#include <iostream>
#include <iomanip>
#include <cmath>
#define FleetAvg = 25.0


double tripMileage;
double CostPerMile;
double TripCost;
double overallMPG;
double totalMiles = 0;
double totalGallons = 0;
double totalCost = 0;
double gallons;
double miles;
double price;
double MileageComp;

char ANSWER;


double getGallons();
double getMiles();
double getPricePerGallon();
double calcTripMileage (double miles, double gallons);
double calcTripCost (double price, double gallons);
double calcTripCostPerMile (double TripCost, double miles);
double calcOverallMPG (double totalMiles, double totalGallons);
void showOneTrip (double TripMileage, double TripCost, double TripCostPerMile);
void showTotals (double totalMiles, double totalGallons, double totalCost, double overallMPG);
void showMileageComparison (double overallMPG);


using namespace std;






double getGallons()
{

double gallons;

	cout << "Enter the number of gallons of fuel: ";
	cin >> gallons;
		
	while (gallons <= 0 || gallons > 40)
		{
			cout << "\n\n";
			cout << "Out of range: must be between 0 and 40 gallons. Re-enter: ";
			cin >> gallons;
			cout << "\n";
		}
}

double getMiles()
{
	
double miles;

	cout << "Enter the number of miles: ";
	cin >> miles;	
		
	while (miles <= 0 || miles > 800)
		{
			cout << "\n\n";
			cout << "Out of range: must be between 0 and 800 miles. Re-enter: ";
			cin >> miles; 
			cout << "\n";	 	 	 
		}
}

double getPricePerGallon()
{

double price;

	cout << "Enter the price per gallon: ";
	cin >> price;
	
	while (price <= 2 || price > 7)
		{
			cout << "\n\n";
			cout << "Out of range: must be between $2.00 and $7.00 dollars. Re-enter: ";
			cin >> price;
			cout << "\n";
		}
	return price;
}

double calcTripMileage (double miles, double gallons)
{

double tripMileage;

	if (gallons == 0)
		{
			tripMileage = 0;
		}
	else if (gallons > 0)
		{
			tripMileage = miles / gallons;
		}
	return tripMileage;
}

double calcTripCost (double price, double gallons)
{

 double TripCost;
 
 	TripCost = price * gallons;
	
	return TripCost;
}

double calcTripCostPerMile (double TripCost, double miles)
{

double CostPerMile;

	if (miles == 0)
		{
			CostPerMile = 0;
		}
	else if (miles > 0)
		{
			CostPerMile = TripCost / miles;
		}
	return CostPerMile;
	
}


double calcOverallMPG (double totalMiles, double totalGallons)
{

double overallMPG;

	if (totalGallons == 0)
		{
			overallMPG = 0;
		}
	else if (totalGallons > 0)
		{
			overallMPG = totalMiles/totalGallons;
		}
	return overallMPG;
				
}



void showOneTrip (double TripMileage, double TripCost, double TripCostPerMile)
{


	cout << "Trip Mileage:           " << fixed << showpoint << setprecision(2) << tripMileage << " MPG" << endl;
	cout << "Trip Cost:             $" << fixed << showpoint << setprecision(2) << TripCost << endl;
	cout << "Trip cost per mile:    $" << fixed << showpoint << setprecision(2) << CostPerMile << endl;
	
}


void showTotals (double totalMiles, double totalGallons, double totalCost, double overallMPG)
{

	cout << "Total Miles:     " << totalMiles << endl;
	cout << "Total Gallons:     " << totalGallons << endl;
	cout << "Total Cost:     " << totalCost << endl;
	cout << "Overall MPG:     " << overallMPG << endl;
}

void showMileageComparison (double overallMPG)
{
float MileageComp = overallMPG - FleetAvg;

		if (MileageComp > 0)
			{
				cout <<	 "Your vehicle's mileage is greater than the fleet average by " << MileageComp << "mpg.";
			}
		else if (MileageComp == 0)
			{
				cout << "Your vehicle's mileage is equal to the fleet average of " << FleetAvg << "mpg.";
			}
		else if (MileageComp < 0)
			{
				cout << "Your vehicle's mileage is is less than the fleet average by " << MileageComp << "mpg.";
			}
}


int main()

{
	cout << "     Fuel Usage Analysis";
	cout << "\n\n";
	
do 
{
		gallons = getGallons ();
		miles = getMiles ();	
		price = getPricePerGallon ();
			
		cout << "\n\n";
		showOneTrip (tripMileage, TripCost, CostPerMile);
		cout << "\n\n";
		
	calcTripMileage (miles, gallons);	 
	calcTripCost (price, gallons);
	calcTripCostPerMile (TripCost, miles);	   
	
		
	 totalMiles += miles;
	 totalGallons += gallons;
	 totalCost += TripCost;
	
		overallMPG = calcOverallMPG (totalMiles, totalGallons);
				
		cout << "Another? (y or n) ";
		cin >> ANSWER;
			
}

while((ANSWER == 'Y')||(ANSWER == 'y'));

cout << "\n\n";
	
	showTotals (totalMiles, totalGallons, totalCost, overallMPG);
	
cout << "\n\n";

	showMileageComparison (overallMPG);	   
	

return 0;

}