{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE MultiWayIf #-}
module Config
  ( Config(..)
  , PasswordSource(..)
  , findConfig
  , getCredentials
  , defaultConfig
  )
where

import           Prelude ()
import           Prelude.MH

import           Control.Monad.Trans.Except
import           Data.Ini.Config
import qualified Data.Map.Strict as M
import qualified Data.Text as T
import qualified Data.Text.IO as T
import           System.Directory ( makeAbsolute )
import           System.Environment ( getExecutablePath )
import           System.FilePath ( (</>), takeDirectory, splitPath, joinPath )
import           System.Process ( readProcess )

import           FilePaths
import           IOUtil
import           Types
import           Types.KeyEvents


defaultPort :: Int
defaultPort = 443

bundledSyntaxPlaceholderName :: String
bundledSyntaxPlaceholderName = "BUNDLED_SYNTAX"

userSyntaxPlaceholderName :: String
userSyntaxPlaceholderName = "USER_SYNTAX"

defaultSkylightingPaths :: IO [FilePath]
defaultSkylightingPaths = do
    xdg <- xdgSyntaxDir
    adjacent <- getBundledSyntaxPath
    return [xdg, adjacent]

getBundledSyntaxPath :: IO FilePath
getBundledSyntaxPath = do
    selfPath <- getExecutablePath
    let distDir = "dist-newstyle/"
        pathBits = splitPath selfPath

    return $ if distDir `elem` pathBits
             then
                 -- We're in development, so use the development
                 -- executable path to locate the XML path in the
                 -- development tree.
                 (joinPath $ takeWhile (/= distDir) pathBits) </> syntaxDirName
             else
                 -- In this case we assume the binary is being run from
                 -- a release, in which case the syntax directory is a
                 -- sibling of the executable path.
                 takeDirectory selfPath </> syntaxDirName

fromIni :: IniParser Config
fromIni = do
  conf <- section "mattermost" $ do
    configUser           <- fieldMbOf "user" stringField
    configHost           <- fieldMbOf "host" stringField
    configTeam           <- fieldMbOf "team" stringField
    configPort           <- fieldDefOf "port" number (configPort defaultConfig)
    configChannelListWidth <- fieldDefOf "channelListWidth" number
                              (configChannelListWidth defaultConfig)
    configLogMaxBufferSize <- fieldDefOf "logMaxBufferSize" number
                              (configLogMaxBufferSize defaultConfig)
    configTimeFormat     <- fieldMbOf "timeFormat" stringField
    configDateFormat     <- fieldMbOf "dateFormat" stringField
    configTheme          <- fieldMbOf "theme" stringField
    configThemeCustomizationFile <- fieldMbOf "themeCustomizationFile" stringField
    configAspellDictionary <- fieldMbOf "aspellDictionary" stringField
    configURLOpenCommand <- fieldMbOf "urlOpenCommand" stringField
    configURLOpenCommandInteractive <- fieldFlagDef "urlOpenCommandIsInteractive" False
    configSmartBacktick  <- fieldFlagDef "smartbacktick"
      (configSmartBacktick defaultConfig)
    configShowOlderEdits <- fieldFlagDef "showOlderEdits"
      (configShowOlderEdits defaultConfig)
    configShowBackground <- fieldDefOf "showBackgroundActivity" backgroundField
      (configShowBackground defaultConfig)
    configShowMessagePreview <- fieldFlagDef "showMessagePreview"
      (configShowMessagePreview defaultConfig)
    configShowChannelList <- fieldFlagDef "showChannelList"
      (configShowChannelList defaultConfig)
    configShowTypingIndicator <- fieldFlagDef "showTypingIndicator"
      (configShowTypingIndicator defaultConfig)
    configEnableAspell <- fieldFlagDef "enableAspell"
      (configEnableAspell defaultConfig)
    configSyntaxDirs <- fieldDefOf "syntaxDirectories" syntaxDirsField []
    configActivityNotifyCommand <- fieldMb "activityNotifyCommand"
    configActivityBell <- fieldFlagDef "activityBell"
      (configActivityBell defaultConfig)
    configHyperlinkingMode <- fieldFlagDef "hyperlinkURLs"
      (configHyperlinkingMode defaultConfig)
    configPass <- (Just . PasswordCommand <$> field "passcmd") <|>
                  (Just . PasswordString  <$> field "pass") <|>
                  pure Nothing
    configUnsafeUseHTTP <-
      fieldFlagDef "unsafeUseUnauthenticatedConnection" False

    let configAbsPath = Nothing
        configUserKeys = mempty
    return Config { .. }
  keys <- sectionMb "keybindings" $ do
    fmap (M.fromList . catMaybes) $ forM allEvents $ \ ev -> do
      kb <- fieldMbOf (keyEventName ev) parseBindingList
      case kb of
        Nothing      -> return Nothing
        Just binding -> return (Just (ev, binding))
  return conf { configUserKeys = fromMaybe mempty keys }

syntaxDirsField :: Text -> Either String [FilePath]
syntaxDirsField = listWithSeparator ":" string

backgroundField :: Text -> Either String BackgroundInfo
backgroundField t =
  case t of
    "Disabled" -> Right Disabled
    "Active" -> Right Active
    "ActiveCount" -> Right ActiveCount
    _ -> Left ("Invalid value " <> show t
              <> "; must be one of: Disabled, Active, ActiveCount")

stringField :: Text -> Either String Text
stringField t =
    case isQuoted t of
        True -> Right $ parseQuotedString t
        False -> Right t

parseQuotedString :: Text -> Text
parseQuotedString t =
    let body = T.drop 1 $ T.init t
        unescapeQuotes s | T.null s = s
                         | "\\\"" `T.isPrefixOf` s = "\"" <> unescapeQuotes (T.drop 2 s)
                         | otherwise = (T.singleton $ T.head s) <> unescapeQuotes (T.drop 1 s)
    in unescapeQuotes body

isQuoted :: Text -> Bool
isQuoted t =
    let quote = "\""
    in (quote `T.isPrefixOf` t) &&
       (quote `T.isSuffixOf` t)

defaultConfig :: Config
defaultConfig =
    Config { configAbsPath                   = Nothing
           , configUser                      = Nothing
           , configHost                      = Nothing
           , configTeam                      = Nothing
           , configPort                      = defaultPort
           , configPass                      = Nothing
           , configTimeFormat                = Nothing
           , configDateFormat                = Nothing
           , configTheme                     = Nothing
           , configThemeCustomizationFile    = Nothing
           , configSmartBacktick             = True
           , configURLOpenCommand            = Nothing
           , configURLOpenCommandInteractive = False
           , configActivityNotifyCommand     = Nothing
           , configActivityBell              = False
           , configShowBackground            = Disabled
           , configShowMessagePreview        = False
           , configShowChannelList           = True
           , configEnableAspell              = False
           , configAspellDictionary          = Nothing
           , configUnsafeUseHTTP             = False
           , configChannelListWidth          = 20
           , configLogMaxBufferSize          = 200
           , configShowOlderEdits            = True
           , configUserKeys                  = mempty
           , configShowTypingIndicator       = False
           , configHyperlinkingMode          = True
           , configSyntaxDirs                = []
           }

findConfig :: Maybe FilePath -> IO (Either String Config)
findConfig Nothing = do
    cfg <- locateConfig configFileName
    fixupSyntaxDirs =<< case cfg of
        Nothing -> return $ Right defaultConfig
        Just path -> getConfig path
findConfig (Just path) = fixupSyntaxDirs =<< getConfig path

-- | If the configuration has no syntax directories specified (the
-- default if the user did not provide the setting), fill in the
-- list with the defaults. Otherwise replace any bundled directory
-- placeholders in the config's syntax path list.
fixupSyntaxDirs :: Either String Config -> IO (Either String Config)
fixupSyntaxDirs (Left e) = return $ Left e
fixupSyntaxDirs (Right c) =
    if configSyntaxDirs c == []
    then do
        dirs <- defaultSkylightingPaths
        return $ Right c { configSyntaxDirs = dirs }
    else do
        newDirs <- forM (configSyntaxDirs c) $ \dir ->
            if | dir == bundledSyntaxPlaceholderName -> getBundledSyntaxPath
               | dir == userSyntaxPlaceholderName    -> xdgSyntaxDir
               | otherwise                           -> return dir

        return $ Right $ c { configSyntaxDirs = newDirs }

getConfig :: FilePath -> IO (Either String Config)
getConfig fp = runExceptT $ do
  absPath <- convertIOException $ makeAbsolute fp
  t <- (convertIOException $ T.readFile absPath) `catchE`
       (\e -> throwE $ "Could not read " <> show absPath <> ": " <> e)
  case parseIniFile t fromIni of
    Left err -> do
      throwE $ "Unable to parse " ++ absPath ++ ":" ++ err
    Right conf -> do
      actualPass <- case configPass conf of
        Just (PasswordCommand cmdString) -> do
          let (cmd:rest) = T.unpack <$> T.words cmdString
          output <- convertIOException (readProcess cmd rest "") `catchE`
                    (\e -> throwE $ "Could not execute password command: " <> e)
          return $ Just $ T.pack (takeWhile (/= '\n') output)
        Just (PasswordString pass) -> return $ Just pass
        Nothing -> return Nothing

      return conf { configPass = PasswordString <$> actualPass
                  , configAbsPath = Just absPath
                  }

-- | Returns the hostname, username, and password from the config. Only
-- returns Just if all three have been provided. The idea is that if
-- this returns Nothing, we're missing at least some of these values.
getCredentials :: Config -> Maybe ConnectionInfo
getCredentials config = do
    pass <- configPass config
    passStr <- case pass of
        PasswordString p -> return p
        PasswordCommand _ ->
            error $ "BUG: unexpected credentials state: " <>
                    show (configPass config)

    ConnectionInfo <$> configHost config
                   <*> (pure $ configPort config)
                   <*> configUser config
                   <*> (pure passStr)