{-# LANGUAGE LambdaCase #-}

module Test.Cardano.Mirror (
  mainnetEpochFiles,
) where

import Cardano.Prelude
import System.Directory (doesDirectoryExist, getDirectoryContents)
import System.Environment (lookupEnv)
import System.FilePath (isExtensionOf, (</>))

-- Failing here (with 'exitFailure') is fine because this function is only ever
-- used to test maiinnet validaton. It is never used in production code.
mainnetEpochFiles :: IO [FilePath]
mainnetEpochFiles :: IO [String]
mainnetEpochFiles =
  String -> IO (Maybe String)
lookupEnv String
"CARDANO_MAINNET_MIRROR" IO (Maybe String) -> (Maybe String -> IO [String]) -> IO [String]
forall a b. IO a -> (a -> IO b) -> IO b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= \case
    Maybe String
Nothing -> do
      String -> IO ()
forall a (m :: * -> *). (Print a, MonadIO m) => a -> m ()
forall (m :: * -> *). MonadIO m => String -> m ()
putStrLn String
"mainnetEpochFiles: CARDANO_MAINNET_MIRROR variable is not set"
      IO [String]
forall a. IO a
exitFailure
    Just String
fpath -> do
      exists <- String -> IO Bool
doesDirectoryExist String
fpath
      if exists
        then
          sort
            . fmap (fpath </>)
            . filter ("epoch" `isExtensionOf`)
            <$> getDirectoryContents fpath
        else do
          putStrLn
            $ "mainnetEpochFiles: directory '"
            ++ fpath
            ++ "' does not exist."
          exitFailure