module Main where

import Prelude hiding (readFile)

import Data.ByteString.Char8 (readFile)
import qualified Data.Text.IO as TextIO
import qualified Data.Text.Lazy.IO as LazyText
import Options.Applicative (Parser, execParser, info, helper, fullDesc, long, short, metavar, value, help, strOption, progDesc, (<**>), option, auto)
import SpecUp (invokeTemplateOnSpec)
import System.Exit (exitFailure)
import System.IO (hPutStr, stderr)

data Args = Args {
  specFile :: !String
, template :: !String
}

argParser :: Parser Args
argParser = Args
  <$> strOption
        (  long "spec"
        <> short 's'
        <> metavar "YAML_FILE"
        <> value defaultSpecFile
        <> help ("File to read the yaml specification from. Defaults to " <> defaultSpecFile)
        )
  <*> strOption
        (  long "mustache"
        <> short 't'
        <> metavar "TEMPLATE_FILE"
        <> value defaultTemplateFile
        <> help ("File to read the mustache template from. Defaults to " <> defaultTemplateFile)
        )
  where defaultSpecFile = "spec.yaml"
        defaultTemplateFile = "markup.mustache"


run :: Args -> IO ()
run args = do
  spec <- readFile $ specFile args
  template <- TextIO.readFile $ template args
  either (\s -> hPutStr stderr s >> exitFailure)
         LazyText.putStrLn
         $ invokeTemplateOnSpec template spec

main :: IO ()
main = execParser (
         info (argParser <**> helper)
         (fullDesc
            <> progDesc "Generate markup from a custom yaml spec"
         )
       ) >>= run