graphql-engine/server/src-lib/Hasura/NativeQuery/Metadata.hs

{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE UndecidableInstances #-}

-- | Metadata representation of a native query in the metadata,
--   as well as a parser and prettyprinter for the query code.
module Hasura.NativeQuery.Metadata
  ( NativeQueryName (..),
    NativeQueryMetadata (..),
    nqmArguments,
    nqmCode,
    nqmDescription,
    nqmReturns,
    nqmRootFieldName,
    NativeQueryArgumentName (..),
    InterpolatedItem (..),
    InterpolatedQuery (..),
    parseInterpolatedQuery,
    module Hasura.NativeQuery.Types,
  )
where

import Autodocodec
import Autodocodec qualified as AC
import Control.Lens (makeLenses)
import Data.Aeson (FromJSON, FromJSONKey, ToJSON, ToJSONKey)
import Data.Bifunctor (first)
import Data.Text qualified as T
import Hasura.CustomReturnType.Metadata (CustomReturnTypeName)
import Hasura.Metadata.DTO.Utils (codecNamePrefix)
import Hasura.NativeQuery.Types (NativeQueryName (..), NullableScalarType)
import Hasura.Prelude hiding (first)
import Hasura.RQL.Types.Backend
import Hasura.SQL.Backend
import Language.Haskell.TH.Syntax (Lift)

newtype RawQuery = RawQuery {getRawQuery :: Text}
  deriving newtype (Eq, Ord, Show, FromJSON, ToJSON)

instance HasCodec RawQuery where
  codec = AC.dimapCodec RawQuery getRawQuery codec

---------------------------------------

-- | A component of an interpolated query
data InterpolatedItem variable
  = -- | normal text
    IIText Text
  | -- | a captured variable
    IIVariable variable
  deriving stock (Eq, Ord, Show, Functor, Foldable, Data, Generic, Lift, Traversable)

-- | Converting an interpolated query back to text.
--   Should roundtrip with the 'parseInterpolatedQuery'.
ppInterpolatedItem :: InterpolatedItem NativeQueryArgumentName -> Text
ppInterpolatedItem (IIText t) = t
ppInterpolatedItem (IIVariable v) = "{{" <> getNativeQueryArgumentName v <> "}}"

deriving instance (Hashable variable) => Hashable (InterpolatedItem variable)

deriving instance (NFData variable) => NFData (InterpolatedItem variable)

---------------------------------------

-- | A list of native query components representing a single native query,
--   separating the variables from the text.
newtype InterpolatedQuery variable = InterpolatedQuery
  { getInterpolatedQuery :: [InterpolatedItem variable]
  }
  deriving newtype (Eq, Ord, Show, Generic)
  deriving stock (Data, Functor, Foldable, Lift, Traversable)

deriving newtype instance (Hashable variable) => Hashable (InterpolatedQuery variable)

deriving newtype instance (NFData variable) => NFData (InterpolatedQuery variable)

ppInterpolatedQuery :: InterpolatedQuery NativeQueryArgumentName -> Text
ppInterpolatedQuery (InterpolatedQuery parts) = foldMap ppInterpolatedItem parts

-- | We store the interpolated query as the user text and parse it back
--   when converting back to Haskell code.
instance v ~ NativeQueryArgumentName => HasCodec (InterpolatedQuery v) where
  codec =
    CommentCodec
      ("An interpolated query expressed in native code (SQL)")
      $ bimapCodec
        (first T.unpack . parseInterpolatedQuery)
        ppInterpolatedQuery
        textCodec

deriving via
  (Autodocodec (InterpolatedQuery NativeQueryArgumentName))
  instance
    v ~ NativeQueryArgumentName =>
    ToJSON (InterpolatedQuery v)

---------------------------------------

newtype NativeQueryArgumentName = NativeQueryArgumentName
  { getNativeQueryArgumentName :: Text
  }
  deriving newtype (Eq, Ord, Show, Hashable)
  deriving stock (Generic)

instance HasCodec NativeQueryArgumentName where
  codec = dimapCodec NativeQueryArgumentName getNativeQueryArgumentName codec

deriving newtype instance ToJSON NativeQueryArgumentName

deriving newtype instance FromJSON NativeQueryArgumentName

deriving newtype instance ToJSONKey NativeQueryArgumentName

deriving newtype instance FromJSONKey NativeQueryArgumentName

instance NFData NativeQueryArgumentName

---------------------------------------

-- | The representation of native queries within the metadata structure.
data NativeQueryMetadata (b :: BackendType) = NativeQueryMetadata
  { _nqmRootFieldName :: NativeQueryName,
    _nqmCode :: InterpolatedQuery NativeQueryArgumentName,
    _nqmReturns :: CustomReturnTypeName,
    _nqmArguments :: HashMap NativeQueryArgumentName (NullableScalarType b),
    _nqmDescription :: Maybe Text
  }
  deriving (Generic)

deriving instance Backend b => Eq (NativeQueryMetadata b)

deriving instance Backend b => Show (NativeQueryMetadata b)

instance (Backend b) => HasCodec (NativeQueryMetadata b) where
  codec =
    CommentCodec
      ("A native query as represented in metadata.")
      $ AC.object (codecNamePrefix @b <> "NativeQueryMetadata")
      $ NativeQueryMetadata
        <$> requiredField "root_field_name" fieldNameDoc
          AC..= _nqmRootFieldName
        <*> requiredField "code" sqlDoc
          AC..= _nqmCode
        <*> requiredField "returns" returnsDoc
          AC..= _nqmReturns
        <*> optionalFieldWithDefault "arguments" mempty argumentDoc
          AC..= _nqmArguments
        <*> optionalField "description" descriptionDoc
          AC..= _nqmDescription
    where
      fieldNameDoc = "Root field name for the native query"
      sqlDoc = "Native code expression (SQL) to run"
      argumentDoc = "Free variables in the expression and their types"
      returnsDoc = "Return type (table) of the expression"
      descriptionDoc = "A description of the native query which appears in the graphql schema"

deriving via
  (Autodocodec (NativeQueryMetadata b))
  instance
    (Backend b) => (FromJSON (NativeQueryMetadata b))

deriving via
  (Autodocodec (NativeQueryMetadata b))
  instance
    (Backend b) => (ToJSON (NativeQueryMetadata b))

-- | extract all of the `{{ variable }}` inside our query string
parseInterpolatedQuery ::
  Text ->
  Either Text (InterpolatedQuery NativeQueryArgumentName)
parseInterpolatedQuery =
  fmap
    ( InterpolatedQuery
        . mergeAdjacent
        . trashEmpties
    )
    . consumeString
    . T.unpack
  where
    trashEmpties = filter (/= IIText "")

    mergeAdjacent = \case
      (IIText a : IIText b : rest) ->
        mergeAdjacent (IIText (a <> b) : rest)
      (a : rest) -> a : mergeAdjacent rest
      [] -> []

    consumeString :: String -> Either Text [InterpolatedItem NativeQueryArgumentName]
    consumeString str =
      let (beforeCurly, fromCurly) = break (== '{') str
       in case fromCurly of
            ('{' : '{' : rest) ->
              (IIText (T.pack beforeCurly) :) <$> consumeVar rest
            ('{' : other) ->
              (IIText (T.pack (beforeCurly <> "{")) :) <$> consumeString other
            _other -> pure [IIText (T.pack beforeCurly)]

    consumeVar :: String -> Either Text [InterpolatedItem NativeQueryArgumentName]
    consumeVar str =
      let (beforeCloseCurly, fromClosedCurly) = break (== '}') str
       in case fromClosedCurly of
            ('}' : '}' : rest) ->
              (IIVariable (NativeQueryArgumentName $ T.pack beforeCloseCurly) :) <$> consumeString rest
            _ -> Left "Found '{{' without a matching closing '}}'"

makeLenses ''NativeQueryMetadata