Add Encode typeclass

src/FilePack/FileData.hs

@@ -0,0 +1,42 @@
+module FilePack.FileData where
+
+import Data.ByteString (ByteString)
+
+import Data.Text (Text)
+
+import Data.ByteString.Base64 qualified as B64
+import Data.ByteString.Char8 qualified as BC
+import GHC.Natural (Natural)
+import System.Posix.Types (CMode (..), FileMode)
+import Text.Read (readEither)
+
+import FilePack.Encode ()
+
+data FileData = FileData
+    { fileName :: Text
+    , fileSize :: Natural
+    , filePermissions :: FileMode
+    , fileData :: ByteString
+    }
+    deriving (Eq, Read, Show)
+
+newtype FilePack = FilePack {getPackedFiles :: [FileData]}
+    deriving (Eq, Read, Show)
+
+{- | @packFiles@ takes a FilePack and encodes it into a serialized form.
+
+ >>> import Data.Text qualified as T
+ >>> import Data.ByteString qualified as BS
+ >>> import System.Posix.Files (stdFileMode)
+ >>> let sampleFileData = FileData{fileName=T.pack "foo.txt", fileSize = 1024, filePermissions = stdFileMode, fileData = BS.empty}
+ >>> let sampleFilePack = FilePack [sampleFileData]
+ >>> (Right sampleFilePack) == (unpackFiles . packFiles $ sampleFilePack)
+ True
+-}
+packFiles :: FilePack -> ByteString
+packFiles = B64.encode . BC.pack . show
+
+-- | @unpackFiles@ tries to recover a FilePack from its serialized form.
+unpackFiles :: ByteString -> Either String FilePack
+unpackFiles serializedData =
+    B64.decode serializedData >>= readEither . BC.unpack