module Initialize (buildFromSource, getSortedModuleNames) where

import Control.Applicative ((<$>))
import Control.Monad.Error
import Data.List (lookup,nub)
import qualified Data.Map as Map

import Ast
import Data.Either (lefts,rights)
import Data.List (intercalate,partition)
import Parse.Parser (parseProgram, parseDependencies)
import Rename
import qualified Libraries as Libs
import Types.Types ((-:))
import Types.Hints (hints)
import Types.Unify (unify)
import Types.Alias (dealias, mistakes)
import Optimize
import System.Exit
import System.FilePath

checkMistakes :: Module -> Either String Module
checkMistakes modul@(Module name ex im stmts) = 
  case mistakes stmts of
    m:ms -> Left (unlines (m:ms))
    []   -> return modul

checkTypes :: Module -> Either String Module
checkTypes modul =
  do subs <- unify hints modul
     subs `seq` return (optimize (renameModule modul))

check :: Module -> Either String Module
check = checkMistakes >=> checkTypes

buildFromSource :: Bool -> String -> Either String Module
buildFromSource noPrelude src =
    let add = if noPrelude then id else Libs.addPrelude in
    (check . add) =<< (parseProgram src)

getSortedModuleNames :: FilePath -> IO [String]
getSortedModuleNames root =
    sortDeps =<< readDeps [] root

type Deps = (String, [String])

sortDeps :: [Deps] -> IO [String]
sortDeps deps = go [] (nub deps)
    where
      msg = "A cyclical or missing module dependency or was detected in: "

      go :: [String] -> [Deps] -> IO [String]
      go sorted [] = return (map toFilePath sorted)
      go sorted unsorted =
          case partition (all (`elem` sorted) . snd) unsorted of
            ([],m:ms) -> do putStrLn (msg ++ intercalate ", " (map fst (m:ms)) ++ show sorted ++ show unsorted)
                            exitFailure
            (srtd,unsrtd) -> go (sorted ++ map fst srtd) unsrtd

readDeps :: [FilePath] -> FilePath -> IO [Deps]
readDeps seen root = do
  txt <- readFile root
  case parseDependencies txt of
    Left err ->
        let msg = "Error resolving dependencies in " ++ root ++ ":\n" in
        putStrLn (msg ++ err) >> exitFailure
    Right (name,deps) ->
        do rest <- mapM (readDeps seen' . toFilePath) newDeps
           return ((name, realDeps) : concat rest)
        where
          realDeps = filter (`notElem` builtIns) deps
          newDeps = filter (\d -> d `notElem` seen && not (isNative d)) realDeps
          seen' = root : seen ++ newDeps
          builtIns = Map.keys Libs.libraries
                       

isNative name = takeWhile (/='.') name == "Native"

toFilePath :: String -> FilePath
toFilePath name = map swapDots name ++ ext
    where swapDots '.' = '/'
          swapDots  c  =  c
          ext = if isNative name then ".js" else ".elm"