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Diffstat (limited to 'users/Profpatsch/my-webstuff/src/Multipart2.hs')
| -rw-r--r-- | users/Profpatsch/my-webstuff/src/Multipart2.hs | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/users/Profpatsch/my-webstuff/src/Multipart2.hs b/users/Profpatsch/my-webstuff/src/Multipart2.hs new file mode 100644 index 000000000000..17246546ab35 --- /dev/null +++ b/users/Profpatsch/my-webstuff/src/Multipart2.hs @@ -0,0 +1,220 @@ +{-# LANGUAGE QuasiQuotes #-} + +module Multipart2 where + +import Control.Monad.Logger (MonadLogger) +import Control.Selective (Selective) +import Data.ByteString.Lazy qualified as Lazy +import Data.DList (DList) +import Data.DList qualified as DList +import Data.Error.Tree +import Data.Functor.Compose +import Data.List qualified as List +import FieldParser +import Label +import Network.Wai qualified as Wai +import Network.Wai.Parse qualified as Wai +import PossehlAnalyticsPrelude +import ValidationParseT + +data FormFields = FormFields + { inputs :: [Wai.Param], + files :: [MultipartFile Lazy.ByteString] + } + +-- | A parser for a HTTP multipart form (a form sent by the browser) +newtype MultipartParseT backend m a = MultipartParseT + { unMultipartParseT :: + FormFields -> + m (Validation (NonEmpty Error) a) + } + deriving + (Functor, Applicative, Selective) + via (ValidationParseT FormFields m) + +-- | After parsing a form, either we get the result or a list of form fields that failed +newtype FormValidation a + = FormValidation + (DList FormValidationResult, Maybe a) + deriving (Functor, Applicative, Selective) via (Compose ((,) (DList FormValidationResult)) Maybe) + deriving stock (Show) + +data FormValidationResult = FormValidationResult + { hasError :: Maybe Error, + formFieldName :: ByteString, + originalValue :: ByteString + } + deriving stock (Show) + +mkFormValidationResult :: + ( HasField "formFieldName" form ByteString, + HasField "originalValue" form ByteString + ) => + form -> + Maybe Error -> + FormValidationResult +mkFormValidationResult form err = + FormValidationResult + { hasError = err, + formFieldName = form.formFieldName, + originalValue = form.originalValue + } + +eitherToFormValidation :: + ( HasField "formFieldName" form ByteString, + HasField "originalValue" form ByteString + ) => + form -> + Either Error a -> + FormValidation a +eitherToFormValidation form = \case + Left err -> + FormValidation $ (DList.singleton $ mkFormValidationResult form (Just err), Nothing) + Right a -> + FormValidation $ ((DList.singleton $ mkFormValidationResult form Nothing), Just a) + +failFormValidation :: + ( HasField "formFieldName" form ByteString, + HasField "originalValue" form ByteString + ) => + form -> + Error -> + FormValidation a +failFormValidation form err = + FormValidation (DList.singleton $ mkFormValidationResult form (Just err), Nothing) + +-- | Parse the multipart form or throw a user error with a descriptive error message. +parseMultipartOrThrow :: + (MonadLogger m, MonadIO m) => + (ErrorTree -> m a) -> + MultipartParseT backend m a -> + Wai.Request -> + m a +parseMultipartOrThrow throwF parser req = do + -- TODO: this throws all errors with `error`, so leads to 500 on bad input … + formFields <- + liftIO $ + Wai.parseRequestBodyEx + Wai.defaultParseRequestBodyOptions + Wai.lbsBackEnd + req + parser.unMultipartParseT + FormFields + { inputs = fst formFields, + files = map fileDataToMultipartFile $ snd formFields + } + >>= \case + Failure errs -> throwF (errorTree "Cannot parse the multipart form" errs) + Success a -> pure a + +-- | Parse the field out of the multipart message +field :: Applicative m => ByteString -> FieldParser ByteString a -> MultipartParseT backend m a +field fieldName fieldParser = MultipartParseT $ \mp -> + mp.inputs + & findMaybe (\input -> if fst input == fieldName then Just (snd input) else Nothing) + & annotate [fmt|Field "{fieldName}" does not exist in the multipart form|] + >>= runFieldParser fieldParser + & eitherToListValidation + & pure + +-- | Parse the field out of the multipart message +field' :: Applicative m => ByteString -> FieldParser ByteString a -> MultipartParseT backend m (FormValidation a) +field' fieldName fieldParser = MultipartParseT $ \mp -> + mp.inputs + & findMaybe (\input -> if fst input == fieldName then Just $ snd input else Nothing) + & annotate [fmt|Field "{fieldName}" does not exist in the multipart form|] + <&> ( \originalValue -> + originalValue + & runFieldParser fieldParser + & eitherToFormValidation + ( T2 + (label @"formFieldName" fieldName) + (label @"originalValue" originalValue) + ) + ) + & eitherToListValidation + & pure + +-- | Parse the field out of the multipart message, and into a 'Label' of the given name. +fieldLabel :: forall lbl backend m a. Applicative m => ByteString -> FieldParser ByteString a -> MultipartParseT backend m (Label lbl a) +fieldLabel fieldName fieldParser = label @lbl <$> field fieldName fieldParser + +-- | Parse the field out of the multipart message, and into a 'Label' of the given name. +fieldLabel' :: forall lbl backend m a. Applicative m => ByteString -> FieldParser ByteString a -> MultipartParseT backend m (FormValidation (Label lbl a)) +fieldLabel' fieldName fieldParser = fmap (label @lbl) <$> field' fieldName fieldParser + +-- | parse all fields out of the multipart message, with the same parser +allFields :: Applicative m => FieldParser (T2 "key" ByteString "value" ByteString) b -> MultipartParseT backend m [b] +allFields fieldParser = MultipartParseT $ \mp -> + mp.inputs + <&> tupToT2 @"key" @"value" + & traverseValidate (runFieldParser fieldParser) + & eitherToValidation + & pure + +tupToT2 :: forall l1 l2 t1 t2. (t1, t2) -> T2 l1 t1 l2 t2 +tupToT2 (a, b) = T2 (label a) (label b) + +-- | Parse a file by name out of the multipart message +file :: + Applicative m => + ByteString -> + MultipartParseT backend m (MultipartFile Lazy.ByteString) +file fieldName = MultipartParseT $ \mp -> + mp.files + & List.find (\input -> input.multipartNameAttribute == fieldName) + & annotate [fmt|File "{fieldName}" does not exist in the multipart form|] + & ( \case + Left err -> Failure (singleton err) + Right filePath -> Success filePath + ) + & pure + +-- | Return all files from the multipart message +allFiles :: + Applicative m => + MultipartParseT backend m [MultipartFile Lazy.ByteString] +allFiles = MultipartParseT $ \mp -> do + pure $ Success $ mp.files + +-- | Ensure there is exactly one file and return it (ignoring the field name) +exactlyOneFile :: + Applicative m => + MultipartParseT backend m (MultipartFile Lazy.ByteString) +exactlyOneFile = MultipartParseT $ \mp -> + mp.files + & \case + [] -> pure $ failParse "Expected to receive a file, but the multipart form did not contain any files" + [file_] -> pure $ Success file_ + more -> pure $ failParse [fmt|Expected to receive exactly one file, but the multipart form contained {List.length more} files|] + where + -- \| Fail to parse the multipart form with the given error message. + failParse :: Text -> Validation (NonEmpty Error) a + failParse = Failure . singleton . newError + +newtype GetFileContent backend m content = GetFileContent + {unGetFileContent :: (Wai.Request -> m (Either Error content))} + +-- | A file field in a multipart message. +data MultipartFile content = MultipartFile + { -- | @name@ attribute of the corresponding HTML @\<input\>@ + multipartNameAttribute :: ByteString, + -- | name of the file on the client's disk + fileNameOnDisk :: ByteString, + -- | MIME type for the file + fileMimeType :: ByteString, + -- | Content of the file + content :: content + } + +-- | Convert the multipart library struct of a multipart file to our own. +fileDataToMultipartFile :: + Wai.File Lazy.ByteString -> + (MultipartFile Lazy.ByteString) +fileDataToMultipartFile (multipartNameAttribute, file_) = do + MultipartFile + { multipartNameAttribute, + fileNameOnDisk = file_.fileName, + fileMimeType = file_.fileContentType, + content = file_.fileContent + } |