module Hasura.Server.Query where

import           Data.Aeson
import           Data.Aeson.Casing
import           Data.Aeson.TH
import           Data.Time                          (UTCTime)
import           Language.Haskell.TH.Syntax         (Lift)

import qualified Data.HashMap.Strict                as HM
import qualified Network.HTTP.Client                as HTTP

import           Hasura.EncJSON
import           Hasura.Prelude
import           Hasura.RQL.DDL.EventTrigger
import           Hasura.RQL.DDL.Metadata
import           Hasura.RQL.DDL.Permission
import           Hasura.RQL.DDL.QueryCollection
import           Hasura.RQL.DDL.Relationship
import           Hasura.RQL.DDL.Relationship.Rename
import           Hasura.RQL.DDL.RemoteSchema
import           Hasura.RQL.DDL.Schema
import           Hasura.RQL.DML.Count
import           Hasura.RQL.DML.Delete
import           Hasura.RQL.DML.Insert
import           Hasura.RQL.DML.Select
import           Hasura.RQL.DML.Update
import           Hasura.RQL.Types
import           Hasura.Server.Init                 (InstanceId (..))
import           Hasura.Server.Utils

import qualified Database.PG.Query                  as Q

data RQLQueryV1
  = RQAddExistingTableOrView !TrackTable
  | RQTrackTable !TrackTable
  | RQUntrackTable !UntrackTable
  | RQSetTableIsEnum !SetTableIsEnum

  | RQTrackFunction !TrackFunction
  | RQUntrackFunction !UnTrackFunction

  | RQCreateObjectRelationship !CreateObjRel
  | RQCreateArrayRelationship !CreateArrRel
  | RQDropRelationship !DropRel
  | RQSetRelationshipComment !SetRelComment
  | RQRenameRelationship !RenameRel

  | RQCreateInsertPermission !CreateInsPerm
  | RQCreateSelectPermission !CreateSelPerm
  | RQCreateUpdatePermission !CreateUpdPerm
  | RQCreateDeletePermission !CreateDelPerm

  | RQDropInsertPermission !DropInsPerm
  | RQDropSelectPermission !DropSelPerm
  | RQDropUpdatePermission !DropUpdPerm
  | RQDropDeletePermission !DropDelPerm
  | RQSetPermissionComment !SetPermComment

  | RQGetInconsistentMetadata !GetInconsistentMetadata
  | RQDropInconsistentMetadata !DropInconsistentMetadata

  | RQInsert !InsertQuery
  | RQSelect !SelectQuery
  | RQUpdate !UpdateQuery
  | RQDelete !DeleteQuery
  | RQCount !CountQuery
  | RQBulk ![RQLQuery]

  -- schema-stitching, custom resolver related
  | RQAddRemoteSchema !AddRemoteSchemaQuery
  | RQRemoveRemoteSchema !RemoteSchemaNameQuery
  | RQReloadRemoteSchema !RemoteSchemaNameQuery

  | RQCreateEventTrigger !CreateEventTriggerQuery
  | RQDeleteEventTrigger !DeleteEventTriggerQuery
  | RQRedeliverEvent     !RedeliverEventQuery
  | RQInvokeEventTrigger !InvokeEventTriggerQuery

  -- query collections, allow list related
  | RQCreateQueryCollection !CreateCollection
  | RQDropQueryCollection !DropCollection
  | RQAddQueryToCollection !AddQueryToCollection
  | RQDropQueryFromCollection !DropQueryFromCollection
  | RQAddCollectionToAllowlist !CollectionReq
  | RQDropCollectionFromAllowlist !CollectionReq

  | RQRunSql !RunSQL

  | RQReplaceMetadata !ReplaceMetadata
  | RQExportMetadata !ExportMetadata
  | RQClearMetadata !ClearMetadata
  | RQReloadMetadata !ReloadMetadata

  | RQDumpInternalState !DumpInternalState
  deriving (Show, Eq, Lift)

data RQLQueryV2
  = RQV2TrackTable !TrackTableV2
  | RQV2SetTableCustomFields !SetTableCustomFields
  deriving (Show, Eq, Lift)

data RQLQuery
  = RQV1 !RQLQueryV1
  | RQV2 !RQLQueryV2
  deriving (Show, Eq, Lift)

instance FromJSON RQLQuery where
  parseJSON = withObject "Object" $ \o -> do
    mVersion <- o .:? "version"
    let version = fromMaybe VIVersion1 mVersion
        val = Object o
    case version of
      VIVersion1 -> RQV1 <$> parseJSON val
      VIVersion2 -> RQV2 <$> parseJSON val

instance ToJSON RQLQuery where
  toJSON = \case
    RQV1 q -> embedVersion VIVersion1 $ toJSON q
    RQV2 q -> embedVersion VIVersion2 $ toJSON q
    where
      embedVersion version (Object o) =
        Object $ HM.insert "version" (toJSON version) o
      -- never happens since JSON value of RQL queries are always objects
      embedVersion _ _ = error "Unexpected: toJSON of RQL queries are not objects"

$(deriveJSON
  defaultOptions { constructorTagModifier = snakeCase . drop 2
                 , sumEncoding = TaggedObject "type" "args"
                 }
  ''RQLQueryV1)

$(deriveJSON
  defaultOptions { constructorTagModifier = snakeCase . drop 4
                 , sumEncoding = TaggedObject "type" "args"
                 , tagSingleConstructors = True
                 }
  ''RQLQueryV2
 )

data RunCtx
  = RunCtx
  { _rcUserInfo      :: !UserInfo
  , _rcHttpMgr       :: !HTTP.Manager
  , _rcSqlGenCtx     :: !SQLGenCtx
  , _rcSystemDefined :: !SystemDefined
  }

newtype Run a
  = Run {unRun :: StateT SchemaCache (ReaderT RunCtx (LazyTx QErr)) a}
  deriving ( Functor, Applicative, Monad
           , MonadError QErr
           , MonadState SchemaCache
           , MonadReader RunCtx
           , CacheRM
           , CacheRWM
           , MonadTx
           , MonadIO
           )

instance UserInfoM Run where
  askUserInfo = asks _rcUserInfo

instance HasHttpManager Run where
  askHttpManager = asks _rcHttpMgr

instance HasSQLGenCtx Run where
  askSQLGenCtx = asks _rcSqlGenCtx

instance HasSystemDefined Run where
  askSystemDefined = asks _rcSystemDefined

fetchLastUpdate :: Q.TxE QErr (Maybe (InstanceId, UTCTime))
fetchLastUpdate = do
  Q.withQE defaultTxErrorHandler
    [Q.sql|
       SELECT instance_id::text, occurred_at
       FROM hdb_catalog.hdb_schema_update_event
       ORDER BY occurred_at DESC LIMIT 1
          |] () True

recordSchemaUpdate :: InstanceId -> Q.TxE QErr ()
recordSchemaUpdate instanceId =
  liftTx $ Q.unitQE defaultTxErrorHandler [Q.sql|
             INSERT INTO hdb_catalog.hdb_schema_update_event
               (instance_id, occurred_at) VALUES ($1::uuid, DEFAULT)
             ON CONFLICT ((occurred_at IS NOT NULL))
             DO UPDATE SET instance_id = $1::uuid, occurred_at = DEFAULT
            |] (Identity instanceId) True

peelRun
  :: SchemaCache
  -> RunCtx
  -> PGExecCtx
  -> Run a
  -> ExceptT QErr IO (a, SchemaCache)
peelRun sc runCtx@(RunCtx userInfo _ _ _) pgExecCtx (Run m) =
  runLazyTx pgExecCtx $ withUserInfo userInfo lazyTx
  where
    lazyTx = runReaderT (runStateT m sc) runCtx

runQuery
  :: (MonadIO m, MonadError QErr m)
  => PGExecCtx -> InstanceId
  -> UserInfo -> SchemaCache -> HTTP.Manager
  -> SQLGenCtx -> SystemDefined -> RQLQuery -> m (EncJSON, SchemaCache)
runQuery pgExecCtx instanceId userInfo sc hMgr sqlGenCtx systemDefined query = do
  resE <- liftIO $ runExceptT $ peelRun sc runCtx pgExecCtx $ runQueryM query
  either throwError withReload resE
  where
    runCtx = RunCtx userInfo hMgr sqlGenCtx systemDefined
    withReload r = do
      when (queryNeedsReload query) $ do
        e <- liftIO $ runExceptT $ runLazyTx pgExecCtx
             $ liftTx $ recordSchemaUpdate instanceId
        liftEither e
      return r

queryNeedsReload :: RQLQuery -> Bool
queryNeedsReload (RQV1 qi) = case qi of
  RQAddExistingTableOrView _      -> True
  RQTrackTable _                  -> True
  RQUntrackTable _                -> True
  RQTrackFunction _               -> True
  RQUntrackFunction _             -> True
  RQSetTableIsEnum _              -> True

  RQCreateObjectRelationship _    -> True
  RQCreateArrayRelationship  _    -> True
  RQDropRelationship  _           -> True
  RQSetRelationshipComment  _     -> False
  RQRenameRelationship _          -> True

  RQCreateInsertPermission _      -> True
  RQCreateSelectPermission _      -> True
  RQCreateUpdatePermission _      -> True
  RQCreateDeletePermission _      -> True

  RQDropInsertPermission _        -> True
  RQDropSelectPermission _        -> True
  RQDropUpdatePermission _        -> True
  RQDropDeletePermission _        -> True
  RQSetPermissionComment _        -> False

  RQGetInconsistentMetadata _     -> False
  RQDropInconsistentMetadata _    -> True

  RQInsert _                      -> False
  RQSelect _                      -> False
  RQUpdate _                      -> False
  RQDelete _                      -> False
  RQCount _                       -> False

  RQAddRemoteSchema _             -> True
  RQRemoveRemoteSchema _          -> True
  RQReloadRemoteSchema _          -> True

  RQCreateEventTrigger _          -> True
  RQDeleteEventTrigger _          -> True
  RQRedeliverEvent _              -> False
  RQInvokeEventTrigger _          -> False

  RQCreateQueryCollection _       -> True
  RQDropQueryCollection _         -> True
  RQAddQueryToCollection _        -> True
  RQDropQueryFromCollection _     -> True
  RQAddCollectionToAllowlist _    -> True
  RQDropCollectionFromAllowlist _ -> True

  RQRunSql _                      -> True

  RQReplaceMetadata _             -> True
  RQExportMetadata _              -> False
  RQClearMetadata _               -> True
  RQReloadMetadata _              -> True

  RQDumpInternalState _           -> False

  RQBulk qs                       -> any queryNeedsReload qs
queryNeedsReload (RQV2 qi) = case qi of
  RQV2TrackTable _           -> True
  RQV2SetTableCustomFields _ -> True

runQueryM
  :: ( QErrM m, CacheRWM m, UserInfoM m, MonadTx m
     , MonadIO m, HasHttpManager m, HasSQLGenCtx m
     , HasSystemDefined m
     )
  => RQLQuery
  -> m EncJSON
runQueryM rq =
  withPathK "args" $ runQueryM' <* rebuildGCtx
  where
    rebuildGCtx = when (queryNeedsReload rq) buildGCtxMap

    runQueryM' = case rq of
      RQV1 q -> runQueryV1M q
      RQV2 q -> runQueryV2M q

    runQueryV1M = \case
      RQAddExistingTableOrView q   -> runTrackTableQ q
      RQTrackTable q               -> runTrackTableQ q
      RQUntrackTable q             -> runUntrackTableQ q
      RQSetTableIsEnum q           -> runSetExistingTableIsEnumQ q

      RQTrackFunction q            -> runTrackFunc q
      RQUntrackFunction q          -> runUntrackFunc q

      RQCreateObjectRelationship q -> runCreateObjRel q
      RQCreateArrayRelationship  q -> runCreateArrRel q
      RQDropRelationship  q        -> runDropRel q
      RQSetRelationshipComment  q  -> runSetRelComment q
      RQRenameRelationship q       -> runRenameRel q

      RQCreateInsertPermission q   -> runCreatePerm q
      RQCreateSelectPermission q   -> runCreatePerm q
      RQCreateUpdatePermission q   -> runCreatePerm q
      RQCreateDeletePermission q   -> runCreatePerm q

      RQDropInsertPermission q     -> runDropPerm q
      RQDropSelectPermission q     -> runDropPerm q
      RQDropUpdatePermission q     -> runDropPerm q
      RQDropDeletePermission q     -> runDropPerm q
      RQSetPermissionComment q     -> runSetPermComment q

      RQGetInconsistentMetadata q  -> runGetInconsistentMetadata q
      RQDropInconsistentMetadata q -> runDropInconsistentMetadata q

      RQInsert q                   -> runInsert q
      RQSelect q                   -> runSelect q
      RQUpdate q                   -> runUpdate q
      RQDelete q                   -> runDelete q
      RQCount  q                   -> runCount q

      RQAddRemoteSchema    q       -> runAddRemoteSchema q
      RQRemoveRemoteSchema q       -> runRemoveRemoteSchema q
      RQReloadRemoteSchema q       -> runReloadRemoteSchema q

      RQCreateEventTrigger q       -> runCreateEventTriggerQuery q
      RQDeleteEventTrigger q       -> runDeleteEventTriggerQuery q
      RQRedeliverEvent q           -> runRedeliverEvent q
      RQInvokeEventTrigger q       -> runInvokeEventTrigger q

      RQCreateQueryCollection q        -> runCreateCollection q
      RQDropQueryCollection q          -> runDropCollection q
      RQAddQueryToCollection q         -> runAddQueryToCollection q
      RQDropQueryFromCollection q      -> runDropQueryFromCollection q
      RQAddCollectionToAllowlist q     -> runAddCollectionToAllowlist q
      RQDropCollectionFromAllowlist q  -> runDropCollectionFromAllowlist q

      RQReplaceMetadata q          -> runReplaceMetadata q
      RQClearMetadata q            -> runClearMetadata q
      RQExportMetadata q           -> runExportMetadata q
      RQReloadMetadata q           -> runReloadMetadata q

      RQDumpInternalState q        -> runDumpInternalState q

      RQRunSql q                   -> runRunSQL q

      RQBulk qs                    -> encJFromList <$> indexedMapM runQueryM qs

    runQueryV2M = \case
      RQV2TrackTable q           -> runTrackTableV2Q q
      RQV2SetTableCustomFields q -> runSetTableCustomFieldsQV2 q