{-# LANGUAGE DeriveDataTypeable        #-}
{-# LANGUAGE DeriveGeneric             #-}
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE OverloadedStrings         #-}
{-# LANGUAGE RecordWildCards           #-}
{- |
Module      :  Neovim.Plugin.IPC.Classes
Description :  Classes used for Inter Plugin Communication
Copyright   :  (c) Sebastian Witte
License     :  Apache-2.0

Maintainer  :  woozletoff@gmail.com
Stability   :  experimental
Portability :  GHC

-}
module Neovim.Plugin.IPC.Classes (
    SomeMessage(..),
    Message(..),
    FunctionCall(..),
    Request(..),
    Notification(..),

    UTCTime,
    getCurrentTime,

    module Data.Int,
    ) where

import           Neovim.Classes
import           Neovim.Plugin.Classes     (FunctionName)

import           Control.Concurrent.STM
import           Data.Data                 (Typeable, cast)
import           Data.Int                  (Int64)
import           Data.MessagePack
import           Data.Time                 (UTCTime, formatTime, getCurrentTime)
import           Data.Time.Locale.Compat   (defaultTimeLocale)

import           Data.Text.Prettyprint.Doc (Pretty (..), nest, hardline, (<+>), (<>), viaShow)

import           Prelude

-- | Taken from xmonad and based on ideas in /An Extensible Dynamically-Typed
-- Hierarchy of Exceptions/, Simon Marlow, 2006.
--
-- User-extensible messages must be put into a value of this type, so that it
-- can be sent to other plugins.
data SomeMessage = forall msg. Message msg => SomeMessage msg


-- | This class allows type safe casting of 'SomeMessage' to an actual message.
-- The cast is successful if the type you're expecting matches the type in the
-- 'SomeMessage' wrapper. This way, you can subscribe to an arbitrary message
-- type withouth having to pattern match on the constructors. This also allows
-- plugin authors to create their own message types without having to change the
-- core code of /nvim-hs/.
class Typeable message => Message message where
    -- | Try to convert a given message to a value of the message type we are
    -- interested in. Will evaluate to 'Nothing' for any other type.
    fromMessage :: SomeMessage -> Maybe message
    fromMessage (SomeMessage message) = cast message


-- | Haskell representation of supported Remote Procedure Call messages.
data FunctionCall
    = FunctionCall FunctionName [Object] (TMVar (Either Object Object)) UTCTime
    -- ^ Method name, parameters, callback, timestamp
    deriving (Typeable)


instance Message FunctionCall


instance Pretty FunctionCall where
    pretty (FunctionCall fname args _ t) =
        nest 2 $ "Function call for:" <+> pretty fname
            <> hardline <> "Arguments:" <+> viaShow args
            <> hardline <> "Timestamp:"
                <+> (viaShow . formatTime defaultTimeLocale "%H:%M:%S (%q)") t


-- | A request is a data type containing the method to call, its arguments and
-- an identifier used to map the result to the function that has been called.
data Request = Request
    { reqMethod :: FunctionName
    -- ^ Name of the function to call.
    , reqId     :: !Int64
    -- ^ Identifier to map the result to a function call invocation.
    , reqArgs   :: [Object]
    -- ^ Arguments for the function.
    } deriving (Eq, Ord, Show, Typeable, Generic)


instance NFData Request


instance Message Request


instance Pretty Request where
    pretty Request{..} =
        nest 2 $ "Request" <+> "#" <> pretty reqId
            <> hardline <> "Method:" <+> pretty reqMethod
            <> hardline <> "Arguments:" <+> viaShow reqArgs


-- | A notification is similar to a 'Request'. It essentially does the same
-- thing, but the function is only called for its side effects. This type of
-- message is sent by neovim if the caller there does not care about the result
-- of the computation.
data Notification = Notification
    { notMethod :: FunctionName
    -- ^ Name of the function to call.
    , notArgs   :: [Object]
    -- ^ Arguments for the function.
    } deriving (Eq, Ord, Show, Typeable, Generic)


instance NFData Notification


instance Message Notification


instance Pretty Notification where
    pretty Notification{..} =
        nest 2 $ "Notification"
            <> hardline <> "Method:" <+> pretty notMethod
            <> hardline <> "Arguments:" <+> viaShow notArgs