/*
 * Curses demo for CS435
 * Feel free to forget / not use all this stuff if you don't like it
 * But, if you like writing stuff for the terminal, this is probably useful
 * This is a valid, if excessive, solution to lab 3.
 *
 * A couple points that might not be obvious:
 * 	- It's important to call endwin() after using curses, or the terminal might get all messed
 * 		up.  That's why SIGINT has to be handled.
 * 	- The network stuff can fail before the display is even initiated.  Also, when we endwin(), 
 * 		there's no information left on the screen.  So we use perror to display errors, so that 
 * 		the user can figure out what they did wrong and try again.  Same for the usage info.
 * 	- Newlines are added, because the user pressed enter (they're not in the output from 
 * 		wgetstr normally).
 * 	- Newlines are added to incoming info.  If this was going to be a program people actually
 * 		used, this should be an option.
 */

#include<ncurses.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/ip.h>
#include<arpa/inet.h>
#include<netdb.h>
#include<pthread.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h> // For initial printf, later perror
#include<signal.h>
#include<unistd.h>

struct receive_info {
	int sockfd;
	WINDOW* top;
	WINDOW* bottom;
};

void exit_graceful(int signal){
	endwin();
	exit(0);
}

void* receive_print(void* arg){
	struct receive_info* prfi = (struct receive_info*)arg;
	char readstring[1024*1024];
	ssize_t readsize;
	for(;;){
		readsize = read(prfi->sockfd, readstring, 1024*1024);
		/*
		 * If we read nothing at all, that probably means the connection was terminated.  It's 
		 * certainly possible an internal OS error could cause read to stop blocking despite an
		 * active connection, but that's not our fault, and system errors are expected to cause
		 * programs to act strange.
		 */
		if(!readsize){
			wattron(prfi->top, COLOR_PAIR(2));
			wprintw(prfi->top, "Connection Terminated\n");
			wattroff(prfi->top, COLOR_PAIR(2));
			wmove(prfi->bottom, LINES/4 - 2, 0);
			wrefresh(prfi->top);
			wrefresh(prfi->bottom);
			break;
		}
		readstring[readsize] = 0;
		wprintw(prfi->top, readstring); 
		wprintw(prfi->top, "\n");
		wmove(prfi->bottom, LINES/4 - 2, 0);
		wrefresh(prfi->top);
		wrefresh(prfi->bottom);
	}
	return 0; 
}

int main(int argc, char ** argv){
	// Usage Information
	if(argc < 3){
		printf("Usage:  %s hostname port\n", argv[0]);
		return 1;
	}

	// Prepare the network connection, but don't call connect yet
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd == -1)
		goto err;
	short port = atoi(argv[2]);
	struct sockaddr_in connect_addr;
	connect_addr.sin_port = htons(port);
	connect_addr.sin_family = AF_INET;
	struct hostent* entry = gethostbyname(argv[1]);
	if(!entry)
		goto err;
	struct in_addr **addr_list = (struct in_addr**)entry->h_addr_list;
	struct in_addr* c_addr = addr_list[0];
	char* ip_string = inet_ntoa(*c_addr);
	connect_addr.sin_addr = *c_addr;
	
	// Set up curses.  This is probably easier in Python.
	initscr();
	start_color();
	use_default_colors();
	init_pair(1, COLOR_GREEN, -1);
	init_pair(2, COLOR_RED, -1);
	refresh();
	WINDOW* top = newwin(LINES*3/4, COLS, 0, 0);
	WINDOW* bottom = newwin(LINES/4 - 1, COLS, LINES*3/4 + 1, 0);
	refresh();
	wmove(stdscr, LINES*3/4, 0);
	whline(stdscr, ACS_HLINE , COLS);
	wmove(bottom, LINES/4 - 2, 0);
	scrollok(bottom, 1);
	scrollok(top, 1);
	wrefresh(top);
	wrefresh(bottom);
	refresh();
	
	// Handle Signals
	struct sigaction sa;
	sa.sa_handler = exit_graceful;
	sigaction(SIGINT, &sa, 0);

	// The UI is up, let's reassure the user that whatever name they typed resolved to something
	wattron(top, COLOR_PAIR(1));
	wprintw(top, "Connecting to host %s (%s)\n", entry->h_name, ip_string);
	wrefresh(top);
	
	// Actually connect.  It might connect right away, or sit here and hang - depends on how the
	// host is feeling today
	if(connect(sockfd, (struct sockaddr*)&connect_addr, sizeof(struct sockaddr_in)))
		goto err;
	
	// Let the user know we're connected, so they can start doing whatever they do.
	wprintw(top, "Connected\n");
	wrefresh(top);
	wattroff(top, COLOR_PAIR(1));

	// Start the receive thread
	struct receive_info rfi;
	rfi.sockfd = sockfd;
	rfi.top = top;
	rfi.bottom = bottom;
	pthread_t t;
	pthread_create(&t, 0, receive_print, &rfi);
	
	// Get user input.  Ctrl + C is the way out now.
	char input[1024*1024];
	wmove(bottom, LINES/4 - 2, 0);
	wgetnstr(bottom, input, 1024*1024-1); 
	size_t length;
	for(;;){
		length = strlen(input);
		if(!strcmp(input, "exit"))
			exit_graceful(0);
		input[length] = '\n';
		input[length+1] = 0;
		write(sockfd, input, length+1);
		wscrl(bottom, 0);
		wrefresh(bottom);
		wgetnstr(bottom, input, 1024*1024-1); 
		wrefresh(bottom);
	}

err:
	endwin();
	perror(argv[0]);
	return 1;
}