local is_window_setup = false
local cube_entity = nil

---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 dump(o)
    if type(o) == 'table' then
       local s = '{ '
       for k,v in pairs(o) do
          if type(k) ~= 'number' then k = '"'..k..'"' end
          s = s .. '['..k..'] = ' .. dump(v) .. ','
       end
       return s .. '} '
    else
       return tostring(o)
    end
 end
 

function on_init()
    local cube = world:request_asset("../assets/cube-texture-embedded.gltf") --[[@as GltfHandle]]
    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)
    cube_entity = e
    print("spawned entity " .. tostring(e))
end

function on_first()
    if not is_window_setup then
        local view = View.new(Window)
        local res = world:view(view)

        ---@param w Window
        for en, w in res:iter() do
            if w.cursor_grab == CursorGrabMode.NONE then
                w.cursor_grab = CursorGrabMode.LOCKED
                w.cursor_visible = false
                en:update(w)
            else
                is_window_setup = true
                print("Window setup")
            end
        end
    end

    ---@type EventReader
    local reader = world:read_event(DeviceEvent)

    ---@param ev DeviceEvent
    for ev in reader:read() do
        if ev.event.kind == DeviceEventKind.MOTION then
            local motion_ev = ev.event --[[@as DeviceEventMotion]]
            print("axis: " .. tostring(motion_ev.axis) .. " = " .. tostring(motion_ev.value))
        end
    end
end

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

function on_update()
    -- Get entities without WorldTransform
    local view = View.new(Transform, Not(Has(WorldTransform)), Res(DeltaTime))
    local res = world:view(view)
    ---@param transform Transform
    ---@param dt DeltaTime
    for entity, transform, dt in res:iter() do
        transform:translate(0, 0.15 * dt, 0)
        entity:update(transform)
    end

    local changed_view = View.new(Changed(Transform))
    local changed_res = world:view(changed_view)
    ---@param transform Transform
    for _, transform in changed_res:iter() do
        print("Entity transform changed to: '" .. tostring(transform) .. "' on tick " .. tostring(world:get_tick()))
    end

    local tick_view = View.new(TickOf(Transform))
    local tick_res = world:view(tick_view)
    ---@param tick number
    for _, tick in tick_res:iter() do
        print("Entity transform last changed on tick " .. tostring(tick))
    end

    local pos_view = View.new(Transform)
    local vone = world:view_one(cube_entity --[[@as Entity]], pos_view)
    local r = vone() -- short hand for 'vone:get()'
    if r then
        ---@type Transform
        local pos = r[1]
        print("Found cube entity at '" .. tostring(pos) .. "'")
    end
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 ]]