{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE OverloadedStrings #-}

module Hadolint.Config (applyConfig, ConfigFile (..)) where

import Control.Monad (filterM)
import qualified Data.ByteString as Bytes
import Data.Coerce (coerce)
import Data.Maybe (fromMaybe, listToMaybe)
import qualified Data.Set as Set
import Data.YAML ((.:?))
import qualified Data.YAML as Yaml
import GHC.Generics (Generic)
import qualified Hadolint.Lint as Lint
import qualified Hadolint.Rules as Rules
import qualified Language.Docker as Docker
import System.Directory
  ( XdgDirectory (..),
    doesFileExist,
    getCurrentDirectory,
    getXdgDirectory,
  )
import System.FilePath ((</>))

data ConfigFile = ConfigFile
  { ignoredRules :: Maybe [Lint.IgnoreRule],
    trustedRegistries :: Maybe [Lint.TrustedRegistry]
  }
  deriving (Show, Eq, Generic)

instance Yaml.FromYAML ConfigFile where
  parseYAML = Yaml.withMap "ConfigFile" $ \m ->
    ConfigFile
      <$> m .:? "ignored"
      <*> m .:? "trustedRegistries"

-- | If both the ignoreRules and rulesConfig properties of Lint options are empty
-- then this function will fill them with the default found in the passed config
-- file. If there is an error parsing the default config file, this function will
-- return the error string.
applyConfig :: Maybe FilePath -> Lint.LintOptions -> IO (Either String Lint.LintOptions)
applyConfig maybeConfig o
  | not (null (Lint.ignoreRules o)) && Lint.rulesConfig o /= mempty = return (Right o)
  | otherwise = do
    theConfig <-
      case maybeConfig of
        Nothing -> findConfig
        c -> return c
    case theConfig of
      Nothing -> return (Right o)
      Just config -> parseAndApply config
  where
    findConfig = do
      localConfigFile <- (</> ".hadolint.yaml") <$> getCurrentDirectory
      configFile <- getXdgDirectory XdgConfig "hadolint.yaml"
      listToMaybe <$> filterM doesFileExist [localConfigFile, configFile]

    parseAndApply :: FilePath -> IO (Either String Lint.LintOptions)
    parseAndApply configFile = do
      contents <- Bytes.readFile configFile
      case Yaml.decode1Strict contents of
        Left (_, err) -> return $ Left (formatError err configFile)
        Right (ConfigFile ignore trusted) -> return (Right (override ignore trusted))

    override ignore trusted = applyTrusted trusted . applyIgnore ignore $ o
    applyIgnore ignore opts =
      case Lint.ignoreRules opts of
        [] -> opts {Lint.ignoreRules = fromMaybe [] ignore}
        _ -> opts

    applyTrusted trusted opts
      | null (Rules.allowedRegistries (Lint.rulesConfig opts)) =
        opts {Lint.rulesConfig = toRules trusted <> Lint.rulesConfig opts}
      | otherwise = opts

    toRules (Just trusted) = Rules.RulesConfig (Set.fromList . coerce $ trusted)
    toRules _ = mempty

    formatError err config =
      unlines
        [ "Error parsing your config file in  '" ++ config ++ "':",
          "It should contain one of the keys 'ignored' or 'trustedRegistries'. For example:\n",
          "ignored:",
          "\t- DL3000",
          "\t- SC1099\n\n",
          "The key 'trustedRegistries' should contain the names of the allowed docker registries:\n",
          "allowedRegistries:",
          "\t- docker.io",
          "\t- my-company.com",
          "",
          err
        ]