/*
Copyright (C) 2016 Draios inc.

This file is part of falco.

falco is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.

falco 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 falco.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <fstream>

#include "config_falco_engine.h"
#include "falco_common.h"

falco_common::falco_common()
{
	m_ls = lua_open();
	if(!m_ls)
	{
		throw falco_exception("Cannot open lua");
	}
	luaL_openlibs(m_ls);
}

falco_common::~falco_common()
{
	if(m_ls)
	{
		lua_close(m_ls);
	}
}

void falco_common::set_inspector(sinsp *inspector)
{
	m_inspector = inspector;
}

void falco_common::init(const char *lua_main_filename, const char *source_dir)
{
	ifstream is;
	string lua_dir = FALCO_ENGINE_LUA_DIR;
	string lua_main_path = lua_dir + lua_main_filename;

	is.open(lua_main_path);
	if (!is.is_open())
	{
		lua_dir = source_dir;
		lua_main_path = lua_dir + lua_main_filename;

		is.open(lua_main_path);
		if (!is.is_open())
		{
			throw falco_exception("Could not find Falco Lua entrypoint (tried " +
					      string(FALCO_ENGINE_LUA_DIR) + lua_main_filename + ", " +
					      string(source_dir) + lua_main_filename + ")");
		}
	}

	// Initialize Lua interpreter
	add_lua_path(lua_dir);

	// Load the main program, which defines all the available functions.
	string scriptstr((istreambuf_iterator<char>(is)),
			 istreambuf_iterator<char>());

	if(luaL_loadstring(m_ls, scriptstr.c_str()) || lua_pcall(m_ls, 0, 0, 0))
	{
		throw falco_exception("Failed to load script " +
			lua_main_path + ": " + lua_tostring(m_ls, -1));
	}
}

void falco_common::add_lua_path(string &path)
{
	string cpath = string(path);
	path += "?.lua";
	cpath += "?.so";

	lua_getglobal(m_ls, "package");

	lua_getfield(m_ls, -1, "path");
	string cur_path = lua_tostring(m_ls, -1 );
	cur_path += ';';
	lua_pop(m_ls, 1);

	cur_path.append(path.c_str());

	lua_pushstring(m_ls, cur_path.c_str());
	lua_setfield(m_ls, -2, "path");

	lua_getfield(m_ls, -1, "cpath");
	string cur_cpath = lua_tostring(m_ls, -1 );
	cur_cpath += ';';
	lua_pop(m_ls, 1);

	cur_cpath.append(cpath.c_str());

	lua_pushstring(m_ls, cur_cpath.c_str());
	lua_setfield(m_ls, -2, "cpath");

	lua_pop(m_ls, 1);
}