#include <iostream>
#include <memory>

// 接收者：灯
class Light {
public:
    void turnOn() {
        std::cout << "灯打开了。\n";
    }

    void turnOff() {
        std::cout << "灯关闭了。\n";
    }
};

// 命令接口
class Command {
public:
    virtual ~Command() = default;
    virtual void execute() = 0;
};

// 具体命令：开灯
class LightOnCommand : public Command {
private:
    Light& light;
public:
    LightOnCommand(Light& l) : light(l) {}

    void execute() override {
        light.turnOn();
    }
};

// 具体命令：关灯
class LightOffCommand : public Command {
private:
    Light& light;
public:
    LightOffCommand(Light& l) : light(l) {}

    void execute() override {
        light.turnOff();
    }
};

// 调用者：遥控器
class RemoteControl {
private:
    std::unique_ptr<Command> command;
public:
    void setCommand(std::unique_ptr<Command> cmd) {
        command = std::move(cmd);
    }

    void pressButton() {
        if (command) {
            command->execute();
        }
    }
};

int main() {
    Light livingRoomLight; // 接收者

    // 创建具体命令
    auto onCommand = std::make_unique<LightOnCommand>(livingRoomLight);
    auto offCommand = std::make_unique<LightOffCommand>(livingRoomLight);

    RemoteControl remote; // 调用者

    // 执行开灯
    remote.setCommand(std::move(onCommand));
    remote.pressButton();

    // 执行关灯
    remote.setCommand(std::make_unique<LightOffCommand>(livingRoomLight));
    remote.pressButton();

    return 0;
}

class FunctionCommand : public Command {
    std::function<void()> action;
public:
    FunctionCommand(std::function<void()> act) : action(std::move(act)) {}
    
    void execute() override {
        action();
    }
};