Errors.hs

-- | Module      : MultiFormats.CID.Errors
--   Description : Provides Errors for CIDs
--   Copyright   : Zoey McBride (c) 2026
--   License     : AGPL-3.0-or-later
--   Maintainer  : zoeymcbride@mailbox.org
--   Stability   : experimental
module MultiFormats.CID.Errors
  ( Error (..),
    Okay,
    DataError (..),
    EncodingError (..),
    HashError (..),
  )
where

import Control.DeepSeq (NFData (..))
import MultiFormats.MultiCodec (MultiCodec (..))
import MultiFormats.VarInt.Errors qualified as VarInt

-- | Functor for wrapping CID processing function's return values.
type Okay t = Either Error t

-- | Everything that can go wrong in the CID modules.
data Error
  = InvalidData DataError
  | InvalidEncoding EncodingError
  | InvalidVarInt VarInt.Error
  | InvalidHash HashError
  deriving (Eq, Show)

-- | Evaluates Error into normal form.
instance NFData Error where
  rnf (InvalidData dataerr) = rnf dataerr
  rnf (InvalidEncoding encerr) = rnf encerr
  rnf (InvalidVarInt varerr) = rnf varerr
  rnf (InvalidHash hasherr) = rnf hasherr

-- | Errors with the CID itself, general/user caused errors.
data DataError
  = -- | When the total input is empty.
    EmptyCID
  | -- | When the Item's codec can't be resolved from the MultiCodec table.
    UnknownCodec
  | -- | When String data was processed, but has extra unaccounted bytes.
    TrailingBytes
  deriving (Eq, Show)

-- | Evaluates DataError into normal form.
instance NFData DataError where
  rnf _ = ()

-- | Errors arrising from the decoding process.
data EncodingError
  = -- | When the leading byte indicates CIDv0 but is malformed.
    MalformedCIDv0
  | -- | When the CIDv1 is detected, but has an invalid leading codec.
    ExpectedCIDv1
  | -- | When the String encoding has an unknown/unimplemented prefix char.
    UnknownBasePrefix
  | -- | When the given string has an invalid character.
    ImproperDigit
  deriving (Eq, Show)

-- | Evaluates EncodingError into normal form.
instance NFData EncodingError where
  rnf _ = ()

-- | Errors with the CID's MultiHash.
data HashError
  = -- | If the given hash codec isn't known as a hash function (isn't
    -- provided here, or isn't a hash codec value or is a invalid multicodec)
    UnknownHashCodec MultiCodec
  | -- | If the encoded hash length doesn't match the digest size.
    IncorrectLength
  deriving (Eq, Show)

-- | Evaluates HashError into normal form.
instance NFData HashError where
  rnf (UnknownHashCodec mc) = rnf mc
  rnf _ = ()