#include <stdio.h>
#include <string.h>
#include <curl/curl.h>

bool change_speed = false;

static int progress_callback(void *clientp,   double dltotal,   double dlnow,   double ultotal,   double ulnow)
{
    static time_t time_last = 0;
    static time_t time_start = 0;
    static double dlnow_last = 0;

    time_t now = time(NULL);
    if (time_last == 0) {
        time_last = now;
        time_start = now;
        dlnow_last = dlnow;
    }

    if (now > time_last + 1) {
        printf("Speed: %.2f KB/S\n", (dlnow - dlnow_last) / (now - time_last) / 1024);
        time_last = now;
        dlnow_last = dlnow;
    }

    if (dlnow / dltotal > 0.5 || now > time_start + 10) {
        change_speed = true;
    }

    return 0;
}

static size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata)
{
    return size * nmemb;
}

int main()
{
    CURL *easy_handle = curl_easy_init();
    if (!easy_handle) {
        return -1;
    }

    const char *url = "https://speed.hetzner.de/100MB.bin";
    curl_easy_setopt(easy_handle, CURLOPT_URL, url);
    curl_easy_setopt(easy_handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
    curl_easy_setopt(easy_handle, CURLOPT_NOPROGRESS, 0L);
    curl_easy_setopt(easy_handle, CURLOPT_WRITEFUNCTION, write_callback);
    curl_easy_setopt(easy_handle, CURLOPT_VERBOSE, 1L);
    curl_easy_setopt(easy_handle, CURLOPT_SSL_VERIFYPEER, 0L);

    CURLM *multi_handle = curl_multi_init();
    if (!multi_handle) {
        return -1;
    }

    bool done = false;
    CURLcode result = CURLE_OK;

    CURLMcode mcode = curl_multi_add_handle(multi_handle, easy_handle);

    while (!mcode) {
        int still_running = 0;
        int numfds = 0;

        mcode = curl_multi_perform(multi_handle, &still_running);

        if (!still_running && !mcode) {
            int rc;
            CURLMsg *msg = curl_multi_info_read(multi_handle, &rc);
            if (msg) {
                result = msg->data.result;
                printf("Curl result: %d\n", result);
                break;
            }
        }else {
            long timeout;
            curl_multi_timeout(multi_handle, &timeout);
            if (timeout < 0) {
                timeout = 100;
            }

            curl_multi_wait(multi_handle, NULL, 0, timeout, &numfds);
        }

        static bool speed_changed = false;
        if (change_speed && !speed_changed) {
            curl_easy_setopt(easy_handle, CURLOPT_MAX_RECV_SPEED_LARGE, (curl_off_t)31415);

            speed_changed = true;
            printf("CURLOPT_MAX_RECV_SPEED_LARGE\n");
        }
    }

    curl_multi_remove_handle(multi_handle, easy_handle);
    curl_easy_cleanup(easy_handle);
    curl_multi_cleanup(multi_handle);

    return 0;
}