{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric #-}
module Stack.PackageDump
    ( Line
    , eachSection
    , eachPair
    , DumpPackage (..)
    , conduitDumpPackage
    , ghcPkgDump
    , ghcPkgDescribe
    , InstalledCache
    , InstalledCacheEntry (..)
    , newInstalledCache
    , loadInstalledCache
    , saveInstalledCache
    , addProfiling
    , addHaddock
    , sinkMatching
    , pruneDeps
    ) where

import           Control.Applicative
import           Control.Arrow ((&&&))
import           Control.Exception.Enclosed (tryIO)
import           Control.Monad (liftM)
import           Control.Monad.Catch
import           Control.Monad.IO.Class
import           Control.Monad.Logger (MonadLogger)
import           Control.Monad.Trans.Control
import           Data.Attoparsec.Args
import           Data.Attoparsec.Text as P
import           Data.Binary.VersionTagged
import           Data.ByteString (ByteString)
import qualified Data.ByteString as S
import qualified Data.ByteString.Char8 as S8
import           Data.Conduit
import qualified Data.Conduit.Binary as CB
import qualified Data.Conduit.List as CL
import           Data.Either (partitionEithers)
import           Data.IORef
import           Data.Map (Map)
import qualified Data.Map as Map
import           Data.Maybe (catMaybes, listToMaybe, fromMaybe)
import qualified Data.Set as Set
import qualified Data.Text.Encoding as T
import           Data.Typeable (Typeable)
import           GHC.Generics (Generic)
import           Path
import           Path.IO (createTree)
import           Prelude -- Fix AMP warning
import           Stack.GhcPkg
import           Stack.Types
import           System.Directory (getDirectoryContents, doesFileExist)
import           System.Process.Read

-- | Cached information on whether package have profiling libraries and haddocks.
newtype InstalledCache = InstalledCache (IORef InstalledCacheInner)
newtype InstalledCacheInner = InstalledCacheInner (Map GhcPkgId InstalledCacheEntry)
    deriving (Binary, NFData, Generic)
instance HasStructuralInfo InstalledCacheInner
instance HasSemanticVersion InstalledCacheInner

-- | Cached information on whether a package has profiling libraries and haddocks.
data InstalledCacheEntry = InstalledCacheEntry
    { installedCacheProfiling :: !Bool
    , installedCacheHaddock :: !Bool
    , installedCacheIdent :: !PackageIdentifier }
    deriving (Eq, Generic)
instance Binary InstalledCacheEntry
instance HasStructuralInfo InstalledCacheEntry
instance NFData InstalledCacheEntry

-- | Call ghc-pkg dump with appropriate flags and stream to the given @Sink@, for a single database
ghcPkgDump
    :: (MonadIO m, MonadLogger m, MonadBaseControl IO m, MonadCatch m, MonadThrow m)
    => EnvOverride
    -> WhichCompiler
    -> [Path Abs Dir] -- ^ if empty, use global
    -> Sink ByteString IO a
    -> m a
ghcPkgDump = ghcPkgCmdArgs ["dump"]

-- | Call ghc-pkg describe with appropriate flags and stream to the given @Sink@, for a single database
ghcPkgDescribe
    :: (MonadIO m, MonadLogger m, MonadBaseControl IO m, MonadCatch m, MonadThrow m)
    => PackageName
    -> EnvOverride
    -> WhichCompiler
    -> [Path Abs Dir] -- ^ if empty, use global
    -> Sink ByteString IO a
    -> m a
ghcPkgDescribe pkgName = ghcPkgCmdArgs ["describe", "--simple-output", packageNameString pkgName]

-- | Call ghc-pkg and stream to the given @Sink@, for a single database
ghcPkgCmdArgs
    :: (MonadIO m, MonadLogger m, MonadBaseControl IO m, MonadCatch m, MonadThrow m)
    => [String]
    -> EnvOverride
    -> WhichCompiler
    -> [Path Abs Dir] -- ^ if empty, use global
    -> Sink ByteString IO a
    -> m a
ghcPkgCmdArgs cmd menv wc mpkgDbs sink = do
    case reverse mpkgDbs of
        (pkgDb:_) -> createDatabase menv wc pkgDb -- TODO maybe use some retry logic instead?
        _ -> return ()
    sinkProcessStdout Nothing menv (ghcPkgExeName wc) args sink
  where
    args = concat
        [ case mpkgDbs of
            [] -> ["--global", "--no-user-package-db"]
            _ -> ["--user", "--no-user-package-db"] ++ concatMap (\pkgDb -> ["--package-db", toFilePath pkgDb]) mpkgDbs
        , cmd
        , ["--expand-pkgroot"]
        ]

-- | Create a new, empty @InstalledCache@
newInstalledCache :: MonadIO m => m InstalledCache
newInstalledCache = liftIO $ InstalledCache <$> newIORef (InstalledCacheInner Map.empty)

-- | Load a @InstalledCache@ from disk, swallowing any errors and returning an
-- empty cache.
loadInstalledCache :: (MonadLogger m, MonadIO m) => Path Abs File -> m InstalledCache
loadInstalledCache path = do
    m <- taggedDecodeOrLoad path (return $ InstalledCacheInner Map.empty)
    liftIO $ fmap InstalledCache $ newIORef m

-- | Save a @InstalledCache@ to disk
saveInstalledCache :: MonadIO m => Path Abs File -> InstalledCache -> m ()
saveInstalledCache path (InstalledCache ref) = liftIO $ do
    createTree (parent path)
    readIORef ref >>= taggedEncodeFile path

-- | Prune a list of possible packages down to those whose dependencies are met.
--
-- * id uniquely identifies an item
--
-- * There can be multiple items per name
pruneDeps
    :: (Ord name, Ord id)
    => (id -> name) -- ^ extract the name from an id
    -> (item -> id) -- ^ the id of an item
    -> (item -> [id]) -- ^ get the dependencies of an item
    -> (item -> item -> item) -- ^ choose the desired of two possible items
    -> [item] -- ^ input items
    -> Map name item
pruneDeps getName getId getDepends chooseBest =
      Map.fromList
    . (map $ \item -> (getName $ getId item, item))
    . loop Set.empty Set.empty []
  where
    loop foundIds usedNames foundItems dps =
        case partitionEithers $ map depsMet dps of
            ([], _) -> foundItems
            (s', dps') ->
                let foundIds' = Map.fromListWith chooseBest s'
                    foundIds'' = Set.fromList $ map getId $ Map.elems foundIds'
                    usedNames' = Map.keysSet foundIds'
                    foundItems' = Map.elems foundIds'
                 in loop
                        (Set.union foundIds foundIds'')
                        (Set.union usedNames usedNames')
                        (foundItems ++ foundItems')
                        (catMaybes dps')
      where
        depsMet dp
            | name `Set.member` usedNames = Right Nothing
            | all (`Set.member` foundIds) (getDepends dp) = Left (name, dp)
            | otherwise = Right $ Just dp
          where
            id' = getId dp
            name = getName id'

-- | Find the package IDs matching the given constraints with all dependencies installed.
-- Packages not mentioned in the provided @Map@ are allowed to be present too.
sinkMatching :: Monad m
             => Bool -- ^ require profiling?
             -> Bool -- ^ require haddock?
             -> Map PackageName Version -- ^ allowed versions
             -> Consumer (DumpPackage Bool Bool)
                         m
                         (Map PackageName (DumpPackage Bool Bool))
sinkMatching reqProfiling reqHaddock allowed = do
    dps <- CL.filter (\dp -> isAllowed (dpPackageIdent dp) &&
                             (not reqProfiling || dpProfiling dp) &&
                             (not reqHaddock || dpHaddock dp))
       =$= CL.consume
    return $ Map.fromList $ map (packageIdentifierName . dpPackageIdent &&& id) $ Map.elems $ pruneDeps
        id
        dpGhcPkgId
        dpDepends
        const -- Could consider a better comparison in the future
        dps
  where
    isAllowed (PackageIdentifier name version) =
        case Map.lookup name allowed of
            Just version' | version /= version' -> False
            _ -> True

-- | Add profiling information to the stream of @DumpPackage@s
addProfiling :: MonadIO m
             => InstalledCache
             -> Conduit (DumpPackage a b) m (DumpPackage Bool b)
addProfiling (InstalledCache ref) =
    CL.mapM go
  where
    go dp = liftIO $ do
        InstalledCacheInner m <- readIORef ref
        let gid = dpGhcPkgId dp
        p <- case Map.lookup gid m of
            Just installed -> return (installedCacheProfiling installed)
            Nothing | null (dpLibraries dp) -> return True
            Nothing -> do
                let loop [] = return False
                    loop (dir:dirs) = do
                        econtents <- tryIO $ getDirectoryContents dir
                        let contents = either (const []) id econtents
                        if or [isProfiling content lib
                              | content <- contents
                              , lib <- dpLibraries dp
                              ] && not (null contents)
                            then return True
                            else loop dirs
                loop $ dpLibDirs dp
        return dp { dpProfiling = p }

isProfiling :: FilePath -- ^ entry in directory
            -> ByteString -- ^ name of library
            -> Bool
isProfiling content lib =
    prefix `S.isPrefixOf` S8.pack content
  where
    prefix = S.concat ["lib", lib, "_p"]

-- | Add haddock information to the stream of @DumpPackage@s
addHaddock :: MonadIO m
           => InstalledCache
           -> Conduit (DumpPackage a b) m (DumpPackage a Bool)
addHaddock (InstalledCache ref) =
    CL.mapM go
  where
    go dp = liftIO $ do
        InstalledCacheInner m <- readIORef ref
        let gid = dpGhcPkgId dp
        h <- case Map.lookup gid m of
            Just installed -> return (installedCacheHaddock installed)
            Nothing | not (dpHasExposedModules dp) -> return True
            Nothing -> do
                let loop [] = return False
                    loop (ifc:ifcs) = do
                        exists <- doesFileExist ifc
                        if exists
                            then return True
                            else loop ifcs
                loop $ dpHaddockInterfaces dp
        return dp { dpHaddock = h }

-- | Dump information for a single package
data DumpPackage profiling haddock = DumpPackage
    { dpGhcPkgId :: !GhcPkgId
    , dpPackageIdent :: !PackageIdentifier
    , dpLibDirs :: ![FilePath]
    , dpLibraries :: ![ByteString]
    , dpHasExposedModules :: !Bool
    , dpDepends :: ![GhcPkgId]
    , dpHaddockInterfaces :: ![FilePath]
    , dpHaddockHtml :: !(Maybe FilePath)
    , dpProfiling :: !profiling
    , dpHaddock :: !haddock
    , dpIsExposed :: !Bool
    }
    deriving (Show, Eq, Ord)

data PackageDumpException
    = MissingSingleField ByteString (Map ByteString [Line])
    | Couldn'tParseField ByteString [Line]
    deriving Typeable
instance Exception PackageDumpException
instance Show PackageDumpException where
    show (MissingSingleField name values) = unlines $ concat
        [ return $ concat
            [ "Expected single value for field name "
            , show name
            , " when parsing ghc-pkg dump output:"
            ]
        , map (\(k, v) -> "    " ++ show (k, v)) (Map.toList values)
        ]
    show (Couldn'tParseField name ls) =
        "Couldn't parse the field " ++ show name ++ " from lines: " ++ show ls

-- | Convert a stream of bytes into a stream of @DumpPackage@s
conduitDumpPackage :: MonadThrow m
                   => Conduit ByteString m (DumpPackage () ())
conduitDumpPackage = (=$= CL.catMaybes) $ eachSection $ do
    pairs <- eachPair (\k -> (k, ) <$> CL.consume) =$= CL.consume
    let m = Map.fromList pairs
    let parseS k =
            case Map.lookup k m of
                Just [v] -> return v
                _ -> throwM $ MissingSingleField k m
        -- Can't fail: if not found, same as an empty list. See:
        -- https://github.com/fpco/stack/issues/182
        parseM k = fromMaybe [] (Map.lookup k m)

        parseDepend :: MonadThrow m => ByteString -> m (Maybe GhcPkgId)
        parseDepend "builtin_rts" = return Nothing
        parseDepend bs =
            liftM Just $ parseGhcPkgId bs'
          where
            (bs', _builtinRts) =
                case stripSuffixBS " builtin_rts" bs of
                    Nothing ->
                        case stripPrefixBS "builtin_rts " bs of
                            Nothing -> (bs, False)
                            Just x -> (x, True)
                    Just x -> (x, True)
    case Map.lookup "id" m of
        Just ["builtin_rts"] -> return Nothing
        _ -> do
            name <- parseS "name" >>= parsePackageName
            version <- parseS "version" >>= parseVersion
            ghcPkgId <- parseS "id" >>= parseGhcPkgId

            -- if a package has no modules, these won't exist
            let libDirKey = "library-dirs"
                libraries = parseM "hs-libraries"
                exposedModules = parseM "exposed-modules"
                exposed = parseM "exposed"
            depends <- mapM parseDepend $ parseM "depends"

            let parseQuoted key =
                    case mapM (P.parseOnly (argsParser NoEscaping) . T.decodeUtf8) val of
                        Left{} -> throwM (Couldn'tParseField key val)
                        Right dirs -> return (concat dirs)
                  where
                    val = parseM key
            libDirPaths <- parseQuoted libDirKey
            haddockInterfaces <- parseQuoted "haddock-interfaces"
            haddockHtml <- parseQuoted "haddock-html"

            return $ Just DumpPackage
                { dpGhcPkgId = ghcPkgId
                , dpPackageIdent = PackageIdentifier name version
                , dpLibDirs = libDirPaths
                , dpLibraries = S8.words $ S8.unwords libraries
                , dpHasExposedModules = not (null libraries || null exposedModules)
                , dpDepends = catMaybes (depends :: [Maybe GhcPkgId])
                , dpHaddockInterfaces = haddockInterfaces
                , dpHaddockHtml = listToMaybe haddockHtml
                , dpProfiling = ()
                , dpHaddock = ()
                , dpIsExposed = exposed == ["True"]
                }

stripPrefixBS :: ByteString -> ByteString -> Maybe ByteString
stripPrefixBS x y
    | x `S.isPrefixOf` y = Just $ S.drop (S.length x) y
    | otherwise = Nothing

stripSuffixBS :: ByteString -> ByteString -> Maybe ByteString
stripSuffixBS x y
    | x `S.isSuffixOf` y = Just $ S.take (S.length y - S.length x) y
    | otherwise = Nothing

-- | A single line of input, not including line endings
type Line = ByteString

-- | Apply the given Sink to each section of output, broken by a single line containing ---
eachSection :: Monad m
            => Sink Line m a
            -> Conduit ByteString m a
eachSection inner =
    CL.map (S.filter (/= _cr)) =$= CB.lines =$= start
  where
    _cr = 13

    peekBS = await >>= maybe (return Nothing) (\bs ->
        if S.null bs
            then peekBS
            else leftover bs >> return (Just bs))

    start = peekBS >>= maybe (return ()) (const go)

    go = do
        x <- toConsumer $ takeWhileC (/= "---") =$= inner
        yield x
        CL.drop 1
        start

-- | Grab each key/value pair
eachPair :: Monad m
         => (ByteString -> Sink Line m a)
         -> Conduit Line m a
eachPair inner =
    start
  where
    start = await >>= maybe (return ()) start'

    _colon = 58
    _space = 32

    start' bs1 =
        toConsumer (valSrc =$= inner key) >>= yield >> start
      where
        (key, bs2) = S.break (== _colon) bs1
        (spaces, bs3) = S.span (== _space) $ S.drop 1 bs2
        indent = S.length key + 1 + S.length spaces

        valSrc
            | S.null bs3 = noIndent
            | otherwise = yield bs3 >> loopIndent indent

    noIndent = do
        mx <- await
        case mx of
            Nothing -> return ()
            Just bs -> do
                let (spaces, val) = S.span (== _space) bs
                if S.length spaces == 0
                    then leftover val
                    else do
                        yield val
                        loopIndent (S.length spaces)

    loopIndent i =
        loop
      where
        loop = await >>= maybe (return ()) go

        go bs
            | S.length spaces == i && S.all (== _space) spaces =
                yield val >> loop
            | otherwise = leftover bs
          where
            (spaces, val) = S.splitAt i bs

-- | General purpose utility
takeWhileC :: Monad m => (a -> Bool) -> Conduit a m a
takeWhileC f =
    loop
  where
    loop = await >>= maybe (return ()) go

    go x
        | f x = yield x >> loop
        | otherwise = leftover x
