Add a command-line interface to allow processing stdin or a given file and...

Add a command-line interface to allow processing stdin or a given file and create files corresponding to both parts of the XML (raw text / empty tree structure)

InvisiXML.cabal

@@ -36,9 +36,13 @@ library
 
 executable invisiXML
   main-is:             Main.hs
+  other-modules:       CLI
+                     , Paths_InvisiXML
   build-depends:       base >=4.12 && <4.15
+                     , filepath
                      , InvisiXML
                      , mtl
+                     , optparse-applicative
                      , text
   hs-source-dirs:      app
   default-language:    Haskell2010

app/CLI.hs

+module CLI (
+      Command(..)
+    , Input(..)
+    , getCommand
+  ) where
+
+import Data.Version (showVersion)
+import Control.Applicative ((<*>), optional)
+import Options.Applicative (
+      Parser, ReadM, argument, execParser, fullDesc, header
+    , help, helper, info, long, metavar, option, short, str, switch, value
+  )
+import qualified Paths_InvisiXML as InvisiXML (version)
+
+data Input = StdIn | FileInput FilePath
+
+data Command = Command {
+      input :: Input
+    , outputPrefix :: Maybe FilePath
+    , pristine :: Bool
+  }
+
+inputArg :: ReadM Input
+inputArg = fileOrStdIn <$> str
+  where
+    fileOrStdIn "-" = StdIn
+    fileOrStdIn f = FileInput f
+
+command :: Parser Command
+command = Command
+  <$> argument inputArg (metavar "INPUT_FILE" <> value StdIn
+          <> help "XML file to process"
+        )
+  <*> option (optional str) (short 'o' <> long "outputPrefix" <> value Nothing
+          <> help "prefix for the output files"
+        )
+  <*> switch (short 'p' <> long "pristine"
+          <> help "keep input exactly as is, not unindenting or normalizing it in any way"
+        )
+
+getCommand :: IO Command
+getCommand = execParser $
+  info
+    (helper <*> command)
+    (fullDesc <> header ("InvisiXML v" ++ showVersion InvisiXML.version))

app/Main.hs

+{-# LANGUAGE NamedFieldPuns #-}
 module Main where
 
-
+import CLI (Command(..), Input(..), getCommand)
 import Control.Monad.Except (runExceptT)
-import qualified Data.Text.IO as Text (putStr)
+import Data.Maybe (fromMaybe)
+import Data.Text (Text)
+import qualified Data.Text.IO as Text (getContents, readFile, writeFile)
 import Text.InvisiXML (InvisiXML(..), parse)
 import Text.XML.Light.Serializer (encode)
+import System.FilePath ((<.>), dropExtension)
 
-main :: IO ()
-main = getContents >>= runExceptT . parse >>= either (fail . show) display
+endPoints :: Command -> (IO Text, FilePath)
+endPoints (Command {input = StdIn, outputPrefix}) =
+  (Text.getContents, fromMaybe noOutputPrefix outputPrefix)
+  where
+    noOutputPrefix = error "output prefix (-o) is necessary when running on stdin"
+endPoints (Command {input = FileInput f, outputPrefix}) =
+  (Text.readFile f, fromMaybe (dropExtension f) outputPrefix)
+
+run :: Command -> IO ()
+run command =
+  source >>= runExceptT . parse >>= either (fail . show) create
   where
-    display result = do
-      Text.putStr $ text result
-      putStr . encode $ structure result
+    (source, prefix) = endPoints command
+    create (InvisiXML {text, structure}) = do
+      Text.writeFile (prefix <.> "txt") text
+      writeFile (prefix <.> "ixml") $ encode structure
+
+main :: IO ()
+main = getCommand >>= run