{-# LANGUAGE BangPatterns               #-}
{-# LANGUAGE ConstraintKinds            #-}
{-# LANGUAGE DataKinds                  #-}
{-# LANGUAGE DeriveDataTypeable         #-}
{-# LANGUAGE DeriveGeneric              #-}
{-# LANGUAGE FlexibleContexts           #-}
{-# LANGUAGE GADTs                      #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE KindSignatures             #-}
{-# LANGUAGE LambdaCase                 #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE PatternGuards              #-}
{-# LANGUAGE RankNTypes                 #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE TupleSections              #-}
{-# LANGUAGE ViewPatterns               #-}
{-# LANGUAGE ScopedTypeVariables        #-}

-- | Dealing with the 00-index file and all its cabal files.
module Stack.PackageIndex
    ( updateAllIndices
    , getPackageCaches
    , getPackageCachesIO
    , getPackageVersions
    , getPackageVersionsIO
    , lookupPackageVersions
    ) where

import qualified Codec.Archive.Tar as Tar
import           Control.Exception (Exception)
import           Control.Exception.Safe (tryIO)
import           Control.Monad (unless, when, liftM, void)
import           Control.Monad.Catch (throwM)
import qualified Control.Monad.Catch as C
import           Control.Monad.IO.Class (MonadIO, liftIO)
import           Control.Monad.Logger (logDebug, logInfo, logWarn, logError)
import           Control.Monad.Reader (asks)
import           Control.Monad.Trans.Control
import           Data.Aeson.Extended
import qualified Data.ByteString.Lazy as L
import           Data.Conduit (($$), (=$))
import           Data.Conduit.Binary (sinkHandle, sourceHandle)
import           Data.Conduit.Zlib (ungzip)
import           Data.Foldable (forM_)
import           Data.IORef
import           Data.Int (Int64)
import           Data.Map (Map)
import qualified Data.Map.Strict as Map
import           Data.Monoid
import           Data.Set (Set)
import qualified Data.Set as Set
import           Data.Store.Version
import           Data.Store.VersionTagged
import           Data.Streaming.Process (ProcessExitedUnsuccessfully(..))
import           Data.Text (Text)
import qualified Data.Text as T
import           Data.Text.Unsafe (unsafeTail)
import           Data.Traversable (forM)
import           Data.Typeable (Typeable)
import           Network.HTTP.Download
import           Path (mkRelDir, mkRelFile, parent, parseRelDir, toFilePath, parseAbsFile, (</>))
import           Path.IO
import           Prelude -- Fix AMP warning
import           Stack.Types.Config
import           Stack.Types.PackageIdentifier
import           Stack.Types.PackageIndex
import           Stack.Types.PackageName
import           Stack.Types.StackT
import           Stack.Types.Version
import           System.FilePath (takeBaseName, (<.>))
import           System.IO (IOMode (ReadMode, WriteMode), withBinaryFile)
import           System.Process.Read (EnvOverride, ReadProcessException(..), doesExecutableExist, readProcessNull, tryProcessStdout)
import           System.Process.Run (Cmd(..), callProcessInheritStderrStdout)
import           System.Exit (exitFailure)

-- | Populate the package index caches and return them.
populateCache
    :: (StackMiniM env m, HasConfig env)
    => EnvOverride
    -> PackageIndex
    -> m (Map PackageIdentifier PackageCache)
populateCache menv index = do
    requireIndex menv index
    -- This uses full on lazy I/O instead of ResourceT to provide some
    -- protections. Caveat emptor
    path <- configPackageIndex (indexName index)
    let loadPIS = do
            $logSticky "Populating index cache ..."
            lbs <- liftIO $ L.readFile $ Path.toFilePath path
            loop 0 Map.empty (Tar.read lbs)
    pis <- loadPIS `C.catch` \e -> do
        $logWarn $ "Exception encountered when parsing index tarball: "
                <> T.pack (show (e :: Tar.FormatError))
        $logWarn "Automatically updating index and trying again"
        updateIndex menv index
        loadPIS

    when (indexRequireHashes index) $ forM_ (Map.toList pis) $ \(ident, pc) ->
        case pcDownload pc of
            Just _ -> return ()
            Nothing -> throwM $ MissingRequiredHashes (indexName index) ident

    $logStickyDone "Populated index cache."

    return pis
  where
    loop !blockNo !m (Tar.Next e es) =
        loop (blockNo + entrySizeInBlocks e) (goE blockNo m e) es
    loop _ m Tar.Done = return m
    loop _ _ (Tar.Fail e) = throwM e

    goE blockNo m e =
        case Tar.entryContent e of
            Tar.NormalFile lbs size ->
                case parseNameVersion $ Tar.entryPath e of
                    Just (ident, ".cabal") -> addCabal ident size
                    Just (ident, ".json") -> addJSON ident lbs
                    _ -> m
            _ -> m
      where
        addCabal ident size = Map.insertWith
            (\_ pcOld -> pcNew { pcDownload = pcDownload pcOld })
            ident
            pcNew
            m
          where
            pcNew = PackageCache
                { pcOffset = (blockNo + 1) * 512
                , pcSize = size
                , pcDownload = Nothing
                }
        addJSON ident lbs =
            case decode lbs of
                Nothing -> m
                Just !pd -> Map.insertWith
                    (\_ pc -> pc { pcDownload = Just pd })
                    ident
                    PackageCache
                        { pcOffset = 0
                        , pcSize = 0
                        , pcDownload = Just pd
                        }
                    m

    breakSlash x
        | T.null z = Nothing
        | otherwise = Just (y, unsafeTail z)
      where
        (y, z) = T.break (== '/') x

    parseNameVersion t1 = do
        (p', t3) <- breakSlash
                  $ T.map (\c -> if c == '\\' then '/' else c)
                  $ T.pack t1
        p <- parsePackageName p'
        (v', t5) <- breakSlash t3
        v <- parseVersion v'
        let (t6, suffix) = T.break (== '.') t5
        if t6 == p'
            then return (PackageIdentifier p v, suffix)
            else Nothing

data PackageIndexException
  = GitNotAvailable IndexName
  | MissingRequiredHashes IndexName PackageIdentifier
  deriving Typeable
instance Exception PackageIndexException
instance Show PackageIndexException where
    show (GitNotAvailable name) = concat
        [ "Package index "
        , T.unpack $ indexNameText name
        , " only provides Git access, and you do not have"
        , " the git executable on your PATH"
        ]
    show (MissingRequiredHashes name ident) = concat
        [ "Package index "
        , T.unpack $ indexNameText name
        , " is configured to require package hashes, but no"
        , " hash is available for "
        , packageIdentifierString ident
        ]

-- | Require that an index be present, updating if it isn't.
requireIndex :: (StackMiniM env m, HasConfig env)
             => EnvOverride -> PackageIndex -> m ()
requireIndex menv index = do
    tarFile <- configPackageIndex $ indexName index
    exists <- doesFileExist tarFile
    unless exists $ updateIndex menv index

-- | Update all of the package indices
updateAllIndices :: (StackMiniM env m, HasConfig env)
                 => EnvOverride -> m ()
updateAllIndices menv = do
    clearPackageCaches
    asks (configPackageIndices . getConfig) >>= mapM_ (updateIndex menv)

-- | Update the index tarball
updateIndex :: (StackMiniM env m, HasConfig env)
            => EnvOverride -> PackageIndex -> m ()
updateIndex menv index =
  do let name = indexName index
         logUpdate mirror = $logSticky $ "Updating package index " <> indexNameText (indexName index) <> " (mirrored at " <> mirror  <> ") ..."
     git <- isGitInstalled menv
     case (git, indexLocation index) of
        (True, ILGit url) -> logUpdate url >> updateIndexGit menv name index url
        (True, ILGitHttp url _) -> logUpdate url >> updateIndexGit menv name index url
        (_, ILHttp url) -> logUpdate url >> updateIndexHTTP name index url
        (False, ILGitHttp _ url) -> logUpdate url >> updateIndexHTTP name index url
        (False, ILGit url) -> logUpdate url >> throwM (GitNotAvailable name)

-- | Update the index Git repo and the index tarball
updateIndexGit :: (StackMiniM env m, HasConfig env)
               => EnvOverride
               -> IndexName
               -> PackageIndex
               -> Text -- ^ Git URL
               -> m ()
updateIndexGit menv indexName' index gitUrl = do
     tarFile <- configPackageIndex indexName'
     let idxPath = parent tarFile
     ensureDir idxPath
     do
            repoName <- parseRelDir $ takeBaseName $ T.unpack gitUrl
            let cloneArgs =
                  ["clone"
                  ,T.unpack gitUrl
                  ,toFilePath repoName
                  ,"-b" --
                  ,"display"]
            sDir <- configPackageIndexRoot indexName'
            let suDir =
                  sDir </>
                  $(mkRelDir "git-update")
                acfDir = suDir </> repoName
            repoExists <- doesDirExist acfDir
            let doClone = readProcessNull (Just suDir) menv "git" cloneArgs
            unless repoExists doClone
            isShallow <- doesFileExist $ acfDir </> $(mkRelDir ".git") </> $(mkRelFile "shallow")
            when isShallow $ do
              $logWarn "Shallow package index repo detected, transitioning to a full clone..."
              let handleUnshallowError =
                    C.handle $ \case
                      ProcessFailed{} -> do
                        $logInfo $ "Failed to convert to full clone, deleting and re-cloning."
                        ignoringAbsence (removeDirRecur acfDir)
                        doClone
                      err -> throwM err
              -- See https://github.com/commercialhaskell/stack/issues/2748
              -- for an explanation of --git-dir=.git
              handleUnshallowError $
                  readProcessNull (Just acfDir) menv "git"
                                  ["--git-dir=.git", "fetch", "--unshallow"]
            $logSticky "Fetching package index ..."
            let runFetch = callProcessInheritStderrStdout
                    (Cmd (Just acfDir) "git" menv ["--git-dir=.git","fetch","--tags"])
            runFetch `C.catch` \(ex :: ProcessExitedUnsuccessfully) -> do
                -- we failed, so wipe the directory and try again, see #1418
                $logWarn (T.pack (show ex))
                $logStickyDone "Failed to fetch package index, retrying."
                removeDirRecur acfDir
                readProcessNull (Just suDir) menv "git" cloneArgs
                $logSticky "Fetching package index ..."
                runFetch
            $logStickyDone "Fetched package index."

            when (indexGpgVerify index) $ do
                 result <- C.try $ readProcessNull (Just acfDir) menv "git" ["--git-dir=.git","tag","-v","current-hackage"]
                 case result of
                     Left ex -> do
                         $logError (T.pack (show ex))
                         case ex of
                             ProcessFailed{} -> $logError $ T.unlines
                                 ["Signature verification failed. "
                                 ,"Please ensure you've set up your"
                                 ,"GPG keychain to accept the D6CF60FD signing key."
                                 ,"For more information, see:"
                                 ,"https://github.com/fpco/stackage-update#readme"]
                             _ -> return ()
                         liftIO exitFailure
                     Right () -> return ()
            -- generate index archive when commit id differs from cloned repo
            tarId <- getTarCommitId (toFilePath tarFile)
            cloneId <- getCloneCommitId acfDir
            unless (tarId `equals` cloneId)
                (generateArchive acfDir tarFile)
   where
     getTarCommitId fp =
         tryProcessStdout Nothing menv "sh" ["-c","git get-tar-commit-id < "++fp]

     getCloneCommitId dir =
         tryProcessStdout (Just dir) menv "git" ["rev-parse","current-hackage^{}"]

     equals (Right cid1) (Right cid2) = cid1 == cid2
     equals _ _ = False

     generateArchive acfDir tarFile = do
         ignoringAbsence (removeFile tarFile)
         deleteCache indexName'
         $logDebug ("Exporting a tarball to " <> (T.pack . toFilePath) tarFile)
         let tarFileTmp = toFilePath tarFile ++ ".tmp"
         readProcessNull (Just acfDir) menv
             "git" ["--git-dir=.git","archive","--format=tar","-o",tarFileTmp,"current-hackage"]
         tarFileTmpPath <- parseAbsFile tarFileTmp
         renameFile tarFileTmpPath tarFile

-- | Update the index tarball via HTTP
updateIndexHTTP :: (StackMiniM env m, HasConfig env)
                => IndexName
                -> PackageIndex
                -> Text -- ^ url
                -> m ()
updateIndexHTTP indexName' index url = do
    req <- parseRequest $ T.unpack url
    $logInfo ("Downloading package index from " <> url)
    gz <- configPackageIndexGz indexName'
    tar <- configPackageIndex indexName'
    wasDownloaded <- redownload req gz
    toUnpack <-
        if wasDownloaded
            then return True
            else not `liftM` doesFileExist tar

    when toUnpack $ do
        let tmp = toFilePath tar <.> "tmp"
        tmpPath <- parseAbsFile tmp

        deleteCache indexName'

        liftIO $ do
            withBinaryFile (toFilePath gz) ReadMode $ \input ->
                withBinaryFile tmp WriteMode $ \output ->
                    sourceHandle input
                    $$ ungzip
                    =$ sinkHandle output
            renameFile tmpPath tar

    when (indexGpgVerify index)
        $ $logWarn
        $ "You have enabled GPG verification of the package index, " <>
          "but GPG verification only works with Git downloading"

-- | Is the git executable installed?
isGitInstalled :: MonadIO m
               => EnvOverride
               -> m Bool
isGitInstalled = flip doesExecutableExist "git"

-- | Delete the package index cache
deleteCache
    :: (StackMiniM env m, HasConfig env)
    => IndexName -> m ()
deleteCache indexName' = do
    fp <- configPackageIndexCache indexName'
    eres <- liftIO $ tryIO $ removeFile fp
    case eres of
        Left e -> $logDebug $ "Could not delete cache: " <> T.pack (show e)
        Right () -> $logDebug $ "Deleted index cache at " <> T.pack (toFilePath fp)

-- | Lookup a package's versions from 'IO'.
getPackageVersionsIO
    :: (StackMiniM env m, HasConfig env)
    => m (PackageName -> IO (Set Version))
getPackageVersionsIO = do
    getCaches <- getPackageCachesIO
    return $ \name ->
        fmap (lookupPackageVersions name) getCaches

-- | Get the known versions for a given package from the package caches.
--
-- See 'getPackageCaches' for performance notes.
getPackageVersions
    :: (StackMiniM env m, HasConfig env)
    => PackageName
    -> m (Set Version)
getPackageVersions pkgName =
    fmap (lookupPackageVersions pkgName) getPackageCaches

lookupPackageVersions :: PackageName -> Map PackageIdentifier a -> Set Version
lookupPackageVersions pkgName pkgCaches =
    Set.fromList [v | PackageIdentifier n v <- Map.keys pkgCaches, n == pkgName]

-- | Access the package caches from 'IO'.
--
-- FIXME: This is a temporary solution until a better solution
-- to access the package caches from Stack.Build.ConstructPlan
-- has been found.
getPackageCachesIO
    :: (StackMiniM env m, HasConfig env)
    => m (IO (Map PackageIdentifier (PackageIndex, PackageCache)))
getPackageCachesIO = toIO getPackageCaches
  where
    toIO :: (MonadIO m, MonadBaseControl IO m) => m a -> m (IO a)
    toIO m = do
        runInBase <- liftBaseWith $ \run -> return (void . run)
        return $ do
            i <- newIORef (error "Impossible evaluation in toIO")
            runInBase $ do
                x <- m
                liftIO $ writeIORef i x
            readIORef i

-- | Load the package caches, or create the caches if necessary.
--
-- This has two levels of caching: in memory, and the on-disk cache. So,
-- feel free to call this function multiple times.
getPackageCaches
    :: (StackMiniM env m, HasConfig env)
    => m (Map PackageIdentifier (PackageIndex, PackageCache))
getPackageCaches = do
    menv <- getMinimalEnvOverride
    config <- askConfig
    mcached <- liftIO $ readIORef (configPackageCaches config)
    case mcached of
        Just cached -> return cached
        Nothing -> do
            result <- liftM mconcat $ forM (configPackageIndices config) $ \index -> do
                fp <- configPackageIndexCache (indexName index)
                PackageCacheMap pis' <-
                    $(versionedDecodeOrLoad (storeVersionConfig "pkg-v1" "aHzcZ6_w3rL6NtEJUqEfh6fcjAc="
                                             :: VersionConfig PackageCacheMap))
                    fp
                    (liftM PackageCacheMap (populateCache menv index))
                return (fmap (index,) pis')
            liftIO $ writeIORef (configPackageCaches config) (Just result)
            return result

-- | Clear the in-memory hackage index cache. This is needed when the
-- hackage index is updated.
clearPackageCaches :: (StackMiniM env m, HasConfig env) => m ()
clearPackageCaches = do
    cacheRef <- asks (configPackageCaches . getConfig)
    liftIO $ writeIORef cacheRef Nothing

--------------- Lifted from cabal-install, Distribution.Client.Tar:
-- | Return the number of blocks in an entry.
entrySizeInBlocks :: Tar.Entry -> Int64
entrySizeInBlocks entry = 1 + case Tar.entryContent entry of
  Tar.NormalFile     _   size -> bytesToBlocks size
  Tar.OtherEntryType _ _ size -> bytesToBlocks size
  _                           -> 0
  where
    bytesToBlocks s = 1 + ((fromIntegral s - 1) `div` 512)