File I/O Practice
-----------------


Problem: Write a program that will keep a list of contacts. The contact will have a name (first name and last name), and a phone number (no dashes). The program will read in all the saved contacts at the start of program. The user will be able to either look at all their contacts or add a new contact or quit the app. Once the contact is added it should be saved. The names should be no more than 256 characters.

//============================================================================
// Name        : FileIO.cpp
// Author      : 
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <fstream>
#include <cstring>
#include "Utils.h"

using namespace std;

const int MAX_NAME_SIZE = 256;
const char * CONTACTS_FILE_NAME = "Contacts.bin";
const char * INPUT_ERROR_STRING = "Input Error! Please try again.";

struct Contact
{
	char firstName[MAX_NAME_SIZE];
	char lastName[MAX_NAME_SIZE];
	int phoneNumber;
};

struct ContactsDB
{
	Contact * optrContacts;
	int contactsCapacity;
	int numberOfContacts;
};

void CreateContactsFile();
bool LoadContacts(ContactsDB& contactsDB);
void SaveContacts(const ContactsDB & db);
void ResizeContactsDB(ContactsDB & contactsDB, int newCapacity);
char GetOptionFromUser();
void ExecuteOption(char option, ContactsDB & contactsDB);
void DisplayOption(const ContactsDB& contactsDB);
void AddOption(ContactsDB & contactsDB);

int main()
{
	ContactsDB contactsDB;
	contactsDB.optrContacts = nullptr;
	contactsDB.contactsCapacity = 0;
	contactsDB.numberOfContacts = 0;

	CreateContactsFile();

	if(!LoadContacts(contactsDB))
	{
		cout << "Error reading file: " << CONTACTS_FILE_NAME << endl;
		return 0;
	}

	char option;

	do
	{
		option = GetOptionFromUser();

		ExecuteOption(option, contactsDB);

	}while(option != 'q');


	SaveContacts(contactsDB);

	if(contactsDB.optrContacts != nullptr)
	{
		delete [] contactsDB.optrContacts;
		contactsDB.optrContacts = nullptr;
	}

	return 0;
}

void CreateContactsFile()
{
	ifstream inFile;

	inFile.open(CONTACTS_FILE_NAME, fstream::binary);
	if(!inFile.is_open())
	{
		ofstream outFile;
		outFile.open(CONTACTS_FILE_NAME, fstream::binary);
		outFile << flush;
		outFile.close();
	}
	else
	{
		inFile.close();
	}
}

bool LoadContacts(ContactsDB& contactsDB)
{
	ifstream inFile;

	inFile.open(CONTACTS_FILE_NAME, fstream::binary);

	if(inFile.is_open())
	{
		inFile.seekg(0, inFile.end);
		int lengthOfFileInBytes = inFile.tellg();
		inFile.seekg(0, inFile.beg);

		int numberOfContacts = lengthOfFileInBytes / sizeof(Contact);
		int capacity = numberOfContacts*2 + 10;

		contactsDB.optrContacts = new Contact[capacity];
		contactsDB.numberOfContacts = numberOfContacts;
		contactsDB.contactsCapacity = capacity;

		inFile.read((char*)contactsDB.optrContacts, lengthOfFileInBytes);

		inFile.close();

		return true;

	}
	return false;
}

void SaveContacts(const ContactsDB & contactsDB)
{
	ofstream outFile;

	outFile.open(CONTACTS_FILE_NAME, fstream::binary);

	if(outFile.is_open())
	{
		outFile.write((char*)contactsDB.optrContacts, contactsDB.numberOfContacts * sizeof(Contact));
		outFile.close();
	}
}

void ResizeContactsDB(ContactsDB & contactsDB, int newCapacity)
{
	Contact* newContactsPtr = new Contact[newCapacity];

	for(int i = 0; i < contactsDB.numberOfContacts; i++)
	{
		if(contactsDB.optrContacts != nullptr)
		{
			strcpy( newContactsPtr[i].firstName, contactsDB.optrContacts[i].firstName);
			strcpy( newContactsPtr[i].lastName, contactsDB.optrContacts[i].lastName);
			newContactsPtr[i].phoneNumber = contactsDB.optrContacts[i].phoneNumber;
		}
	}

	if(contactsDB.optrContacts != nullptr)
	{
		delete [] contactsDB.optrContacts;
		contactsDB.optrContacts = nullptr;
	}

	contactsDB.optrContacts = newContactsPtr;
	contactsDB.contactsCapacity = newCapacity;
}

char GetOptionFromUser()
{
	const char options[] = {'d', 'a', 'q'};

	return GetCharacter("Please choose an option:\n\n(D)isplay Contacts\n(A)dd Contact\n(Q)uit\n\nWhat is your choice: ", INPUT_ERROR_STRING, options, 3, CC_LOWER_CASE);
}

void ExecuteOption(char option, ContactsDB & contactsDB)
{
	switch(option)
	{
	case 'a':
		AddOption(contactsDB);
		break;
	case 'd':
		DisplayOption(contactsDB);
		break;
	}
}

void DisplayOption(const ContactsDB& contactsDB)
{
	for(int i = 0; i < contactsDB.numberOfContacts; i++)
	{
		cout << "Name: " << contactsDB.optrContacts[i].firstName << " " << contactsDB.optrContacts[i].lastName << endl;
		cout << "Phone number: " << contactsDB.optrContacts[i].phoneNumber << endl << endl;
	}
}

void AddOption(ContactsDB & contactsDB)
{
	if(contactsDB.numberOfContacts == contactsDB.contactsCapacity)
	{
		ResizeContactsDB(contactsDB, contactsDB.contactsCapacity*2 + 10);
	}

	GetString("Please enter the first name: ", INPUT_ERROR_STRING, contactsDB.optrContacts[contactsDB.numberOfContacts].firstName, MAX_NAME_SIZE-1);
	GetString("Please enter the last name: ", INPUT_ERROR_STRING, contactsDB.optrContacts[contactsDB.numberOfContacts].lastName, MAX_NAME_SIZE-1);

	cout << "Please input the phone number: ";
	cin >> contactsDB.optrContacts[contactsDB.numberOfContacts].phoneNumber;


	contactsDB.numberOfContacts++;

	SaveContacts(contactsDB);

	cout << "Saved!" << endl;

}