//TCP Server


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


//Function Prototypes
void myabort(char *);



//Some Global Variables
int serverport = 3000;
char * eptr = NULL;
int listen_socket, client_socket;
struct sockaddr_in Server_Address, Client_Address;
int result;
socklen_t csize;




//main()
int
main(int argc, char **argv){
	
	char buf[100];
	char tmp[100];
	char * ptr;
	int n, sent, length;

	//Step 0: Process Command Line
	if (argc > 2){
		myabort("Usage: server <port>");
	}
	if (argc == 2){
		serverport =  (int) strtol(argv[1], &eptr, 10);
		if (*eptr != '\0') myabort("Invalid Port Number!");
	}
	
	
	//Step 1: Create a socket
	listen_socket = socket(PF_INET, SOCK_STREAM, 0);
	if (listen_socket == -1) myabort("socket()");
	
	
	//Step 2: Setup Address structure
	bzero(&Server_Address, sizeof(Server_Address));
	Server_Address.sin_family = AF_INET;
	Server_Address.sin_port = htons(serverport);
	Server_Address.sin_addr.s_addr = INADDR_ANY;
	
	
	//Step 3: Bind the socket to the port
	result = bind(listen_socket, (struct sockaddr *) &Server_Address, sizeof(Server_Address));
	if (result == -1) myabort("bind()");
	
	
	//Step 4:Listen to the socket
	result = listen(listen_socket, 1);
	if (result == -1) myabort("listen()");
	
	
	//Step 5: Setup an infinite loop to make connections
	while(1){
		
	
		//Step 5a: Accept a Connection
		csize = sizeof(Client_Address);
		client_socket = accept( listen_socket,
		                        (struct sockaddr *) &Client_Address,
		                         &csize
							   );
		if (client_socket == -1) myabort("accept()");
		
		cout << "Client Accepted!" << endl;
		
		
		//Step 5b: Communicate with client
		
		//loop until client closes
		while (1){
		
			
		
			//read string from client
			bzero(&buf, sizeof(buf));
			do{
				bzero(&tmp, sizeof(tmp));
				n = read(client_socket,(char *) &tmp, 100);
				//cout << "server:  " << tmp;
				tmp[n] = '\0';
				if (n == -1) myabort("read()");
				if (n == 0) break;
				strncat(buf, tmp, n-1);
				buf[n-1] = ' ';
			} while (tmp[n-1] != '\n');
			
			buf[ strlen(buf) ] = '\n';
			
			
			
			if (n == 0) break;
			
		
	 		//write string back to client
			sent = 0;
			ptr = buf;
			length = strlen(buf);
			while (sent < length ){
				n = write(client_socket, ptr, strlen(ptr) );
				if ( n == -1) myabort("write()");
				sent += n;
				ptr += n;
			}
		}//end inner while
 		
	    cout << "Client closed! Listening for other clients." << endl;
		close(client_socket);
		
		
	}
	close(listen_socket);
	
	exit(0);
	
}


void
myabort(char * msg){
	cout << "Error!:  " <<  msg << endl;
	exit(1);
}