module Metaplug.Packages ( 
  getPackages,
  getPkgDesc,
  getPkgAuthor,
  getPkgExModules,
  getPkgDepends
) where
import Distribution.InstalledPackageInfo
import Distribution.Package
import Control.Monad
import ParsePkgConf

getPackages :: FilePath -> IO [String]
getPackages path = do
  pkgs <- loadPackageConfig path
  let e = map (showPackageId . package) pkgs
  return e

getPkgDesc :: FilePath -> String -> IO (Maybe String)
getPkgDesc p x = do
  pkgs <- loadPackageConfig p
  let pd = findpkg x pkgs
  return $ case pd of 
             []     -> Nothing
             [x]    -> Just $ description x
             (x:xs) -> Just $ description x

getPkgAuthor :: FilePath -> String -> IO (Maybe String)
getPkgAuthor p x = do
  pkgs <- loadPackageConfig p
  let pa = findpkg x pkgs
  return $ case pa of
             []     -> Nothing
             [x]    -> Just $ author x
             (x:xs) -> Just $ author x


getPkgExModules :: FilePath -> String -> IO (Maybe [String])
getPkgExModules p x = do
  pkgs <- loadPackageConfig p
  let pm = findpkg x pkgs
  return $ case pm of
             []     -> Nothing
             [x]    -> Just $ exposedModules x
             (x:xs) -> Just $ exposedModules x


getPkgDepends :: FilePath -> String -> IO (Maybe [String])
getPkgDepends p x = do
  pkgs <- loadPackageConfig p
  let pa = findpkg x pkgs
  return $ case pa of
             []    -> Nothing
             (x:_) -> let deps = map showPackageId (depends x) in
                      case deps of
                        []       -> Nothing
                        [x]      -> Just [x]
                        z@(x:xs) -> Just z


-- little util
findpkg :: String -> [InstalledPackageInfo] -> [InstalledPackageInfo]
findpkg x pkgs = filter (\pkg -> x == (showPackageId $ package pkg)) pkgs