Str.hs

module Rattletrap.Decode.Str
  ( decodeStr
  , decodeStrBits
  )
where

import Rattletrap.Decode.Common
import Rattletrap.Decode.Int32le
import Rattletrap.Type.Int32le
import Rattletrap.Type.Str
import Rattletrap.Utility.Bytes

import qualified Data.ByteString as Bytes
import qualified Data.Text as Text
import qualified Data.Text.Encoding as Text

decodeStr :: Decode Str
decodeStr = do
  rawSize <- decodeInt32le
  bytes <- getByteString (normalizeTextSize rawSize)
  pure (Str (dropNull (getTextDecoder rawSize bytes)))

decodeStrBits :: DecodeBits Str
decodeStrBits = do
  rawSize <- decodeInt32leBits
  bytes <- getByteStringBits (normalizeTextSize rawSize)
  pure (Str (dropNull (getTextDecoder rawSize (reverseBytes bytes))))

normalizeTextSize :: Integral a => Int32le -> a
normalizeTextSize size = case int32leValue size of
  0x05000000 -> 8
  x -> if x < 0 then (-2 * fromIntegral x) else fromIntegral x

getTextDecoder :: Int32le -> Bytes.ByteString -> Text.Text
getTextDecoder size bytes =
  let
    decode =
      if size < Int32le 0 then Text.decodeUtf16LE else Text.decodeLatin1
  in decode bytes

dropNull :: Text.Text -> Text.Text
dropNull = Text.dropWhileEnd (== '\x00')