#include "lua_type.h"

#include <lua5.1/lauxlib.h>

void lua_type_register (lua_State *L, const struct lua_type *type, const struct lua_method methods[])
{
    const struct lua_method *method;

    // create the metatable
    luaL_newmetatable(L, type->name);

    // set the metatable __index to itself
    lua_pushvalue(L, -1);
    lua_setfield(L, -1, "__index");

    // add the methods to the metatable
    for (method = methods; method->func; method++) {
        lua_pushcfunction(L, method->func);
        lua_setfield(L, -2, method->name);
    }
}

void* lua_type_create (lua_State *L, const struct lua_type *type, size_t size)
{
    // create the new userdata on the stack
    void *ud = lua_newuserdata(L, size);

    // get the type and set it
    luaL_getmetatable(L, type->name);
    lua_setmetatable(L, -2);

    // ok
    return ud;
}

void* lua_type_register_global (lua_State *L, const struct lua_type *type, const struct lua_method methods[],
        const char *global_name, size_t size)
{
    // allocate the global object
    void *obj = lua_newuserdata(L, size);
    
    // create the type metatable
    lua_type_register(L, type, methods);

    // set the userdata's metatable
    lua_setmetatable(L, -2);

    // store it as a global
    lua_setglobal(L, global_name);
    
    // ok
    return obj;
}

void* lua_type_get (lua_State *L, const struct lua_type *type, int index)
{
    void *ud;

    // validate the userdata arg
    // XXX: the luaL_checkudata actually raises an error itself
    if ((ud = luaL_checkudata(L, index, type->name)) == NULL) {
        luaL_error(L, "bad type argument: `%s` expected", type->name); return NULL;

    } else {
        // ok
        return ud;

    }
}