module Hasura.RQL.DDL.Schema.Source where

import           Hasura.Prelude

import qualified Data.Aeson                   as J
import qualified Data.HashMap.Strict          as HM
import qualified Data.HashMap.Strict.InsOrd   as OMap

import           Control.Lens                 (at, (.~), (^.))
import           Control.Monad.Trans.Control  (MonadBaseControl)
import           Data.Aeson
import           Data.Aeson.TH
import           Data.Has
import           Data.Text.Extended

import qualified Hasura.Logging               as L
import qualified Hasura.SQL.AnyBackend        as AB

import           Hasura.Base.Error
import           Hasura.EncJSON
import           Hasura.RQL.DDL.Deps
import           Hasura.RQL.DDL.Schema.Common
import           Hasura.RQL.Types
import           Hasura.Server.Logging        (MetadataLog (..))


--------------------------------------------------------------------------------
-- Add source

data AddSource b
  = AddSource
  { _asName                 :: !SourceName
  , _asConfiguration        :: !(SourceConnConfiguration b)
  , _asReplaceConfiguration :: !Bool
  }

instance (Backend b) => FromJSON (AddSource b) where
  parseJSON = withObject "add source" $ \o ->
    AddSource
      <$> o .: "name"
      <*> o .: "configuration"
      <*> o .:? "replace_configuration" .!= False

runAddSource
  :: forall m b
   . (MonadError QErr m, CacheRWM m, MetadataM m, BackendMetadata b)
  => AddSource b
  -> m EncJSON
runAddSource (AddSource name sourceConfig replaceConfiguration) = do
  sources <- scSources <$> askSchemaCache

  metadataModifier <- MetadataModifier <$>
    if HM.member name sources then
      if replaceConfiguration then pure $ metaSources.ix name.toSourceMetadata @b.smConfiguration .~ sourceConfig
      else throw400 AlreadyExists $ "source with name " <> name <<> " already exists"
    else do
      let sourceMetadata = mkSourceMetadata @b name sourceConfig
      pure $ metaSources %~ OMap.insert name sourceMetadata

  buildSchemaCacheFor (MOSource name) metadataModifier
  pure successMsg


--------------------------------------------------------------------------------
-- Rename source

data RenameSource
  = RenameSource
  { _rmName    :: !SourceName
  , _rmNewName :: !SourceName
  }
$(deriveFromJSON hasuraJSON ''RenameSource)

runRenameSource
  :: forall m
   . (MonadError QErr m, CacheRWM m, MetadataM m)
  => RenameSource
  -> m EncJSON
runRenameSource RenameSource {..} = do
  sources <- scSources <$> askSchemaCache

  unless (HM.member _rmName sources) $
    throw400 NotExists $ "Could not find source with name " <>> _rmName

  when (HM.member _rmNewName sources) $
    throw400 AlreadyExists $ "Source with name " <> _rmNewName <<> " already exists"

  let metadataModifier =
        MetadataModifier
          $ metaSources %~ renameBackendSourceMetadata _rmName _rmNewName
  buildSchemaCacheFor (MOSource _rmNewName) metadataModifier

  pure successMsg
  where
    renameBackendSourceMetadata
      :: SourceName
      -> SourceName
      -> OMap.InsOrdHashMap SourceName BackendSourceMetadata
      -> OMap.InsOrdHashMap SourceName BackendSourceMetadata
    renameBackendSourceMetadata oldKey newKey m =
      case OMap.lookup oldKey m of
        Just val ->
          OMap.insert
            newKey
            (AB.mapBackend val (renameSource newKey))
          . OMap.delete oldKey
          $ m
        Nothing -> m

    renameSource :: forall b. SourceName -> SourceMetadata b -> SourceMetadata b
    renameSource newName metadata = metadata { _smName = newName }


--------------------------------------------------------------------------------
-- Drop source

data DropSource
  = DropSource
  { _dsName    :: !SourceName
  , _dsCascade :: !Bool
  } deriving (Show, Eq)

instance FromJSON DropSource where
  parseJSON = withObject "drop source" $ \o ->
    DropSource <$> o .: "name" <*> o .:? "cascade" .!= False

runDropSource
  :: forall m r.
     ( MonadError QErr m
     , CacheRWM m
     , MonadIO m
     , MonadBaseControl IO m
     , MetadataM m
     , MonadReader r m
     , Has (L.Logger L.Hasura) r
     )
  => DropSource -> m EncJSON
runDropSource (DropSource name cascade) = do
  sc <- askSchemaCache
  logger <- asks getter
  let sources = scSources sc
  case HM.lookup name sources of
    Just backendSourceInfo ->
      AB.dispatchAnyBackend @BackendMetadata backendSourceInfo $ dropSource logger sc

    Nothing -> do
      metadata <- getMetadata
      void $ onNothing (metadata ^. metaSources . at name) $
          throw400 NotExists $ "source with name " <> name <<> " does not exist"
      if cascade
        then
          -- Without sourceInfo we can't cascade, so throw an error
          throw400 Unexpected $ "source with name " <> name <<> " is inconsistent"
        else
          -- Drop source from metadata
          buildSchemaCacheFor (MOSource name) dropSourceMetadataModifier
  pure successMsg
  where
    dropSource :: forall b. (BackendMetadata b) => L.Logger L.Hasura -> SchemaCache -> SourceInfo b -> m ()
    dropSource logger sc sourceInfo = do
      let sourceConfig = _siConfiguration sourceInfo
      let indirectDeps = mapMaybe getIndirectDep $
                         getDependentObjs sc (SOSource name)

      when (not cascade && indirectDeps /= [])
        $ reportDepsExt
            (map (SOSourceObj name . AB.mkAnyBackend) indirectDeps)
            []

      metadataModifier <- execWriterT $ do
        mapM_ (purgeDependentObject name >=> tell) indirectDeps
        tell dropSourceMetadataModifier

      buildSchemaCacheFor (MOSource name) metadataModifier

      -- We only log errors that arise from 'postDropSourceHook' here, and not
      -- surface them as end-user errors. See comment
      -- https://github.com/hasura/graphql-engine/issues/7092#issuecomment-873845282
      runExceptT (postDropSourceHook @b sourceConfig) >>= either logDropSourceHookError pure
      where
        logDropSourceHookError err =
          let msg = "Error executing cleanup actions after removing source '" <> toTxt name
                    <> "'. Consider cleaning up tables in hdb_catalog schema manually."
          in L.unLogger logger $ MetadataLog L.LevelWarn msg (J.toJSON err)

        getIndirectDep :: SchemaObjId -> Maybe (SourceObjId b)
        getIndirectDep = \case
          SOSourceObj s o ->
            if s == name
              then Nothing
              -- consider only *this* backend specific dependencies
              else AB.unpackAnyBackend o
          _               -> Nothing

    dropSourceMetadataModifier = MetadataModifier $ metaSources %~ OMap.delete name