-- | The module Data.GraphQl provides the
--   functions graphql and graphqlSubs to parse
--   and execute GraphQL queries.
module Data.GraphQL where

import Control.Applicative (Alternative)

import Data.Text (Text)

import qualified Data.Aeson as Aeson
import qualified Data.Attoparsec.Text as Attoparsec

import Data.GraphQL.Execute
import Data.GraphQL.Parser
import Data.GraphQL.Schema

import Data.GraphQL.Error

-- | graphql takes a schema and text representing a GraphQL request document.
--   If the text parses correctly as a GraphQl query
--   the query is executed according to the given schema.
--   Returns the response to the query wrapped in an Aeson.Value.
graphql :: (Alternative m, Monad m) => Schema m -> Text -> m Aeson.Value
graphql = flip graphqlSubs $ const Nothing

-- | graphqlsubs takes in a schema, a substitution and text representing
--   a GraphQL request document.
--   If the text parses correctly as a GraphQl query
--   the substitution is applied to the query and
--   the query is then executed according to the given schema.
--   Returns the response to the query wrapped in an Aeson.Value.
graphqlSubs :: (Alternative m, Monad m) => Schema m -> Subs -> Text -> m Aeson.Value
graphqlSubs schema f =
    either parseError (execute schema f)
  . Attoparsec.parseOnly document