import           Control.Concurrent
import           Control.Exception
import           Control.Monad ((<=<), void, unless)
import           Data.Function
import qualified Data.Map.Strict as Map
import           Data.Maybe
import           Data.Monoid
import           Data.Monoid.Generic
import           Data.List
import qualified Data.Set as Set
import           Data.String
import qualified Database.PostgreSQL.Simple as PG
import qualified Database.PostgreSQL.Simple.Options as Client
import           Database.Postgres.Temp.Internal
import           Database.Postgres.Temp.Internal.Config
import           Database.Postgres.Temp.Internal.Core
import           GHC.Generics (Generic)
-- import qualified Network.Socket as N
import           Network.Socket.Free
import           System.Directory
import           System.Environment
import           System.Exit
import           System.IO.Error
import           System.IO.Temp
import           System.Posix.Files
import           System.Process
import           System.Timeout
import           Test.Hspec

withConn :: DB -> (PG.Connection -> IO a) -> IO a
withConn db f = do
  let connStr = toConnectionString db
  bracket (PG.connectPostgreSQL connStr) PG.close f

withConfig' :: Config -> (DB -> IO a) -> IO a
withConfig' config = either throwIO pure <=< withConfig config

countPostgresProcesses :: IO Int
countPostgresProcesses = countProcesses "postgres"

countInitdbProcesses :: IO Int
countInitdbProcesses = countProcesses "initdb"

countCreatedbProcesses :: IO Int
countCreatedbProcesses = countProcesses "createdb"

countProcesses :: String -> IO Int
countProcesses processName = do
  -- TODO we should restrict to child process
  (exitCode, xs, _) <-  readProcessWithExitCode "pgrep" [processName] []

  unless (exitCode == ExitSuccess || exitCode == ExitFailure 1) $ throwIO exitCode

  pure $ length $ lines xs

assertConnection :: DB -> IO ()
assertConnection db = do
  one <- fmap (PG.fromOnly . head) $
      withConn db $ \conn -> PG.query_ conn "SELECT 1"

  one `shouldBe` (1 :: Int)

testSuccessfulConfigNoTmp :: ConfigAndAssertion -> IO ()
testSuccessfulConfigNoTmp ConfigAndAssertion {..} = do
  initialPostgresCount <- countPostgresProcesses
  initialInitdbCount <- countInitdbProcesses
  initialCreatedbCount <- countCreatedbProcesses

  withConfig' cConfig $ \db -> do
    cAssert db
    assertConnection db

  countPostgresProcesses `shouldReturn` initialPostgresCount
  countInitdbProcesses `shouldReturn` initialInitdbCount
  countCreatedbProcesses `shouldReturn` initialCreatedbCount

testSuccessfulConfig :: ConfigAndAssertion -> IO ()
testSuccessfulConfig configAssert@ConfigAndAssertion{..} = do
  -- get the temp listing before
  let tmpDir = fromMaybe (error "test is bad")
        $ getLast $ temporaryDirectory cConfig
  initialContents <- listDirectory tmpDir
  testSuccessfulConfigNoTmp configAssert
  -- get the temp listing after
  listDirectory tmpDir `shouldReturn` initialContents

testWithTemporaryDirectory :: ConfigAndAssertion -> (ConfigAndAssertion -> IO a) -> IO a
testWithTemporaryDirectory x f =
  withTempDirectory "/tmp" "tmp-postgres-spec" $ \directoryPath ->
    f x
      { cConfig = (cConfig x) { temporaryDirectory = pure directoryPath }
      , cAssert = cAssert x <> (\db -> toTemporaryDirectory db `shouldBe` directoryPath)
      }

data ConfigAndAssertion = ConfigAndAssertion
  { cConfig :: Config
  , cAssert :: DB -> IO ()
  }
  deriving (Generic)
  deriving Semigroup via GenericSemigroup ConfigAndAssertion
  deriving Monoid    via GenericMonoid ConfigAndAssertion

-- Set all the things we support

memptyConfigAndAssertion :: ConfigAndAssertion
memptyConfigAndAssertion = memptyConfigAndAssertion' "postgres"

memptyConfigAndAssertion' :: String -> ConfigAndAssertion
memptyConfigAndAssertion' expectedDbName =
  let
    cConfig = mempty
    cAssert db = do
      let
        Client.Options {..} = toConnectionOptions db
        Last (Just hostString) = host
      -- I'm assuming here that I'm going to test
      -- with this prefix
      hostString `shouldStartWith` "/tmp/tmp-postgres-"
      -- Ephemeral range
      let Just thePort = getLast port
      thePort `shouldSatisfy` (>32768)
      toDataDirectory db `shouldStartWith` "/tmp/tmp-postgres-"
      dbname `shouldBe` pure expectedDbName

  in ConfigAndAssertion {..}

optionsToDefaultConfigMempty :: ConfigAndAssertion
optionsToDefaultConfigMempty = memptyConfigAndAssertion
  { cConfig = optionsToDefaultConfig mempty
  }

-- can't be combined
optionsToDefaultConfigSocket :: FilePath -> ConfigAndAssertion
optionsToDefaultConfigSocket socketPath =
  let
    cConfig = optionsToDefaultConfig mempty
      { Client.host = pure socketPath
      }
    cAssert db = do
      let
        Client.Options {..} = toConnectionOptions db
        Last (Just hostString) = host
      -- I'm assuming here that I'm going to test
      -- with this prefix
      hostString `shouldStartWith` "/tmp/tmp-postgres-"

  in ConfigAndAssertion {..}

optionsToDefaultConfigFilledOutConfigAssert :: Int -> ConfigAndAssertion
optionsToDefaultConfigFilledOutConfigAssert expectedPort =
  let
    expectedDbName   = "foobar"
    expectedUser     = "some_user"
    expectedPassword = "password"
    expectedHost     = "localhost"

    cConfig = optionsToDefaultConfig mempty
      { Client.port     = pure expectedPort
      , Client.dbname   = pure expectedDbName
      , Client.user     = pure expectedUser
      , Client.password = pure expectedPassword
      , Client.host     = pure expectedHost
      }

    cAssert db = do
      let Client.Options {..} = toConnectionOptions db
      port     `shouldBe` pure expectedPort
      user     `shouldBe` pure expectedUser
      dbname   `shouldBe` pure expectedDbName
      password `shouldBe` pure expectedPassword
      host     `shouldBe` pure expectedHost

  in ConfigAndAssertion {..}

extraConfigAssert :: ConfigAndAssertion
extraConfigAssert =
  let
    cConfig = mempty
        { postgresConfigFile = [("log_min_duration_statement","'100ms'")]
        }

    cAssert db = withConn db $ \conn -> do
      [PG.Only actualDuration] <- PG.query_ conn "SHOW log_min_duration_statement"
      actualDuration `shouldBe` ("100ms" :: String)

  in ConfigAndAssertion {..}

defaultIpConfig :: ConfigAndAssertion
defaultIpConfig =
  let
    cConfig = mempty
      { connectionOptions = mempty
        { Client.host = pure "127.0.0.1"
        }
      }

    cAssert db = do
      let Client.Options {..} = toConnectionOptions db
      host `shouldBe` pure "127.0.0.1"

  in ConfigAndAssertion {..}


specificUnixSocket :: FilePath -> ConfigAndAssertion
specificUnixSocket filePath =
  let
    cConfig = mempty
      { socketDirectory = Permanent filePath
      }
    cAssert db = do
      let
        Client.Options {..} = toConnectionOptions db
        Last (Just hostString) = host
      -- I'm assuming here that I'm going to test
      -- with this prefix
      hostString `shouldStartWith` filePath

  in ConfigAndAssertion {..}

defaultConfigAssert :: ConfigAndAssertion
defaultConfigAssert = ConfigAndAssertion defaultConfig mempty

createdbAndDescription :: ConfigAndAssertion
createdbAndDescription =
  let
    expectedDescription = "newdb description"
    cConfig = mempty
          { createDbConfig = pure silentProcessConfig
              { commandLine = mempty
                { indexBased = Map.fromList
                    [ (0, "newdb")
                    , (1, expectedDescription)
                    ]
                }
              }
          }

    cAssert db = withConn db $ \conn -> do
      [PG.Only actualDescription] <- PG.query_ conn $ fromString $ unlines
        [ "SELECT description FROM pg_shdescription"
        , "JOIN pg_database ON objoid = pg_database.oid"
        , "WHERE datname = 'newdb'"
        ]
      actualDescription `shouldBe` expectedDescription
  in ConfigAndAssertion {..}

happyPaths :: Spec
happyPaths = describe "succeeds with" $ do
  it "mempty and extra postgresql.conf" $
    testWithTemporaryDirectory
      (defaultConfigAssert <> memptyConfigAndAssertion <> extraConfigAssert)
      testSuccessfulConfig

  it "optionsToDefaultConfig mempty is the same as mempty Config" $
    testWithTemporaryDirectory
      optionsToDefaultConfigMempty
      testSuccessfulConfig

  it "postgres db name does not cause createdb failure" $ do
    testWithTemporaryDirectory
      (  defaultConfigAssert
      <> memptyConfigAndAssertion
      <> ConfigAndAssertion (optionsToDefaultConfig mempty { Client.dbname = pure "postgres" }) mempty
      )
      testSuccessfulConfig

  it "template1 db name does not cause createdb failure" $ do
    testWithTemporaryDirectory
      (  defaultConfigAssert
      <> memptyConfigAndAssertion' "template1"
      <> ConfigAndAssertion (optionsToDefaultConfig mempty { Client.dbname = pure "template1" }) mempty
      )
      testSuccessfulConfig

  it "specific socket works with optionsToDefaultConfig" $
    withTempDirectory "/tmp" "tmp-postgres-spec-socket" $ \socketFilePath ->
      testWithTemporaryDirectory
        (optionsToDefaultConfigSocket socketFilePath)
        testSuccessfulConfig

  it "filled out optionsToDefaultConfig" $ do
    thePort <- getFreePort
    testWithTemporaryDirectory
      (optionsToDefaultConfigFilledOutConfigAssert thePort)
      testSuccessfulConfig

  it "default ip option works" $
    testWithTemporaryDirectory
      (defaultConfigAssert <> defaultIpConfig)
      testSuccessfulConfig

  it "specific unix socket works" $
    withTempDirectory "/tmp" "tmp-postgres-spec-socket" $ \socketFilePath ->
      testWithTemporaryDirectory
        (defaultConfigAssert <> specificUnixSocket socketFilePath)
        testSuccessfulConfig

  it "works with the default temporary directory to some degree at least" $
    testSuccessfulConfigNoTmp $ defaultConfigAssert <>
      memptyConfigAndAssertion <> createdbAndDescription

  it "works if on non-empty if initdb is disabled" $
    withTempDirectory "/tmp" "tmp-postgres-preinitdb" $ \dirPath -> do
      throwIfNotSuccess id . (\(x, _, _) -> x) =<<
        readProcessWithExitCode "initdb" [dirPath] ""
      let nonEmptyFolderConfig = memptyConfigAndAssertion
            { cConfig = defaultConfig
              { dataDirectory = Permanent dirPath
              , initDbConfig = Zlich
              }
            }
      testWithTemporaryDirectory nonEmptyFolderConfig testSuccessfulConfig

  it "makeResourcesDataDirPermanent works" $
    withTempDirectory "/tmp" "tmp-postgres-make-premanent" $ \dirPath -> do
       let config = defaultConfig { temporaryDirectory = pure dirPath }
       pathToCheck <- bracket (either throwIO (pure . makeDataDirectoryPermanent) =<< startConfig config) stop $
        pure . toDataDirectory
       doesDirectoryExist pathToCheck >>= \case
         True -> pure ()
         False -> fail "temporary file was not made permanent"

  it "withDbCacheConfig actually caches the config and cleans up" $
    withTempDirectory "/tmp" "tmp-postgres-cache-test" $ \dirPath -> do
      let config = defaultConfig { temporaryDirectory = pure dirPath }
          theCacheConfig = CacheConfig
            { cacheTemporaryDirectory = dirPath
            , cacheDirectoryType      = Temporary
            , cacheUseCopyOnWrite     = True
            }
      withDbCacheConfig theCacheConfig $ \cacheInfo -> do
        withConfig' (config <> cacheConfig cacheInfo) $ const $ pure ()
        -- see if there is a cache
        tmpFiles <- listDirectory dirPath

        cacheDir <- case filter ("tmp-postgres-cache" `isPrefixOf`) tmpFiles of
          [x] -> pure x
          xs -> fail $ "expected single cache dir got: " <> show xs

        listDirectory (dirPath <> "/" <> cacheDir) >>= \case
          [versionDir] -> listDirectory  (dirPath <> "/" <> cacheDir <> "/" <> versionDir) >>= \case
            [initDbCacheDir] ->
              writeFile
                (  dirPath
                <> "/"
                <> cacheDir
                <> "/"
                <> versionDir
                <> "/"
                <> initDbCacheDir
                <> "/data/cacheCheck.txt"
                )
                "test"
            xs -> fail $ "expected a single initdb cache directory but got " <> show xs
          xs -> fail $ "expected a single version directory but got " <> show xs

        -- add a file to look for later
        withConfig' (config <> cacheConfig cacheInfo) $ \db -> do
          -- see if the file is in the data directory
          let theDataDirectory = toDataDirectory db
          xs <- listDirectory theDataDirectory
          xs `shouldContain` ["cacheCheck.txt"]

          assertConnection db

      -- See if cache has been cleaned up
      tmpFiles <- listDirectory dirPath

      case filter ("tmp-postgres-cache" `isPrefixOf`) tmpFiles of
        [] -> pure ()
        xs -> fail $ "unexpected cache dirs. Should be cleaned up. Got: " <> show xs

  it "withDbCache seems to work" $
    withDbCache $ \cacheInfo ->
      either throwIO pure =<< withConfig (cacheConfig cacheInfo) assertConnection

  it "postgresql.conf append last wins" $
    withConfig' (defaultPostgresConf [("fsync", "on")]) $ \db -> do
      toPostgresqlConfigFile db `shouldContain` "fsync=on"
--
-- Error Plans. Can't be combined. Just list them out inline since they can't be combined
--

errorPaths :: Spec
errorPaths = describe "fails when" $ do
  -- Should this test ensure that atleast a single connection
  -- attempt was made? probably.
  it "timesout if the connection parameters are wrong" $ do
    let invalidConfig = mempty
          { connectionTimeout = pure 0
          , connectionOptions = mempty
                  { Client.dbname = pure "doesnotexist"
                  }
          }

    withConfig (defaultConfig <> invalidConfig) (const $ pure ())
      `shouldReturn` Left ConnectionTimedOut

  it "does not timeout quickly with an invalid connection and large timeout" $ do
    let invalidConfig = mempty
          { connectionTimeout = pure maxBound
          , connectionOptions = mempty
                  { Client.dbname = pure "doesnotexist"
                  }
          }

    timeout 100000 (withConfig (defaultConfig <> invalidConfig) (const $ pure ()))
      `shouldReturn` Nothing
{-
  it "throws StartPostgresFailed if the port is taken" $
    bracket openFreePort (N.close . snd) $ \(thePort, _) -> do
      let invalidConfig' = optionsToDefaultConfig mempty
            { Client.port = pure thePort
            , Client.host = pure "127.0.0.1"
            } <> verboseConfig

          invalidConfig = invalidConfig'
            { plan = (plan invalidConfig')
                { connectionTimeout = pure 1000000
                }
            }

      withConfig invalidConfig (const $ pure ())
        `shouldReturn` Left (StartPostgresFailed $ ExitFailure 1)
-}
  it "throws StartPostgresFailed if the host does not exist" $ do
    let invalidConfig = optionsToDefaultConfig mempty
          { Client.host = pure "focalhost"
          }

        invalidConfig' = invalidConfig
          { connectionTimeout = pure 100000
          }
    withConfig invalidConfig' (const $ pure ())
      `shouldReturn` Left ConnectionTimedOut

  it "throws StartPostgresFailed if the host does not resolve to ip that is local" $ do
    let invalidConfig = optionsToDefaultConfig mempty
          { Client.host = pure "yahoo.com"
          }

        invalidConfig' = invalidConfig
          { connectionTimeout = pure 100000
          }

    withConfig invalidConfig' (const $ pure ())
      `shouldReturn` Left ConnectionTimedOut

  it "throws IOException if the path is not writable" $ do
    let invalidConfig = optionsToDefaultConfig mempty
          { Client.host = pure "/focalhost"
          }
    withConfig invalidConfig (const $ pure ()) >>= \case
      Left CompleteDirectoryFailed {} -> pure ()
      _ -> fail "expected Left CompleteDirectoryFailed"

  it "No initdb plan causes failure" $ do
    let dontTimeout = defaultConfig
          { connectionTimeout = pure maxBound
          , initDbConfig = Zlich
          }

    withConfig dontTimeout (const $ pure ())
      `shouldReturn` Left EmptyDataDirectory

  it "initdb with non-empty data directory fails with InitDbFailed" $
    withTempDirectory "/tmp" "tmp-postgres-test" $ \dirPath -> do
      writeFile (dirPath <> "/PG_VERSION") "1 million"
      let nonEmptyFolderPlan = defaultConfig
            { dataDirectory = Permanent dirPath
            }

      withConfig nonEmptyFolderPlan mempty >>= \case
        Right () -> fail "Should not succeed"
        Left ((InitDbFailed _ _ code)) ->
          code `shouldBe` ExitFailure 1
        Left err -> fail $ "Wrong type of error " <> show err

  it "invalid initdb options cause an error" $ do
    let invalidConfig = defaultConfig
          { initDbConfig = pure silentProcessConfig
            { commandLine = mempty
              { keyBased = Map.singleton "--super-sync" Nothing
              }
            }
          }

    withConfig invalidConfig (const $ pure ()) >>= \case
      Right () -> fail "Should not succeed"
      Left (InitDbFailed {}) -> pure ()
      Left err -> fail $ "Wrong type of error " <> show err

  it "invalid createdb plan causes an error" $ do
    let invalidConfig = defaultConfig
          { createDbConfig = pure silentProcessConfig
            { commandLine = mempty
              { indexBased =
                  Map.singleton 0 "template1"
              }
            }
          }

    withConfig invalidConfig (const $ pure ()) >>= \case
      Right () -> fail "Should not succeed"
      Left (CreateDbFailed {}) -> pure ()
      Left err -> fail $ "Wrong type of error " <> show err

  it "throws if initdb is not on the path" $ do
    path <-  getEnv "PATH"

    bracket (setEnv "PATH" "/bin") (const $ setEnv "PATH" path) $ \_ ->
      withConfig defaultConfig (const $ pure ())
        `shouldThrow` isDoesNotExistError

  it "throws if createdb is not on the path" $
    withTempDirectory "/tmp" "createdb-not-on-path-test" $ \dir -> do
      Just initDbPath   <- findExecutable "initdb"
      Just postgresPath <- findExecutable "postgres"
      Just rmPath       <- findExecutable "rm"
      Just chmod        <- findExecutable "chmod"

      -- create symlinks
      createSymbolicLink initDbPath $ dir <> "/initdb"
      createSymbolicLink postgresPath $ dir <> "/postgres"
      createSymbolicLink rmPath $ dir <> "/rm"
      createSymbolicLink chmod $ dir <> "/chmod"

      path <-  getEnv "PATH"

      let config = defaultConfig
                { createDbConfig = pure mempty
                }

      bracket (setEnv "PATH" dir) (const $ setEnv "PATH" path) $ \_ ->
        withConfig config (const $ pure ())
          `shouldThrow` isDoesNotExistError

withConfigSpecs :: Spec
withConfigSpecs = describe "withConfig" $ do
  happyPaths
  errorPaths

withSnapshotSpecs :: Spec
withSnapshotSpecs = describe "withSnapshot" $ do
  it "works" $ withConfig' defaultConfig $ \db -> do
    withConn db $ \conn -> do
      _ <- PG.execute_ conn "BEGIN; CREATE TABLE foo ( id int );"
      void $ PG.execute_ conn "INSERT INTO foo (id) VALUES (1); END;"

    either throwIO pure <=< withSnapshot Temporary db $ \snapshotDir -> do
      let theSnapshotConfig = defaultConfig <> snapshotConfig snapshotDir
          snapshotConfigAndAssert = ConfigAndAssertion theSnapshotConfig $ flip withConn $ \conn -> do
            oneAgain <- fmap (PG.fromOnly . head) $ PG.query_ conn "SELECT id FROM foo"
            oneAgain `shouldBe` (1 :: Int)

      testWithTemporaryDirectory
        snapshotConfigAndAssert
        testSuccessfulConfig

  it "doesn't create the snapshot if it exists" $ withConfig' defaultConfig $ \db -> do
    withConn db $ \conn -> do
      _ <- PG.execute_ conn "BEGIN; CREATE TABLE foo ( id int );"
      void $ PG.execute_ conn "INSERT INTO foo (id) VALUES (1); END;"

    either throwIO pure <=< withSnapshot (Permanent $ "~/.tmp-postgres/test-snapshot/") db $ \snapshotDir -> do
      let theSnapshotConfig = defaultConfig <> snapshotConfig snapshotDir
      -- A file to the snapshot directory
      writeFile (toFilePath (unSnapshot snapshotDir) <> "/testModification.txt") "yes"
      -- start postgres
      withConfig' theSnapshotConfig $ \newDb -> do
        -- modify it in the data directory
        writeFile (toDataDirectory newDb <> "/testModification.txt") "no"
        -- add a new file
        writeFile (toDataDirectory newDb <> "/newFile.txt") "yes"
        -- take another snapshot
        either throwIO pure <=< withSnapshot (Permanent $ "~/.tmp-postgres/test-snapshot") db $ \snapshotDir1 -> do
          -- ensure the original is still there
          readFile (toFilePath (unSnapshot snapshotDir1) <> "/testModification.txt")
            `shouldReturn` "yes"
          -- ensure the file is not``
          doesFileExist (toFilePath (unSnapshot snapshotDir1) <> "/newFile.txt") `shouldReturn` False
          let
            theSnapshotConfig1 = defaultConfig <> snapshotConfig snapshotDir1
            snapshotConfigAndAssert = ConfigAndAssertion theSnapshotConfig1 $ flip withConn $ \conn -> do
              oneAgain <- fmap (PG.fromOnly . head) $ PG.query_ conn "SELECT id FROM foo"
              oneAgain `shouldBe` (1 :: Int)

          testWithTemporaryDirectory
            snapshotConfigAndAssert
            testSuccessfulConfig
spec :: Spec
spec = do
  withConfigSpecs

  withSnapshotSpecs

  it "stopPostgres cannot be connected to" $ withConfig' defaultConfig $ \db -> do
    stopPostgres db `shouldReturn` ExitSuccess
    PG.connectPostgreSQL (toConnectionString db) `shouldThrow`
      (\(_ :: IOError) -> True)

  -- Not a great test but don't want to be too rigid
  let createdbPlan = optionsToDefaultConfig mempty { Client.dbname = pure "newdb" }
  it "prettyPrintConfig seems to work" $ do
    let configString = prettyPrintConfig createdbPlan

        wordsToSearchFor = Set.fromList
          [ "commandLine:"
          , "connectionOptions:"
          , "connectionTimeout:"
          , "dataDirectory:"
          , "environmentVariables:"
          , "inherit:"
          , "initDbConfig:"
          , "port:"
          , "postgresConfig:"
          , "postgresConfigFile:"
          , "socketDirectory:"
          , "specific:"
          , "stdErr:"
          , "stdIn:"
          , "stdOut:"
          ]
    shouldSatisfy (Set.fromList $ words configString) $
      Set.isSubsetOf wordsToSearchFor

  it "prettyPrintDB seems to work" $ withConfig' (createdbPlan <> defaultConfig) $ \db -> do
    let dbString = prettyPrintDB db

        wordsToSearchFor = Set.fromList
          [ "completePlanInitDb:"
          , "completePlanCreateDb:"
          , "completePlanPostgres:"
          , "completePlanConfig:"
          , "completePlanDataDirectory:"
          ]

    shouldSatisfy (Set.fromList $ words dbString) $
      Set.isSubsetOf wordsToSearchFor

  let justBackupResources = defaultPostgresConf
        [ ("wal_level", "replica")
        , ("archive_mode","on")
        , ("max_wal_senders","2")
        ]
      backupResources = justBackupResources

  it "can support backup and restore" $ withConfig' backupResources $ \db@DB {..} -> do
    let dataDir = toFilePath (resourcesDataDir dbResources)
    appendFile (dataDir ++ "/pg_hba.conf") $ "local replication all trust"
    withTempDirectory "/tmp" "tmp-postgres-backup" $ \tempDir -> do
      let walArchiveDir = tempDir ++ "/archive"
          baseBackupFile = tempDir ++ "/backup"
          archiveLine = "archive_command = " ++
            "'test ! -f " ++ walArchiveDir ++ "/%f && cp %p " ++ walArchiveDir ++ "/%f'\n"
      appendFile (dataDir ++ "/postgresql.conf") $ archiveLine

      createDirectory walArchiveDir

      bracket (PG.connectPostgreSQL $ toConnectionString db) PG.close $ \conn ->
        (void :: IO [PG.Only Bool] -> IO ()) $
          PG.query_ conn "SELECT pg_reload_conf()"

      let Just port = getLast $ Client.port $ postgresProcessClientOptions dbPostgresProcess
          Just host = getLast $ Client.host $ postgresProcessClientOptions dbPostgresProcess
          backupCommandFlags =
            [ "-D" ++ baseBackupFile
            , "--format=tar"
            , "-p" ++ show port
            , "-h" ++ host
            ]

      (exitCode, stdouts, errs) <-  readProcessWithExitCode "pg_basebackup" backupCommandFlags []
      case exitCode of
        ExitSuccess -> pure ()
        ExitFailure _ -> do
          putStrLn stdouts
          putStrLn errs
          fail $ "pg_basebackup failed with flags " ++ unwords backupCommandFlags

      bracket (PG.connectPostgreSQL $ toConnectionString db ) PG.close $ \conn -> do
        _ <- PG.execute_ conn "CREATE TABLE foo(id int PRIMARY KEY);"
        _ <- PG.execute_ conn "BEGIN ISOLATION LEVEL READ COMMITTED READ WRITE; INSERT INTO foo (id) VALUES (1); COMMIT"
        _ :: [PG.Only String] <- PG.query_ conn "SELECT pg_walfile_name(pg_switch_wal())"
        _ :: [PG.Only String] <- PG.query_ conn "SELECT pg_walfile_name(pg_create_restore_point('pitr'))"
        _ <- PG.execute_ conn "BEGIN ISOLATION LEVEL READ COMMITTED READ WRITE; INSERT INTO foo (id) VALUES (2); COMMIT"

        PG.query_ conn "SELECT id FROM foo ORDER BY id ASC"
          `shouldReturn` [PG.Only (1 :: Int), PG.Only 2]

      stopPostgresGracefully db `shouldReturn` ExitSuccess

      removeDirectoryRecursive dataDir
      createDirectory dataDir

      let untarCommand = "tar -C" ++ dataDir ++ " -xf " ++ baseBackupFile ++ "/base.tar"
      system untarCommand `shouldReturn` ExitSuccess

      system ("chmod -R 700 " ++ dataDir) `shouldReturn` ExitSuccess

      writeFile (dataDir ++ "/recovery.conf") $ "recovery_target_name='pitr'\nrecovery_target_action='promote'\nrecovery_target_inclusive=true\nrestore_command='"
         ++ "cp " ++ walArchiveDir ++ "/%f %p'"

      either throwIO pure <=< withRestart db $ \newDb -> do
        bracket (PG.connectPostgreSQL $ toConnectionString newDb) PG.close $ \conn -> do
          fix $ \next -> do
            fmap (PG.fromOnly . head) (PG.query_ conn "SELECT pg_is_in_recovery()") >>= \case
              True -> threadDelay 100000 >> next
              False -> pure ()

          PG.query_ conn "SELECT id FROM foo ORDER BY id ASC"
            `shouldReturn` [PG.Only (1 :: Int)]


main :: IO ()
main = hspec spec