module Hasura.GraphQL.Schema.Action
  ( mkActionsSchema
  ) where

import qualified Data.HashMap.Strict           as Map
import qualified Data.HashSet                  as Set
import qualified Language.GraphQL.Draft.Syntax as G

import           Data.Coerce                   (coerce)

import           Hasura.GraphQL.Schema.Builder
import           Hasura.GraphQL.Schema.Common  (mkDescriptionWith)

import           Hasura.GraphQL.Resolve.Types
import           Hasura.GraphQL.Validate.Types
import           Hasura.Prelude
import           Hasura.RQL.Types
import           Hasura.SQL.Types

mkAsyncActionSelectionType :: ActionName -> G.NamedType
mkAsyncActionSelectionType = G.NamedType . unActionName

mkAsyncActionQueryResponseObj
  :: ActionName
  -- Name of the action
  -> GraphQLType
  -- output type
  -> ObjTyInfo
mkAsyncActionQueryResponseObj actionName outputType =
  mkHsraObjTyInfo
  (Just description)
  (mkAsyncActionSelectionType actionName) -- "(action_name)"
  mempty -- no arguments
  (mapFromL _fiName fieldDefinitions)
  where
    description = G.Description $ "fields of action: " <>> actionName

    mkFieldDefinition (fieldName, fieldDescription, fieldType) =
      mkHsraObjFldInfo
      (Just fieldDescription)
      fieldName
      mempty
      fieldType

    fieldDefinitions = map mkFieldDefinition
      [ ( "id", "the unique id of an action"
        , G.toGT $ mkScalarTy PGUUID)
      , ( "created_at", "the time at which this action was created"
        , G.toGT $ mkScalarTy PGTimeStampTZ)
      , ( "errors", "errors related to the invocation"
        , G.toGT $ mkScalarTy PGJSON)
      , ( "output", "the output fields of this action"
        , unGraphQLType outputType)
      ]

mkMutationField
  :: ActionName
  -> ActionInfo
  -> [(PGCol, PGScalarType)]
  -> (ActionExecutionContext, ObjFldInfo)
mkMutationField actionName actionInfo definitionList =
  ( actionExecutionContext
  , fieldInfo
  )
  where
    definition = _aiDefinition actionInfo
    actionExecutionContext =
      case _adKind definition of
        ActionSynchronous  ->
          ActionExecutionSyncWebhook $ SyncActionExecutionContext actionName
          (_adOutputType definition)
          (getActionOutputFields $ _aiOutputObject actionInfo)
          definitionList
          (_adHandler definition)
          (_adHeaders definition)
          (_adForwardClientHeaders definition)
        ActionAsynchronous -> ActionExecutionAsync

    description = mkDescriptionWith (PGDescription <$> _aiComment actionInfo) $
                  "perform the action: " <>> actionName

    fieldInfo =
      mkHsraObjFldInfo
      (Just description)
      (unActionName actionName)
      (mapFromL _iviName $ map mkActionArgument $ _adArguments definition)
      actionFieldResponseType

    mkActionArgument argument =
      InpValInfo (_argDescription argument) (unArgumentName $ _argName argument)
      Nothing $ unGraphQLType $ _argType argument

    actionFieldResponseType =
      case _adKind definition of
        ActionSynchronous  -> unGraphQLType $ _adOutputType definition
        ActionAsynchronous -> G.toGT $ G.toNT $ mkScalarTy PGUUID

mkQueryField
  :: ActionName
  -> Maybe Text
  -> ResolvedActionDefinition
  -> [(PGCol, PGScalarType)]
  -> Maybe (ActionSelectOpContext, ObjFldInfo, TypeInfo)
mkQueryField actionName comment definition definitionList =
  case _adKind definition of
    ActionAsynchronous ->
      Just ( ActionSelectOpContext (_adOutputType definition) definitionList

           , mkHsraObjFldInfo (Just description) (unActionName actionName)
             (mapFromL _iviName [idArgument])
             (G.toGT $ G.toGT $ mkAsyncActionSelectionType actionName)

           , TIObj $ mkAsyncActionQueryResponseObj actionName $
             _adOutputType definition
           )
    ActionSynchronous -> Nothing
  where
    description = mkDescriptionWith (PGDescription <$> comment) $
                  "retrieve the result of action: " <>> actionName

    idArgument =
      InpValInfo (Just idDescription) "id" Nothing $ G.toNT $ mkScalarTy PGUUID
      where
        idDescription = G.Description $ "id of the action: " <>> actionName

mkActionFieldsAndTypes
  :: ActionInfo
  -> ActionPermissionInfo
  -> ( Maybe (ActionSelectOpContext, ObjFldInfo, TypeInfo)
       -- context, field, response type info
     , (ActionExecutionContext, ObjFldInfo) -- mutation field
     , FieldMap
     )
mkActionFieldsAndTypes actionInfo permission =
  ( mkQueryField actionName comment definition definitionList
  , mkMutationField actionName actionInfo definitionList
  , fieldMap
  )
  where
    actionName = _aiName actionInfo
    annotatedOutputType = _aiOutputObject actionInfo
    definition = _aiDefinition actionInfo
    roleName = _apiRole permission
    comment = _aiComment actionInfo

    -- all the possible field references
    fieldReferences =
      Map.unions $ map _trFieldMapping $ Map.elems $
      _aotRelationships annotatedOutputType

    mkPGFieldType fieldName (fieldType, fieldTypeInfo) =
      case (G.isListType fieldType, fieldTypeInfo) of
        -- for scalar lists, we treat them as json columns
        (True, _) -> PGJSON
        -- enums the same
        (False, OutputFieldEnum _) -> PGJSON
        -- default to PGJSON unless you have to join with a postgres table
        -- i.e, if this field is specified as part of some relationship's
        -- mapping, we can cast this column's value as the remote column's type
        (False, OutputFieldScalar _) ->
          case Map.lookup fieldName fieldReferences of
            Just columnInfo -> unsafePGColumnToRepresentation $ pgiType columnInfo
            Nothing         -> PGJSON

    definitionList =
      [ (unsafePGCol $ coerce k, mkPGFieldType k v)
      | (k, v) <- Map.toList $ _aotAnnotatedFields annotatedOutputType
      ]
    -- mkFieldMap annotatedOutputType =
    fieldMap =
      Map.fromList $ fields <> catMaybes relationships
      where
        fields =
          flip map (Map.toList $ _aotAnnotatedFields annotatedOutputType) $
          \(fieldName, (fieldType, fieldTypeInfo)) ->
            ( (actionOutputBaseType, unObjectFieldName fieldName)
            , RFPGColumn $ PGColumnInfo
              (unsafePGCol $ coerce fieldName)
              (coerce fieldName)
              0
              (PGColumnScalar $ mkPGFieldType fieldName (fieldType, fieldTypeInfo))
              (G.isNullable fieldType)
              Nothing
            )
        relationships =
          flip map (Map.toList $ _aotRelationships annotatedOutputType) $
          \(relationshipName, relationship) ->
            let remoteTableInfo = _trRemoteTable relationship
                remoteTable = _tciName $ _tiCoreInfo remoteTableInfo
                filterAndLimitM = getFilterAndLimit remoteTableInfo
                columnMapping = Map.fromList $
                  [ (unsafePGCol $ coerce k, pgiColumn v)
                  | (k, v) <- Map.toList $ _trFieldMapping relationship
                  ]
            in case filterAndLimitM of
              Just (tableFilter, tableLimit) ->
                Just ( ( actionOutputBaseType
                       , unRelationshipName relationshipName
                       )
                     , RFRelationship $ RelationshipField
                       (RelInfo
                        -- RelationshipName, which is newtype wrapper over G.Name is always
                        -- non-empty text so as to conform GraphQL spec
                        (RelName $ mkNonEmptyTextUnsafe $ coerce relationshipName)
                        (_trType relationship)
                        columnMapping remoteTable True)
                       False mempty
                       tableFilter
                       tableLimit
                     )
              Nothing -> Nothing
    getFilterAndLimit remoteTableInfo =
      if roleName == adminRole
      then Just (annBoolExpTrue, Nothing)
      else do
        selectPermisisonInfo <-
          getSelectPermissionInfoM remoteTableInfo roleName
        return (spiFilter selectPermisisonInfo, spiLimit selectPermisisonInfo)
    actionOutputBaseType =
      G.getBaseType $ unGraphQLType $ _adOutputType $ _aiDefinition actionInfo

mkActionSchemaOne
  :: ActionInfo
  -> Map.HashMap RoleName
       ( Maybe (ActionSelectOpContext, ObjFldInfo, TypeInfo)
       , (ActionExecutionContext, ObjFldInfo)
       , FieldMap
       )
mkActionSchemaOne actionInfo =
  flip Map.map permissions $ \permission ->
    mkActionFieldsAndTypes actionInfo permission
  where
    adminPermission = ActionPermissionInfo adminRole
    permissions = Map.insert adminRole adminPermission $ _aiPermissions actionInfo

mkActionsSchema
  :: ActionCache
  -> Map.HashMap RoleName (RootFields, TyAgg)
mkActionsSchema =
  foldl'
  (\aggregate actionInfo ->
     Map.foldrWithKey (accumulate (_aiPgScalars actionInfo)) aggregate $ mkActionSchemaOne actionInfo
  )
  mempty
  where
    -- we'll need to add uuid and timestamptz for actions
    mkNewRoleState pgScalars =
      ( mempty
      , foldr addScalarToTyAgg mempty $
        pgScalars <> Set.fromList [PGJSON, PGTimeStampTZ, PGUUID]
      )

    accumulate pgScalars roleName (queryFieldM, mutationField, fields) =
      Map.alter (Just . addToState . fromMaybe (mkNewRoleState pgScalars)) roleName
      where
        addToState = case queryFieldM of
          Just (fldCtx, fldDefinition, responseTypeInfo) ->
            addToStateAsync (fldCtx, fldDefinition) responseTypeInfo
          Nothing -> addToStateSync
        addToStateSync (rootFields, tyAgg) =
          ( addMutationField (first MCAction mutationField) rootFields
          , addFieldsToTyAgg fields tyAgg
          )
        addToStateAsync queryField responseTypeInfo (rootFields, tyAgg) =
          ( addMutationField (first MCAction mutationField) $
            addQueryField
            (first QCActionFetch queryField)
            rootFields
          , addTypeInfoToTyAgg responseTypeInfo $
            addFieldsToTyAgg fields tyAgg
          )