) preferredRepoKind)
  where
    thisFirst :: PD.SourceRepo -> Int
    thisFirst r = case PD.repoKind r of
      RepoThis -> 0
      RepoHead -> case PD.repoTag r of
        -- If the type is 'head' but the author specified a tag, they
        -- probably meant to create a 'this' repository but screwed up.
        Just _ -> 0
        Nothing -> 1
      RepoKindUnknown _ -> 2
