// nasza-klasa.pl mutual friend finder
// Written by Leszek Godlewski

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

// friends list request flags
#define FLF_UID					(1 << 0)
#define FLF_FIRST_NAME			(1 << 1)
#define FLF_LAST_NAME			(1 << 2)
#define FLF_AVATAR				(1 << 3)
#define FLF_FRIENDS_COUNT		(1 << 4)
#define FLF_LOCATION			(1 << 5)	// city
#define FLF_MSGC_STATUS			(1 << 6)	// messaging centre status
#define FLF_MSGC_STATUS_DESC	(1 << 7)	// messaging centre status description string
#define FLF_UNKNOWN				(1 << 8)	// unknown flag
#define FLF_ARTIFICIALITY		(1 << 9)	// whether or not the person in the account is a fictitious one or a real one

typedef unsigned char	bool_t;
#define btrue			1
#define bfalse			0

CURL	*easyhandle = NULL;

char	*response = NULL;
int		responseSize = 0;

void printHelp(char *argv0) {
	printf("Compares the friend lists of 2 given users and returns mutual friends.\n"
		"\n"
		"Usage: %s <username> <password> <UID1> <UID2>\n"
		"   username    - your nasza-klasa.pl username/e-mail address\n"
		"   password    - your nasza-klasa.pl password\n"
		"   UID1        - the UID of the first person\n"
		"   UID2        - the UID of the second person\n", argv0);
}

size_t writeDocument(void *buf, size_t size, size_t nmemb, void *p) {
	int		bytes = size * nmemb;
	char	*target;
	if (!response) {
		responseSize = bytes + 1;
		response = malloc(responseSize);
		target = response;
	} else {
		response = realloc(response, responseSize + bytes);
		target = response + responseSize - 1;
		responseSize += bytes;
	}
	memcpy(target, buf, bytes);
	response[responseSize - 1] = 0;	// ensure a trailing 0
	return bytes;
}

struct curl_slist	*headers = NULL;

void initCurl(void) {
	curl_global_init(CURL_GLOBAL_WIN32);
	easyhandle = curl_easy_init();
	curl_easy_setopt(easyhandle, CURLOPT_WRITEFUNCTION, writeDocument);
	curl_easy_setopt(easyhandle, CURLOPT_COOKIEFILE, "dummyfile");
	curl_easy_setopt(easyhandle, CURLOPT_FOLLOWLOCATION, 1);
#if 0	// debugging
	curl_easy_setopt(easyhandle, CURLOPT_VERBOSE, 1);
#endif

	// the server requires a user agent
	headers = curl_slist_append(headers, "User-Agent: nasza-klasa.pl mutual friend finder");
	curl_easy_setopt(easyhandle, CURLOPT_HTTPHEADER, headers);
}

bool_t login(char *l, char *p) {
	char				postdata[1024], *el, *ep;
	int					retval;

	el = curl_easy_escape(easyhandle, l, strlen(l));
	ep = curl_easy_escape(easyhandle, p, strlen(p));
	snprintf(postdata, sizeof(postdata), "login=%s&password=%s", el, ep);
	curl_free(el);
	curl_free(ep);
	curl_easy_setopt(easyhandle, CURLOPT_POSTFIELDS, postdata);

	curl_easy_setopt(easyhandle, CURLOPT_URL, "http://nasza-klasa.pl/login");
	retval = curl_easy_perform(easyhandle);

	curl_easy_setopt(easyhandle, CURLOPT_POSTFIELDS, "");

	if (strstr(response, "Nieprawid\305\202owa nazwa u\305\274ytkownika lub has\305\202o."))
		retval = bfalse;
	else
		retval = (retval == 0);

	free(response);
	response = NULL;
	responseSize = 0;

	return retval;
}

#define CLIENT_VERSION		135		// version of the nasza-klasa.pl software we're identifying as

#define MAX_NAME_LENGTH		100		// limit present in the nasza-klasa.pl website's source code

typedef struct {
	int		uid;
	char	fname[MAX_NAME_LENGTH];
	char	lname[MAX_NAME_LENGTH];
	bool_t	mutual;
} contact_t;

contact_t	*contacts = NULL;
int			numContacts = 0;

bool_t getContactLists(char *u1, char *u2) {
	char	url[1024];
	char	*r1 = NULL, *r2 = NULL;
	char	*in, *out;
	int		retval, i, j, n;

	snprintf(url, sizeof(url), "http://nasza-klasa.pl/friends_list/%s/%d/%d", u1, FLF_UID | FLF_FIRST_NAME | FLF_LAST_NAME, CLIENT_VERSION);
	curl_easy_setopt(easyhandle, CURLOPT_URL, url);
	retval = curl_easy_perform(easyhandle);
	if (retval != 0) {
		if (response) {
			free(response);
			response = NULL;
		}
		return bfalse;
	}
	r1 = response;

	response = NULL;
	responseSize = 0;

	// we don't need as much info from the other person, fetch the UIDs only
	snprintf(url, sizeof(url), "http://nasza-klasa.pl/friends_list/%s/%d/%d", u2, FLF_UID, CLIENT_VERSION);
	curl_easy_setopt(easyhandle, CURLOPT_URL, url);
	retval = curl_easy_perform(easyhandle);
	if (retval != 0) {
		if (response) {
			free(response);
			response = NULL;
		}
		if (r1)
			free(r1);
		return bfalse;
	}
	r2 = response;

	response = NULL;
	responseSize = 0;

	// parse the first contact list
	// get the friends count and allocate memory
	in = strstr(r1 + 3, "\"FRIENDS_COUNT\":");
	if (!in) {
		if (response) {
			free(response);
			response = NULL;
		} if (r1)
			free(r1);
		if (r2)
			free(r2);
		return bfalse;
	}
	in += 16;
	out = url;	// reuse the variable
	while (*in < '0' || *in > '9')
		in++;
	while (*in >= '0' && *in <= '9')
		*out++ = *in++;
	*out = 0;
	numContacts = atoi(url);
	contacts = malloc(numContacts * sizeof(*contacts));
	memset(contacts, 0, numContacts * sizeof(*contacts));

	// get the UIDs
	in = strstr(r1 + 3, "\"UID\":");
	if (!in) {
		if (response) {
			free(response);
			response = NULL;
		}
		if (r1)
			free(r1);
		if (r2)
			free(r2);
		free(contacts);
		return bfalse;
	}
	in += 6;
	while (*in != '[')
		in++;
	for (i = 0; i < numContacts; i++) {
		out = url;
		while (*in < '0' || *in > '9')
			in++;
		while (*in >= '0' && *in <= '9')
			*out++ = *in++;
		*out = 0;
		contacts[i].uid = atoi(url);
	}

	// get the first names
	in = strstr(r1 + 3, "\"FIRST_NAME\":");
	if (!in) {
		if (response) {
			free(response);
			response = NULL;
		} if (r1)
			free(r1);
		if (r2)
			free(r2);
		free(contacts);
		return bfalse;
	}
	in += 13;
	while (*in != '[')
		in++;
	for (i = 0; i < numContacts; i++) {
		out = url;
		while (*in != '\"')
			in++;
		in++;
		while (*in != '\"')
			*out++ = *in++;
		in++;
		*out = 0;
		strncpy(contacts[i].fname, url, sizeof(contacts->fname));
	}

	// get the last names
	in = strstr(r1 + 3, "\"LAST_NAME\":");
	if (!in) {
		if (response) {
			free(response);
			response = NULL;
		} if (r1)
			free(r1);
		if (r2)
			free(r2);
		free(contacts);
		return bfalse;
	}
	in += 12;
	while (*in != '[')
		in++;
	for (i = 0; i < numContacts; i++) {
		out = url;
		while (*in != '\"')
			in++;
		in++;
		while (*in != '\"')
			*out++ = *in++;
		in++;
		*out = 0;
		strncpy(contacts[i].lname, url, sizeof(contacts->lname));
	}

	// parse the second contact list
	// get the friends count
	in = strstr(r2 + 3, "\"FRIENDS_COUNT\":");
	if (!in) {
		if (response) {
			free(response);
			response = NULL;
		}
		if (r1)
			free(r1);
		if (r2)
			free(r2);
		return bfalse;
	}
	in += 16;
	out = url;	// reuse the variable
	while (*in < '0' || *in > '9')
		in++;
	while (*in >= '0' && *in <= '9')
		*out++ = *in++;
	*out = 0;
	retval = atoi(url);	// reuse the variable

	// get the UIDs
	in = strstr(r2 + 3, "\"UID\":");
	if (!in) {
		if (response) {
			free(response);
			response = NULL;
		}
		if (r1)
			free(r1);
		if (r2)
			free(r2);
		free(contacts);
		return bfalse;
	}
	in += 6;
	while (*in != '[')
		in++;
	for (i = 0; i < retval; i++) {
		out = url;
		while (*in < '0' || *in > '9')
			in++;
		while (*in >= '0' && *in <= '9')
			*out++ = *in++;
		*out = 0;
		n = atoi(url);
		for (j = 0; j < numContacts; j++) {
			if (contacts[j].uid == n) {
				contacts[j].mutual = btrue;
				break;
			}
		}
	}

	free(r1);
	free(r2);
	return btrue;
}

void logout(void) {
	curl_easy_setopt(easyhandle, CURLOPT_URL, "http://nasza-klasa.pl/logout?l=1");
	curl_easy_perform(easyhandle);
}

void cleanupCurl(void) {
	curl_slist_free_all(headers);
	curl_easy_cleanup(easyhandle);
	curl_global_cleanup();
}

void printMutualFriends(void) {
	int	i;

	for (i = 0; i < numContacts; i++) {
		if (!contacts[i].mutual)
			continue;
		printf("%s %s (http://nasza-klasa.pl/profile/%d)\n", contacts[i].fname, contacts[i].lname, contacts[i].uid);
	}
}

int main(int argc, char *argv[]) {
	printf("nasza-klasa.pl mutual friend finder\n"
		"Written by Leszek Godlewski\n"
		"This program is free software under the WTFPL license.\n"
		"\n"
		);
	if (argc != 5) {
		printHelp(argv[0]);
		exit(0);
	}
	initCurl();
	printf("Logging in...\n");
	if (!login(argv[1], argv[2])) {
		printf("Logging in failed. Check your login details and internet connection.\n");
		exit(0);
	}
	printf("Downloading and processing contact lists...\n");
	if (!getContactLists(argv[3], argv[4])) {
		printf("Retrieving contact lists failed. Check your internet connection.\n");
		exit(0);
	}
	printf("Logging out...\n");
	logout();
	cleanupCurl();
	printf("Mutual friends are:\n");
	printMutualFriends();
	free(contacts);
    return 0;
}