{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE PartialTypeSignatures #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}

module TestCommon where

import           Control.Monad.Catch
import           Control.Monad.IO.Class
import           Data.Text                      ( Text
                                                , unpack
                                                )
import           Data.Time
import           Nix
import           Nix.Exec                       ( )
import           Nix.Standard
import           Nix.Fresh.Basic
import           System.Environment
import           System.IO
import           System.Posix.Files
import           System.Posix.Temp
import           System.Process
import           Test.Tasty.HUnit

hnixEvalFile :: Options -> FilePath -> IO (StdValue (StandardT (StdIdT IO)))
hnixEvalFile opts file = do
  parseResult <- parseNixFileLoc file
  case parseResult of
    Failure err ->
      error $ "Parsing failed for file `" ++ file ++ "`.\n" ++ show err
    Success expr -> do
      setEnv "TEST_VAR" "foo"
      runWithBasicEffects opts
        $ catch (evaluateExpression (Just file) nixEvalExprLoc normalForm expr)
        $ \case
            NixException frames ->
              errorWithoutStackTrace
                .   show
                =<< renderFrames @(StdValue (StandardT (StdIdT IO)))
                      @(StdThunk (StandardT (StdIdT IO)))
                      frames

hnixEvalText :: Options -> Text -> IO (StdValue (StandardT (StdIdT IO)))
hnixEvalText opts src = case parseNixText src of
  Failure err ->
    error
      $  "Parsing failed for expressien `"
      ++ unpack src
      ++ "`.\n"
      ++ show err
  Success expr ->
    runWithBasicEffects opts $ normalForm =<< nixEvalExpr Nothing expr

nixEvalString :: String -> IO String
nixEvalString expr = do
  (fp, h) <- mkstemp "nix-test-eval"
  hPutStr h expr
  hClose h
  res <- nixEvalFile fp
  removeLink fp
  return res

nixEvalFile :: FilePath -> IO String
nixEvalFile fp = readProcess "nix-instantiate" ["--eval", "--strict", fp] ""

assertEvalFileMatchesNix :: FilePath -> Assertion
assertEvalFileMatchesNix fp = do
  time    <- liftIO getCurrentTime
  hnixVal <- (++ "\n") . printNix <$> hnixEvalFile (defaultOptions time) fp
  nixVal  <- nixEvalFile fp
  assertEqual fp nixVal hnixVal

assertEvalMatchesNix :: Text -> Assertion
assertEvalMatchesNix expr = do
  time    <- liftIO getCurrentTime
  hnixVal <- (++ "\n") . printNix <$> hnixEvalText (defaultOptions time) expr
  nixVal  <- nixEvalString expr'
  assertEqual expr' nixVal hnixVal
  where expr' = unpack expr