{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE TemplateHaskellQuotes #-}

module Hasura.GraphQL.Schema.OrderBy
  ( orderByExp,
  )
where

import Data.Has
import Data.HashMap.Strict.Extended qualified as HashMap
import Data.Text.Casing qualified as C
import Data.Text.Extended
import Hasura.GraphQL.Parser.Class
import Hasura.GraphQL.Schema.Backend
import Hasura.GraphQL.Schema.Common
import Hasura.GraphQL.Schema.NamingCase
import Hasura.GraphQL.Schema.Parser
  ( InputFieldsParser,
    Kind (..),
    Parser,
  )
import Hasura.GraphQL.Schema.Parser qualified as P
import Hasura.GraphQL.Schema.Table
import Hasura.GraphQL.Schema.Typename
import Hasura.Name qualified as Name
import Hasura.Prelude
import Hasura.RQL.IR.OrderBy qualified as IR
import Hasura.RQL.IR.Select qualified as IR
import Hasura.RQL.IR.Value qualified as IR
import Hasura.RQL.Types.Backend
import Hasura.RQL.Types.Column
import Hasura.RQL.Types.Common
import Hasura.RQL.Types.ComputedField
import Hasura.RQL.Types.Function
import Hasura.RQL.Types.Relationships.Local
import Hasura.RQL.Types.SchemaCache hiding (askTableInfo)
import Hasura.RQL.Types.Source
import Hasura.RQL.Types.SourceCustomization
import Hasura.RQL.Types.Table
import Language.GraphQL.Draft.Syntax qualified as G

{-# INLINE orderByOperator #-}
orderByOperator ::
  forall b n.
  (BackendSchema b, MonadParse n) =>
  NamingCase ->
  SourceInfo b ->
  Parser 'Both n (Maybe (BasicOrderType b, NullsOrderType b))
orderByOperator tCase sourceInfo = case tCase of
  HasuraCase -> orderByOperatorsHasuraCase @b sourceInfo
  GraphqlCase -> orderByOperatorsGraphqlCase @b sourceInfo

-- | Corresponds to an object type for an order by.
--
-- > input table_order_by {
-- >   col1: order_by
-- >   col2: order_by
-- >   .     .
-- >   .     .
-- >   coln: order_by
-- >   obj-rel: <remote-table>_order_by
-- > }
orderByExp ::
  forall b r m n.
  MonadBuildSchema b r m n =>
  TableInfo b ->
  SchemaT r m (Parser 'Input n [IR.AnnotatedOrderByItemG b (IR.UnpreparedValue b)])
orderByExp tableInfo = do
  sourceInfo <- asks getter
  P.memoizeOn 'orderByExp (_siName sourceInfo, tableInfoName tableInfo) do
    let customization = _siCustomization sourceInfo
        tCase = _rscNamingConvention customization
        mkTypename = runMkTypename $ _rscTypeNames customization
    tableGQLName <- getTableIdentifierName tableInfo
    let name = mkTypename $ applyTypeNameCaseIdentifier tCase $ mkTableOrderByTypeName tableGQLName
        description =
          G.Description $
            "Ordering options when selecting data from " <> tableInfoName tableInfo <<> "."
    tableFields <- tableSelectFields tableInfo
    fieldParsers <- sequenceA . catMaybes <$> traverse (mkField sourceInfo tCase) tableFields
    pure $ concat . catMaybes <$> P.object name (Just description) fieldParsers
  where
    mkField ::
      SourceInfo b ->
      NamingCase ->
      FieldInfo b ->
      SchemaT r m (Maybe (InputFieldsParser n (Maybe [IR.AnnotatedOrderByItemG b (IR.UnpreparedValue b)])))
    mkField sourceInfo tCase fieldInfo = runMaybeT $ do
      roleName <- retrieve scRole
      case fieldInfo of
        FIColumn columnInfo -> do
          let !fieldName = ciName columnInfo
          pure $
            P.fieldOptional
              fieldName
              Nothing
              (orderByOperator @b tCase sourceInfo)
              <&> fmap (pure . mkOrderByItemG @b (IR.AOCColumn columnInfo)) . join
        FIRelationship relationshipInfo -> do
          remoteTableInfo <- askTableInfo $ riRTable relationshipInfo
          perms <- hoistMaybe $ tableSelectPermissions roleName remoteTableInfo
          fieldName <- hoistMaybe $ G.mkName $ relNameToTxt $ riName relationshipInfo
          let newPerms = fmap partialSQLExpToUnpreparedValue <$> spiFilter perms
          case riType relationshipInfo of
            ObjRel -> do
              otherTableParser <- lift $ orderByExp remoteTableInfo
              pure $ do
                otherTableOrderBy <- join <$> P.fieldOptional fieldName Nothing (P.nullable otherTableParser)
                pure $ fmap (map $ fmap $ IR.AOCObjectRelation relationshipInfo newPerms) otherTableOrderBy
            ArrRel -> do
              let aggregateFieldName = applyFieldNameCaseIdentifier tCase $ C.fromAutogeneratedTuple (fieldName, [G.convertNameToSuffix Name._aggregate])
              aggregationParser <- lift $ orderByAggregation sourceInfo remoteTableInfo
              pure $ do
                aggregationOrderBy <- join <$> P.fieldOptional aggregateFieldName Nothing (P.nullable aggregationParser)
                pure $ fmap (map $ fmap $ IR.AOCArrayAggregation relationshipInfo newPerms) aggregationOrderBy
        FIComputedField ComputedFieldInfo {..} -> do
          let ComputedFieldFunction {..} = _cfiFunction
              mkComputedFieldOrderBy =
                let functionArgs =
                      flip FunctionArgsExp mempty $
                        fromComputedFieldImplicitArguments @b IR.UVSession _cffComputedFieldImplicitArgs
                 in IR.ComputedFieldOrderBy _cfiXComputedFieldInfo _cfiName _cffName functionArgs
          fieldName <- hoistMaybe $ G.mkName $ toTxt _cfiName
          guard $ _cffInputArgs == mempty -- No input arguments other than table row and session argument
          case computedFieldReturnType @b _cfiReturnType of
            ReturnsScalar scalarType -> do
              let computedFieldOrderBy = mkComputedFieldOrderBy $ IR.CFOBEScalar scalarType
              pure $
                P.fieldOptional
                  fieldName
                  Nothing
                  (orderByOperator @b tCase sourceInfo)
                  <&> fmap (pure . mkOrderByItemG @b (IR.AOCComputedField computedFieldOrderBy)) . join
            ReturnsTable table -> do
              let aggregateFieldName = applyFieldNameCaseIdentifier tCase $ C.fromAutogeneratedTuple (fieldName, [G.convertNameToSuffix Name._aggregate])
              tableInfo' <- askTableInfo table
              perms <- hoistMaybe $ tableSelectPermissions roleName tableInfo'
              let newPerms = fmap partialSQLExpToUnpreparedValue <$> spiFilter perms
              aggregationParser <- lift $ orderByAggregation sourceInfo tableInfo'
              pure $ do
                aggregationOrderBy <- join <$> P.fieldOptional aggregateFieldName Nothing (P.nullable aggregationParser)
                pure $
                  fmap
                    ( map $
                        fmap $
                          IR.AOCComputedField
                            . mkComputedFieldOrderBy
                            . IR.CFOBETableAggregation table newPerms
                    )
                    aggregationOrderBy
            ReturnsOthers -> empty
        FIRemoteRelationship _ -> empty

-- FIXME!
-- those parsers are directly using Postgres' SQL representation of
-- order, rather than using a general intermediary representation

orderByAggregation ::
  forall b r m n.
  MonadBuildSchema b r m n =>
  SourceInfo b ->
  TableInfo b ->
  SchemaT r m (Parser 'Input n [IR.OrderByItemG b (IR.AnnotatedAggregateOrderBy b)])
orderByAggregation sourceInfo tableInfo = P.memoizeOn 'orderByAggregation (_siName sourceInfo, tableName) do
  -- WIP NOTE
  -- there is heavy duplication between this and Select.tableAggregationFields
  -- it might be worth putting some of it in common, just to avoid issues when
  -- we change one but not the other?
  tableGQLName <- getTableGQLName @b tableInfo
  let customization = _siCustomization sourceInfo
      tCase = _rscNamingConvention customization
      mkTypename = _rscTypeNames customization
  tableIdentifierName <- getTableIdentifierName @b tableInfo
  allColumns <- tableSelectColumns tableInfo
  let numColumns = stdAggOpColumns tCase $ onlyNumCols allColumns
      compColumns = stdAggOpColumns tCase $ onlyComparableCols allColumns
      numOperatorsAndColumns = HashMap.fromList $ (,numColumns) <$> numericAggOperators
      compOperatorsAndColumns = HashMap.fromList $ (,compColumns) <$> comparisonAggOperators
      customOperatorsAndColumns =
        getCustomAggOpsColumns tCase allColumns <$> getCustomAggregateOperators @b (_siConfiguration sourceInfo)
      allOperatorsAndColumns =
        HashMap.catMaybes $
          HashMap.unionsWith (<>) [numOperatorsAndColumns, compOperatorsAndColumns, customOperatorsAndColumns]
      aggFields =
        fmap (concat . catMaybes . concat) $
          sequenceA $
            catMaybes
              [ -- count
                Just $
                  P.fieldOptional
                    Name._count
                    Nothing
                    (orderByOperator @b tCase sourceInfo)
                    <&> pure . fmap (pure . mkOrderByItemG @b IR.AAOCount) . join,
                -- other operators
                if null allOperatorsAndColumns
                  then Nothing
                  else Just $
                    for (HashMap.toList allOperatorsAndColumns) \(operator, fields) -> do
                      parseOperator mkTypename operator tableGQLName fields
              ]
  let objectName = runMkTypename mkTypename $ applyTypeNameCaseIdentifier tCase $ mkTableAggregateOrderByTypeName tableIdentifierName
      description = G.Description $ "order by aggregate values of table " <>> tableName
  pure $ P.object objectName (Just description) aggFields
  where
    tableName = tableInfoName tableInfo

    stdAggOpColumns ::
      NamingCase ->
      [ColumnInfo b] ->
      Maybe (InputFieldsParser n [(ColumnInfo b, ColumnType b, (BasicOrderType b, NullsOrderType b))])
    stdAggOpColumns tCase columns =
      columns
        -- ALl std aggregate functions return the same type as the column used with it
        & fmap (\colInfo -> (colInfo, ciType colInfo))
        & mkAgOpsFields tCase

    -- Build an InputFieldsParser only if the column list is non-empty
    mkAgOpsFields ::
      NamingCase ->
      -- Assoc list of column types with the type returned by the aggregate function when it is applied to that column
      [(ColumnInfo b, ColumnType b)] ->
      Maybe (InputFieldsParser n [(ColumnInfo b, ColumnType b, (BasicOrderType b, NullsOrderType b))])
    mkAgOpsFields tCase =
      fmap (fmap (catMaybes . toList) . traverse (mkField tCase)) . nonEmpty

    getCustomAggOpsColumns ::
      NamingCase ->
      -- All columns
      [ColumnInfo b] ->
      -- Map of type the aggregate function accepts to the type it returns
      HashMap (ScalarType b) (ScalarType b) ->
      Maybe (InputFieldsParser n [(ColumnInfo b, ColumnType b, (BasicOrderType b, NullsOrderType b))])
    getCustomAggOpsColumns tCase allColumns typeMap =
      allColumns
        -- Filter by columns with a scalar type supported by this aggregate function
        -- and retrieve the result type of the aggregate function
        & mapMaybe
          ( \columnInfo ->
              case ciType columnInfo of
                ColumnEnumReference _ -> Nothing
                ColumnScalar scalarType ->
                  (\resultType -> (columnInfo, ColumnScalar resultType)) <$> HashMap.lookup scalarType typeMap
          )
        & mkAgOpsFields tCase

    mkField :: NamingCase -> (ColumnInfo b, ColumnType b) -> InputFieldsParser n (Maybe (ColumnInfo b, ColumnType b, (BasicOrderType b, NullsOrderType b)))
    mkField tCase (columnInfo, resultType) =
      P.fieldOptional
        (ciName columnInfo)
        (ciDescription columnInfo)
        (orderByOperator @b tCase sourceInfo)
        <&> fmap (columnInfo,resultType,) . join

    parseOperator ::
      MkTypename ->
      G.Name ->
      G.Name ->
      InputFieldsParser n [(ColumnInfo b, ColumnType b, (BasicOrderType b, NullsOrderType b))] ->
      InputFieldsParser n (Maybe [IR.OrderByItemG b (IR.AnnotatedAggregateOrderBy b)])
    parseOperator makeTypename operator tableGQLName columns =
      let opText = G.unName operator
          objectName = runMkTypename makeTypename $ tableGQLName <> Name.__ <> operator <> Name.__order_by
          objectDesc = Just $ G.Description $ "order by " <> opText <> "() on columns of table " <>> tableName
       in P.fieldOptional operator Nothing (P.object objectName objectDesc columns)
            `mapField` map (\(col, resultType, info) -> mkOrderByItemG (IR.AAOOp opText resultType col) info)

orderByOperatorsHasuraCase ::
  forall b n.
  (BackendSchema b, MonadParse n) =>
  SourceInfo b ->
  Parser 'Both n (Maybe (BasicOrderType b, NullsOrderType b))
orderByOperatorsHasuraCase = orderByOperator' @b HasuraCase

orderByOperatorsGraphqlCase ::
  forall b n.
  (BackendSchema b, MonadParse n) =>
  SourceInfo b ->
  Parser 'Both n (Maybe (BasicOrderType b, NullsOrderType b))
orderByOperatorsGraphqlCase = orderByOperator' @b GraphqlCase

orderByOperator' ::
  forall b n.
  (BackendSchema b, MonadParse n) =>
  NamingCase ->
  SourceInfo b ->
  Parser 'Both n (Maybe (BasicOrderType b, NullsOrderType b))
orderByOperator' tCase sourceInfo =
  let (sourcePrefix, orderOperators) = orderByOperators @b sourceInfo tCase
   in P.nullable $ P.enum (applyTypeNameCaseCust tCase sourcePrefix) (Just "column ordering options") $ orderOperators

mkOrderByItemG :: forall b a. a -> (BasicOrderType b, NullsOrderType b) -> IR.OrderByItemG b a
mkOrderByItemG column (orderType, nullsOrder) =
  IR.OrderByItemG
    { obiType = Just orderType,
      obiColumn = column,
      obiNulls = Just nullsOrder
    }