#include <cilk/cilk.h>
#include <iostream>
#include <chrono>
#include <thread>
#include <vector>
#include <queue>

using namespace std;
using namespace std::chrono;

void simulateRequest(int req, milliseconds delay) {
    this_thread::sleep_for(delay);
    cout << "request " << req << " " << system_clock::now().time_since_epoch().count() << endl;
}

int main() {
    // First we'll look at basic rate limiting. Suppose
    // we want to limit our handling of incoming requests.
    // We'll serve these requests off a queue.
    queue<int> requests;
    for (int i = 1; i <= 5; i++) {
        requests.push(i);
    }

    // This limiter will delay each request by 200 milliseconds.
    // This is the regulator in our rate limiting scheme.
    milliseconds limiter(200);

    // By introducing a delay before serving each request,
    // we limit ourselves to 1 request every 200 milliseconds.
    while (!requests.empty()) {
        int req = requests.front();
        requests.pop();
        cilk_spawn simulateRequest(req, limiter);
    }
    cilk_sync;

    cout << endl;

    // We may want to allow short bursts of requests in
    // our rate limiting scheme while preserving the
    // overall rate limit. We can accomplish this by
    // using a token bucket algorithm.
    vector<int> burstyRequests;
    for (int i = 1; i <= 5; i++) {
        burstyRequests.push_back(i);
    }

    int tokens = 3; // Allow bursts of up to 3 events
    auto lastTime = system_clock::now();

    for (int req : burstyRequests) {
        auto now = system_clock::now();
        auto timePassed = duration_cast<milliseconds>(now - lastTime);
        tokens += timePassed.count() / 200; // Add tokens based on time passed
        if (tokens > 3) tokens = 3; // Cap at 3 tokens

        if (tokens > 0) {
            tokens--;
            cilk_spawn simulateRequest(req, milliseconds(0));
        } else {
            auto waitTime = milliseconds(200) - (timePassed % milliseconds(200));
            cilk_spawn simulateRequest(req, waitTime);
        }

        lastTime = now;
    }
    cilk_sync;
}