{-
 DB.hsc: Haskell bindings to libdpkg
   Copyright (C) 2011, 2012 Clint Adams

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
-}

{-# LANGUAGE CPP, ForeignFunctionInterface #-}

#include <bindings.dsl.h>

module Debian.Dpkg.DB (
    msdbInit
  , setDbDir
  , pkgList
  , parseVersion
  , c'parseversion
  , c'versioncompare
) where
#strict_import

import Foreign.Ptr (nullPtr)
import Foreign.C.String (withCString, peekCString)
import Foreign.Marshal.Utils (with)
import Control.Monad (liftM, join)
import Control.Monad.Loops (unfoldrM)
import qualified Data.ByteString as BS
import Debian.Dpkg.Types

#include <dpkg/dpkg-db.h>

#callconv modstatdb_open , ccall unsafe , CInt -> IO ()
#callconv push_error_context , ccall unsafe , IO ()
#callconv dpkg_set_progname , ccall unsafe , CString -> IO ()
#callconv dpkg_db_set_dir , ccall unsafe , CString -> IO ()

#callconv pkg_db_iter_new , ccall unsafe , IO (Ptr <pkgiterator>)
#callconv pkg_db_iter_next_pkg , ccall unsafe , Ptr <pkgiterator> -> IO (Ptr <pkginfo>)

msdbInit :: IO ()
msdbInit = do
	c'push_error_context
	c'modstatdb_open 0
	withCString "haskell-dpkg" c'dpkg_set_progname

setDbDir :: String -> IO ()
setDbDir x = withCString x  c'dpkg_db_set_dir

pkgDbIterNext :: Ptr C'pkgiterator -> IO (Maybe (Ptr C'pkginfo, Ptr C'pkgiterator))
pkgDbIterNext i = do
         pptr <- c'pkg_db_iter_next_pkg i
         if pptr == nullPtr
             then
                return Nothing
             else
                return $ Just (pptr, i)

pkgpList :: IO [Ptr C'pkginfo]
pkgpList = c'pkg_db_iter_new >>= unfoldrM (pkgDbIterNext)

pkgList :: IO [C'pkginfo]
pkgList = pkgpList >>= mapM peek

#callconv parseversion , ccall unsafe , Ptr C'versionrevision -> CString -> Ptr C'dpkg_error -> IO CInt
#callconv versioncompare , ccall unsafe , Ptr C'versionrevision -> Ptr C'versionrevision -> IO CInt

parseVersion :: BS.ByteString -> IO (Either String C'versionrevision)
parseVersion verstr = BS.useAsCString verstr $ \vercstr -> alloca $ \vrptr -> alloca $ \deptr -> do
        i <- c'parseversion vrptr vercstr deptr
        vr <- peek vrptr
        if i == 0
            then
                return $ Right vr
            else
                do
                    de <- peek deptr
                    errmsg <- peekCString (c'dpkg_error'str de)
                    if (c'dpkg_error'type de) == 1
                        then
                            return $ Right vr
                        else
                            return $ Left errmsg