{-# LANGUAGE CPP #-}
module Composite.Swagger.TH where

import Composite.CoRecord (Field)
import Composite.Swagger.Base (wrappedSchema)
import Data.Proxy (Proxy (Proxy))
import Data.Swagger (ToSchema, declareNamedSchema)
import Language.Haskell.TH
  ( Dec, Name, Q, mkName
  , bang, bangType, clause, conT, cxt, funD, instanceD, newtypeD, normalB, recC, varBangType , wildP
  , noSourceStrictness, noSourceUnpackedness )

-- |TH splice which makes it more convenient to define 'ToSchema' instance for 'Record' types.
--
-- For example:
--
-- @
--   type MyRecord = '[FFoo, FBar]
--   newtype MyRecordWrapper = MyRecordWrapper { unMyRecordWrapper :: Record MyRecord }
--   makeToSchema "MyRecordWrapper" ''MyRecordWrapper
-- @
--
-- is equivalent to:
--
-- @
--   instance ToSchema MyRecordWrapper where
--     declareNamedSchema = wrappedSchema (Proxy :: Proxy MyRecordWrapper) "MyRecordWrapper"
-- @
makeToSchema :: String -> Name -> Q [Dec]
makeToSchema :: String -> Name -> Q [Dec]
makeToSchema String
schemaName Name
wrapperName =
  [Q Dec] -> Q [Dec]
forall (t :: * -> *) (m :: * -> *) a.
(Traversable t, Monad m) =>
t (m a) -> m (t a)
sequence
    [ CxtQ -> TypeQ -> [Q Dec] -> Q Dec
instanceD
        ([TypeQ] -> CxtQ
cxt [])
        [t| ToSchema $(conT wrapperName) |]
        [ Name -> [ClauseQ] -> Q Dec
funD
            'declareNamedSchema
            [ [PatQ] -> BodyQ -> [Q Dec] -> ClauseQ
clause [PatQ
wildP] (ExpQ -> BodyQ
normalB [| wrappedSchema (Proxy :: Proxy $(conT wrapperName)) schemaName |]) [] ]
        ]
    ]

-- |TH splice which makes it more convenient to define 'ToSchema' instance for 'Record' types.
--
-- For example:
--
-- @
--   type MyRecord = '[FFoo, FBar]
--   makeToSchemaWrapper "MyRecordWrapper" ''MyRecord
-- @
--
-- is equivalent to:
--
-- @
--   newtype MyRecordWrapper = MyRecordWrapper { unMyRecordWrapper :: Record MyRecord }
--   instance ToSchema MyRecordWrapper where
--     declareNamedSchema = wrappedSchema (Proxy :: Proxy MyRecordWrapper) "MyRecordWrapper"
-- @
makeToSchemaWrapper :: String -> Name -> Q [Dec]
makeToSchemaWrapper :: String -> Name -> Q [Dec]
makeToSchemaWrapper String
wrapperNameStr Name
fieldsTyName = do
  let wrapperName :: Name
wrapperName = String -> Name
mkName String
wrapperNameStr
      extractorName :: Name
extractorName = String -> Name
mkName (String -> Name) -> String -> Name
forall a b. (a -> b) -> a -> b
$ String
"un" String -> String -> String
forall a. Semigroup a => a -> a -> a
<> String
wrapperNameStr
      fieldTy :: TypeQ
fieldTy = [t| Field $(conT fieldsTyName) |]
  Dec
wrapperNewtype <- CxtQ
-> Name
-> [TyVarBndr]
-> Maybe Kind
-> ConQ
-> [DerivClauseQ]
-> Q Dec
newtypeD
    ([TypeQ] -> CxtQ
cxt [])
    Name
wrapperName
    [] -- TyVarBndrs
    Maybe Kind
forall a. Maybe a
Nothing -- kind
    (Name -> [VarBangTypeQ] -> ConQ
recC Name
wrapperName [Name -> BangTypeQ -> VarBangTypeQ
varBangType Name
extractorName (BangQ -> TypeQ -> BangTypeQ
bangType (SourceUnpackednessQ -> SourceStrictnessQ -> BangQ
bang SourceUnpackednessQ
noSourceUnpackedness SourceStrictnessQ
noSourceStrictness) TypeQ
fieldTy)])
#if MIN_VERSION_template_haskell(2,12,0)
    [] -- deriving context
#else
    (cxt [])
#endif
  [Dec]
wrapperInstances <- String -> Name -> Q [Dec]
makeToSchema String
wrapperNameStr Name
wrapperName
  [Dec] -> Q [Dec]
forall (f :: * -> *) a. Applicative f => a -> f a
pure ([Dec] -> Q [Dec]) -> [Dec] -> Q [Dec]
forall a b. (a -> b) -> a -> b
$ Dec
wrapperNewtypeDec -> [Dec] -> [Dec]
forall a. a -> [a] -> [a]
:[Dec]
wrapperInstances