Arguments.hs

-- | Module      : IPLD.DagCBOR.Encoder.Arguments
--   Description : Functions for encoding CBOR major-type information.
--   Copyright   : Zoey McBride (c) 2026
--   License     : AGPL-3.0-or-later
--   Maintainer  : zoeymcbride@mailbox.org
--   Stability   : experimental
module IPLD.DagCBOR.Encoder.Arguments
  ( -- * Encodes CBOR type argument configuration into a byte.
    MajorArg,
    ParamArg,
    encodeArgument,
  )
where

import Data.Bits ((.<<.), (.|.))
import Data.ByteString.Builder (Builder)
import Data.ByteString.Builder qualified as BSB
import Data.Word (Word8)

-- | 3-bit identifier for idenitifying the major data types of CBOR.
type MajorArg = Word8

-- | 5-bit identifier that configures the data-type parameters for CBOR objects.
type ParamArg = Word8

-- | Encodes and validates the major type id and the parameter data.
{-# INLINE encodeArgument #-}
encodeArgument :: MajorArg -> ParamArg -> Builder
encodeArgument major param
  | major > 0b111 = error "major overflow"
  | param > 0b11111 = error "param overflow"
  | otherwise = BSB.word8 $ majorbits .|. param
  where
    majorbits = fromIntegral (fromEnum major .<<. 5)