module Main where

import Control.Monad
import System.Environment
import System.Exit

import Compiler
import CompilerMacros
import Optimiser
import Parser
import VM


usage :: IO ()
usage = do
    progname <- getProgName
    putStrLn $ "Usage: " ++ progname ++ " [-h] [-ast] [-ir] [filename.lisp]"
    putStrLn $ "When no filename is given, will read from stdin."
    putStrLn $ "  -h     Show this help"
    putStrLn $ "  -ast   Print AST after compiler macro's"
    putStrLn $ "  -ir    Print IR after optimisation"

data Options = Options { optAST :: Bool, optIR :: Bool }

parseOptions' :: (Options, Maybe FilePath) -> [String] -> IO (Options, Maybe FilePath)
parseOptions' pair [] = return pair
parseOptions' _ ("-h":_) = usage >> exitSuccess
parseOptions' (opt, fp) ("-ast":as) = parseOptions' (opt { optAST = True }, fp) as
parseOptions' (opt, fp) ("-ir":as) = parseOptions' (opt { optIR = True }, fp) as
parseOptions' _ (('-':a):_) = putStrLn ("Unknown option '" ++ a ++ "'") >> usage >> exitFailure
parseOptions' (opt, Nothing) (f:as) = parseOptions' (opt, Just f) as
parseOptions' (_, Just _) (_:_) = putStrLn "At most one filename argument expected" >> usage >> exitFailure

parseOptions :: [String] -> IO (Options, Maybe FilePath)
parseOptions = parseOptions' (Options False False, Nothing)

main :: IO ()
main = do
    (opts, mfname) <- getArgs >>= parseOptions
    source <- maybe getContents readFile mfname

    prog <- parseProgram mfname source >>= either (die . show) return
    let prog' = compilerMacros prog
    when (optAST opts) $ print prog'
    irprog <- either die return (compileProgram prog')
    let opt = optimise irprog
    when (optIR opts) $ print opt
    vmRun opt