#include <stdlib.h>
#include <opencc/opencc.h>
#include <lua.h>
#include <lauxlib.h>

static opencc_t *L_checkocc(lua_State *L, int i) {
	opencc_t *cc = luaL_checkudata(L, i, "luaocc");
	luaL_argcheck(L, cc != NULL, 1, "expected instance of opencc_t");
	return cc;
}

static int L_open(lua_State *L) {
	const char *fn = luaL_optstring(L, 1, NULL);
	opencc_t *cc = (opencc_t*) lua_newuserdata(L, sizeof(opencc_t));
	*cc = opencc_open(fn);
	luaL_getmetatable(L, "luaocc");
	lua_setmetatable(L, -2);
	return 1;
}

static int L_convert(lua_State *L) {
	opencc_t *cc = L_checkocc(L, 1);
	size_t l;
	const char *s = luaL_checklstring(L, 2, &l);
	char *c = opencc_convert_utf8(*cc, s, l);
	lua_pushstring(L, c);
	opencc_convert_utf8_free(c);
	return 1;
}

/* This function should not be publicly available as the user may otherwise hold an invalid reference to an opencc_t instance */
static int L_close(lua_State *L) {
	opencc_t *cc = L_checkocc(L, 1);
	opencc_close(*cc);
	return 0;
}

static const struct luaL_Reg occlib[] = {
	{"open", L_open},
	{"convert", L_convert},
	{NULL, NULL}
};

static const struct luaL_Reg occmt[] = {
	{"__call", L_convert},
	{"__gc", L_close},
	{NULL, NULL}
};

#if (LUA_VERSION_NUM >= 502)
	#define luaL_register(L, _, l) luaL_setfuncs(L, l, 0)
#endif

int luaopen_luaocc(lua_State *L) {
	luaL_newmetatable(L, "luaocc");
	luaL_register(L, NULL, occmt);
	lua_newtable(L);
	luaL_register(L, NULL, occlib);
	return 1;
}