在Defold中，如何实现复杂的游戏逻辑和状态管理

-- 定义状态机
local state_machine = {
    current = "menu"
}

-- 状态机切换状态
function state_machine:change_state(new_state)
    self.current = new_state
    self[self.current](self)
end

-- 定义每个状态的行为
function state_machine:menu()
    -- 菜单逻辑
end

function state_machine:game()
    -- 游戏逻辑
end

-- 状态机初始化
function state_machine:init()
    self:change_state("menu")
end

-- 初始化状态机
state_machine:init()

-- 发送消息
go.send_message(id, "start_game")

-- 接收消息
function on_message(self, message_id, message)
    if message_id == hash("start_game") then
        -- 处理开始游戏的逻辑
    end
end

local function create_state(name, behavior)
    return {
        name = name,
        enter  = behavior.enter  or function() end,
        update = behavior.update or function() end,
        exit   = behavior.exit   or function() end,
    }
end

local machine = {
    current_name = nil,
    current_state = nil,
    states = {},
}

function machine:add_state(name, behavior)
    self.states[name] = create_state(name, behavior)
end

function machine:change_state(new_name, ...)
    if self.current_state and self.current_state.exit then
        self.current_state.exit(self.owner, ...)
    end
    self.current_name = new_name
    self.current_state = self.states[new_name]
    if self.current_state and self.current_state.enter then
        self.current_state.enter(self.owner, ...)
    end
end

function machine:update(dt)
    if self.current_state and self.current_state.update then
        self.current_state.update(self.owner, dt)
    end
end

self.pending = {}

function on_message(self, message_id, message, sender)
    if message_id == hash("damage") then
        table.insert(self.pending, { type = "damage", value = message.amount })
    elseif message_id == hash("heal") then
        table.insert(self.pending, { type = "heal", value = message.amount })
    end
end

function update(self, dt)
    -- 每帧只处理一条高优先级消息
    while #self.pending > 0 do
        local action = table.remove(self.pending, 1)
        apply_action(self, action)
    end
    self.state_machine:update(dt)
end

local Pool = {}

function Pool:create(url, capacity)
    self.url = url
    self.free = {}
    self.active = {}
    for i = 1, capacity do
        local id = factory.create(url, vmath.vector3(-1000, -1000, 0))
        go.set_scale(vmath.vector3(0), id)  -- 视觉上隐藏
        table.insert(self.free, id)
    end
end

function Pool:spawn(position)
    if #self.free == 0 then return nil end
    local id = table.remove(self.free)
    go.set_position(position, id)
    go.set_scale(vmath.vector3(1), id)
    self.active[id] = true
    return id
end

function Pool:despawn(id)
    if not self.active[id] then return end
    go.set_position(vmath.vector3(-1000, -1000, 0), id)
    go.set_scale(vmath.vector3(0), id)
    self.active[id] = nil
    table.insert(self.free, id)
end