#include <cstdio>
#include <lua.hpp>
#include <cerrno>
#include <cstring>
#include <stdlib.h>

#include <new>

void lua_stack_dump(lua_State *L);

#define _strify(str) #str
#define _concat(str1, str2) str1 ## str2

#define register_class(state, class_name, meta_table, class_table) do { \
    luaL_newmetatable(state, #class_name); \
    lua_pushvalue(state, -1); \
    lua_setfield(state, -2, "__index"); \
    luaL_setfuncs(state, class_table, 0); \
    luaL_newlib(state, meta_table); \
    /* lua_pushvalue(state, -1);*/ \
    lua_setglobal(state, #class_name); \
    lua_stack_dump(state); \
} while(0)

#define create_lua_object(state, class_name, obj) do { \
    void *udata__ = lua_newuserdata(state, sizeof(_concat(Lua,class_name))); \
    _concat(Lua,class_name) *obj__ = ::new (udata__) _concat(Lua,class_name)(state, obj); \
    \
    luaL_getmetatable(state, #class_name); \
    lua_setmetatable(state, -2); \
    lua_stack_dump(state); \
} while(0)

#define get_lua_object(state, class_name) *(_concat(Lua,class_name) **)luaL_checkudata(state, 1, #class_name)

#define destroy_lua_object(state, class_name) do { \
    _concat(Lua, class_name) *udata__ = *(_concat(Lua, class_name) **)luaL_checkudata(state, 1, #class_name); \
    udata__->~_concat(Lua, class_name)(); \
} while(0)

class Test
{
    public:
        Test() { printf("new Test!\n"); }
        ~Test() { printf("delete Test!\n"); }

        void it() { printf("TEST IT!\n"); }
};

class LuaTest
{
    public:
        LuaTest(lua_State *, Test *test) : test(test) { printf("new LuaTest!\n"); }
        ~LuaTest() { printf("delete LuaTest!\n"); }
        void it() { test->it(); }
    private:
        Test *test;
};

static int Test_destroy(lua_State *state)
{
    printf("Test_destroy\n");
    destroy_lua_object(state, Test);
    return 0;
}

static int Test_it(lua_State *state)
{
    printf("Test_it\n");
    LuaTest *test = get_lua_object(state, Test);
    test->it();
    return 0;
}

static int Test_new(lua_State *state)
{
    printf("Test_new begin\n");
    Test *newTest = new Test();
    create_lua_object(state, Test, newTest);
    printf("Test_new end\n");
    return 1;
}

static const luaL_Reg test_meta_methods[] = {
    { "new", &Test_new },
    { "__gc", &Test_destroy },
    { 0, 0 }
};

static const luaL_Reg test_methods[] = {
    { "it", &Test_it },
    { 0, 0 }
};

int main(int argc, char **argv)
{
    printf("start\n");
    lua_State *state = luaL_newstate();
    luaL_openlibs(state);

    printf("call register_class\n");
    register_class(state, Test, test_meta_methods, test_methods);

    printf("open lua file\n");
    FILE *fh = fopen("luaobjtest.lua", "r");
    if(!fh)
    {
        printf("failed to open luaobjtest.lua: %s\n", strerror(errno));
        return 0;
    }

    fseek(fh, 0, SEEK_END);
    long len = ftell(fh);
    fseek(fh, 0, SEEK_SET);

    char *script = (char *)malloc(len+1);
    if(!script)
    {
        printf("failed to allocate enough memory to load luaobjtest.lua\n");
        return 0;
    }

    script[len] = 0;
    size_t ret = fread(script, 1, len, fh);
    if(ret != (size_t)len)
    {
        printf("failed to read entire luaobjtest.lua file, read %li bytes, expected %li bytes.\n", ret, len);
        return 0;
    }

    fclose(fh);

    printf("call luaL_loadstring\n");
    if(luaL_loadstring(state, script) != LUA_OK)
    {
        const char *errstr = luaL_checklstring(state, 1, 0);
        printf("failed to load luaobjtest.lua: %s\n", errstr);
        free(script);
        return 0;
    }

    printf("call lua_pcall\n");
    if(lua_pcall(state, 0, LUA_MULTRET, 0) != LUA_OK)
    {
        const char *errstr = luaL_checklstring(state, 1, 0);
        printf("failed to run luaobjtest.lua: %s\n", errstr);
        free(script);
        return 0;
    }

    printf("done!\n");

    return 0;
}

void lua_stack_dump(lua_State *L)
{
    int i;
    int top = lua_gettop(L);
    for (i = 1; i <= top; i++) {  /* repeat for each level */
        int t = lua_type(L, i);
        switch (t) {

            case LUA_TSTRING:  /* strings */
            printf("`%s'", lua_tostring(L, i));
            break;

            case LUA_TBOOLEAN:  /* booleans */
            printf(lua_toboolean(L, i) ? "true" : "false");
            break;

            case LUA_TNUMBER:  /* numbers */
            printf("%g", lua_tonumber(L, i));
            break;

            default:  /* other values */
            printf("%s", lua_typename(L, t));
            break;

        }
        printf("  ");  /* put a separator */
    }
    printf("\n");  /* end the listing */
}