feat(users/Profpatsch/mailbox-org): list & update filters r/5562

One step closer towards a declarative description of filters.
In the end, the filters should be updated by their `rulename` field.

This implements a simple scheme where we list all filters, parse some
of their fields, use those fields to determine whether we want to
change the filters, and then only update the filters where we changed
something.

Unfortunately, we can only update the filters one-by-one (a common
mistake in APIs).

Pulls in some modules for Json parsing that I like to use, and an
`ErrorTree` abstraction over `Error` and `Data.Tree`.

Change-Id: Iea45d5aa0a3fee7ec570f06d3e77009769091274
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7720
Autosubmit: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

4 files changed, 315 insertions, 1 deletions

diff --git a/users/Profpatsch/my-prelude/Aeson.hs b/users/Profpatsch/my-prelude/Aeson.hs
new file mode 100644
index 000000000000..ad095e1b43a7
--- /dev/null
+++ b/users/Profpatsch/my-prelude/Aeson.hs
@@ -0,0 +1,188 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GHC2021 #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE UndecidableInstances #-}
+
+module Aeson where
+
+import Data.Aeson (Encoding, FromJSON (parseJSON), GFromJSON, GToEncoding, GToJSON, Options (fieldLabelModifier), ToJSON (toEncoding, toJSON), Value (..), Zero, defaultOptions, genericParseJSON, genericToEncoding, genericToJSON, withObject)
+import Data.Aeson.BetterErrors qualified as Json
+import Data.Aeson.Encoding qualified as Enc
+import Data.Aeson.Key qualified as Key
+import Data.Aeson.KeyMap qualified as KeyMap
+import Data.Char qualified
+import Data.Error.Tree
+import Data.Foldable qualified as Foldable
+import Data.Int (Int64)
+import Data.List (isPrefixOf)
+import Data.List qualified as List
+import Data.Map.Strict qualified as Map
+import Data.Maybe (catMaybes)
+import Data.String (IsString (fromString))
+import Data.Text.Lazy qualified as Lazy
+import Data.Vector qualified as Vector
+import GHC.Generics (Generic (Rep))
+import GHC.TypeLits (KnownSymbol, Symbol, symbolVal)
+import Label
+import MyPrelude
+import Test.Hspec (describe, it, shouldBe)
+import Test.Hspec qualified as Hspec
+
+-- | Convert a 'Json.ParseError' to a corresponding 'ErrorTree'
+parseErrorTree :: Error -> Json.ParseError Error -> ErrorTree
+parseErrorTree contextMsg errs =
+  errs
+    & Json.displayError prettyError
+    <&> newError
+    & nonEmpty
+    & \case
+      Nothing -> singleError contextMsg
+      Just errs' -> errorTree contextMsg errs'
+
+-- | 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 <$> Json.key key parser
+
+-- | Parse an optional key from the object, à la 'Json.keyMay', return a labelled value.
+--
+-- We don’t provide a version that infers the json object key,
+-- since that conflates internal naming with the external API, which is dangerous.
+--
+-- @@
+-- do
+--   txt <- keyLabelMay @"myLabel" "jsonKeyName" Json.asText
+--   pure (txt :: Label "myLabel" (Maybe Text))
+-- @@
+keyLabelMay ::
+  forall label err m a.
+  Monad m =>
+  Text ->
+  Json.ParseT err m a ->
+  Json.ParseT err m (Label label (Maybe a))
+keyLabelMay = do
+  keyLabelMay' (Proxy @label)
+
+-- | Parse an optional key from the object, à la 'Json.keyMay', return a labelled value.
+-- Version of 'keyLabelMay' that requires a proxy.
+--
+-- @@
+-- do
+--   txt <- keyLabelMay' (Proxy @"myLabel") "jsonKeyName" Json.asText
+--   pure (txt :: Label "myLabel" (Maybe Text))
+-- @@
+keyLabelMay' ::
+  forall label err m a.
+  Monad m =>
+  Proxy label ->
+  Text ->
+  Json.ParseT err m a ->
+  Json.ParseT err m (Label label (Maybe a))
+keyLabelMay' Proxy key parser = label @label <$> Json.keyMay key parser
+
+-- | 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
+
+test_keyRenamed :: Hspec.Spec
+test_keyRenamed = do
+  describe "keyRenamed" $ do
+    let parser = keyRenamed ("new" :| ["old"]) Json.asText
+    let p = Json.parseValue @() parser
+    it "accepts the new key and the old key" $ do
+      p (Object (KeyMap.singleton "new" (String "text")))
+        `shouldBe` (Right "text")
+      p (Object (KeyMap.singleton "old" (String "text")))
+        `shouldBe` (Right "text")
+    it "fails with the old key in the error if the inner parser is wrong" $ do
+      p (Object (KeyMap.singleton "old" Null))
+        `shouldBe` (Left (Json.BadSchema [Json.ObjectKey "old"] (Json.WrongType Json.TyString Null)))
+    it "fails with the new key in the error if the inner parser is wrong" $ do
+      p (Object (KeyMap.singleton "new" Null))
+        `shouldBe` (Left (Json.BadSchema [Json.ObjectKey "new"] (Json.WrongType Json.TyString Null)))
+    it "fails if the key is missing" $ do
+      p (Object KeyMap.empty)
+        `shouldBe` (Left (Json.BadSchema [] (Json.KeyMissing "new")))
+  describe "keyRenamedMay" $ do
+    let parser = keyRenamedMay ("new" :| ["old"]) Json.asText
+    let p = Json.parseValue @() parser
+    it "accepts the new key and the old key" $ do
+      p (Object (KeyMap.singleton "new" (String "text")))
+        `shouldBe` (Right (Just "text"))
+      p (Object (KeyMap.singleton "old" (String "text")))
+        `shouldBe` (Right (Just "text"))
+    it "allows the old and new key to be missing" $ do
+      p (Object KeyMap.empty)
+        `shouldBe` (Right Nothing)
+
+-- | Create a json array from a list of json values.
+jsonArray :: [Value] -> Value
+jsonArray xs = xs & Vector.fromList & Array
diff --git a/users/Profpatsch/my-prelude/Data/Error/Tree.hs b/users/Profpatsch/my-prelude/Data/Error/Tree.hs
new file mode 100644
index 000000000000..e8e45e704882
--- /dev/null
+++ b/users/Profpatsch/my-prelude/Data/Error/Tree.hs
@@ -0,0 +1,113 @@
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE GHC2021 #-}
+{-# LANGUAGE OverloadedRecordDot #-}
+
+module Data.Error.Tree where
+
+import Data.String (IsString (..))
+import Data.Tree qualified as Tree
+import MyPrelude
+
+-- | A tree of 'Error's, with a single root 'Error' and 0..n nested 'ErrorTree's.
+--
+-- @@
+-- top error
+-- |
+-- |-- error 1
+-- | |
+-- |  -- error 1.1
+-- |
+-- |-- error 2
+-- @@
+newtype ErrorTree = ErrorTree {unErrorTree :: (Tree.Tree Error)}
+  deriving stock (Show)
+
+instance IsString ErrorTree where
+  fromString = singleError . fromString
+
+-- deriving newtype (Ord) -- TODO: Add this instance with containers-0.6.5
+
+-- | Turn a single 'Error' into an 'ErrorTree', a leaf.
+singleError :: Error -> ErrorTree
+singleError e = ErrorTree $ Tree.Node e []
+
+-- | Take a list of errors & create a new 'ErrorTree' with the given 'Error' as the root.
+errorTree :: Error -> NonEmpty Error -> ErrorTree
+errorTree topLevelErr nestedErrs =
+  ErrorTree
+    ( Tree.Node
+        topLevelErr
+        (nestedErrs <&> (\e -> Tree.Node e []) & toList)
+    )
+
+-- | Attach more context to the root 'Error' of the 'ErrorTree', via 'errorContext'.
+errorTreeContext :: Text -> ErrorTree -> ErrorTree
+errorTreeContext context (ErrorTree tree) =
+  ErrorTree $
+    tree
+      { Tree.rootLabel = tree.rootLabel & errorContext context
+      }
+
+-- | Nest the given 'Error' around the ErrorTree
+--
+-- @@
+-- top level error
+-- |
+-- -- nestedError
+--   |
+--   -- error 1
+--   |
+--   -- error 2
+-- @@
+nestedError ::
+  Error -> -- top level
+  ErrorTree -> -- nested
+  ErrorTree
+nestedError topLevelErr nestedErr =
+  ErrorTree $
+    Tree.Node
+      { Tree.rootLabel = topLevelErr,
+        Tree.subForest = [nestedErr.unErrorTree]
+      }
+
+-- | Nest the given 'Error' around the list of 'ErrorTree's.
+--
+-- @@
+-- top level error
+-- |
+-- |- nestedError1
+-- | |
+-- | -- error 1
+-- | |
+-- | -- error 2
+-- |
+-- |- nestedError 2
+-- @@
+nestedMultiError ::
+  Error -> -- top level
+  NonEmpty ErrorTree -> -- nested
+  ErrorTree
+nestedMultiError topLevelErr nestedErrs =
+  ErrorTree $
+    Tree.Node
+      { Tree.rootLabel = topLevelErr,
+        Tree.subForest = nestedErrs & toList <&> (.unErrorTree)
+      }
+
+prettyErrorTree :: ErrorTree -> Text
+prettyErrorTree (ErrorTree tree) =
+  tree
+    <&> prettyError
+    <&> textToString
+    & Tree.drawTree
+    & stringToText
+
+prettyErrorTrees :: NonEmpty ErrorTree -> Text
+prettyErrorTrees forest =
+  forest
+    <&> (.unErrorTree)
+    <&> fmap prettyError
+    <&> fmap textToString
+    & toList
+    & Tree.drawForest
+    & stringToText
diff --git a/users/Profpatsch/my-prelude/default.nix b/users/Profpatsch/my-prelude/default.nix
index 87731394fc47..8ff36a93d4e4 100644
--- a/users/Profpatsch/my-prelude/default.nix
+++ b/users/Profpatsch/my-prelude/default.nix
@@ -9,11 +9,15 @@ pkgs.haskellPackages.mkDerivation {
     ./MyPrelude.hs
     ./Label.hs
     ./Pretty.hs
+    ./Data/Error/Tree.hs
+    ./Aeson.hs
   ];
 
   isLibrary = true;
 
   libraryHaskellDepends = [
+    pkgs.haskellPackages.aeson
+    pkgs.haskellPackages.aeson-better-errors
     pkgs.haskellPackages.PyF
     pkgs.haskellPackages.errors
     pkgs.haskellPackages.profunctors
@@ -21,10 +25,12 @@ pkgs.haskellPackages.mkDerivation {
     pkgs.haskellPackages.these
     pkgs.haskellPackages.validation-selective
     pkgs.haskellPackages.error
-
+    pkgs.haskellPackages.hspec
+    pkgs.haskellPackages.hspec-expectations-pretty-diff
     pkgs.haskellPackages.hscolour
     pkgs.haskellPackages.nicify-lib
     pkgs.haskellPackages.ansi-terminal
+    pkgs.haskellPackages.vector
   ];
 
   license = lib.licenses.mit;
diff --git a/users/Profpatsch/my-prelude/my-prelude.cabal b/users/Profpatsch/my-prelude/my-prelude.cabal
index 48e71bb926a3..8ee3271d10fa 100644
--- a/users/Profpatsch/my-prelude/my-prelude.cabal
+++ b/users/Profpatsch/my-prelude/my-prelude.cabal
@@ -9,6 +9,8 @@ library
       MyPrelude
       Label
       Pretty
+      Data.Error.Tree
+      Aeson
 
     -- Modules included in this executable, other than Main.
     -- other-modules:
@@ -17,6 +19,8 @@ library
     -- other-extensions:
     build-depends:
        base >=4.15 && <5
+     , aeson
+     , aeson-better-errors
      , PyF
      , validation-selective
      , these
@@ -27,7 +31,10 @@ library
      , error
      , bytestring
      , mtl
+     , hspec
+     , hspec-expectations-pretty-diff
      , hscolour
      , nicify-lib
      , ansi-terminal
+     , vector
     default-language: Haskell2010