{-# LANGUAGE NoImplicitPrelude #-}

-- | A ghc-pkg id.

module Stack.Types.GhcPkgId
  ( GhcPkgId
  , unGhcPkgId
  , ghcPkgIdParser
  , parseGhcPkgId
  , ghcPkgIdString
  ) where

import           Data.Aeson.Types ( FromJSON (..), ToJSON (..), withText )
import           Data.Attoparsec.Text
                   ( Parser, (<?>), choice, endOfInput, many1, parseOnly
                   , satisfy
                   )
import           Data.Char ( isAlphaNum )
import qualified Data.Text as T
import           Database.Persist.Sql ( PersistField, PersistFieldSql )
import           Stack.Prelude
import           Text.Read ( Read (..) )

-- | A parse fail.
newtype GhcPkgIdParseFail
  = GhcPkgIdParseFail Text
  deriving (Show, Typeable)

instance Exception GhcPkgIdParseFail where
  displayException (GhcPkgIdParseFail bs) = concat
    [ "Error: [S-5359]\n"
    , "Invalid package ID: "
    , show bs
    ]

-- | A ghc-pkg package identifier.
newtype GhcPkgId
  = GhcPkgId Text
  deriving (Data, Eq, Generic, Ord, PersistField, PersistFieldSql, Typeable)

instance Hashable GhcPkgId

instance NFData GhcPkgId

instance Show GhcPkgId where
  show = show . ghcPkgIdString

instance Read GhcPkgId where
  readsPrec i = map (first (GhcPkgId . T.pack)) . readsPrec i

instance FromJSON GhcPkgId where
  parseJSON = withText "GhcPkgId" $ \t ->
    case parseGhcPkgId t of
      Left e -> fail $ show (e, t)
      Right x -> pure x

instance ToJSON GhcPkgId where
  toJSON g =
    toJSON (ghcPkgIdString g)

-- | Convenient way to parse a package name from a 'Text'.
parseGhcPkgId :: MonadThrow m => Text -> m GhcPkgId
parseGhcPkgId x = go x
 where
  go = either
         (const (throwM (GhcPkgIdParseFail x)))
         pure . parseOnly (ghcPkgIdParser <* endOfInput)

-- | A parser for a package-version-hash pair.
ghcPkgIdParser :: Parser GhcPkgId
ghcPkgIdParser =
  let elements = "_.-" :: String
  in  GhcPkgId . T.pack <$>
        many1 (choice [alphaNum, satisfy (`elem` elements)])

-- | Parse an alphanumerical character, as recognised by `isAlphaNum`.
alphaNum :: Parser Char
alphaNum = satisfy isAlphaNum <?> "alphanumeric"
{-# INLINE alphaNum #-}

-- | Get a string representation of GHC package id.
ghcPkgIdString :: GhcPkgId -> String
ghcPkgIdString (GhcPkgId x) = T.unpack x

-- | Get a text value of GHC package id
unGhcPkgId :: GhcPkgId -> Text
unGhcPkgId (GhcPkgId v) = v