{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Test.StarWars.Schema
    ( schema
    ) where

import Control.Monad.Trans.Reader (asks)
import Control.Monad.Trans.Except (throwE)
import Control.Monad.Trans.Class (lift)
import Data.Functor.Identity (Identity)
import qualified Data.HashMap.Strict as HashMap
import Data.Maybe (catMaybes)
import Data.Text (Text)
import Language.GraphQL.Trans
import Language.GraphQL.Type.Definition
import qualified Language.GraphQL.Type.Out as Out
import Language.GraphQL.Type.Schema
import Test.StarWars.Data
import Prelude hiding (id)

-- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsSchema.js

schema :: Schema Identity
schema = Schema { query = queryType, mutation = Nothing }
  where
    queryType = Out.ObjectType "Query" Nothing [] $ HashMap.fromList
        [ ("hero", Out.Resolver (Out.Field Nothing (Out.NamedObjectType heroObject) mempty) hero)
        , ("human", Out.Resolver (Out.Field Nothing (Out.NamedObjectType heroObject) mempty) human)
        , ("droid", Out.Resolver (Out.Field Nothing (Out.NamedObjectType droidObject) mempty) droid)
        ]

heroObject :: Out.ObjectType Identity
heroObject = Out.ObjectType "Human" Nothing [] $ HashMap.fromList
    [ ("id", Out.Resolver idFieldType (idField "id"))
    , ("name", Out.Resolver nameFieldType (idField "name"))
    , ("friends", Out.Resolver friendsFieldType (idField "friends"))
    , ("appearsIn", Out.Resolver appearsInFieldType (idField "appearsIn"))
    , ("homePlanet", Out.Resolver homePlanetFieldType (idField "homePlanet"))
    , ("secretBackstory", Out.Resolver secretBackstoryFieldType (String <$> secretBackstory))
    , ("__typename", Out.Resolver (Out.Field Nothing (Out.NamedScalarType string) mempty) (idField "__typename"))
    ]
  where
    homePlanetFieldType = Out.Field Nothing (Out.NamedScalarType string) mempty

droidObject :: Out.ObjectType Identity
droidObject = Out.ObjectType "Droid" Nothing [] $ HashMap.fromList
    [ ("id", Out.Resolver idFieldType (idField "id"))
    , ("name", Out.Resolver nameFieldType (idField "name"))
    , ("friends", Out.Resolver friendsFieldType (idField "friends"))
    , ("appearsIn", Out.Resolver appearsInFieldType (idField "appearsIn"))
    , ("primaryFunction", Out.Resolver primaryFunctionFieldType (idField "primaryFunction"))
    , ("secretBackstory", Out.Resolver secretBackstoryFieldType (String <$> secretBackstory))
    , ("__typename", Out.Resolver (Out.Field Nothing (Out.NamedScalarType string) mempty) (idField "__typename"))
    ]
  where
    primaryFunctionFieldType = Out.Field Nothing (Out.NamedScalarType string) mempty

idFieldType :: Out.Field Identity
idFieldType = Out.Field Nothing (Out.NamedScalarType id) mempty

nameFieldType :: Out.Field Identity
nameFieldType = Out.Field Nothing (Out.NamedScalarType string) mempty

friendsFieldType :: Out.Field Identity
friendsFieldType = Out.Field Nothing (Out.ListType $ Out.NamedObjectType droidObject) mempty

appearsInFieldType :: Out.Field Identity
appearsInFieldType = Out.Field Nothing (Out.ListType $ Out.NamedScalarType int) mempty

secretBackstoryFieldType :: Out.Field Identity
secretBackstoryFieldType = Out.Field Nothing (Out.NamedScalarType string) mempty

idField :: Text -> ActionT Identity Value
idField f = do
    v <- ActionT $ lift $ asks values
    let (Object v') = v
    pure $ v' HashMap.! f

hero :: ActionT Identity Value
hero = do
  episode <- argument "episode"
  pure $ character $ case episode of
      Enum "NEWHOPE" -> getHero 4
      Enum "EMPIRE" -> getHero 5
      Enum "JEDI" -> getHero 6
      _ -> artoo

human :: ActionT Identity Value
human = do
    id' <- argument "id"
    case id' of
        String i -> do
            humanCharacter <- lift $ return $ getHuman i >>= Just
            case humanCharacter of
                Nothing -> pure Null
                Just e -> pure $ character e
        _ -> ActionT $ throwE "Invalid arguments."

droid :: ActionT Identity Value
droid = do
    id' <- argument "id"
    case id' of
        String i -> character <$> getDroid i
        _ -> ActionT $ throwE "Invalid arguments."

character :: Character -> Value
character char = Object $ HashMap.fromList
    [ ("id", String $ id_ char)
    , ("name", String $ name_ char)
    , ("friends", List $ character <$> getFriends char)
    , ("appearsIn", List $ Enum <$> catMaybes (getEpisode <$> appearsIn char))
    , ("homePlanet", String $ either mempty homePlanet char)
    , ("__typename", String $ typeName char)
    ]