#include<stdio.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<pthread.h>
#include<errno.h>
#include<stdlib.h>

#define MSIZE 1500       //lungimea maxima a mesajului
#define PORTFORWARD 12345      //portul la care asculta
#define PORTSERVER 9099
#define ADDR_SERVER "172.30.0.5"
#define MAXCLIENTS 10

char buffer[MAXCLIENTS][5*MSIZE];
int n;
struct sockaddr_in clients[MAXCLIENTS];
int sock;
struct sockaddr_in addr_server;

int client_exists(struct sockaddr_in s) {
	 // acest cod nu e bun - trebuie modificat !!!!
	 // aceasta functie trebuie sa intoarca indexul clientului
	 // identificat de s in vectorul clients
	 return n;
}

void handleClient(void *arg) {
	int clientno, i, j, k, sock_client, len_addr;
	char msg[MSIZE];
	
	clientno = *((int*) arg);
	sock_client = socket(AF_INET,SOCK_DGRAM,0);
        if (sock_client == -1) {
                perror("err la creare socket socketd in handleClient:");
                exit(1);
        }
	
	// nu este obligatoriu sa facem bind (?)
	len_addr = sizeof(addr_server);
	while (1) {
		i = recvfrom(sock_client, msg, MSIZE, MSG_DONTWAIT, &addr_server, &len_addr);
		if (i==-1 && errno!=EAGAIN) {
			perror("err receiving in client:");
		}
		if (i>0) {
			j = sendto(sock, msg, i, 0, &clients[clientno], len_addr);
		}
		
		//acest cod trebuie modificat ... trebuie verificat daca
		//sunt date in bufferul client si numai daca sunt sa se trimita
		//pe socketul sock_client...
		sleep(2);
		i = sendto(sock_client, buffer[clientno], strlen(buffer[clientno])+1, 0, &addr_server, len_addr);
		//printf("am trimis %d bytes (%s) din clientul %d la portul %d, adresa %x\n", i, buffer[clientno], clientno, ntohs(addr_server.sin_port), ntohl(addr_server.sin_addr.s_addr));
	}
}

main() {
 	 int i,c,len_addr;
	 char msg[MSIZE];
	 struct sockaddr_in addr,addr_client;
	 struct hostent *hent;
	 pthread_t thid;

 	 sock = socket(AF_INET,SOCK_DGRAM,0);
	 if (sock == -1) {
		perror("err la creare socket:");
		exit(1);
	 }
	 //curat continutul lui sock (scriu 0)
	 memset((char *)&addr,0,sizeof(addr));
	 addr.sin_family=AF_INET;                         //domeniul Internet  
	 addr.sin_addr.s_addr=htonl(INADDR_ANY);          //adresa IP la care asculta serverul (INADDR_ANY=oricare)
	 addr.sin_port=htons(PORTFORWARD);                      //portul server
 
	 if( bind(sock,(struct sockaddr *) &addr,sizeof(addr)) <0) {
       	 	perror("Eroare la bind PORTFORWARD:");
                exit(1);
         }

	 // setam sockaddr_in pentru server
         memset((char *)&addr_server,0,sizeof(addr_server));
         addr_server.sin_family=AF_INET;                    
         addr_server.sin_addr.s_addr=inet_addr(ADDR_SERVER);   
         addr_server.sin_port=htons(PORTSERVER); 

	 // la inceput nu avem clienti
	 n = -1; 

 	 while(1) {
		 len_addr=sizeof(struct sockaddr);
		 i = recvfrom(sock, msg, MSIZE, 0, &addr_client, &len_addr);
		 //printf("received %d bytes from client\n", i);
       	 	 if (i>0) {
		 	if ((c = client_exists(addr_client)) == -1) {
				n++;
				clients[n] = addr_client;
				pthread_create(&thid, NULL, handleClient, (void*) &n);
				c = n;
				sleep(1);
			}
			// aici trebuie modificat .... de sincronizat accesul la buffer
                        memcpy(buffer[c], msg, i);
                        buffer[c][i]=0;
		 }

	 }
 }