type RelayURL = Text

newtype EventId =
  EventId
    { getEventId :: ByteString
    }
  deriving (Eq)

instance Show EventId where
    showsPrec _ = shows . B16.encodeBase16 . getEventId

instance ToJSON EventId where
    toJSON e = AesonTypes.String $ pack $ exportEventId e

instance FromJSON EventId where
    parseJSON = withObject "EventId" $ \i -> do
        i' <- i .: "id"
        case eventId' i' of
            Just e -> return e
            _      -> fail "invalid event id"

eventId' :: Text -> Maybe EventId
eventId' t = do
    bs <- Schnorr.decodeHex t
    case BS.length bs of
        32 -> Just $ EventId bs
        _  -> Nothing

instance FromJSON XOnlyPubKey where
    parseJSON = withObject "XOnlyPubKey" $ \i -> do
        i' <- i .: "id"
        case xOnlyPubKey' i' of
            Just e -> return e
            _      -> fail "invalid XOnlyPubKey"

xOnlyPubKey' :: Text -> Maybe XOnlyPubKey
xOnlyPubKey' t = do
    bs <- Schnorr.decodeHex t
    case BS.length bs of
        32 -> Schnorr.xOnlyPubKey bs
        _  -> Nothing

data Tag
    = ETag (EventId, RelayURL)
    | PTag (XOnlyPubKey, RelayURL)
    deriving (Eq, Show)

newtype TagList = TagList [Tag] deriving (Show)

instance FromJSON TagList where
    parseJSON (AesonTypes.Object o) =
        TagList <$> (o .: "tags")
    parseJSON _ = mzero

instance FromJSON Tag where
    parseJSON (AesonTypes.Array v)
        | V.length v == 3 = do
            t <- parseJSON $ v V.! 0
            case t of
                "e" -> do
                    e <- parseJSON $ v V.! 1
                    r <- parseJSON $ v V.! 2
                    return $ ETag (e, r)
                "p" ->  do
                    x <- parseJSON $ v V.! 1
                    r <- parseJSON $ v V.! 2
                    return $ PTag (x, r)
                _   -> mzero
        | otherwise = mzero
    parseJSON _ = mzero