{-

Copyright © 2017 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>

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 2 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

-}

{- |

   Module      : Text.Pandoc.Lua

   Copyright   : Copyright © 2017 Albert Krewinkel

   License     : GNU GPL, version 2 or above

   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>

   Stability   : alpha

Functions to initialize the Lua interpreter.

-}

module Text.Pandoc.Lua.Init

  ( LuaException (..)

  , LuaPackageParams (..)

  , runPandocLua

  , initLuaState

  , luaPackageParams

  ) where

import Control.Monad.Trans (MonadIO (..))

import Data.IORef (newIORef, readIORef)

import Foreign.Lua (Lua, LuaException (..))

import GHC.IO.Encoding (getForeignEncoding, setForeignEncoding, utf8)

import Text.Pandoc.Class (PandocIO, getCommonState, getUserDataDir, getMediaBag,

                          setMediaBag)

import Text.Pandoc.Lua.Packages (LuaPackageParams (..),

                                 installPandocPackageSearcher)

import Text.Pandoc.Lua.Util (loadScriptFromDataDir)

import qualified Foreign.Lua as Lua

import qualified Foreign.Lua.Module.Text as Lua

-- | Run the lua interpreter, using pandoc's default way of environment

-- initalization.

runPandocLua :: Lua a -> PandocIO (Either LuaException a)

runPandocLua luaOp = do

  luaPkgParams <- luaPackageParams

  enc <- liftIO $ getForeignEncoding <* setForeignEncoding utf8

  res <- liftIO $ Lua.runLuaEither (initLuaState luaPkgParams *> luaOp)

  liftIO $ setForeignEncoding enc

  newMediaBag <- liftIO (readIORef (luaPkgMediaBag luaPkgParams))

  setMediaBag newMediaBag

  return res

-- | Generate parameters required to setup pandoc's lua environment.

luaPackageParams :: PandocIO LuaPackageParams

luaPackageParams = do

  commonState <- getCommonState

  datadir <- getUserDataDir

  mbRef <- liftIO . newIORef =<< getMediaBag

  return LuaPackageParams

    { luaPkgCommonState = commonState

    , luaPkgDataDir = datadir

    , luaPkgMediaBag = mbRef

    }

-- Initialize the lua state with all required values

initLuaState :: LuaPackageParams -> Lua ()

initLuaState luaPkgParams = do

  Lua.openlibs

  Lua.preloadTextModule "text"

  installPandocPackageSearcher luaPkgParams

  loadScriptFromDataDir (luaPkgDataDir luaPkgParams) "init.lua"