{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeOperators #-}

-- | This libraries provides a polysemy effect that provides interactive command
-- line usage.
module Polysemy.Readline
  ( -- * Effect and Actions
    Readline (..),
    getInputLine,
    getInputLineWithInitial,
    getInputChar,
    getPassword,
    waitForAnyKey,
    outputStr,
    outputStrLn,

    -- * Interpreters
    runReadline,
    runReadlineFinal,
    interpretReadlineAsInputT,

    -- * Re-exports from @haskeline@
    H.Settings (..),
    H.defaultSettings,
    H.runInputT,
  )
where

import Control.Monad.Catch
import Control.Monad.IO.Class
import Polysemy
import Polysemy.Embed
import qualified System.Console.Haskeline as H

-- | For documentation on actions see haskeline's functions with the same name
-- and similar type signatures.
data Readline (m :: * -> *) a where
  GetInputLine :: String -> Readline m (Maybe String)
  GetInputLineWithInitial :: String -> (String, String) -> Readline m (Maybe String)
  GetInputChar :: String -> Readline m (Maybe Char)
  GetPassword :: Maybe Char -> String -> Readline m (Maybe String)
  WaitForAnyKey :: String -> Readline m Bool
  OutputStr :: String -> Readline m ()

-- TODO(Devin): add these two values as well
-- WithInterrupt :: m a -> Readline m a
-- HandleInterrupt :: m a -> m a -> Readline m a

makeSem ''Readline

outputStrLn :: Member Readline r => String -> Sem r ()
outputStrLn :: String -> Sem r ()
outputStrLn String
str = String -> Sem r ()
forall (r :: [Effect]).
MemberWithError Readline r =>
String -> Sem r ()
outputStr (String
str String -> String -> String
forall a. Semigroup a => a -> a -> a
<> String
"\n")

-- | The simplest way to run a Readline effect. Immediately eliminates the
-- resulting 'H.InputT'. There is one problem with this approach however.
-- Internal details of polysemy cause 'H.runInputT' to be run once per effect
-- call (e.g. @getInputLine "> " >> getInputLine "> "@ will result in two calls
-- to 'H.runInputT'), and the History state of consecutive runs is not
-- preserved unless there is a history file. If you want history for your repl
-- there are therefore two recommended approaches:
--
-- * Provide a history file in the settings you specify. e.g.
-- @runReadline ('H.defaultSettings' {historyFile = Just ".repl_history"})@.
-- This is the easiest approach but technically suboptimal because the history
-- file will be read between every different primitive effect call.
-- * Use 'interpretReadlineAsInputT' or 'runReadlineFinal' and keep the
-- `H.InputT` around until after using 'runFinal' to escape polysemy land. This
-- way state can be preserved between effect calls. For an example using this
-- see @examples/Echo.hs@.
runReadline ::
  forall m r a.
  (MonadIO m, MonadMask m, Member (Embed m) r) =>
  H.Settings m ->
  Sem (Readline : r) a ->
  Sem r a
runReadline :: Settings m -> Sem (Readline : r) a -> Sem r a
runReadline Settings m
settings =
  (forall x. InputT m x -> m x)
-> Sem (Embed (InputT m) : r) a -> Sem r a
forall (m1 :: * -> *) (m2 :: * -> *) (r :: [Effect]) a.
Member (Embed m2) r =>
(forall x. m1 x -> m2 x) -> Sem (Embed m1 : r) a -> Sem r a
runEmbedded (Settings m -> InputT m x -> m x
forall (m :: * -> *) a.
(MonadIO m, MonadMask m) =>
Settings m -> InputT m a -> m a
H.runInputT Settings m
settings)
    (Sem (Embed (InputT m) : r) a -> Sem r a)
-> (Sem (Readline : r) a -> Sem (Embed (InputT m) : r) a)
-> Sem (Readline : r) a
-> Sem r a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Sem (Readline : Embed (InputT m) : r) a
-> Sem (Embed (InputT m) : r) a
forall (m :: * -> *) (r :: [Effect]) a.
(MonadIO m, MonadMask m, Member (Embed (InputT m)) r) =>
Sem (Readline : r) a -> Sem r a
interpretReadlineAsInputT
    (Sem (Readline : Embed (InputT m) : r) a
 -> Sem (Embed (InputT m) : r) a)
-> (Sem (Readline : r) a
    -> Sem (Readline : Embed (InputT m) : r) a)
-> Sem (Readline : r) a
-> Sem (Embed (InputT m) : r) a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (e1 :: Effect) (r :: [Effect]) a.
Sem (e1 : r) a -> Sem (e1 : Embed (InputT m) : r) a
forall (e2 :: Effect) (e1 :: Effect) (r :: [Effect]) a.
Sem (e1 : r) a -> Sem (e1 : e2 : r) a
raiseUnder @(Embed (H.InputT m))

-- | Interpreter for the somewhat common case of wanting to keep InputT around
-- until after 'runFinal' to ensure that state is preserved between subsequent
-- effects.
runReadlineFinal ::
  forall m r a.
  (MonadIO m, MonadMask m, Member (Final (H.InputT m)) r) =>
  Sem (Readline : r) a ->
  Sem r a
runReadlineFinal :: Sem (Readline : r) a -> Sem r a
runReadlineFinal =
  Sem (Embed (InputT m) : r) a -> Sem r a
forall (m :: * -> *) (r :: [Effect]) a.
(Member (Final m) r, Functor m) =>
Sem (Embed m : r) a -> Sem r a
embedToFinal
    (Sem (Embed (InputT m) : r) a -> Sem r a)
-> (Sem (Readline : r) a -> Sem (Embed (InputT m) : r) a)
-> Sem (Readline : r) a
-> Sem r a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Sem (Readline : Embed (InputT m) : r) a
-> Sem (Embed (InputT m) : r) a
forall (m :: * -> *) (r :: [Effect]) a.
(MonadIO m, MonadMask m, Member (Embed (InputT m)) r) =>
Sem (Readline : r) a -> Sem r a
interpretReadlineAsInputT
    (Sem (Readline : Embed (InputT m) : r) a
 -> Sem (Embed (InputT m) : r) a)
-> (Sem (Readline : r) a
    -> Sem (Readline : Embed (InputT m) : r) a)
-> Sem (Readline : r) a
-> Sem (Embed (InputT m) : r) a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (e1 :: Effect) (r :: [Effect]) a.
Sem (e1 : r) a -> Sem (e1 : Embed (InputT m) : r) a
forall (e2 :: Effect) (e1 :: Effect) (r :: [Effect]) a.
Sem (e1 : r) a -> Sem (e1 : e2 : r) a
raiseUnder @(Embed (H.InputT m))

-- | Interpret in terms of an embedded 'H.InputT' stack.
interpretReadlineAsInputT ::
  forall m r a.
  (MonadIO m, MonadMask m, Member (Embed (H.InputT m)) r) =>
  Sem (Readline : r) a ->
  Sem r a
interpretReadlineAsInputT :: Sem (Readline : r) a -> Sem r a
interpretReadlineAsInputT = (forall x (rInitial :: [Effect]).
 Readline (Sem rInitial) x -> Sem r x)
-> Sem (Readline : r) a -> Sem r a
forall (e :: Effect) (r :: [Effect]) a.
FirstOrder e "interpret" =>
(forall x (rInitial :: [Effect]). e (Sem rInitial) x -> Sem r x)
-> Sem (e : r) a -> Sem r a
interpret ((forall x (rInitial :: [Effect]).
  Readline (Sem rInitial) x -> Sem r x)
 -> Sem (Readline : r) a -> Sem r a)
-> (forall x (rInitial :: [Effect]).
    Readline (Sem rInitial) x -> Sem r x)
-> Sem (Readline : r) a
-> Sem r a
forall a b. (a -> b) -> a -> b
$ \case
  GetInputLine prompt -> InputT m (Maybe String) -> Sem r (Maybe String)
forall (m :: * -> *) (r :: [Effect]) a.
Member (Embed m) r =>
m a -> Sem r a
embed (InputT m (Maybe String) -> Sem r (Maybe String))
-> InputT m (Maybe String) -> Sem r (Maybe String)
forall a b. (a -> b) -> a -> b
$ String -> InputT m (Maybe String)
forall (m :: * -> *).
(MonadIO m, MonadMask m) =>
String -> InputT m (Maybe String)
H.getInputLine String
prompt
  GetInputLineWithInitial prompt initial ->
    InputT m (Maybe String) -> Sem r (Maybe String)
forall (m :: * -> *) (r :: [Effect]) a.
Member (Embed m) r =>
m a -> Sem r a
embed (InputT m (Maybe String) -> Sem r (Maybe String))
-> InputT m (Maybe String) -> Sem r (Maybe String)
forall a b. (a -> b) -> a -> b
$ String -> (String, String) -> InputT m (Maybe String)
forall (m :: * -> *).
(MonadIO m, MonadMask m) =>
String -> (String, String) -> InputT m (Maybe String)
H.getInputLineWithInitial String
prompt (String, String)
initial
  GetInputChar prompt -> InputT m (Maybe Char) -> Sem r (Maybe Char)
forall (m :: * -> *) (r :: [Effect]) a.
Member (Embed m) r =>
m a -> Sem r a
embed (InputT m (Maybe Char) -> Sem r (Maybe Char))
-> InputT m (Maybe Char) -> Sem r (Maybe Char)
forall a b. (a -> b) -> a -> b
$ String -> InputT m (Maybe Char)
forall (m :: * -> *).
(MonadIO m, MonadMask m) =>
String -> InputT m (Maybe Char)
H.getInputChar String
prompt
  GetPassword maskChar prompt -> InputT m (Maybe String) -> Sem r (Maybe String)
forall (m :: * -> *) (r :: [Effect]) a.
Member (Embed m) r =>
m a -> Sem r a
embed (InputT m (Maybe String) -> Sem r (Maybe String))
-> InputT m (Maybe String) -> Sem r (Maybe String)
forall a b. (a -> b) -> a -> b
$ Maybe Char -> String -> InputT m (Maybe String)
forall (m :: * -> *).
(MonadIO m, MonadMask m) =>
Maybe Char -> String -> InputT m (Maybe String)
H.getPassword Maybe Char
maskChar String
prompt
  WaitForAnyKey prompt -> InputT m Bool -> Sem r Bool
forall (m :: * -> *) (r :: [Effect]) a.
Member (Embed m) r =>
m a -> Sem r a
embed (InputT m Bool -> Sem r Bool) -> InputT m Bool -> Sem r Bool
forall a b. (a -> b) -> a -> b
$ String -> InputT m Bool
forall (m :: * -> *).
(MonadIO m, MonadMask m) =>
String -> InputT m Bool
H.waitForAnyKey String
prompt
  OutputStr str -> InputT m () -> Sem r ()
forall (m :: * -> *) (r :: [Effect]) a.
Member (Embed m) r =>
m a -> Sem r a
embed (InputT m () -> Sem r ()) -> InputT m () -> Sem r ()
forall a b. (a -> b) -> a -> b
$ String -> InputT m ()
forall (m :: * -> *). MonadIO m => String -> InputT m ()
H.outputStr String
str