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

module Hasura.Backends.MySQL.Instances.Schema where

import qualified Data.Aeson                            as J
import           Data.ByteString                       (ByteString)
import qualified Data.HashMap.Strict                   as HM
import qualified Data.List.NonEmpty                    as NE
import           Data.Text.Encoding                    (encodeUtf8)
import           Data.Text.Extended
import qualified Database.MySQL.Base.Types             as MySQL
import qualified Hasura.Backends.MySQL.Types           as MySQL
import           Hasura.Base.Error
import           Hasura.GraphQL.Parser                 hiding (EnumValueInfo, field)
import qualified Hasura.GraphQL.Parser                 as P
import           Hasura.GraphQL.Parser.Internal.Parser hiding (field)
import           Hasura.GraphQL.Schema.Backend
import qualified Hasura.GraphQL.Schema.Build           as GSB
import           Hasura.GraphQL.Schema.Select
import           Hasura.Prelude
import           Hasura.RQL.IR
import qualified Hasura.RQL.IR.Select                  as IR
import qualified Hasura.RQL.IR.Update                  as IR
import           Hasura.RQL.Types                      as RQL
import qualified Language.GraphQL.Draft.Syntax         as G

instance BackendSchema 'MySQL where
  buildTableQueryFields          = GSB.buildTableQueryFields
  buildTableRelayQueryFields     = buildTableRelayQueryFields'
  buildTableInsertMutationFields = buildTableInsertMutationFields'
  buildTableUpdateMutationFields = buildTableUpdateMutationFields'
  buildTableDeleteMutationFields = buildTableDeleteMutationFields'
  buildFunctionQueryFields       = buildFunctionQueryFields'
  buildFunctionRelayQueryFields  = buildFunctionRelayQueryFields'
  buildFunctionMutationFields    = buildFunctionMutationFields'
  relayExtension                 = Nothing
  tableArguments                 = mysqlTableArgs
  nodesAggExtension              = Just ()
  columnParser                   = columnParser'
  jsonPathArg                    = jsonPathArg'
  orderByOperators               = orderByOperators'
  comparisonExps                 = comparisonExps'
  updateOperators                = updateOperators'
  mkCountType                    = error "mkCountType: MySQL backend does not support this operation yet."
  aggregateOrderByCountType      = error "aggregateOrderByCountType: MySQL backend does not support this operation yet."
  computedField                  = error "computedField: MySQL backend does not support this operation yet."
  node                           = error "node: MySQL backend does not support this operation yet."
  columnDefaultValue             = error "columnDefaultValue: MySQL backend does not support this operation yet."
  nestedInsertsExtension         = Nothing

mysqlTableArgs
  :: forall r m n
   . MonadBuildSchema 'MySQL r m n
  => SourceName
  -> TableInfo 'MySQL
  -> SelPermInfo 'MySQL
  -> m (InputFieldsParser n (IR.SelectArgsG 'MySQL (UnpreparedValue 'MySQL)))
mysqlTableArgs sourceName tableInfo selectPermissions = do
  whereParser   <- tableWhereArg   sourceName tableInfo selectPermissions
  orderByParser <- tableOrderByArg sourceName tableInfo selectPermissions
  pure do
    whereArg   <- whereParser
    orderByArg <- orderByParser
    limitArg   <- tableLimitArg
    offsetArg  <- tableOffsetArg
    pure $ IR.SelectArgs
      { IR._saWhere    = whereArg
      , IR._saOrderBy  = orderByArg
      , IR._saLimit    = limitArg
      , IR._saOffset   = offsetArg
      , IR._saDistinct = Nothing
      }

buildTableRelayQueryFields' ::
  MonadBuildSchema 'MySQL r m n =>
  SourceName ->
  RQL.SourceConfig 'MySQL ->
  Maybe RQL.QueryTagsConfig ->
  RQL.TableName 'MySQL ->
  TableInfo 'MySQL ->
  G.Name ->
  NESeq (ColumnInfo 'MySQL) ->
  SelPermInfo 'MySQL ->
  m [FieldParser n (QueryRootField UnpreparedValue)]
buildTableRelayQueryFields' _sourceName _sourceInfo _queryTagsConfig _tableName _tableInfo _gqlName _pkeyColumns _selPerms =
  pure []


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


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


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


buildFunctionQueryFields' ::
  MonadBuildSchema 'MySQL r m n =>
  SourceName ->
  RQL.SourceConfig 'MySQL ->
  Maybe RQL.QueryTagsConfig ->
  FunctionName 'MySQL ->
  FunctionInfo 'MySQL ->
  RQL.TableName 'MySQL ->
  SelPermInfo 'MySQL ->
  m [FieldParser n (QueryRootField UnpreparedValue)]
buildFunctionQueryFields' _ _ _ _ _ _ _ =
  pure []


buildFunctionRelayQueryFields' ::
  MonadBuildSchema 'MySQL r m n =>
  SourceName ->
  RQL.SourceConfig 'MySQL ->
  Maybe RQL.QueryTagsConfig ->
  FunctionName 'MySQL ->
  FunctionInfo 'MySQL ->
  RQL.TableName 'MySQL ->
  NESeq (ColumnInfo 'MySQL) ->
  SelPermInfo 'MySQL ->
  m [FieldParser n (QueryRootField UnpreparedValue)]
buildFunctionRelayQueryFields' _sourceName _sourceInfo _queryTagsConfig _functionName _functionInfo _tableName _pkeyColumns _selPerms =
  pure []


buildFunctionMutationFields' ::
  MonadBuildSchema 'MySQL r m n =>
  SourceName ->
  RQL.SourceConfig 'MySQL ->
  Maybe RQL.QueryTagsConfig ->
  FunctionName 'MySQL ->
  FunctionInfo 'MySQL ->
  RQL.TableName 'MySQL ->
  SelPermInfo 'MySQL ->
  m [FieldParser n (MutationRootField UnpreparedValue)]
buildFunctionMutationFields' _ _ _ _ _ _ _ =
  pure []

bsParser :: MonadParse m => Parser 'Both m ByteString
bsParser = encodeUtf8 <$> P.string

columnParser' :: (MonadSchema n m, MonadError QErr m) =>
  ColumnType 'MySQL ->
  G.Nullability ->
  m (Parser 'Both n (ValueWithOrigin (ColumnValue 'MySQL)))
columnParser' columnType (G.Nullability isNullable) =
  peelWithOrigin . fmap (ColumnValue columnType) <$> case columnType of
    ColumnScalar scalarType -> case scalarType of
      MySQL.Decimal  -> pure $ possiblyNullable scalarType $ MySQL.DecimalValue <$> P.float
      MySQL.Tiny     -> pure $ possiblyNullable scalarType $ MySQL.TinyValue <$> P.int
      MySQL.Short    -> pure $ possiblyNullable scalarType $ MySQL.SmallValue <$> P.int
      MySQL.Long     -> pure $ possiblyNullable scalarType $ MySQL.IntValue <$> P.int
      MySQL.Float    -> pure $ possiblyNullable scalarType $ MySQL.FloatValue <$> P.float
      MySQL.Double   -> pure $ possiblyNullable scalarType $ MySQL.DoubleValue <$> P.float
      MySQL.Null     -> pure $ possiblyNullable scalarType $ MySQL.NullValue <$ P.string
      MySQL.LongLong -> pure $ possiblyNullable scalarType $ MySQL.BigValue <$> P.int
      MySQL.Int24    -> pure $ possiblyNullable scalarType $ MySQL.MediumValue <$> P.int
      MySQL.Date -> pure $ possiblyNullable scalarType $ MySQL.DateValue <$> P.string
      MySQL.Year -> pure $ possiblyNullable scalarType $ MySQL.YearValue <$> P.string
      MySQL.Bit      -> pure $ possiblyNullable scalarType $ MySQL.BitValue <$> P.boolean
      MySQL.String   -> pure $ possiblyNullable scalarType $ MySQL.VarcharValue <$> P.string
      MySQL.VarChar     -> pure $ possiblyNullable scalarType $ MySQL.VarcharValue <$> P.string
      MySQL.DateTime -> pure $ possiblyNullable scalarType $ MySQL.DatetimeValue <$> P.string
      MySQL.Blob -> pure $ possiblyNullable scalarType $ MySQL.BlobValue <$> bsParser
      MySQL.Timestamp -> pure $ possiblyNullable scalarType $ MySQL.TimestampValue <$> P.string
      _              -> do
        name <- MySQL.mkMySQLScalarTypeName scalarType
        let schemaType = P.NonNullable $ P.TNamed $ P.mkDefinition name Nothing P.TIScalar
        pure $ Parser
          { pType = schemaType
          , pParser =
              valueToJSON (P.toGraphQLType schemaType) >=>
              either (parseErrorWith ParseFailed . qeError) pure . (MySQL.parseScalarValue scalarType)
          }
    ColumnEnumReference (EnumReference tableName enumValues) ->
      case nonEmpty (HM.toList enumValues) of
        Just enumValuesList -> do
          tableGQLName <- tableGraphQLName @'MySQL tableName `onLeft` throwError
          let enumName = tableGQLName <> $$(G.litName "_enum")
          pure $ possiblyNullable MySQL.VarChar $ P.enum enumName Nothing (mkEnumValue <$> enumValuesList)
        Nothing -> throw400 ValidationFailed "empty enum values"
  where
    possiblyNullable :: (MonadParse m) => MySQL.Type -> Parser 'Both m MySQL.ScalarValue -> Parser 'Both m MySQL.ScalarValue
    possiblyNullable _scalarType
      | isNullable = fmap (fromMaybe MySQL.NullValue) . P.nullable
      | otherwise  = id
    mkEnumValue :: (EnumValue, EnumValueInfo) -> (P.Definition P.EnumValueInfo, RQL.ScalarValue 'MySQL)
    mkEnumValue (RQL.EnumValue value, EnumValueInfo description) =
      ( P.mkDefinition value (G.Description <$> description) P.EnumValueInfo
      , MySQL.VarcharValue $ 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
          }


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


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


-- | TODO: Make this as thorough as the one for MSSQL/PostgreSQL
comparisonExps' ::
  forall m n. (BackendSchema 'MySQL, MonadSchema n m, MonadError QErr m) =>
  ColumnType 'MySQL ->
  m (Parser 'Input n [ComparisonExp 'MySQL])
comparisonExps' = P.memoize 'comparisonExps $ \columnType -> do
  -- see Note [Columns in comparison expression are never nullable]
  typedParser        <- columnParser columnType (G.Nullability False)
  nullableTextParser <- columnParser (ColumnScalar @'MySQL MySQL.VarChar) (G.Nullability True)
  textParser         <- columnParser (ColumnScalar @'MySQL MySQL.VarChar) (G.Nullability False)
  let name = P.getName typedParser <> $$(G.litName "_MySQL_comparison_exp")
      desc = G.Description $ "Boolean expression to compare columns of type "
        <>  P.getName typedParser
        <<> ". All fields are combined with logical 'AND'."
      textListParser = fmap openValueOrigin <$> P.list textParser
      columnListParser = fmap openValueOrigin <$> P.list typedParser
  pure $ P.object name (Just desc) $ catMaybes <$> sequenceA
    [ P.fieldOptional $$(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)
    ]


offsetParser' :: MonadParse n => Parser 'Both n (SQLExpression 'MySQL)
offsetParser' =
  MySQL.ValueExpression . MySQL.BigValue . fromIntegral <$> P.int

-- | Various update operators
updateOperators' ::
  Applicative m =>
  -- | qualified name of the table
  TableInfo 'MySQL ->
  -- | update permissions of the table
  UpdPermInfo 'MySQL ->
  m (Maybe (InputFieldsParser n [(RQL.Column 'MySQL, IR.UpdOpExpG (UnpreparedValue 'MySQL))]))
updateOperators' _table _updatePermissions = pure Nothing