{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE ImportQualifiedPost #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneKindSignatures #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE FlexibleContexts #-}

-- |
-- This module contains basic examples advices.
--
-- __/BEWARE!/__ These are provided for illustrative purposes only, they
-- strive for simplicity and not robustness or efficiency.
module Dep.ReaderAdvice.Basic 
  ( -- * Basic advices
    returnMempty,
    printArgs,
    -- ** Synthetic call stacks
    Simple.MethodName,
    Simple.StackFrame,
    Simple.SyntheticCallStack,
    Simple.HasSyntheticCallStack (..),
    Simple.SyntheticStackTrace,
    Simple.SyntheticStackTraceException (..),
    keepCallStack
  )
where

import Dep.ReaderAdvice
import Control.Monad.Dep
import Data.Proxy
import Data.SOP
import Data.SOP (hctraverse_)
import Data.SOP.NP
import Data.Type.Equality
import System.IO
import Type.Reflection
import Control.Concurrent
import Control.Monad.IO.Unlift
import Control.Exception
import qualified Data.Typeable as T
import Data.List.NonEmpty (NonEmpty (..))
import Data.List.NonEmpty qualified as NonEmpty
import Data.IORef
import Dep.SimpleAdvice.Basic qualified as Simple
import Dep.SimpleAdvice.Basic (HasSyntheticCallStack)

-- $setup
--
-- >>> :set -XTypeApplications
-- >>> :set -XStandaloneKindSignatures
-- >>> :set -XMultiParamTypeClasses
-- >>> :set -XFunctionalDependencies
-- >>> :set -XRankNTypes
-- >>> :set -XTypeOperators
-- >>> :set -XConstraintKinds
-- >>> :set -XNamedFieldPuns
-- >>> :set -XFlexibleContexts
-- >>> :set -XFlexibleInstances
-- >>> :set -XAllowAmbiguousTypes
-- >>> :set -XBlockArguments
-- >>> import Dep.ReaderAdvice
-- >>> import Dep.ReaderAdvice.Basic
-- >>> import Control.Monad
-- >>> import Data.Kind
-- >>> import Data.SOP
-- >>> import Data.SOP.NP
-- >>> import Data.Monoid
-- >>> import System.IO
-- >>> import Data.IORef


-- | Makes functions discard their result and always return 'mempty'.
--
returnMempty :: forall ca env m r. (Monad m, Monoid r) => Advice ca env m r
returnMempty :: forall (ca :: * -> Constraint) env (m :: * -> *) r.
(Monad m, Monoid r) =>
Advice ca env m r
returnMempty =
  forall (ca :: * -> Constraint) e (m :: * -> *) r.
Applicative m =>
(ReaderT e m r -> ReaderT e m r) -> Advice ca e m r
makeExecutionAdvice
    ( \ReaderT env m r
action -> do
        r
_ <- ReaderT env m r
action
        forall (f :: * -> *) a. Applicative f => a -> f a
pure (forall a. Monoid a => a
mempty :: r)
    )

-- | Given a 'Handle' and a prefix string, makes functions print their
-- arguments to the 'Handle'.
--
printArgs :: forall env m r. MonadIO m => Handle -> String -> Advice Show env m r
printArgs :: forall env (m :: * -> *) r.
MonadIO m =>
Handle -> String -> Advice Show env m r
printArgs Handle
h String
prefix =
  forall (ca :: * -> Constraint) e (m :: * -> *) r.
Monad m =>
(forall (as :: [*]). All ca as => NP I as -> ReaderT e m (NP I as))
-> Advice ca e m r
makeArgsAdvice
    ( \NP I as
args -> do
        forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ Handle -> String -> IO ()
hPutStr Handle
h forall a b. (a -> b) -> a -> b
$ String
prefix forall a. [a] -> [a] -> [a]
++ String
":"
        forall k l (h :: (k -> *) -> l -> *) (c :: k -> Constraint)
       (xs :: l) (g :: * -> *) (proxy :: (k -> Constraint) -> *)
       (f :: k -> *).
(HTraverse_ h, AllN h c xs, Applicative g) =>
proxy c -> (forall (a :: k). c a => f a -> g ()) -> h f xs -> g ()
hctraverse_ (forall {k} (t :: k). Proxy t
Proxy @Show) (\(I a
a) -> forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO (Handle -> String -> IO ()
hPutStr Handle
h (String
" " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show a
a))) NP I as
args
        forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ Handle -> String -> IO ()
hPutStrLn Handle
h String
"\n"
        forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ Handle -> IO ()
hFlush Handle
h
        forall (f :: * -> *) a. Applicative f => a -> f a
pure NP I as
args
    )


-- | If the environment carries a 'SyntheticCallStack', make advised functions add
-- themselves to the 'SyntheticCallStack' before they start executing.
--
-- Caught exceptions are rethrown wrapped in 'SyntheticStackTraceException's,
-- with the current 'SyntheticCallStack' added.
keepCallStack ::
  (MonadUnliftIO m, Simple.HasSyntheticCallStack env, Exception e) =>
  -- | A selector for the kinds of exceptions we want to catch.
  -- For example @ fromException \@IOError@.
  (SomeException -> Maybe e) ->
  -- | The path to the current component/method in the environment.
  -- It will be usually obtained through
  -- 'Dep.ReaderAdvice.adviseRecord'.
  NonEmpty (T.TypeRep, Simple.MethodName) ->
  Advice ca env m r
keepCallStack :: forall (m :: * -> *) env e (ca :: * -> Constraint) r.
(MonadUnliftIO m, HasSyntheticCallStack env, Exception e) =>
(SomeException -> Maybe e)
-> NonEmpty (TypeRep, String) -> Advice ca env m r
keepCallStack SomeException -> Maybe e
selector NonEmpty (TypeRep, String)
method = forall (ca :: * -> Constraint) e (m :: * -> *) r.
Applicative m =>
(ReaderT e m r -> ReaderT e m r) -> Advice ca e m r
makeExecutionAdvice \ReaderT env m r
action -> do
  SyntheticCallStack
currentStack <- forall (m :: * -> *). MonadCallStack m => m SyntheticCallStack
Simple.askCallStack
  forall (m :: * -> *) b.
MonadUnliftIO m =>
((forall a. m a -> IO a) -> IO b) -> m b
withRunInIO \forall a. ReaderT env m a -> IO a
unlift -> do
    Either e r
er <- forall e b a.
Exception e =>
(e -> Maybe b) -> IO a -> IO (Either b a)
tryJust SomeException -> Maybe e
selector (forall a. ReaderT env m a -> IO a
unlift (forall (m :: * -> *) r.
MonadCallStack m =>
NonEmpty (TypeRep, String) -> m r -> m r
Simple.addStackFrame NonEmpty (TypeRep, String)
method ReaderT env m r
action))
    case Either e r
er of
      Left e
e -> forall e a. Exception e => e -> IO a
throwIO (SomeException
-> SyntheticStackTrace -> SyntheticStackTraceException
Simple.SyntheticStackTraceException (forall e. Exception e => e -> SomeException
toException e
e) (NonEmpty (TypeRep, String)
method forall a. a -> [a] -> NonEmpty a
:| SyntheticCallStack
currentStack))
      Right r
r -> forall (f :: * -> *) a. Applicative f => a -> f a
pure r
r