#include<string>
#include<iostream>
#include<fstream>
#include<iomanip>
using namespace std;

void print();
int selection();
void save();
void dataEntry();
void load();
void calculate(int);
void editstud();
int getIndex();
void deletestud();

int dataPtr=0;
string filename;
string names[10];
int exam1[10];
int exam2[10];
int exam3[10];
int final[10];
float avg[10];
char g[10];
ifstream infile;
ofstream outfile;

int main()
{
	char a;
	cout << "Would you like to enter data from an existing file (y/n)?  ";
	cin >> a;
	cout << endl;
	if(a=='y')
		load();

	int select(0);
	while(select != 9)
	{
		select=selection();
		switch(select)
		{
			case 1:
				print();
				break;
			case 2:
				dataEntry();	
				break;
			case 3:
				editstud();
				break;
			case 4:
				deletestud();
				break;
//			case 5:
//				sort();
//				break;
		}
	}
	save();
	return 0;
}

void editstud()
{
	int j(1);
	while(j != 0)
	{
		int i = getIndex();	
		cout << "Current value of entry " << i+1;
		cout << " for " << names[i] << " is: " << endl;
		cout << exam1[i]<<" "<<exam2[i]<<" "<<exam3[i]<<" "<<final[i]<< endl;
		cout << "Enter new value: " << endl;
		cin >> exam1[i]>> exam2[i] >> exam3[i] >> final[i];
		cout << "New value of entry " << i+1 << " for " << names[i] << " is: " << endl; 
		cout << exam1[i]<<" "<<exam2[i]<<" "<<exam3[i]<<" "<<final[i]<< endl;
		cout << endl << "Enter 0 to exit or any ";
		cout << "other value to continue editing: ";
		cin >> j;
		calculate(i);
	}
	return;
}

int getIndex()
{
	int i(0);
	while(i < 1 || i > 10)
	{
		cout << endl << "Please enter index of item ";
		cout << "you wish to enter." << endl;
		cout << "Index should be between 1 and 10"<< endl;
		cin >> i;
		if(i < 1 || i > 10)
			cout << "Please enter a number per";
			cout << "following instructions:" << endl;
	}
	return i-1;
}

void deletestud()
{
//	int i(0);
//	int n(0);
	int i;
		cout << endl << "Please enter index of item to be deleted: ";
		cin >> i;
	for (int j = i; j<dataPtr; j++) { 
	names[j] = names[j+1];
	exam1[j] = exam1[j+1];
        exam2[j] = exam2[j+1];
        exam3[j] = exam3[j+1];
        final[j] = final[j+1];
	}
	dataPtr--;		
//		getline(cin, names[i]);
//		int* a = NULL;            
//		a = new int[n]; 
//		a[i] = 0;
//		delete [] a;  
//		a = NULL;  
		return;
}

int selection()
{ 
	int i = 0;
	while(i != 1 && i != 2 && i != 9 && i != 3 && i != 4 && i != 5)
	{
		cout << endl << "Please enter activity selection: " << endl;
		cout << "  1 - Print Student Grades" << endl;
		cout << "  2 - Add Student" << endl;
		cout << "  3 - Edit Student" << endl;
		cout << "  4 - Delete Student" << endl;
		cout << "  5 - Sort Students" << endl;
		cout << "  9 - Exit" << endl;
		cin >> i;
	}
	return i;
}

void dataEntry()
{
	cout << "Please enter student name: ";
	cin >> names[dataPtr];
	cout << "Please enter four exam grades: "<<endl<<endl;
	cin >> exam1[dataPtr];
	cin >> exam2[dataPtr];
	cin >> exam3[dataPtr];
	cin >> final[dataPtr];
	calculate(dataPtr);
	dataPtr++;
	return;
}

void print()
{
cout << endl;
cout <<"  Index   Student  Exam 1   Exam 2   Exam 3   Final   Average   Letter" << endl; 
for(int i=0; i<dataPtr; i++)
{
cout << "   " << i+1 << setw(12)<<names[i]<<setw(8)<<exam1[i]<<setw(9)<<exam2[i]<<setw(9)<<exam3[i]<<setw(8)<<final[i]<<setw(10)<<avg[i]<<setw(7)<<g[i]<<endl;
}
return;
}

void save()
{
	cout << "Enter filename to save output " << endl;
	cout << "example - saved.txt          :  ";
	cin >> filename;
	cout << endl;
	cout << endl;
	cout << "---------------------------------------------------------------------" << endl;
	cout << "File saved in:      " << filename << endl;
	cout << "---------------------------------------------------------------------" << endl;
	cout << endl;
	outfile.open(filename.c_str());
	for(int i = 0; i<dataPtr; i++)
		outfile << names[i]<<" "<<exam1[i]<<" "<<exam2[i]<<" "<<exam3[i]<<" "<<final[i]<<" "<<avg[i]<<" "<<g[i]<<endl;
	outfile.close();
	return;
}
void load()
{
	cout << "Enter filename to read from  " << endl;
	cout << "example - data.txt         :  ";
	cin >> filename;
	infile.open(filename.c_str());
	int loaded=0;
	while(!infile.eof())
	{
		infile >> names[loaded]>>exam1[loaded]>>exam2[loaded]>>exam3[loaded]>>final[loaded]>>avg[loaded]>>g[loaded];
		calculate(loaded);

		if(names[loaded]=="")
			break;
		loaded++;
	}
	dataPtr=loaded;
	infile.close();
	return;
}

void calculate(int i)
{
	avg[i]=((exam1[i]+exam2[i]+exam3[i]+final[i])/4);

	if(avg[i] <= 100 && avg[i] > 89.9)
		g[i]='A';
	else if(avg[i] <= 89.9 && avg[i] > 79.9)
		g[i]='B';
	else if(avg[i] <= 79.9 && avg[i] > 69.9)
		g[i]='C';
	else if(avg[i] <= 69.9 && avg[i] > 59.9)
		g[i]='D';
	else g[i]='F';
return;
}