tempered/app/Main.hs
2017-04-29 16:25:51 -06:00

65 lines
2.0 KiB
Haskell

{-# language OverloadedStrings #-}
module Main where
import System.Environment
import System.Directory
import System.Exit
import Paths_tempered (version)
import Data.Version (showVersion)
import Data.Foldable
import Data.Monoid
import qualified Data.Map as M
import Control.Monad.Reader
import Options.Applicative
import Tempered.Options
import Tempered.Parser
import Tempered.Template
data Options = Options
{ files :: [String]
, versionFlag :: Bool
} deriving (Show)
options :: Parser Options
options = Options <$> many (argument str meta) <*> switch vers
where meta = help "The templates to interpolate" <> metavar "templates"
vers = long "version" <> short 'v' <> help "Show version"
argParser :: ParserInfo Options
argParser = info (options <**> helper)
( fullDesc <>
progDesc "Interpolate templates to stdout" <>
header "Tempered - Templating engine based on shell interpolation")
-- | Run tempered on cmdline args.
main :: IO ()
main = do
Options filenames versionF <- execParser argParser
when versionF $ putStrLn (showVersion version) >> exitSuccess
envVars <- getEnvVars
templates <- getTemplates filenames
runReaderT (renderOutput templates) envVars
where
-- Choose stdin if we're not given any files
getTemplates [] = (:[]) <$> readStdInTemplate
getTemplates filenames = traverse (templateFromFile >=> handleTemplateError) filenames
readStdInTemplate = getContents >>= handleTemplateError . parseTemplate "stdin"
renderOutput = traverse_ (interpTemplate >=> liftIO . putStr)
-- | Combine local and global environment variables
getEnvVars :: IO EnvVars
getEnvVars = do
cwd <- getCurrentDirectory
globalEnvVars <- getEnvironment
localEnvVars <- getProjectOptions cwd
envTemplates <- traverse (handleTemplateError . parseTemplate "env.yaml") localEnvVars
interpolatedLocalEnvVars <- runReaderT (traverse interpTemplate envTemplates) mempty
-- Precedence to local env vars; last in list has precedence
return (globalEnvVars ++ M.toList interpolatedLocalEnvVars)