{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE TemplateHaskell   #-}

-- |
-- Module:      SwiftNav.SBP.TH
-- Copyright:   Copyright (C) 2015-2021 Swift Navigation, Inc.
-- License:     MIT
-- Contact:     https://support.swiftnav.com
-- Stability:   experimental
-- Portability: portable
--
-- Templated generation of SBP and JSON interfaces.

module SwiftNav.SBP.TH
  ( makeSBP
  , makeJSON
  ) where

import           BasicPrelude
import           Control.Lens
import           Data.Aeson.TH
import           Data.Binary
import qualified Data.ByteString      as BS
import qualified Data.ByteString.Lazy as LBS
import           Language.Haskell.TH
import           SwiftNav.SBP.Types

-- | Derive ToSBP typeclass, given an SBP message type name and the
-- name of the implemented type.
makeSBP :: Name -> Name -> Q [Dec]
makeSBP :: Name -> Name -> Q [Dec]
makeSBP Name
msgType Name
name =
  [d|instance ToSBP $(Name -> Q Type
forall (m :: * -> *). Quote m => Name -> m Type
conT Name
name) where
       toSBP m senderID = encoded & msgSBPCrc .~ checkCrc encoded
         where
           payload = LBS.toStrict $ encode m
           len     = fromIntegral $ BS.length payload
           encoded = Msg $(Name -> Q Exp
forall (m :: * -> *). Quote m => Name -> m Exp
varE Name
msgType) senderID len (Bytes payload) 0
    |]

-- | Derive JSON stripping out prefixes of the implemented type.
makeJSON :: String -> Name -> Q [Dec]
makeJSON :: String -> Name -> Q [Dec]
makeJSON String
prefix = Options -> Name -> Q [Dec]
deriveJSON Options
defaultOptions
  { fieldLabelModifier = ap fromMaybe $ stripPrefix prefix
  }