/////////////////////////////////
// 程序一：以协程包装阻塞的库中的功能
/////////////////////////////////

using namespace std::chrono_literals;
namespace coro = concurrencpp;

namespace MyAPI {

    class Api {
    private:
        coro::runtime& runtime;
        std::shared_ptr<coro::executor> mainThreadExecutor;
        std::shared_ptr<coro::thread_pool_executor> workerExecutor; // Thread pool executor

    public:
        Api(coro::runtime &runtime,
            std::shared_ptr<coro::executor> mainThreadExecutor
        ) :
            runtime{ runtime },
            mainThreadExecutor{ std::move(mainThreadExecutor) },
            workerExecutor{ runtime.thread_pool_executor() } { }

        // 调 HTTP 接口
        coro::result<std::string> callHttpApi() {
            // 1. 切换到后台线程池执行耗时操作
            co_await coro::resume_on(workerExecutor);

            // 醒來，已處於 workerExecutor
            std::this_thread::sleep_for(1s); // 模拟耗时网络请求

            // 2. 操作完成，切换回主线程
            co_await coro::resume_on(mainThreadExecutor);

            // 醒來，已處於 mainThreadExecutor
            co_return "asdf";
        }
    };

} // namespace MyAPI


bool btnClicked() {
    static int frame = 0;
    frame++;
    // 模擬第四幀按下按鈕
    return frame == 4;
}

void drawUi() {
    std::println("draw ui");
    std::this_thread::sleep_for(0.3s);
}

int main() {
    coro::runtime runtime;
    auto mainThreadExecutor = runtime.make_manual_executor();

    // --- 实例化 MyAPI::Api ---
    MyAPI::Api myApi{ runtime, mainThreadExecutor };

    while (true) {
        if (btnClicked()) {
            [&]() -> coro::result<void> {
                std::cout << "onBtn started on thread: " << std::this_thread::get_id() << std::endl;
                std::println("耗时任务执行始");

                co_await myApi.callHttpApi();

                std::cout << "onBtn resumed on thread: " << std::this_thread::get_id() << std::endl;
                std::println("耗时任务执行终");
            }();
        }

        mainThreadExecutor->loop_once();
        drawUi();
    }

    return 0;
}

/*
程序一的输出如下：
draw ui
draw ui
draw ui
onBtn started on thread: 12628
耗时任务执行始
draw ui
draw ui
draw ui
draw ui
onBtn resumed on thread: 12628
耗时任务执行终
draw ui
draw ui
draw ui
*/

/////////////////////////////////
// 程序二：Promise 的运用
/////////////////////////////////

using namespace std::chrono_literals;
namespace coro = concurrencpp;

namespace MyAPI {

    struct BackendMsg
    {
        std::string id;
        std::string data;
    };

    class Api {
    public:
        std::unordered_map<std::string, coro::result_promise<std::string>> reqId2Promise;

        // 当收到 websockets 消息时，调用此函数
        void onRecvBackendMsg(BackendMsg msg) {
            if (auto it = reqId2Promise.find(msg.id); it != reqId2Promise.end()) {
                it->second.set_result(msg.data);
            }
        }

        // websockets 发一个信息，并等待这个信息的回复
        coro::result<std::string> sendReqAndWaitForResp(BackendMsg msg) {
            std::println("已发送 ID 为 {} 的消息，正等待回应……", msg.id);
            auto& promise = reqId2Promise[msg.id];
            // sendMsgToBackend(msg);
            std::string resp = co_await promise.get_result();
            std::println("回应：{}", resp);
            co_return resp;
        }
    };

} // namespace MyAPI


bool btn1Clicked() {
    static int frame = 0;
    frame++;
    // 模擬第四幀按下按鈕
    return frame == 4;
}

bool btn2Clicked() {
    static int frame = 0;
    frame++;
    // 模擬第六幀按下按鈕
    return frame == 6;
}

void drawUi() {
    std::println("draw ui");
    std::this_thread::sleep_for(0.3s);
}

int main() {
    MyAPI::Api myApi;

    while (true) {
        if (btn1Clicked()) {
            [&]() -> coro::result<void> {
                std::string resp = co_await myApi.sendReqAndWaitForResp({ "test-msg-1", "PING!" });
                std::println("收到回应{}！", resp);
            }();
        }
        if (btn2Clicked()) {
            myApi.onRecvBackendMsg({ "test-msg-1", "PONG!" });
        }

        drawUi();
    }

    return 0;
}

/*
程序二的输出如下：
draw ui
draw ui
draw ui
已发送 ID 为 test-msg-1 的消息，正等待回应……
draw ui
draw ui
回应：PONG!
收到回应PONG!！
draw ui
draw ui
draw ui
……
*/