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|
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE UndecidableInstances #-}
module Json where
import Builder
import Data.Aeson (FromJSON (parseJSON), ToJSON (toEncoding, toJSON), Value (..), withObject)
import Data.Aeson qualified as Json
import Data.Aeson.BetterErrors qualified as Json
import Data.Aeson.Key qualified as Key
import Data.Aeson.KeyMap qualified as KeyMap
import Data.Aeson.Types qualified
import Data.ByteString qualified as ByteString
import Data.ByteString.Base64 qualified as Base64
import Data.Error.Tree
import Data.Map.Strict qualified as Map
import Data.Maybe (catMaybes)
import Data.Set (Set)
import Data.Set qualified as Set
import Data.Text qualified as Text
import Data.Time (UTCTime)
import Data.Vector qualified as Vector
import FieldParser (FieldParser)
import FieldParser qualified as Field
import Json.Enc (Enc)
import Json.Enc qualified as Enc
import Label
import MyPrelude
import Parse (Parse)
import Parse qualified
-- | Use a "Data.Aeson.BetterErrors" parser to implement 'FromJSON'’s 'parseJSON' method.
--
-- @
-- instance FromJSON Foo where
-- parseJSON = Json.toParseJSON parseFoo
-- @
toParseJSON ::
-- | the error type is 'Error', if you need 'ErrorTree' use 'toParseJSONErrorTree'
Json.Parse Error a ->
Value ->
Data.Aeson.Types.Parser a
toParseJSON = Json.toAesonParser prettyError
-- | Use a "Data.Aeson.BetterErrors" parser to implement 'FromJSON'’s 'parseJSON' method.
--
-- @
-- instance FromJSON Foo where
-- parseJSON = Json.toParseJSON parseFoo
-- @
toParseJSONErrorTree ::
-- | the error type is 'ErrorTree', if you need 'Error' use 'toParseJSON'
Json.Parse ErrorTree a ->
Value ->
Data.Aeson.Types.Parser a
toParseJSONErrorTree = Json.toAesonParser prettyErrorTree
-- | Run the json parser on the given value.
parseJsonValue :: Json.ParseT ErrorTree Identity a -> Parse Value a
parseJsonValue inner = Parse.mkParseNoContext $ \val ->
case Json.parseValue inner val of
Left err -> Left $ err & jsonParseErrorToErrorTree [fmt|Cannot parse json value|]
Right a -> Right a
-- | Convert a 'Json.ParseError' to a corresponding 'ErrorTree'
--
-- TODO: build a different version of 'Json.displayError' so that we can nest 'ErrorTree' as well
jsonParseErrorToErrorTree :: Error -> Json.ParseError ErrorTree -> ErrorTree
jsonParseErrorToErrorTree contextMsg errs =
errs
& Json.displayError prettyErrorTree
& Text.intercalate "\n"
& newError
-- We nest this here because the json errors is multiline, so the result looks like
--
-- @
-- contextMsg
-- \|
-- `- At the path: ["foo"]["bar"]
-- Type mismatch:
-- Expected a value of type object
-- Got: true
-- @
& singleError
& nestedError contextMsg
-- | Convert a 'Json.ParseError' to a pair of error message and a shrunken-down
-- version of the value at the path where the error occurred.
--
-- This version shows some of the value at the path where the error occurred.
jsonParseErrorToErrorTreeValCtx :: Json.Value -> Json.ParseError ErrorTree -> T2 "errorMessage" Enc "valueAtErrorPath" (Maybe Json.Value)
jsonParseErrorToErrorTreeValCtx origValue errs = do
let ctxPath = case errs of
Json.BadSchema path _spec -> Just path
_ -> Nothing
let getSubset (Json.Object o) (Json.ObjectKey k) = o & KeyMap.lookup (Key.fromText k)
getSubset (Json.Array a) (Json.ArrayIndex k) = a Vector.!? k
getSubset _ _ = Nothing
let go v = \case
IsEmpty -> v
IsNonEmpty (p :| path) -> case getSubset v p of
Nothing -> v
Just v' -> go v' path
T2
( label @"errorMessage" $
errs
& displayErrorCustom
)
( label @"valueAtErrorPath" $
ctxPath
<&> ( go origValue
-- make sure we don’t explode the error message by showing too much of the value
>>> restrictJson restriction
)
)
where
restriction =
RestrictJsonOpts
{ maxDepth = 2,
maxSizeObject = 10,
maxSizeArray = 3,
maxStringLength = 100
}
displayErrorCustom :: Json.ParseError ErrorTree -> Enc
displayErrorCustom = \case
Json.InvalidJSON str ->
["The input could not be parsed as JSON: " <> str & stringToText]
& Enc.list Enc.text
Json.BadSchema path spec -> do
let pieceEnc = \case
Json.ObjectKey k -> Enc.text k
Json.ArrayIndex i -> Enc.int i
case spec of
Json.WrongType t val ->
Enc.object
[ ("@", Enc.list pieceEnc path),
( "error",
-- not showing the value here, because we are gonna show it anyway in the valueAtErrorPath
[fmt|Expected a value of type `{displayJSONType t}` but got one of type `{val & Json.jsonTypeOf & displayJSONType}`|]
)
]
other ->
Json.displaySpecifics prettyErrorTree other
& Text.intercalate "\n"
& Enc.text
displayJSONType :: Json.JSONType -> Text
displayJSONType t = case t of
Json.TyObject -> "object"
Json.TyArray -> "array"
Json.TyString -> "string"
Json.TyNumber -> "number"
Json.TyBool -> "boolean"
Json.TyNull -> "null"
-- | Lift the parser error to an error tree
asErrorTree :: (Functor m) => Json.ParseT Error m a -> Json.ParseT ErrorTree m a
asErrorTree = Json.mapError singleError
-- | Parse the json array into a 'Set'.
asArraySet ::
(Ord a, Monad m) =>
Json.ParseT err m a ->
Json.ParseT err m (Set a)
asArraySet inner = Set.fromList <$> Json.eachInArray inner
-- | Parse the json object into a 'Map'.
asObjectMap ::
(Monad m) =>
Json.ParseT err m a ->
Json.ParseT err m (Map Text a)
asObjectMap inner = Map.fromList <$> Json.eachInObject inner
-- | Parse as json array and count the number of elements in the array.
countArrayElements :: (Monad m) => Json.ParseT Error m Natural
countArrayElements = Field.toJsonParser ((jsonArray <&> Vector.length) >>> Field.integralToNatural)
where
-- I don’t want to add this to the FieldParser module, cause users should not be dealing with arrays manually.
jsonArray :: FieldParser Json.Value (Vector Json.Value)
jsonArray = Field.FieldParser $ \case
Json.Array vec -> Right vec
_ -> Left "Not a json array"
-- | Parse as json number and convert it to a 'Double'. Throws an error if the number does not fit into a 'Double'.
asDouble :: (Monad m) => Json.ParseT Error m Double
asDouble =
Field.toJsonParser
( Field.jsonNumber
>>> Field.boundedScientificRealFloat @Double
)
asInt :: (Monad m) => Json.ParseT Error m Int
asInt =
Field.toJsonParser
( Field.jsonNumber
>>> Field.boundedScientificIntegral @Int "Cannot parse into Int"
)
-- | Json string containing a UTC timestamp,
-- @yyyy-mm-ddThh:mm:ss[.sss]Z@ (ISO 8601:2004(E) sec. 4.3.2 extended format)
asUtcTime :: (Monad m) => Json.ParseT Error m UTCTime
asUtcTime = Field.toJsonParser (Field.jsonString >>> Field.utcTime)
-- | Json string containing a UTC timestamp.
-- | Accepts multiple timezone formats.
-- Do not use this if you can force the input to use the `Z` UTC notation (e.g. in a CSV), use 'utcTime' instead.
--
-- Accepts
--
-- * UTC timestamps: @yyyy-mm-ddThh:mm:ss[.sss]Z@
-- * timestamps with time zone: @yyyy-mm-ddThh:mm:ss[.sss]±hh:mm@
--
-- ( both ISO 8601:2004(E) sec. 4.3.2 extended format)
--
-- The time zone of the second kind of timestamp is taken into account, but normalized to UTC (it’s not preserved what the original time zone was)
asUtcTimeLenient :: (Monad m) => Json.ParseT Error m UTCTime
asUtcTimeLenient = Field.toJsonParser (Field.jsonString >>> Field.utcTimeLenient)
-- | Parse a json string as a base64-encoded string. If prefix is provided, the base64 string must start with the prefix.
asBase64 :: (Monad m) => Label "prefix" (Maybe Text) -> Json.ParseT Error m ByteString
asBase64 opts = do
val <- Json.asText <&> textToBytesUtf8
case opts.prefix of
Nothing -> case Base64.decode val of
Left err -> Json.throwCustomError $ [fmt|Invalid base64: {err}|]
Right x -> pure x
Just prefix -> do
let prefix' = prefix & textToBytesUtf8
case ByteString.stripPrefix prefix' val of
Nothing -> Json.throwCustomError $ [fmt|Invalid base64: did not start with the prefix "{prefix}"|]
Just x -> case Base64.decode x of
Left err -> Json.throwCustomError $ [fmt|Invalid base64: {err}|]
Right x' -> pure x'
-- | Parse a key from the object, à la 'Json.key', return a labelled value.
--
-- We don’t provide a version that infers the json object key,
-- since that conflates internal naming with the external API, which is dangerous.
--
-- @
-- do
-- txt <- keyLabel @"myLabel" "jsonKeyName" Json.asText
-- pure (txt :: Label "myLabel" Text)
-- @
keyLabel ::
forall label err m a.
(Monad m) =>
Text ->
Json.ParseT err m a ->
Json.ParseT err m (Label label a)
keyLabel = do
keyLabel' (Proxy @label)
-- | Parse a key from the object, à la 'Json.key', return a labelled value.
-- Version of 'keyLabel' that requires a proxy.
--
-- @
-- do
-- txt <- keyLabel' (Proxy @"myLabel") "jsonKeyName" Json.asText
-- pure (txt :: Label "myLabel" Text)
-- @
keyLabel' ::
forall label err m a.
(Monad m) =>
Proxy label ->
Text ->
Json.ParseT err m a ->
Json.ParseT err m (Label label a)
keyLabel' Proxy key parser = label @label <$> Json.key key parser
-- | Parse an optional key from the object, à la 'Json.keyMay', return a labelled value.
--
-- We don’t provide a version that infers the json object key,
-- since that conflates internal naming with the external API, which is dangerous.
--
-- @
-- do
-- txt <- keyLabelMay @"myLabel" "jsonKeyName" Json.asText
-- pure (txt :: Label "myLabel" (Maybe Text))
-- @
keyLabelMay ::
forall label err m a.
(Monad m) =>
Text ->
Json.ParseT err m a ->
Json.ParseT err m (Label label (Maybe a))
keyLabelMay = do
keyLabelMay' (Proxy @label)
-- | Parse an optional key from the object. The inner parser’s return value has to be a Monoid,
-- and we collapse the missing key into its 'mempty'.
--
-- For example, if the inner parser returns a list, the missing key will be parsed as an empty list.
--
-- @
-- do
-- txt <- keyMay' "jsonKeyName" (Json.eachInArray Json.asText)
-- pure (txt :: [Text])
-- @
--
-- will return @[]@ if the key is missing or if the value is the empty array.
keyMayMempty ::
(Monad m, Monoid a) =>
Text ->
Json.ParseT err m a ->
Json.ParseT err m a
keyMayMempty key parser = Json.keyMay key parser <&> fromMaybe mempty
-- | Parse an optional key from the object, à la 'Json.keyMay', return a labelled value.
-- Version of 'keyLabelMay' that requires a proxy.
--
-- @
-- do
-- txt <- keyLabelMay' (Proxy @"myLabel") "jsonKeyName" Json.asText
-- pure (txt :: Label "myLabel" (Maybe Text))
-- @
keyLabelMay' ::
forall label err m a.
(Monad m) =>
Proxy label ->
Text ->
Json.ParseT err m a ->
Json.ParseT err m (Label label (Maybe a))
keyLabelMay' Proxy key parser = label @label <$> Json.keyMay key parser
-- NOTE: keyRenamed Test in "Json.JsonTest", due to import cycles.
-- | Like 'Json.key', but allows a list of keys that are tried in order.
--
-- This is intended for renaming keys in an object.
-- The first key is the most up-to-date version of a key, the others are for backward-compatibility.
--
-- If a key (new or old) exists, the inner parser will always be executed for that key.
keyRenamed :: (Monad m) => NonEmpty Text -> Json.ParseT err m a -> Json.ParseT err m a
keyRenamed (newKey :| oldKeys) inner =
keyRenamedTryOldKeys oldKeys inner >>= \case
Nothing -> Json.key newKey inner
Just parse -> parse
-- | Like 'Json.keyMay', but allows a list of keys that are tried in order.
--
-- This is intended for renaming keys in an object.
-- The first key is the most up-to-date version of a key, the others are for backward-compatibility.
--
-- If a key (new or old) exists, the inner parser will always be executed for that key.
keyRenamedMay :: (Monad m) => NonEmpty Text -> Json.ParseT err m a -> Json.ParseT err m (Maybe a)
keyRenamedMay (newKey :| oldKeys) inner =
keyRenamedTryOldKeys oldKeys inner >>= \case
Nothing -> Json.keyMay newKey inner
Just parse -> Just <$> parse
-- | Helper function for 'keyRenamed' and 'keyRenamedMay' that returns the parser for the first old key that exists, if any.
keyRenamedTryOldKeys :: (Monad m) => [Text] -> Json.ParseT err m a -> Json.ParseT err m (Maybe (Json.ParseT err m a))
keyRenamedTryOldKeys oldKeys inner = do
oldKeys & traverse tryOld <&> catMaybes <&> nonEmpty <&> \case
Nothing -> Nothing
Just (old :| _moreOld) -> Just old
where
tryOld key =
Json.keyMay key (pure ()) <&> \case
Just () -> Just $ Json.key key inner
Nothing -> Nothing
-- | A simple type isomorphic to `()` that that transforms to an empty json object and parses
data EmptyObject = EmptyObject
deriving stock (Show, Eq)
instance FromJSON EmptyObject where
-- allow any fields, as long as its an object
parseJSON = withObject "EmptyObject" (\_ -> pure EmptyObject)
instance ToJSON EmptyObject where
toJSON EmptyObject = Object mempty
toEncoding EmptyObject = toEncoding $ Object mempty
-- | Create a json array from a list of json values.
mkJsonArray :: [Value] -> Value
mkJsonArray xs = xs & Vector.fromList & Array
-- | Encode a 'ByteString' as a base64-encoded json string
mkBase64Bytes :: ByteString -> Value
mkBase64Bytes = String . bytesToTextUtf8Unsafe . Base64.encode
data RestrictJsonOpts = RestrictJsonOpts
{ maxDepth :: Natural,
maxSizeObject :: Natural,
maxSizeArray :: Natural,
maxStringLength :: Natural
}
-- | Restrict a json object so that its depth and size are within the given bounds.
--
-- Bounds are maximum 'Int' width.
restrictJson ::
RestrictJsonOpts ->
Value ->
Value
restrictJson opts = do
let maxSizeObject = opts.maxSizeObject & naturalToInteger & integerToBoundedClamped
let maxSizeArray = opts.maxSizeArray & naturalToInteger & integerToBoundedClamped
let maxStringLength = opts.maxStringLength & naturalToInteger & integerToBoundedClamped
go (opts.maxDepth, maxSizeObject, maxSizeArray, maxStringLength)
where
go (0, _, _, strLen) (Json.String s) = truncateString strLen s
go (0, _, _, _) (Json.Array arr) = Array $ Vector.singleton [fmt|<{Vector.length arr} elements elided>|]
go (0, _, _, _) (Json.Object obj) =
obj
& buildText (KeyMap.keys >$< ("<object {" <> intersperseT ", " (Key.toText >$< textT) <> "}>"))
& String
go (depth, sizeObject, sizeArray, strLen) val = case val of
Object obj ->
obj
& ( \m ->
if KeyMap.size m > sizeObject
then
m
& KeyMap.toList
& take sizeObject
& KeyMap.fromList
& KeyMap.map (go (depth - 1, sizeObject, sizeArray, strLen))
& \smol ->
smol
& KeyMap.insert
"<some fields elided>"
(m `KeyMap.difference` smol & KeyMap.keys & toJSON)
else
m
& KeyMap.map (go (depth - 1, sizeObject, sizeArray, strLen))
)
& Json.Object
Array arr ->
arr
& ( \v ->
if Vector.length v > sizeArray
then
v
& Vector.take sizeArray
& Vector.map (go (depth - 1, sizeObject, sizeArray, strLen))
& (\v' -> Vector.snoc v' ([fmt|<{Vector.length v - sizeArray} more elements elided>|] & String))
else
v
& Vector.map (go (depth - 1, sizeObject, sizeArray, strLen))
)
& Array
String txt -> truncateString strLen txt
other -> other
truncateString strLen txt =
let truncatedTxt = Text.take strLen txt
finalTxt =
if Text.length txt > strLen
then Text.append truncatedTxt "…"
else truncatedTxt
in String finalTxt
|