{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeApplications #-}

-- |
-- Module      :  ELynx.Tools.Reproduction
-- Description :  Functions to ease reproduction of analyses
-- Copyright   :  (c) Dominik Schrempf 2021
-- License     :  GPL-3.0-or-later
--
-- Maintainer  :  dominik.schrempf@gmail.com
-- Stability   :  unstable
-- Portability :  portable
--
-- Creation date: Tue Nov 19 15:07:09 2019.
--
-- Use of standard input is not supported.
module ELynx.Tools.Reproduction
  ( -- * Reproduction
    SeedOpt (..),
    Reproducible (..),
    getReproductionHash,
    Reproduction (..),
    writeReproduction,
    hashFile,
  )
where

import Control.Monad
import Crypto.Hash.SHA256
import Data.Aeson hiding (encode)
import Data.ByteString.Base16
import qualified Data.ByteString.Char8 as BS
import qualified Data.Vector.Unboxed as VU
import Data.Version
import Data.Word
import GHC.Generics
import Options.Applicative
import Paths_elynx_tools
import System.Environment

-- | Random or fixed seed.
data SeedOpt = RandomUnset | RandomSet (VU.Vector Word32) | Fixed (VU.Vector Word32)
  deriving (Eq, Generic, Show)

instance FromJSON SeedOpt

instance ToJSON SeedOpt

-- | Reproducible commands have
--   - a set of input files to be checked for consistency,
--   - a set of output suffixes which define output files to be checked for consistency,
--   - a function to get the seed, if available,
--   - a function to set the seed, if applicable,
--   - a parser to read the command line,
--   - a nice program name, description, and footer.
class Reproducible a where
  inFiles :: a -> [FilePath]
  outSuffixes :: a -> [String]
  getSeed :: a -> Maybe SeedOpt
  setSeed :: a -> SeedOpt -> a
  parser :: Parser a
  cmdName :: String
  cmdDsc :: [String]
  cmdFtr :: [String]
  cmdFtr = []

-- | A unique hash of the reproduction data type.
getReproductionHash :: forall a. Reproducible a => Reproduction a -> String
getReproductionHash r =
  BS.unpack $
    encode $
      hash $
        BS.pack $
          unlines $
            -- Reproduction.
            progName r :
            argsStr r
              <> [showVersion (rVersion r)]
              <> files r
              <> checkSums r
              -- Reproducible.
              <> inFiles ri
              <> outSuffixes ri
              <> [cmdName @a]
              <> cmdDsc @a
              <> cmdFtr @a
  where
    ri = reproducible r

setHash :: Reproducible a => Reproduction a -> Reproduction a
setHash r = r {rHash = Just h} where h = getReproductionHash r

-- | Necessary information for a reproducible run. Notably, the input files are
-- checked for consistency!
data Reproduction a = Reproduction
  { -- | Program name.
    progName :: String,
    -- | Command line arguments without program name.
    argsStr :: [String],
    rVersion :: Version,
    -- | Unique hash; see 'getReproductionHash'.
    rHash :: Maybe String,
    -- | File paths of used files.
    files :: [FilePath],
    -- | SHA256 sums of used files.
    checkSums :: [String],
    -- | Command argument.
    reproducible :: a
  }
  deriving (Generic)

instance FromJSON a => FromJSON (Reproduction a)

instance ToJSON a => ToJSON (Reproduction a)

-- | Helper function.
hashFile :: FilePath -> IO BS.ByteString
hashFile f = encode . hash <$> BS.readFile f

-- | Write an ELynx reproduction file.
writeReproduction ::
  forall a.
  (Eq a, Show a, Reproducible a, ToJSON a) =>
  String ->
  a ->
  IO ()
writeReproduction bn r = do
  pn <- getProgName
  as <- getArgs
  let outFs = map (bn ++) (outSuffixes r)
  let fs = inFiles r ++ outFs
  cs <- mapM hashFile fs
  let cs' = map BS.unpack cs
      s = Reproduction pn as version Nothing fs cs' r
  void $ encodeFile (bn <> ".elynx") (setHash s)