#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <stdbool.h>

#include <curl/curl.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>

#define URIS_S 2
const char *uris[] = {
	"https://api.turris.cz/updater-defs/3.5/omnia/dev-karel/base.lua",
	"https://api.turris.cz/updater-defs/3.5/omnia/dev-karel/base.lua.sig"
};

CURLM *curl_multi;
struct event_base *e_base;
struct event *e_timer;

struct dwn_data {
	const char *err;
};

static void check() {
	CURLMsg *msg;
	int msgs_left;
	struct dwn_data *data;
	char *url;

	while ((msg = curl_multi_info_read(curl_multi, &msgs_left))) {
		if (msg->msg != CURLMSG_DONE)
			continue; // No other message types are defined in libcurl. We check just because of compatibility with possible future versions.
		curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE, &data);
		curl_easy_getinfo(msg->easy_handle, CURLINFO_EFFECTIVE_URL, &url);
		if (msg->data.result == CURLE_OK) {
			printf("Download succesfull (%s)\n", url);
		} else {
			printf("Download failed (%s): %s\n", url, data->err);
			exit(2);
		}
	}
}

static size_t clb_write(char *ptr, size_t size, size_t nmemb, void *userd) {
	// Drop all data
	return size * nmemb;
}

static void clb_timer(int fd __attribute__((unused)), short kind __attribute__((unused)), void *userp) {
	printf("Timer callback\n");
	int running = 0;
	curl_multi_socket_action(curl_multi, CURL_SOCKET_TIMEOUT, 0, &running);
	check();
}

static int clb_timer_set(CURLM *curl_multi __attribute__((unused)), long timeout_ms, void *userp) {
	printf("Timer set %ld\n", timeout_ms);
	struct timeval timeout;
	timeout.tv_sec = timeout_ms / 1000;
	timeout.tv_usec = (timeout_ms % 1000) * 1000;
	evtimer_add(e_timer, &timeout);
	return 0;
}

struct dt_s {
	size_t id;
	struct event *e;
};

static void clb_socket(int fd, short kind, void *userp) {
	printf("Socket callback\n");
	int action = ((kind & EV_READ) ? CURL_CSELECT_IN : 0) | ((kind & EV_WRITE) ? CURL_CSELECT_OUT : 0);
	int running = 0;
	curl_multi_socket_action(curl_multi, fd, action, &running);
	check();
	if (running <= 0 && evtimer_pending(e_timer, NULL))
		evtimer_del(e_timer);
}

size_t id_next = 0;

static int clb_socket_set(CURL *curl_easy, curl_socket_t s, int what, void *userp, void *socketp) {
	struct dt_s *sdata = socketp;
	if (what == CURL_POLL_REMOVE) {
		printf("Socket remove %ld\n", sdata->id);
		event_free(sdata->e);
		free(sdata);
	} else {
		if (!sdata) { // New socket. No data associated.
			printf("Socket new %ld\n", id_next);
			sdata = malloc(sizeof *sdata);
			sdata->e = NULL;
			sdata->id = id_next++;
			curl_multi_assign(curl_multi, s, sdata);
		} else
			printf("Socket change %ld\n", sdata->id);
		short kind = ((what & CURL_POLL_IN) ? EV_READ : 0) | ((what & CURL_POLL_OUT) ? EV_WRITE : 0) | EV_PERSIST;
		if (sdata->e) {
			event_del(sdata->e);
			event_assign(sdata->e, e_base, s, kind, clb_socket, sdata);
		} else
			sdata->e = event_new(e_base, s, kind, clb_socket, sdata);
		event_add(sdata->e, NULL);
	}
	return 0;
}

static CURL *new_curl(const char *uri, bool simple) {
	CURL *curl = curl_easy_init();
	curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
	curl_easy_setopt(curl, CURLOPT_URL, uri);
	curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "");
	curl_easy_setopt(curl, CURLOPT_CAINFO, "./ca.pem");
	curl_easy_setopt(curl, CURLOPT_CRLFILE, "./crl.pem");
	curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
	curl_easy_setopt(curl, CURLOPT_TIMEOUT, 120);
	curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 30);
	curl_easy_setopt(curl, CURLOPT_CAPATH, NULL);
	curl_easy_setopt(curl, CURLOPT_SSL_CIPHER_LIST, NULL);
	
	if (!simple) {
		struct dwn_data *data = malloc(sizeof *data);
		curl_multi_add_handle(curl_multi, curl);
		curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, clb_write);
		curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, data->err);
		curl_easy_setopt(curl, CURLOPT_PRIVATE, data);
	}

	return curl;
}


int main(int argc, char *argv[]) {
	bool simple = (argc > 1 && !strcmp(argv[1], "-s"));
	bool multi = (argc > 1 && !strcmp(argv[1], "-m"));
	curl_global_init(CURL_GLOBAL_SSL);
	if (!simple) {
		struct event_config *config = event_config_new();
		event_config_require_features(config, EV_FEATURE_FDS);
		event_config_set_flag(config, EVENT_BASE_FLAG_NOLOCK);
		e_base = event_base_new_with_config(config);
		event_config_free(config);
		e_timer = evtimer_new(e_base, clb_timer, NULL);

		curl_multi = curl_multi_init();
		curl_multi_setopt(curl_multi, CURLMOPT_MAX_TOTAL_CONNECTIONS, 1);
		curl_multi_setopt(curl_multi, CURLMOPT_SOCKETFUNCTION, clb_socket_set);
		curl_multi_setopt(curl_multi, CURLMOPT_TIMERFUNCTION, clb_timer_set);
	}

	size_t i;
	CURL *curls[URIS_S];
	for (i = 0; i < URIS_S; i++) {
		curls[i] = new_curl(uris[i], simple);
	}
	if (simple) {
		for (i = 0; i < URIS_S; i++) {
			CURLcode res = curl_easy_perform(curls[i]);
			if (res	== CURLE_OK)
				printf("Download succesfull (%s)\n", uris[i]);
			else
				printf("Download failed (%s): %s\n", uris[i], curl_easy_strerror(res));
		}
	} else if (multi) {
		int sr = 0;
		CURLMcode cd;
		do {
			cd = curl_multi_perform(curl_multi, &sr);
		} while(sr > 0 || cd == CURLM_CALL_MULTI_PERFORM);
		if (cd != CURLM_OK) {
			printf("Download failed: %s\n", curl_multi_strerror(cd));
			exit(3);
		} else
			printf("Download succesfull\n");
	} else
		event_base_dispatch(e_base);

	for (i = 0; i < URIS_S; i++) {
		if (!simple)
			curl_multi_remove_handle(curl_multi, curls[i]);
		curl_easy_cleanup(curls[i]);
	}

	if (!simple) {
		curl_multi_cleanup(curl_multi);

		event_free(e_timer);
		event_base_free(e_base);
	}
	curl_global_cleanup();

	return 0;
}