{-# LANGUAGE DataKinds        #-}
{-# LANGUAGE DeriveAnyClass   #-}
{-# LANGUAGE DeriveGeneric    #-}
{-# LANGUAGE LambdaCase       #-}
{-# LANGUAGE TypeApplications #-}

module Handlers (App, submitImpl,statusImpl) where

import           Bindings.Cli.Git       (gitProc)
import           CheckDir               (DirResult, recursiveCheckDir)
import           Cli.Extras             (CliT, ProcessFailure, Severity (..),
                                         callProcessAndLogOutput, getCliConfig,
                                         prettyProcessFailure, runCli)
import           Control.Concurrent     (MVar, forkIO, withMVar)
import           Control.Monad.Extra    (ifM)
import           Control.Monad.IO.Class (liftIO)
import           Control.Monad.Trans    (lift)
import qualified Data.Map               as M
import           Data.Text              (Text)
import qualified Data.Text              as T
import qualified Data.UUID              as UUID
import qualified Data.UUID.V4           as UUID
import           Servant                (Handler, err404, err500, throwError)
import           Server                 (Config (entrypoint, lintconfig, tmpdir),
                                         JobStatus (..),
                                         RemoteRef (reporef, repourl), State,
                                         setJobStatus)
import           System.Directory       (doesDirectoryExist)
import           System.FilePath        ((</>))

-- | this servant app can run cli programs!
type App = CliT ProcessFailure Handler
type App' = CliT ProcessFailure IO

-- | annoying (and afaik unused), but has to be here for type system reasons
instance MonadFail Handler where
  fail _ = throwError $ err500

-- | someone submitted a map; lint it (synchronously for now)
submitImpl :: Config True -> MVar State -> RemoteRef -> App ()
submitImpl config state ref = do
  liftIO $ setJobStatus state ref Pending
  cliconfig <- getCliConfig
  -- we'll just forget the thread id for now and trust this terminates …
  _ <- liftIO $ forkIO $ do
    res <- runCli cliconfig $ do
      ifM (liftIO $ doesDirectoryExist gitdir)
        gitfetch gitclone
      checkPath config gitdir (reporef ref)
    setJobStatus state ref $ case res of
      Right res -> Linted res
      Left err  -> Failed (prettyProcessFailure err)
  -- the submission itself can't really fail or return anything useful
  pure ()
  where
    -- TODO: these calls fail for dumb http, add some fallback!
    gitclone = callProcessAndLogOutput (Debug, Error)
      $ gitProc gitdir [ "clone", T.unpack $ repourl ref, "--bare", "--depth", "1", "-b", T.unpack (reporef ref)]
    gitfetch = callProcessAndLogOutput (Debug, Error)
      $ gitProc gitdir [ "fetch", "origin", T.unpack (reporef ref), "--depth", "1" ]
    gitdir = tmpdir config </> hashedname
    hashedname = fmap escapeSlash . T.unpack . repourl $ ref
    escapeSlash = \case { '/' -> '-'; a -> a }

statusImpl :: MVar State -> RemoteRef -> App JobStatus
statusImpl state ref = do
   status <- liftIO $ withMVar state (pure . M.lookup ref)
   case status of
     Just res -> pure res
     Nothing  -> lift $ throwError err404



checkPath :: Config True -> FilePath -> Text -> App' DirResult
checkPath config gitdir ref = do
  rand <- liftIO UUID.nextRandom
  let workdir = "/tmp" </> ("worktree-" <> UUID.toString rand)
  callProcessAndLogOutput (Debug, Error)
    $ gitProc gitdir [ "worktree", "add", workdir ]
  callProcessAndLogOutput (Debug, Error)
    $ gitProc workdir [ "checkout", T.unpack ref ]
  res <- liftIO $ recursiveCheckDir (lintconfig config) gitdir (entrypoint config)
  callProcessAndLogOutput (Debug, Error)
    $ gitProc gitdir [ "worktree", "remove", "-f", "-f", workdir ]
  pure res