module Database.Bolt.Connection
  ( BoltActionT
  , run
  , queryP, query
  , queryP', query'
  , queryP_, query_
  ) where

import           Database.Bolt.Connection.Pipe
import           Database.Bolt.Connection.Instances
import           Database.Bolt.Connection.Type
import           Database.Bolt.Value.Type
import           Database.Bolt.Record

import           Control.Monad.IO.Class        (MonadIO (..), liftIO)
import           Control.Monad.Trans.Reader    (ReaderT (..), ask, runReaderT)
import           Data.Text                     (Text)
import           Data.Map.Strict               (Map, empty)

import           System.IO.Unsafe              (unsafeInterleaveIO)

-- |Monad Transformer to do all BOLT actions in
type BoltActionT = ReaderT Pipe

-- |Runs BOLT action on selected pipe
run :: Pipe -> BoltActionT m a -> m a
run = flip runReaderT

-- |Runs Cypher query with parameters and returns list of obtained 'Record's. Lazy version
queryP :: MonadIO m => Text -> Map Text Value -> BoltActionT m [Record]
queryP = querySL False

-- |Runs Cypher query and returns list of obtained 'Record's. Lazy version
query :: MonadIO m => Text -> BoltActionT m [Record]
query cypher = queryP cypher empty

-- |Runs Cypher query with parameters and returns list of obtained 'Record's. Strict version
queryP' :: MonadIO m => Text -> Map Text Value -> BoltActionT m [Record]
queryP' = querySL True

-- |Runs Cypher query and returns list of obtained 'Record's. Strict version
query' :: MonadIO m => Text -> BoltActionT m [Record]
query' cypher = queryP' cypher empty

-- |Runs Cypher query with parameters and ignores response
queryP_ :: MonadIO m => Text -> Map Text Value -> BoltActionT m ()
queryP_ cypher params =
  do pipe <- ask
     liftIO $ sendRequest pipe cypher params $ \_ -> discardAll pipe
     
-- |Runs Cypher query and ignores response
query_ :: MonadIO m => Text -> BoltActionT m ()
query_ cypher = queryP_ cypher empty

-- Helper functions

querySL :: MonadIO m => Bool -> Text -> Map Text Value -> BoltActionT m [Record]
querySL strict cypher params = do pipe <- ask
                                  keys <- liftIO $ pullKeys pipe cypher params
                                  liftIO $ pullRecords pipe keys strict

pullKeys :: Pipe -> Text -> Map Text Value -> IO [Text]
pullKeys pipe cypher params = sendRequest pipe cypher params $ \status -> do
  flush pipe RequestPullAll
  mkKeys status

pullRecords :: Pipe -> [Text] -> Bool -> IO [Record]
pullRecords pipe keys strict = do resp <- fetch pipe
                                  if isSuccess resp
                                    then pure []
                                    else do let record = mkRecord keys resp
                                            let pull = pullRecords pipe keys strict
                                            rest <- if strict then pull
                                                              else unsafeInterleaveIO pull
                                            pure (record:rest)

-- |Sends request to database and makes an action
sendRequest :: Pipe -> Text -> Map Text Value -> (Response -> IO a) -> IO a
sendRequest pipe cypher params f =
  do flush pipe $ RequestRun cypher params
     status <- fetch pipe
     if isSuccess status then f status
       else do ackFailure pipe
               mkFailure status