{-# OPTIONS_GHC -fno-warn-orphans #-}

module Hasura.Backends.BigQuery.Instances.Schema () where

import           Hasura.Prelude

import qualified Data.Aeson                            as J
import qualified Data.HashMap.Strict                   as Map
import qualified Data.List.NonEmpty                    as NE
import qualified Data.Text                             as T

import           Data.Text.Extended

import qualified Hasura.Backends.BigQuery.Types        as BigQuery
import qualified Hasura.GraphQL.Parser                 as P
import qualified Hasura.GraphQL.Schema.Build           as GSB
import qualified Hasura.RQL.IR.Select                  as IR
import qualified Hasura.RQL.IR.Update                  as IR
import qualified Language.GraphQL.Draft.Syntax         as G

import           Hasura.Base.Error
import           Hasura.GraphQL.Context
import           Hasura.GraphQL.Parser                 hiding (EnumValueInfo, field)
import           Hasura.GraphQL.Parser.Internal.Parser hiding (field)
import           Hasura.GraphQL.Schema.Backend
import           Hasura.GraphQL.Schema.Common
import           Hasura.RQL.Types


----------------------------------------------------------------
-- BackendSchema instance

instance BackendSchema 'BigQuery where
  -- top level parsers
  buildTableQueryFields          = GSB.buildTableQueryFields
  buildTableRelayQueryFields     = msBuildTableRelayQueryFields
  buildTableInsertMutationFields = msBuildTableInsertMutationFields
  buildTableUpdateMutationFields = msBuildTableUpdateMutationFields
  buildTableDeleteMutationFields = msBuildTableDeleteMutationFields
  buildFunctionQueryFields       = msBuildFunctionQueryFields
  buildFunctionRelayQueryFields  = msBuildFunctionRelayQueryFields
  buildFunctionMutationFields    = msBuildFunctionMutationFields
  -- backend extensions
  relayExtension    = Nothing
  nodesAggExtension = Just ()
  -- indivdual components
  columnParser              = msColumnParser
  jsonPathArg               = msJsonPathArg
  orderByOperators          = msOrderByOperators
  comparisonExps            = msComparisonExps
  updateOperators           = msUpdateOperators
  offsetParser              = msOffsetParser
  mkCountType               = msMkCountType
  aggregateOrderByCountType = BigQuery.IntegerScalarType
  computedField             = msComputedField
  node                      = msNode
  tableDistinctOn           = msTableDistinctOn
  remoteRelationshipField   = msRemoteRelationshipField
  -- SQL literals
  columnDefaultValue = error "TODO: Make impossible by the type system. BigQuery doesn't support insertions."


----------------------------------------------------------------
-- Top level parsers

msBuildTableRelayQueryFields
  :: MonadBuildSchema 'BigQuery r m n
  => SourceName
  -> SourceConfig 'BigQuery
  -> TableName    'BigQuery
  -> TableInfo    'BigQuery
  -> G.Name
  -> NESeq (ColumnInfo 'BigQuery)
  -> SelPermInfo  'BigQuery
  -> m (Maybe (FieldParser n (QueryRootField UnpreparedValue)))
msBuildTableRelayQueryFields _sourceName _sourceInfo _tableName _tableInfo _gqlName _pkeyColumns _selPerms =
  pure Nothing

msBuildTableInsertMutationFields
  :: MonadBuildSchema 'BigQuery r m n
  => SourceName
  -> SourceConfig 'BigQuery
  -> TableName 'BigQuery
  -> TableInfo 'BigQuery
  -> G.Name
  -> InsPermInfo 'BigQuery
  -> Maybe (SelPermInfo 'BigQuery)
  -> Maybe (UpdPermInfo 'BigQuery)
  -> m [FieldParser n (MutationRootField UnpreparedValue)]
msBuildTableInsertMutationFields _sourceName _sourceInfo _tableName _tableInfo _gqlName _insPerms _selPerms _updPerms =
  pure []

msBuildTableUpdateMutationFields
  :: MonadBuildSchema 'BigQuery r m n
  => SourceName
  -> SourceConfig 'BigQuery
  -> TableName 'BigQuery
  -> TableInfo 'BigQuery
  -> G.Name
  -> UpdPermInfo 'BigQuery
  -> Maybe (SelPermInfo 'BigQuery)
  -> m [FieldParser n (MutationRootField UnpreparedValue)]
msBuildTableUpdateMutationFields _sourceName _sourceInfo _tableName _tableInfo _gqlName _updPerns _selPerms =
  pure []

msBuildTableDeleteMutationFields
  :: MonadBuildSchema 'BigQuery r m n
  => SourceName
  -> SourceConfig 'BigQuery
  -> TableName 'BigQuery
  -> TableInfo 'BigQuery
  -> G.Name
  -> DelPermInfo 'BigQuery
  -> Maybe (SelPermInfo 'BigQuery)
  -> m [FieldParser n (MutationRootField UnpreparedValue)]
msBuildTableDeleteMutationFields _sourceName _sourceInfo _tableName _tableInfo _gqlName _delPerns _selPerms =
  pure []

msBuildFunctionQueryFields
    :: MonadBuildSchema 'BigQuery r m n
    => SourceName
    -> SourceConfig 'BigQuery
    -> FunctionName 'BigQuery
    -> FunctionInfo 'BigQuery
    -> TableName 'BigQuery
    -> SelPermInfo 'BigQuery
    -> m [FieldParser n (QueryRootField UnpreparedValue)]
msBuildFunctionQueryFields _ _ _ _ _ _ =
  pure []

msBuildFunctionRelayQueryFields
  :: MonadBuildSchema 'BigQuery r m n
  => SourceName
  -> SourceConfig 'BigQuery
  -> FunctionName 'BigQuery
  -> FunctionInfo 'BigQuery
  -> TableName    'BigQuery
  -> NESeq (ColumnInfo 'BigQuery)
  -> SelPermInfo  'BigQuery
  -> m (Maybe (FieldParser n (QueryRootField UnpreparedValue)))
msBuildFunctionRelayQueryFields _sourceName _sourceInfo _functionName _functionInfo _tableName _pkeyColumns _selPerms =
  pure Nothing

msBuildFunctionMutationFields
    :: MonadBuildSchema 'BigQuery r m n
    => SourceName
    -> SourceConfig 'BigQuery
    -> FunctionName 'BigQuery
    -> FunctionInfo 'BigQuery
    -> TableName 'BigQuery
    -> SelPermInfo 'BigQuery
    -> m [FieldParser n (MutationRootField UnpreparedValue)]
msBuildFunctionMutationFields _ _ _ _ _ _ =
  pure []


----------------------------------------------------------------
-- Individual components

msColumnParser
  :: (MonadSchema n m, MonadError QErr m)
  => ColumnType 'BigQuery
  -> G.Nullability
  -> m (Parser 'Both n (Opaque (ColumnValue 'BigQuery)))
msColumnParser columnType (G.Nullability isNullable) =
  opaque . fmap (ColumnValue columnType) <$> case columnType of
    ColumnScalar scalarType -> case scalarType of
      -- bytestrings
      -- we only accept string literals
      BigQuery.BytesScalarType  -> pure $ possiblyNullable scalarType $  BigQuery.StringValue <$> P.string
      -- text
      BigQuery.StringScalarType -> pure $ possiblyNullable scalarType $  BigQuery.StringValue <$> P.string
      -- floating point values
      -- TODO: we do not perform size checks here, meaning we would accept an
      -- out-of-bounds value as long as it can be represented by a GraphQL float; this
      -- will in all likelihood error on the BigQuery side. Do we want to handle those
      -- properly here?
      BigQuery.FloatScalarType   -> pure $ possiblyNullable scalarType $  BigQuery.FloatValue . BigQuery.doubleToFloat64 <$> P.float
      BigQuery.IntegerScalarType -> pure $ possiblyNullable scalarType $  BigQuery.IntegerValue . BigQuery.intToInt64 . fromIntegral <$> P.int
      BigQuery.DecimalScalarType -> pure $ possiblyNullable scalarType $  BigQuery.DecimalValue . BigQuery.doubleToDecimal <$> P.float
      BigQuery.BigDecimalScalarType -> pure $ possiblyNullable scalarType $  BigQuery.BigDecimalValue . BigQuery.doubleToBigDecimal <$> P.float
      -- boolean type
      BigQuery.BoolScalarType -> pure $ possiblyNullable scalarType $  BigQuery.BoolValue <$> P.boolean
      BigQuery.DateScalarType -> pure $ possiblyNullable scalarType $  BigQuery.DateValue . BigQuery.Date <$> P.string
      BigQuery.TimeScalarType -> pure $ possiblyNullable scalarType $  BigQuery.TimeValue . BigQuery.Time <$> P.string
      BigQuery.DatetimeScalarType -> pure $ possiblyNullable scalarType $  BigQuery.DatetimeValue . BigQuery.Datetime <$> P.string
      BigQuery.GeographyScalarType -> pure $ possiblyNullable scalarType $  BigQuery.GeographyValue . BigQuery.Geography <$> P.string
      BigQuery.TimestampScalarType -> do
        let schemaType =  P.Nullable . P.TNamed $ P.mkDefinition stringScalar Nothing P.TIScalar
        pure $ possiblyNullable scalarType $ Parser
          { pType = schemaType
          , pParser =
              valueToJSON (P.toGraphQLType schemaType)
                >=> fmap (BigQuery.StringValue . BigQuery.utctimeToISO8601Text)
                    . either (parseErrorWith ParseFailed . qeError) pure
                    . runAesonParser (J.withText "TimestampColumn" BigQuery.textToUTCTime)
          }
      ty -> throwError $ internalError $ T.pack $ "Type currently unsupported for BigQuery: " ++ show ty
    ColumnEnumReference (EnumReference tableName enumValues) ->
      case nonEmpty (Map.toList enumValues) of
        Just enumValuesList -> do
          tableGQLName <- tableGraphQLName @'BigQuery tableName `onLeft` throwError
          let enumName = tableGQLName <> $$(G.litName "_enum")
          pure $ possiblyNullable BigQuery.StringScalarType $ P.enum enumName Nothing (mkEnumValue <$> enumValuesList)
        Nothing -> throw400 ValidationFailed "empty enum values"
  where
    -- Sadly, this combinator is not sound in general, so we can’t export it
    -- for general-purpose use. If we did, someone could write this:
    --
    --   mkParameter <$> opaque do
    --     n <- int
    --     pure (mkIntColumnValue (n + 1))
    --
    -- Now we’d end up with a UVParameter that has a variable in it, so we’d
    -- parameterize over it. But when we’d reuse the plan, we wouldn’t know to
    -- increment the value by 1, so we’d use the wrong value!
    --
    -- We could theoretically solve this by retaining a reference to the parser
    -- itself and re-parsing each new value, using the saved parser, which
    -- would admittedly be neat. But it’s more complicated, and it isn’t clear
    -- that it would actually be useful, so for now we don’t support it.
    opaque :: MonadParse m => Parser 'Both m a -> Parser 'Both m (Opaque a)
    opaque parser = parser
      { pParser = \case
          P.GraphQLValue (G.VVariable var@Variable{ vInfo, vValue }) -> do
            typeCheck False (P.toGraphQLType $ pType parser) var
            P.mkOpaque (Just vInfo) <$> pParser parser (absurd <$> vValue)
          value -> P.mkOpaque Nothing <$> pParser parser value
      }
    possiblyNullable _scalarType
      | isNullable = fmap (fromMaybe BigQuery.NullValue) . P.nullable
      | otherwise  = id
    mkEnumValue :: (EnumValue, EnumValueInfo) -> (P.Definition P.EnumValueInfo, ScalarValue 'BigQuery)
    mkEnumValue (EnumValue value, EnumValueInfo description) =
      ( P.mkDefinition value (G.Description <$> description) P.EnumValueInfo
      , BigQuery.StringValue $ G.unName value
      )
    throughJSON scalarName =
      let schemaType = P.NonNullable $ P.TNamed $ P.mkDefinition scalarName Nothing P.TIScalar
      in  Parser
          { pType = schemaType
          , pParser =
            valueToJSON (P.toGraphQLType schemaType) >=>
            either (parseErrorWith ParseFailed . qeError) pure . runAesonParser J.parseJSON
          }

msJsonPathArg
  :: MonadParse n
  => ColumnType 'BigQuery
  -> InputFieldsParser n (Maybe (IR.ColumnOp 'BigQuery))
msJsonPathArg _columnType = pure Nothing

msOrderByOperators
  :: NonEmpty
      ( Definition P.EnumValueInfo
      , (BasicOrderType 'BigQuery, NullsOrderType 'BigQuery)
      )
msOrderByOperators = NE.fromList
  [ ( define $$(G.litName "asc") "in ascending order, nulls first"
    , (BigQuery.AscOrder, BigQuery.NullsFirst)
    )
  , ( define $$(G.litName "asc_nulls_first") "in ascending order, nulls first"
    , (BigQuery.AscOrder, BigQuery.NullsFirst)
    )
  , ( define $$(G.litName "asc_nulls_last") "in ascending order, nulls last"
    , (BigQuery.AscOrder, BigQuery.NullsLast)
    )
  , ( define $$(G.litName "desc") "in descending order, nulls last"
    , (BigQuery.DescOrder, BigQuery.NullsLast)
    )
  , ( define $$(G.litName "desc_nulls_first") "in descending order, nulls first"
    , (BigQuery.DescOrder, BigQuery.NullsFirst)
    )
  , ( define $$(G.litName "desc_nulls_last") "in descending order, nulls last"
    , (BigQuery.DescOrder, BigQuery.NullsLast)
    )
  ]
  where
    define name desc = P.mkDefinition name (Just desc) P.EnumValueInfo

msComparisonExps
  :: forall m n
  . (BackendSchema 'BigQuery, MonadSchema n m, MonadError QErr m)
  => ColumnType 'BigQuery
  -> m (Parser 'Input n [ComparisonExp 'BigQuery])
msComparisonExps = P.memoize 'comparisonExps $ \columnType -> do
  -- see Note [Columns in comparison expression are never nullable]
  typedParser        <- columnParser columnType (G.Nullability False)
  nullableTextParser <- columnParser (ColumnScalar @'BigQuery BigQuery.StringScalarType) (G.Nullability True)
  textParser         <- columnParser (ColumnScalar @'BigQuery BigQuery.StringScalarType) (G.Nullability False)
  let name = P.getName typedParser <> $$(G.litName "_BigQuery_comparison_exp")
      desc = G.Description $ "Boolean expression to compare columns of type "
        <>  P.getName typedParser
        <<> ". All fields are combined with logical 'AND'."
      textListParser = P.list textParser `P.bind` traverse P.openOpaque
      columnListParser = P.list typedParser `P.bind` traverse P.openOpaque
  pure $ P.object name (Just desc) $ catMaybes <$> sequenceA
    [ P.fieldOptional $$(G.litName "_is_null") Nothing (bool ANISNOTNULL ANISNULL <$> P.boolean)
    , P.fieldOptional $$(G.litName "_eq")      Nothing (AEQ True . mkParameter <$> typedParser)
    , P.fieldOptional $$(G.litName "_neq")     Nothing (ANE True . mkParameter <$> typedParser)
    , P.fieldOptional $$(G.litName "_gt")      Nothing (AGT  . mkParameter <$> typedParser)
    , P.fieldOptional $$(G.litName "_lt")      Nothing (ALT  . mkParameter <$> typedParser)
    , P.fieldOptional $$(G.litName "_gte")     Nothing (AGTE . mkParameter <$> typedParser)
    , P.fieldOptional $$(G.litName "_lte")     Nothing (ALTE . mkParameter <$> typedParser)
    ]


msOffsetParser :: MonadParse n => Parser 'Both n (SQLExpression 'BigQuery)
msOffsetParser =
  BigQuery.ValueExpression . BigQuery.IntegerValue . BigQuery.intToInt64 . fromIntegral <$>
  P.int

msMkCountType
  :: Maybe Bool
  -- ^ distinct values
  -> Maybe [Column 'BigQuery]
  -> CountType 'BigQuery
msMkCountType _           Nothing     = BigQuery.StarCountable
msMkCountType (Just True) (Just cols) =
  maybe BigQuery.StarCountable BigQuery.DistinctCountable $ nonEmpty cols
msMkCountType _           (Just cols) =
  maybe BigQuery.StarCountable BigQuery.NonNullFieldCountable $ nonEmpty cols

-- | Argument to distinct select on columns returned from table selection
-- > distinct_on: [table_select_column!]
msTableDistinctOn
  -- :: forall m n. (BackendSchema 'BigQuery, MonadSchema n m, MonadTableInfo r m, MonadRole r m)
  :: Applicative m
  => Applicative n
  => SourceName
  -> TableInfo 'BigQuery
  -> SelPermInfo 'BigQuery
  -> m (InputFieldsParser n (Maybe (XDistinct 'BigQuery, NonEmpty (Column 'BigQuery))))
msTableDistinctOn _sourceName _tableInfo _selectPermissions = pure (pure Nothing)

-- | Various update operators
msUpdateOperators
  -- :: forall m n r. (MonadSchema n m, MonadTableInfo r m)
  :: Applicative m
  => TableInfo 'BigQuery         -- ^ qualified name of the table
  -> UpdPermInfo 'BigQuery       -- ^ update permissions of the table
  -> m (Maybe (InputFieldsParser n [(Column 'BigQuery, IR.UpdOpExpG (UnpreparedValue 'BigQuery))]))
msUpdateOperators _tableInfo _updatePermissions = pure Nothing

-- | Computed field parser.
-- Currently unsupported: returns Nothing for now.
msComputedField
  :: MonadBuildSchema 'BigQuery r m n
  => SourceName
  -> ComputedFieldInfo 'BigQuery
  -> TableName 'BigQuery
  -> SelPermInfo 'BigQuery
  -> m (Maybe (FieldParser n (AnnotatedField 'BigQuery)))
msComputedField _sourceName _fieldInfo _table _selectPemissions = pure Nothing


-- | Remote join field parser.
-- Currently unsupported: returns Nothing for now.
msRemoteRelationshipField
  :: MonadBuildSchema 'BigQuery r m n
  => RemoteFieldInfo 'BigQuery
  -> m (Maybe [FieldParser n (AnnotatedField 'BigQuery)])
msRemoteRelationshipField _remoteFieldInfo = pure Nothing

-- | The 'node' root field of a Relay request. Relay is currently unsupported on BigQuery,
-- meaning this parser will never be called: any attempt to create this parser should
-- therefore fail.
msNode
  :: MonadBuildSchema 'BigQuery r m n
  => m ( Parser 'Output n
         ( HashMap
           ( TableName 'BigQuery)
           ( SourceName, SourceConfig 'BigQuery
           , SelPermInfo 'BigQuery
           , PrimaryKeyColumns 'BigQuery
           , AnnotatedFields 'BigQuery
           )
         )
       )
msNode = throw500 "BigQuery does not support relay; `node` should never be exposed in the schema."