{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE NoImplicitPrelude #-}

module Data.Morpheus.Validation.Internal.Directive
  ( shouldIncludeSelection,
    validateDirectives,
  )
where

import Data.Morpheus.Error.Utils
  ( validationErrorMessage,
  )
import Data.Morpheus.Internal.Utils
  ( Failure (..),
    selectOr,
  )
import Data.Morpheus.Types.Internal.AST
  ( Argument (..),
    Directive (..),
    DirectiveDefinition (..),
    DirectiveLocation (..),
    Directives,
    FieldName,
    Ref (..),
    ScalarValue (..),
    Schema (..),
    VALID,
    Value (..),
    msg,
  )
import Data.Morpheus.Types.Internal.Validation
  ( Validator,
    askSchema,
    selectKnown,
    selectRequired,
    withDirective,
  )
import Data.Morpheus.Validation.Internal.Arguments
  ( ArgumentsConstraints,
    validateDirectiveArguments,
  )
import Relude

validateDirectives ::
  ArgumentsConstraints ctx schemaS s =>
  DirectiveLocation ->
  Directives s ->
  Validator schemaS ctx (Directives VALID)
validateDirectives location = traverse (validate location)

validate ::
  ArgumentsConstraints c schemaS s =>
  DirectiveLocation ->
  Directive s ->
  Validator schemaS c (Directive VALID)
validate location directive@Directive {..} =
  withDirective directive $ do
    Schema {directiveDefinitions} <- askSchema
    directiveDef <- selectKnown directive directiveDefinitions
    Directive directivePosition directiveName
      <$> ( validateDirectiveLocation location directive directiveDef
              *> validateDirectiveArguments directiveDef directiveArgs
          )

validateDirectiveLocation ::
  DirectiveLocation ->
  Directive s ->
  DirectiveDefinition s' ->
  Validator schemaS ctx ()
validateDirectiveLocation
  loc
  Directive {directiveName, directivePosition}
  DirectiveDefinition {directiveDefinitionLocations}
    | loc `elem` directiveDefinitionLocations = pure ()
    | otherwise =
      failure $
        validationErrorMessage
          (Just directivePosition)
          ("Directive " <> msg directiveName <> " may not to be used on " <> msg loc)

directiveFulfilled ::
  Bool ->
  FieldName ->
  Directives s ->
  Validator schemaS ctx Bool
directiveFulfilled target = selectOr (pure True) (argumentIf target)

shouldIncludeSelection ::
  Directives VALID ->
  Validator schemaS ctx Bool
shouldIncludeSelection directives = do
  dontSkip <- directiveFulfilled False "skip" directives
  include <- directiveFulfilled True "include" directives
  pure (dontSkip && include)

argumentIf ::
  Bool ->
  Directive s ->
  Validator schemaS ctx Bool
argumentIf target Directive {directiveArgs, directivePosition} =
  selectRequired (Ref "if" directivePosition) directiveArgs
    >>= assertArgument target

assertArgument ::
  Bool ->
  Argument s ->
  Validator schemaS ctx Bool
assertArgument asserted Argument {argumentValue = Scalar (Boolean actual)} = pure (asserted == actual)
assertArgument _ Argument {argumentValue, argumentPosition} =
  failure
    $ validationErrorMessage
      (Just argumentPosition)
    $ "Expected type Boolean!, found " <> msg argumentValue <> "."