From 4321bb0b5b90c0f92217ccd07a67f17fce44b388 Mon Sep 17 00:00:00 2001
From: stuebinm
Date: Thu, 6 Jun 2024 18:26:42 +0200
Subject: nested values, tests, and aeson

---
 src/Conftrack/Source.hs         |  37 +++------------
 src/Conftrack/Source/Aeson.hs   | 101 ++++++++++++++++++++++++++++++++++++++++
 src/Conftrack/Source/Trivial.hs |  41 ++++++++++++++++
 src/Conftrack/Value.hs          |  54 +++++++++++++++++----
 4 files changed, 195 insertions(+), 38 deletions(-)
 create mode 100644 src/Conftrack/Source/Aeson.hs
 create mode 100644 src/Conftrack/Source/Trivial.hs

(limited to 'src/Conftrack')

diff --git a/src/Conftrack/Source.hs b/src/Conftrack/Source.hs
index df6f82c..ecfa20d 100644
--- a/src/Conftrack/Source.hs
+++ b/src/Conftrack/Source.hs
@@ -3,44 +3,21 @@
 {-# LANGUAGE ImpredicativeTypes #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE AllowAmbiguousTypes #-}
-{-# LANGUAGE OverloadedStrings #-}
 
-module Conftrack.Source (ConfigSource(..), SomeSource(..), Trivial(..)) where
+module Conftrack.Source (ConfigSource(..), SomeSource(..)) where
 
-import Conftrack.Value (Key, Value(..), ConfigError(..), Origin)
+import Conftrack.Value (Key, Value(..), ConfigError(..))
 
-import Control.Monad.State (get, modify, StateT (..), MonadState (..))
-import Data.Map.Strict (Map)
-import qualified Data.Map.Strict as M
-import Data.Function ((&))
+import Control.Monad.State (StateT (..))
 import Data.Text (Text)
-import qualified Data.Text as T
 
 
 class ConfigSource s where
-  type ConfigState s
-  fetchValue :: Key ->  s -> StateT (ConfigState s) IO (Either ConfigError (Value, Text))
-  leftovers ::  s -> StateT (ConfigState s) IO (Maybe [Key])
+  type SourceState s
+  fetchValue :: Key -> s -> StateT (SourceState s) IO (Either ConfigError (Value, Text))
+  leftovers :: s -> StateT (SourceState s) IO (Maybe [Key])
 
 data SomeSource = forall source. ConfigSource source
-   => SomeSource (source, ConfigState source)
+   => SomeSource (source, SourceState source)
 
 
-newtype Trivial = Trivial (Map Key Value)
-
-instance ConfigSource Trivial where
-  type ConfigState Trivial = [Key]
-  fetchValue key (Trivial tree) = do
-    case M.lookup key tree of
-      Nothing -> pure $ Left NotPresent
-      Just val -> do
-        modify (key :)
-        pure $ Right (val, "Trivial source with keys "<> T.pack (show (M.keys tree)))
-
-  leftovers (Trivial tree) = do
-    used <- get
-
-    M.keys tree
-     & filter (`notElem` used)
-     & Just
-     & pure
diff --git a/src/Conftrack/Source/Aeson.hs b/src/Conftrack/Source/Aeson.hs
new file mode 100644
index 0000000..97353d0
--- /dev/null
+++ b/src/Conftrack/Source/Aeson.hs
@@ -0,0 +1,101 @@
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE QuantifiedConstraints #-}
+{-# LANGUAGE ImpredicativeTypes #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE LambdaCase #-}
+
+module Conftrack.Source.Aeson (JsonSource(..), mkJsonSource, mkJsonSourceWith, mkJsonFileSource) where
+
+import Conftrack.Value (Key (..), ConfigError(..), Value (..), KeyPart)
+import Conftrack.Source (SomeSource(..), ConfigSource (..))
+
+import Prelude hiding (readFile)
+import qualified Data.Aeson as A
+import Control.Monad.State (get, modify, MonadState (..))
+import Data.Function ((&))
+import Data.Text (Text)
+import qualified Data.Aeson.Text as A
+import qualified Data.Text as T
+import qualified Data.Text.Lazy as LT
+import qualified Data.Aeson.Types as A
+import qualified Data.Aeson.Key as A
+import Data.Aeson.Types (unexpected)
+import qualified Data.List.NonEmpty as NonEmpty
+import Control.Monad ((>=>))
+import Data.Functor ((<&>))
+import System.OsPath (OsPath)
+import qualified System.OsPath as OS
+import System.File.OsPath (readFile)
+import qualified Data.Aeson.KeyMap as A
+import qualified Data.Text.Encoding as BS
+
+data JsonSource = JsonSource
+  { jsonSourceValue :: A.Value
+  , jsonSourceDescription :: Text
+  } deriving (Show)
+
+mkJsonSource :: A.Value -> SomeSource
+mkJsonSource value = mkJsonSourceWith ("JSON string " <> LT.toStrict (A.encodeToLazyText value)) value
+
+mkJsonSourceWith :: Text -> A.Value -> SomeSource
+mkJsonSourceWith description value = SomeSource (source, [])
+  where source = JsonSource value description
+
+mkJsonFileSource :: OsPath -> IO (Maybe SomeSource)
+mkJsonFileSource path = do
+  bytes <- readFile path
+  pathAsText <- OS.decodeUtf path <&> LT.toStrict . LT.pack
+  pure $ A.decode bytes
+    <&> mkJsonSourceWith ("JSON file " <> pathAsText)
+
+instance ConfigSource JsonSource where
+  type SourceState JsonSource = [Key]
+
+  fetchValue key@(Key parts) JsonSource{..} = do
+    case A.parseEither (lookupJsonPath (NonEmpty.toList parts) >=> parseJsonValue) jsonSourceValue of
+      Left a -> pure $ Left (ParseError (T.pack a))
+      Right val -> do
+        modify (key :)
+        pure $ Right (val, jsonSourceDescription)
+
+  leftovers JsonSource{..} = do
+    used <- get
+
+    allJsonPaths jsonSourceValue
+     & filter (`notElem` used)
+     & Just
+     & pure
+
+-- | this is essentially a FromJSON instance for Value, but not written as one
+-- so as to not introduce an orphan
+parseJsonValue :: A.Value -> A.Parser Value
+parseJsonValue = \case
+  (A.String bytes) -> pure $ ConfigString (BS.encodeUtf8 bytes)
+  (A.Number num) ->
+    A.parseJSON (A.Number num) <&> ConfigInteger
+  (A.Bool b) -> pure $ ConfigBool b
+  A.Null -> pure ConfigNull
+  (A.Object _) -> unexpected "unexpected json object"
+  (A.Array _) -> unexpected "unexpected json array"
+
+lookupJsonPath ::  [KeyPart] -> A.Value -> A.Parser A.Value
+lookupJsonPath [] value = pure value
+lookupJsonPath (part:parts) value = do
+  A.withObject "blub" (\obj -> obj A..: A.fromText part) value
+  >>= lookupJsonPath parts
+
+allJsonPaths :: A.Value -> [Key]
+allJsonPaths = fmap keyToKey . subKeys []
+  where
+    keyToKey keys = Key (fmap aesonKeyToText keys)
+    aesonKeyToText (key :: A.Key) = case A.parseMaybe A.parseJSON (A.toJSON key) of
+      Nothing -> error "key not representable as text; this is a bug in conftrack-aeson."
+      Just a -> a
+    subKeys prefix (A.Object keymap) =
+      A.foldMapWithKey (\key v -> subKeys (prefix <> [key]) v) keymap
+    subKeys prefix _ = case NonEmpty.nonEmpty prefix of
+      Just key -> [key]
+      _ -> undefined
diff --git a/src/Conftrack/Source/Trivial.hs b/src/Conftrack/Source/Trivial.hs
new file mode 100644
index 0000000..bb06e77
--- /dev/null
+++ b/src/Conftrack/Source/Trivial.hs
@@ -0,0 +1,41 @@
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE QuantifiedConstraints #-}
+{-# LANGUAGE ImpredicativeTypes #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Conftrack.Source.Trivial where
+
+import Conftrack.Value (Key, Value(..), ConfigError(..), Origin)
+import Conftrack.Source (SomeSource(..), ConfigSource (..))
+
+import Control.Monad.State (get, modify, StateT (..), MonadState (..))
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Function ((&))
+import qualified Data.Text as T
+
+
+newtype Trivial = Trivial (Map Key Value)
+
+mkTrivialSource :: [(Key, Value)] -> SomeSource
+mkTrivialSource pairs = SomeSource (source, [])
+  where source = Trivial (M.fromList pairs)
+
+instance ConfigSource Trivial where
+  type SourceState Trivial = [Key]
+  fetchValue key (Trivial tree) = do
+    case M.lookup key tree of
+      Nothing -> pure $ Left NotPresent
+      Just val -> do
+        modify (key :)
+        pure $ Right (val, "Trivial source with keys "<> T.pack (show (M.keys tree)))
+
+  leftovers (Trivial tree) = do
+    used <- get
+
+    M.keys tree
+     & filter (`notElem` used)
+     & Just
+     & pure
diff --git a/src/Conftrack/Value.hs b/src/Conftrack/Value.hs
index c5768cc..f934d51 100644
--- a/src/Conftrack/Value.hs
+++ b/src/Conftrack/Value.hs
@@ -3,24 +3,40 @@
 {-# LANGUAGE ImpredicativeTypes #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE StrictData #-}
+{-# LANGUAGE OverloadedStrings #-}
 
-module Conftrack.Value (Value(..), ConfigError(..), Key(..), ConfigValue(..), Origin(..)) where
+module Conftrack.Value (Value(..), ConfigError(..), Key(..), ConfigValue(..), Origin(..), KeyPart, prefixedWith) where
 
 import Data.Text(Text)
-import Data.List.NonEmpty (NonEmpty)
+import qualified Data.Text as T
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Lazy as LB
+import Data.List.NonEmpty (NonEmpty, prependList)
+import System.OsPath (OsPath, encodeUtf)
+import qualified Data.Text.Encoding as BS
 
 data Value =
-  ConfigText Text
+  ConfigString BS.ByteString
   | ConfigInteger Integer
   | ConfigOther Text Text
+  | ConfigBool Bool
+  | ConfigNull
   deriving Show
 
-newtype Key = Key (NonEmpty Text)
+type KeyPart = Text
+
+newtype Key = Key (NonEmpty KeyPart)
   deriving newtype (Eq, Ord, Show)
 
+prefixedWith :: Key -> [KeyPart] -> Key
+prefixedWith (Key key) prefix = Key (prependList prefix key)
+
 data ConfigError =
-  ParseError
+  ParseError Text
+  | TypeMismatch Text Value
   | NotPresent
+  | Shadowed
   deriving Show
 
 class ConfigValue a where
@@ -30,9 +46,31 @@ data Origin = Origin Key Text
   deriving Show
 
 instance ConfigValue Text where
-  fromConfig (ConfigText a) = Right a
-  fromConfig _ = Left ParseError
+  fromConfig (ConfigString a) = Right (BS.decodeUtf8 a)
+  fromConfig val = Left (TypeMismatch "text" val)
 
 instance ConfigValue Integer where
   fromConfig (ConfigInteger a) = Right a
-  fromConfig _ = Left ParseError
+  fromConfig val = Left (TypeMismatch "integer" val)
+
+instance ConfigValue Bool where
+  fromConfig (ConfigBool b) = Right b
+  fromConfig val = Left (TypeMismatch "bool" val)
+
+instance ConfigValue a => ConfigValue (Maybe a) where
+  fromConfig ConfigNull = Right Nothing
+  fromConfig just = fmap Just (fromConfig just)
+
+instance ConfigValue OsPath where
+  fromConfig (ConfigString text) = case encodeUtf (T.unpack (BS.decodeUtf8 text)) of
+    Right path -> Right path
+    Left err -> Left (ParseError (T.pack $ show err))
+  fromConfig val = Left (TypeMismatch "path" val)
+
+instance ConfigValue LB.ByteString where
+  fromConfig (ConfigString strict) = Right (LB.fromStrict strict)
+  fromConfig val = Left (TypeMismatch "string" val)
+
+instance ConfigValue BS.ByteString where
+  fromConfig (ConfigString string) = Right string
+  fromConfig val = Left (TypeMismatch "string" val)
-- 
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