module Main where

import Language.Haskell.Exts

import HSX.Transform

import System.Environment (getArgs)
import Data.List (isPrefixOf)

checkParse :: ParseResult b -> b
checkParse p = case p of
                  ParseOk m -> m
                  ParseFailed loc s -> error $ "Error at " ++ show loc ++ ":\n" ++ s

transformFile :: String -> String -> String -> IO ()
transformFile origfile infile outfile = do
        f <- readFile infile
        let fm = process origfile f
        writeFile outfile fm

testFile :: String -> IO ()
testFile file = do
        f <- readFile file
        putStrLn $ process file f

testTransform :: String -> IO ()
testTransform file = do
        f <- readFile file
        putStrLn $ show $ transform $ checkParse $ parse file f

testPretty :: String -> IO ()
testPretty file = do
        f <- readFile file
        putStrLn $ prettyPrint $ checkParse $ parse file f

testParse :: String -> IO ()
testParse file = do
        f <- readFile file
        putStrLn $ show $ parse file f

main :: IO ()
main = do args <- getArgs
          case args of
           [origfile, infile, outfile] -> transformFile origfile infile outfile
           [infile, outfile] -> transformFile infile infile outfile
           [infile] -> testFile infile
           _ -> putStrLn usageString

process :: FilePath -> String -> String
process fp fc = prettyPrintWithMode (defaultMode {linePragmas=True}) $
                 transform $ checkParse $ parse fp fc

parse :: String -> String -> ParseResult HsModule
parse fn fc = parseModuleWithMode (ParseMode fn) fcuc
  where fcuc= unlines $ filter (not . isPrefixOf "#") $ lines fc

usageString :: String
usageString = "Usage: trhsx <infile> [<outfile>]"