---Return the userdata's name from its metatable.
---
---Returns nil if the userdata doesn't have a metatable.
---@param val userdata
---@return string|nil
function udname(val)
    local tbl = debug.getmetatable(val)

    if tbl == nil then
        return nil
    end

    return tbl.__name
end
 

function on_init()
    local cube = world:request_res("../assets/cube-texture-embedded.gltf")
    print("Loaded textured cube (" .. udname(cube) .. ")")

    cube:wait_until_loaded()
    local scenes = cube:scenes()
    local cube_scene = scenes[1]

    local pos = Transform.from_translation(Vec3.new(0, 0, -8.0))

    local e = world:spawn(pos, cube_scene)
    print("spawned entity " .. tostring(e))
end

--[[ function on_first()
    print("Lua's first function was called")
end

function on_pre_update()
    print("Lua's pre-update function was called")
end ]]

function on_update()
    --[[ ---@type number
    local dt = world:resource(DeltaTime)
    local act = world:resource(ActionHandler)
    ---@type number
    local move_objs = act:get_axis("ObjectsMoveUpDown")

    world:view(function (t)
        if move_objs ~= nil then
            t:translate(0, move_objs * 0.35 * dt, 0)
            return t
        end
    end, Transform) ]]

    ---@type number
    local dt = world:resource(DeltaTime)

    world:view(function (t)
        t:translate(0, 0.15 * dt, 0)
        return t
    end, Transform)
end

--[[ function on_post_update()
    print("Lua's post-update function was called")
end

function on_last()
    print("Lua's last function was called")
end ]]