{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric      #-}
{-# LANGUAGE OverloadedStrings  #-}
{-# LANGUAGE RecordWildCards    #-}

-- |
-- Module:      Network.Distributed.Types
-- Copyright:   (c) 2018 Sean McGroarty
-- License:     BSD3
-- Maintainer:  Sean McGroarty <mcgroas@tcd.ie.com>
-- Stability:   experimental
--
module Network.Distributed.Types where

import           Control.Distributed.Process.Backend.SimpleLocalnet (Backend)
import           Control.Distributed.Process.Lifted                 (Process,
                                                                     ProcessId,
                                                                     SendPort)
import           Control.Monad.Reader
import           Data.Binary                                        (Binary)
import           Data.ByteString                                    (ByteString)
import           Data.Text                                          (Text)
import           Data.Typeable                                      (Typeable)
import           Filesystem.Path.CurrentOS                          (decode)
import           GHC.Generics                                       (Generic)

---------------------------------------------------------------------------------
-- | Configuration for the master node
data AppConfig = AppConfig
  { nodes   :: Int
  -- ^ Number of slave nodes the master should wait for before attempting a build
  , backend :: Backend
  }

-- | A Monad which wraps Process with ReaderT
type App a = ReaderT AppConfig Process a

-- | Runs App
runApp :: AppConfig -> App a -> Process a
runApp = flip runReaderT

---------------------------------------------------------------------------------
-- | Host and Port of a Node
data NetworkConfig = NetworkConfig
  { hostNetworkConfig :: String
  , portNetworkConfig :: String
  }

instance Show NetworkConfig where
  show NetworkConfig {..} =
    "//" ++ hostNetworkConfig ++ ":" ++ portNetworkConfig

---------------------------------------------------------------------------------
-- | A Node is used for communication
type Node = ProcessId

-- | A collection of Nodes
type Network = [Node]

-- | The dependecies a Node has, represented as a list of Strings
type Deps = [String]

-- | A Node and its dependencies
type ProcessDeps = (Deps, ProcessId)

-- | Tuple of file name and bytes
type FileInfo = (Text, ByteString)

---------------------------------------------------------------------------------
-- | All Types used messaging are derived from a Message
data Message
  = Request
  | Response

-- | Only masters can make a Request
data Request
  = Ping ProcessId
  -- ^ Used to transmit masters ProcessId to a slabe
  | TransferReq (SendPort Transfer)
  -- ^ FacilitateS a Transfer
  | Terminate
  -- ^ Terminates a slaves connection to the network
  deriving (Generic, Typeable)

instance Binary Request

-- | Only slaves can issue a Reponse in reply to a Request
data Response
  = PD ProcessDeps
  -- ^ Response to a Ping
  | Transfer
  -- ^ Reponse to a TransferReq
  deriving (Generic, Typeable)

instance Binary Response

-- | Data-Type used in a Transfer
data Transfer
  = TransferInProg FileInfo
  -- ^ Transfer In Progress
  | TransferDone
  -- ^ Informs master the Transfer is complete
  deriving (Generic, Typeable)

instance Binary Transfer

instance Show Transfer where
  show (TransferInProg (s, _)) = show $ decode s
  show _                       = "Transfer Complete"

---------------------------------------------------------------------------------
data ProcessError =
  SlaveError

instance Show ProcessError where
  show SlaveError = "Slave died during transfer. Aborting to retry..."
---------------------------------------------------------------------------------