[hs] Make cli fancier

hs/app/Main.hs

@@ -4,18 +4,32 @@ import           Control.Monad
 
 import           Options.Applicative
 
-import           Aoc.Day             (Day (..))
-import qualified Aoc.Y2019           as Y2019
+import           Aoc.Day             (Day (..), Year (..))
 import qualified Aoc.Y2020           as Y2020
 
-toCommand :: Day -> Mod CommandFields (IO ())
-toCommand (DayPure name f) = command name $ info (helper <*> pure f) mempty
-toCommand (DayFile name f) = command name $ info (helper <*> p) mempty
-  where
-    p = f <$> strArgument (metavar "INPUTFILE")
+lpad :: a -> Int -> [a] -> [a]
+lpad a n as = replicate (n - length as) a ++ as
+
+yearsToParser :: [Year] -> Parser (IO ())
+yearsToParser = hsubparser . mconcat . map yearToCommand
+
+yearToCommand :: Year -> Mod CommandFields (IO ())
+yearToCommand y = command (show $ yNum y) $ flip info mempty $ daysToParser $ yDays y
+
+daysToParser :: [(Int, Day)] -> Parser (IO ())
+daysToParser = hsubparser . mconcat . map (uncurry dayToCommand)
+
+dayToCommand :: Int -> Day -> Mod CommandFields (IO ())
+dayToCommand dNum = command (lpad '0' 2 $ show dNum) . flip info mempty . dayToParser
+
+dayToParser :: Day -> Parser (IO ())
+dayToParser (DayPure f) = pure f
+dayToParser (DayFile f) = f <$> strArgument (metavar "INPUTFILE")
 
 parser :: Parser (IO ())
-parser = subparser $ mconcat $ map toCommand $ Y2019.days ++ Y2020.days
+parser = yearsToParser
+  [ Y2020.year
+  ]
 
 opts :: ParserInfo (IO ())
 opts = info (helper <*> parser) $ fullDesc <> failureCode 1