{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}
module Notmuch where

import qualified Data.ByteString.Lazy as LBS
import qualified Data.ByteString.Lazy.Char8 as LBS8
import Control.Concurrent
import Control.DeepSeq (rnf)
import Control.Exception
import Data.Aeson
import Data.Monoid
import Data.Tree
import Notmuch.Class
import Notmuch.Message
import Notmuch.SearchResult
import System.Exit
import System.IO
import System.Process
import TagUtils


-- | Fork a thread while doing something else, but kill it if there's an
-- exception.
--
-- This is important in the cases above because we want to kill the thread
-- that is holding the Handle lock, because when we clean up the process we
-- try to close that handle, which could otherwise deadlock.
--
withForkWait :: IO () -> (IO () ->  IO a) -> IO a
withForkWait async body = do
  waitVar <- newEmptyMVar :: IO (MVar (Either SomeException ()))
  mask $ \restore -> do
    tid <- forkIO $ try (restore async) >>= putMVar waitVar
    let wait = takeMVar waitVar >>= either throwIO return
    restore (body wait) `onException` killThread tid




notmuch :: [String] -> IO LBS.ByteString
notmuch args = do
    (_, Just hout, _, ph) <- createProcess (proc "notmuch" args)
                                          { std_out = CreatePipe }
    output <- LBS.hGetContents hout


    withForkWait (evaluate $ rnf output) $ \waitOut -> do

      ---- now write any input
      --unless (null input) $
      --  ignoreSigPipe $ hPutStr inh input
      -- hClose performs implicit hFlush, and thus may trigger a SIGPIPE
      --ignoreSigPipe $ hClose inh

      -- wait on the output
      waitOut
      hClose hout

    -- wait on the process
    _ex <- waitForProcess ph
    --return (ex, output)

    --case ex of
    --    ExitSuccess   -> return output
    --    ExitFailure r -> processFailedException "readProcess" cmd args r

    return output


notmuch' :: [String] -> IO (ExitCode, LBS.ByteString, LBS.ByteString)
notmuch' args = do
    (_, Just hout, Just herr, ph) <-
        createProcess (proc "notmuch" args)
            { std_out = CreatePipe
            , std_err = CreatePipe
            }
    out <- LBS.hGetContents hout
    err <- LBS.hGetContents herr

    withForkWait (evaluate $ rnf out) $ \waitOut -> do
        withForkWait (evaluate $ rnf err) $ \waitErr -> do

          ---- now write any input
          --unless (null input) $
          --  ignoreSigPipe $ hPutStr inh input
          -- hClose performs implicit hFlush, and thus may trigger a SIGPIPE
          --ignoreSigPipe $ hClose inh

          -- wait on the output
          waitOut
          waitErr
          hClose hout
          hClose herr

    -- wait on the process
    exitCode <- waitForProcess ph

    return (exitCode, out, err)


notmuchWithInput
    :: [String]
    -> LBS.ByteString
    -> IO (ExitCode, LBS.ByteString, LBS.ByteString)
notmuchWithInput args input = do
    (Just hin, Just hout, Just herr, ph) <-
        createProcess (proc "notmuch" args)
            { std_in = CreatePipe
            , std_out = CreatePipe
            , std_err = CreatePipe
            }
    LBS.hPut hin input
    hClose hin

    out <- LBS.hGetContents hout
    err <- LBS.hGetContents herr

    withForkWait (evaluate $ rnf out) $ \waitOut -> do
        withForkWait (evaluate $ rnf err) $ \waitErr -> do

          ---- now write any input
          --unless (null input) $
          --  ignoreSigPipe $ hPutStr inh input
          -- hClose performs implicit hFlush, and thus may trigger a SIGPIPE
          --ignoreSigPipe $ hClose inh

          -- wait on the output
          waitOut
          waitErr
          hClose hout
          hClose herr

    -- wait on the process
    exitCode <- waitForProcess ph

    return (exitCode, out, err)


search :: String -> IO (Either String [SearchResult])
search term =
    notmuch [ "search", "--format=json", "--format-version=2", term ]
        >>= return . eitherDecode'


data ReplyTo = ToAll | ToSender
instance Show ReplyTo where
    show ToAll = "all"
    show ToSender = "sender"

--notmuchReply :: String -> IO (Either String [SearchResult])
notmuchReply :: ReplyTo -> String -> IO LBS.ByteString
notmuchReply replyTo term =
    notmuch
        [ "reply"
        , "--reply-to=" ++ show replyTo
        , term
        ]
 --       >>= return . eitherDecode'


notmuchShow :: String -> IO (Forest Message)
notmuchShow term = do
    c' <- notmuch [ "show", "--format=json", "--format-version=2"
                   , term ]
    -- TODO why head?
    return $ threadForest $ head $
        either error id (eitherDecode' c')


notmuchShowPart :: String -> Int -> IO (Either String MessagePart)
notmuchShowPart term partId = do
    -- TODO handle partId == 0 and partId > N
    (exitCode, out, err) <-
        notmuch' [ "show", "--format=json", "--format-version=2"
                 , "--part=" <> show partId
                 , term ]
    return $ case exitCode of
        ExitSuccess -> eitherDecode' out
        _ -> Left $ show exitCode <> ": " <> LBS8.unpack err


notmuchTag :: HasNotmuchId a => [TagOp] -> a -> IO ()
notmuchTag tagOps x =
    notmuch ("tag" : tagOpsToArgs tagOps ++ [notmuchId x]) >> return ()