{-# LANGUAGE NamedFieldPuns  #-}
{-# LANGUAGE RecordWildCards #-}

module Main where

import           Control.Applicative
import           Control.Exception
import           Control.Monad.Trans.Managed        (ManagedT (..), lowerManagedT)
import           Data.Int                           (Int64)
import           Data.Text.Conversions              (convertText)
import           Data.Time.Clock                    (getCurrentTime)
import           Data.Time.Clock.POSIX              (getPOSIXTime)

import           Hasura.App
import           Hasura.Logging                     (Hasura, LogLevel (..),
                                                     defaultEnabledEngineLogTypes)
import           Hasura.Metadata.Class
import           Hasura.Prelude
import           Hasura.RQL.DDL.Schema
import           Hasura.RQL.DDL.Schema.Cache.Common
import           Hasura.RQL.DDL.Schema.Source
import           Hasura.RQL.Types
import           Hasura.Server.Init
import           Hasura.Server.Migrate              (downgradeCatalog)
import           Hasura.Server.Types                (MaintenanceMode (..))
import           Hasura.Server.Version

import qualified Control.Concurrent.Extended        as C
import qualified Data.ByteString.Char8              as BC
import qualified Data.ByteString.Lazy               as BL
import qualified Data.ByteString.Lazy.Char8         as BLC
import qualified Data.Environment                   as Env
import qualified Database.PG.Query                  as Q
import qualified Hasura.GC                          as GC
import qualified Hasura.Tracing                     as Tracing
import qualified System.Exit                        as Sys
import qualified System.Metrics                     as EKG
import qualified System.Posix.Signals               as Signals


main :: IO ()
main = do
  tryExit $ do
    args <- parseArgs
    env  <- Env.getEnvironment
    runApp env args
  where
    tryExit io = try io >>= \case
      Left (ExitException _code msg) -> BC.putStrLn msg >> Sys.exitFailure
      Right r                        -> return r

runApp :: Env.Environment -> HGEOptions Hasura -> IO ()
runApp env (HGEOptionsG rci metadataDbUrl hgeCmd) = do
  initTime <- liftIO getCurrentTime
  globalCtx@GlobalCtx{..} <- initGlobalCtx env metadataDbUrl rci
  let (maybeDefaultPgConnInfo, maybeRetries) = _gcDefaultPostgresConnInfo

  withVersion $$(getVersionFromEnvironment) $ case hgeCmd of
    HCServe serveOptions -> do
      ekgStore <- liftIO do
        s <- EKG.newStore
        EKG.registerGcMetrics s

        let getTimeMs :: IO Int64
            getTimeMs = (round . (* 1000)) `fmap` getPOSIXTime

        EKG.registerCounter "ekg.server_timestamp_ms" getTimeMs s
        pure s

      -- It'd be nice if we didn't have to call runManagedT twice here, but
      -- there is a data dependency problem since the call to runPGMetadataStorageApp
      -- below depends on serveCtx.
      runManagedT (initialiseServeCtx env globalCtx serveOptions) $ \serveCtx -> do
        -- Catches the SIGTERM signal and initiates a graceful shutdown.
        -- Graceful shutdown for regular HTTP requests is already implemented in
        -- Warp, and is triggered by invoking the 'closeSocket' callback.
        -- We only catch the SIGTERM signal once, that is, if the user hits CTRL-C
        -- once again, we terminate the process immediately.

        -- The function is written in this style to avoid the shutdown
        -- handler retaining a reference to the entire serveCtx (see #344)
        -- If you modify this code then you should check the core to see
        -- that serveCtx is not retained.
        _ <- case serveCtx of
               ServeCtx{_scShutdownLatch} ->
                liftIO $ do
                   void $ Signals.installHandler Signals.sigTERM (Signals.CatchOnce (shutdownGracefully _scShutdownLatch)) Nothing
                   void $ Signals.installHandler Signals.sigINT  (Signals.CatchOnce (shutdownGracefully _scShutdownLatch)) Nothing

        let Loggers _ logger pgLogger = _scLoggers serveCtx

        _idleGCThread <- C.forkImmortal "ourIdleGC" logger $
          GC.ourIdleGC logger (seconds 0.3) (seconds 10) (seconds 60)

        serverMetrics <- liftIO $ createServerMetrics ekgStore
        flip runPGMetadataStorageApp (_scMetadataDbPool serveCtx, pgLogger) . lowerManagedT $ do
          runHGEServer (const $ pure ()) env serveOptions serveCtx initTime Nothing serverMetrics ekgStore

    HCExport -> do
      res <- runTxWithMinimalPool _gcMetadataDbConnInfo fetchMetadataFromCatalog
      either (printErrJExit MetadataExportError) printJSON res

    HCClean -> do
      res <- runTxWithMinimalPool _gcMetadataDbConnInfo dropHdbCatalogSchema
      let cleanSuccessMsg = "successfully cleaned graphql-engine related data"
      either (printErrJExit MetadataCleanError) (const $ liftIO $ putStrLn cleanSuccessMsg) res

    HCExecute -> do
      queryBs <- liftIO BL.getContents
      let sqlGenCtx = SQLGenCtx False False
          remoteSchemaPermsCtx = RemoteSchemaPermsDisabled
          pgLogger = print
          pgSourceResolver = mkPgSourceResolver pgLogger
          functionPermsCtx = FunctionPermissionsInferred
          maintenanceMode = MaintenanceModeDisabled
          serverConfigCtx =
            ServerConfigCtx functionPermsCtx remoteSchemaPermsCtx sqlGenCtx maintenanceMode mempty
          cacheBuildParams =
            CacheBuildParams _gcHttpManager pgSourceResolver serverConfigCtx
      runManagedT (mkMinimalPool _gcMetadataDbConnInfo) $ \metadataDbPool -> do
        res <- flip runPGMetadataStorageApp (metadataDbPool, pgLogger) $
          runMetadataStorageT $ liftEitherM do
          (metadata, _) <- fetchMetadata
          runAsAdmin _gcHttpManager serverConfigCtx $ do
            schemaCache <- runCacheBuild cacheBuildParams $
                           buildRebuildableSchemaCache env metadata
            execQuery env queryBs
              & Tracing.runTraceTWithReporter Tracing.noReporter "execute"
              & runMetadataT metadata
              & runCacheRWT schemaCache
              & fmap (\((res, _), _, _) -> res)
        either (printErrJExit ExecuteProcessError) (liftIO . BLC.putStrLn) res

    HCDowngrade opts -> do
      let defaultSourceConfig = maybeDefaultPgConnInfo <&> \(dbUrlConf, _) ->
            let pgSourceConnInfo = PostgresSourceConnInfo dbUrlConf
                                   (Just setPostgresPoolSettings{_ppsRetries = maybeRetries <|> Just 1})
                                   False
                                   Q.ReadCommitted
                                   Nothing
            in PostgresConnConfiguration pgSourceConnInfo Nothing
      res <- runTxWithMinimalPool _gcMetadataDbConnInfo $ downgradeCatalog defaultSourceConfig opts initTime
      either (printErrJExit DowngradeProcessError) (liftIO . print) res

    HCVersion -> liftIO $ putStrLn $ "Hasura GraphQL Engine: " ++ convertText currentVersion
  where
    runTxWithMinimalPool connInfo tx = lowerManagedT $ do
      minimalPool <- mkMinimalPool connInfo
      liftIO $ runExceptT $ Q.runTx minimalPool (Q.ReadCommitted, Nothing) tx

    -- | Generate Postgres pool with single connection.
    -- It is useful when graphql-engine executes a transaction on database
    -- and exits in commands other than 'serve'.
    mkMinimalPool connInfo = do
      pgLogger <- _lsPgLogger <$> mkLoggers defaultEnabledEngineLogTypes LevelInfo
      let connParams = Q.defaultConnParams { Q.cpConns = 1 }
      liftIO $ Q.initPGPool connInfo connParams pgLogger