chat++.cpp

/*!
Chat++ The best UNIX chat program at BGSU probbably.
Author: Dylan Bickerstaff
Date: 4/30/2018
Description: This chat program allows multiple users to chat over a UNIX terminal.
*/
#include <iostream>
#include <fstream> //Library used for file access.
#include <unistd.h> //Library used for sleep function.
#include <cctype> //Library used for input validation.
#include <ctime> //Library used for the date/time.
using namespace std;

/* Constants */
const string CHAT_FILE = "chatData.txt";

/* Global Variables */
int pastChatCount = 0;
string username = "";

/* Global function prototypes */

void goto_menu_main();
void goto_chat_display();
void goto_chat_input();
void goto_set_username();

void do_output_chat_difference();
void do_clear_chat();

void remove_ctrl_characters(string &input);

/* Global fstream object */

fstream chatData;

/*
main(): First entry point for Chat++
*/
int main()
{
	goto_menu_main();
	return 0;
}

/*
goto_menu_main(): Displays the main menu for Chat++.
*/
void goto_menu_main() {
	int choice = 0;
	
	do {
		cout << "\f" //Clear the screen.
		<< "Chat++ Main Menu\n" //Output the menu options.
		<< "----------------\n\n"
		<< "Pick a number:\n\n"
		<< "1) Chat Display Screen...\n"
		<< "2) Chat Input Screen...\n"
		<< "3) Exit Chat++\n\n"
		<< "> ";
		cin >> choice; //Capture the user's choice.
		if(cin.fail()) { //Check if input is the same as type as choice.
			cin.clear(); //Clear the warning flags on cin.
			cin.ignore(1000, '\n'); //Flush the input.
		}
	} while(choice > 3 || choice < 1); //While choice is invalid.
	
	switch(choice) {
		case 1: {
			goto_chat_display();
			return;
		}
		case 2: {
			goto_chat_input();
			return;
		}
	}
}

/*
goto_chat_display(): Displays and checks for updates in the chat every second. This screen allows the user to view the chat.
*/
void goto_chat_display() {
	cout << "\nPress \"Ctrl\" + \"C\" to quit.\n\n"; //Output instructions on how to quit the program in this mode.
	usleep(1000 * 1000); //Wait 1 second to allow time for the user to read the above instruction.
	fflush(stdout); //Flush the output.
	
	while(true) { //Every second check the chat difference on file and output it to the user.
		do_output_chat_difference();
		fflush(stdout);
		usleep(1000 * 1000);
	}
}

/*
goto_chat_input(): Displays the chat input screen. This screen allows the user to input messages or commands.
*/
void goto_chat_input() {
	/* Local Variables */
	bool loop = true;
	bool firstLoop = true;
	string input; //Used to capture the user's input.
	string message; //Used to send the user's message to chat.
	string control; //Used to send control keys, and global messages to chat.
	string oldName; //Used to store the user's old username if the user decides to change their username.
	
	if(username == "") { //If username is not set, display the username prompt.
		goto_set_username();
	}
	
	control = username + " has joined the chat"; //Prepare an announcement to chat that a user has joined.
	while(loop) {
		cout << "\f" //Clear the screen.
		<< "Chat Input Commands:\n\n" //Display the commands
		<< "/quit        - Returns to the main menu.\n"
		<< "/clear       - Clears the chat.\n"
		<< "/changename  - Changes your username.\n"
		<< "/bell        - Produces an audible sound on every terminal.\n\n"
		<< "Type a message, then press \"Enter\" to send:\n\n"
		<< message << "\n\n" //Display a message to the user.
		<< username << "> "; //Show the user's current username.
		
		message = ""; //Clear the message.
		
		if(!firstLoop) { //Skip input capture on first loop.
			getline(cin, input); //Capture the user's input including spaces.
			remove_ctrl_characters(input); //Remove ctrl characters from the input.
		}
		time_t now = time(0);
		tm *time = localtime(&now);
		
		if(input[0] == '/') { //If the first character is a forward slash.
			if(input == "/quit") { //Announce to chat that the user has left the chat, then stop the loop.
				control = username + " has left the chat";
				loop = false;
			} else if(input == "/clear") { //Call the clear chat function, then announce to the chat that the user has cleared the chat.
				do_clear_chat();
				control = username + " has cleared the chat";
			} else if(input == "/changename") { //Show the username prompt, then announce the username change to chat.
				oldName = username;
				goto_set_username();
				control = oldName + " changed their username to " + username;
			} else if(input == "/bell") { //Announce that a bell was sent to chat and send a bell to chat.
				control = username + " has sent a bell\a";
			} else { //Otherwise, tell the user that their input was not a valid command.
				message = "Warning: Not a valid command!";
			}
			input = ""; //Clear the input.
		}
		
		if(input != "" || control != "") { //If there is an input or control set.
			if(control == "") { //If control is empty, substitute if for the username.
				control = username;
			}
			chatData.open(CHAT_FILE, fstream::app); //Open the chat file in append mode.
			chatData 
			<< "[" << 1 + time->tm_mon << "/" << time->tm_mday << "/" << 1900 + time->tm_year << " " << time->tm_hour << ":" << time->tm_min << "]" //Append the date/time to chat.
			<< "<" << control << "> " << input << endl; //Append the control and input to the chat file.
			chatData.close(); //Close the file.
			control = ""; //Clear the control.
		} else if(message == "") { //If the message is empty, show a warning to the user.
			message = "Warning: Cannot send empty message!";
		}
		
		firstLoop = false;
	}
	goto_menu_main(); //If the loop exits, show the main menu.
}

/*
goto_set_username(): Displays the username prompt.
*/
void goto_set_username() {
	/* Local Variable */
	string input;
	
	cout << "\fEnter a username: "; //Clear the screen and ask the user to input a username.
	cin >> input; //Capture the input.
	remove_ctrl_characters(input); //Remove control characters from the input.
	if(input != "") { //If the input is not empty
		username = input; //Set the username.
	}
	cin.ignore(100000, '\n'); //Flush the input buffer.
}

/*
do_output_chat_difference(): This function pulls the chat from file, then only outputs the new chat lines.
*/
void do_output_chat_difference() {
	/* Local Variables */
	string chatLine;
	string output = "";
	int count = 0;
	
	chatData.open(CHAT_FILE); //Open the chat file.
	while(getline(chatData, chatLine)) { //For each line in the chat file.
		if(count >= pastChatCount) { //If a new line.
			output.append(chatLine + "\n"); //Append to a string instead of cout-ing every line, then cout later to improve console / network performance with large chat history.
		}
		count++;
	}
	chatData.close(); //Close the chat file.
	cout << output; //Output the new chat lines to the user.
	if(pastChatCount > count) { //If there are less lines than before, assume the chat has been cleared.
		cout << "\f" << chatLine; //Clear the user's screen.
		pastChatCount = 0; //Reset past chat count to zero.
	} else { //Otherwise set the past chat count to the current chat count.
		pastChatCount = count;
	}
}

/*
do_clear_chat(): This function clears out the chat file on disk. 
*/
void do_clear_chat() {
	chatData.open(CHAT_FILE, ofstream::out | fstream::trunc); //Clear the chat file.
	chatData.close(); //Close the chat file.
}

/*
remove_ctrl_characters(): This function will remove all ctrl sequences from a string.
*/
void remove_ctrl_characters(string &input) {
	for(unsigned int count = 0; input.length() > count; count++) { //For each character.
		if(iscntrl(input[count])) { //If the character is a ctrl character.
			input[count] = '\0'; //Set it to null.
		}
	}
}