// Zeinalipour-Yazti Demetrios
// csyiazti
// cs10xx -
// Lab Sec#24
// lab8
	/*	A program that will compute the monthly payment of a fully amortized loan.
	 */
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <iomanip>

#include <string>
using namespace std;


const int COLSPAN  = 30;	/* defines the width of the first column (on output) */
const int COLSPANB = 14;		/* defines the width of all subsequent columns (on output) */


/* returns true if the given character is an integer */
bool isInt(char c)
{
	return (c>=48 && c<=57);
}


/* returns true if the given string is a real number */
bool isReal(string instring)
{
	int size = instring.size();
	int dotcount = 0;
	char c;
	for (int i=0; i<size; i++)
	{
		c = instring[i];
		if (c=='.')
		{ dotcount++; }
		else if (!isInt(c))
		{ return false; }
	}

	/* check if this number has more than 1 dots '.' */
	if (dotcount<=1)
	{ return true; }
	else
	{ return false; }

}

/* returns true if the given string is a name */
bool isName(string instring)
{
	int size = instring.size();
	char c;	
	for (int i=0; i<size; i++)
	{
		c = instring[i];		
		if ( ((c<65) || (c>122)) )
		{  return false; }
	}
	return true;
}

/* This function asks the user to input the value: type[]
   It then returns this value as a string.
 */
string getName(string type)
{
	 /* defining local scope variables*/
	 string stringvalue = "";

	 while (true)
	 {
		 cout << "\nPlease enter '" << type << "' : ";
		 cin >> stringvalue;
		 if (isName(stringvalue))
		 { break; }
		 else
		 { cout << "#Error - The name has to be a valid name!\n"; }
	 }
     return stringvalue;
}


/* This function asks the user to input the value: type[] repetively until a
 * correct (>0) double value is given. It then returns this value
 */
double getRealNumber(string type)
{
	 /* defining local scope variables - although we are seeking for a double
	    value we will read the users entry as a 'string' (to avoid any exceptions)
		and if the value is a 'double' value we will proceed.
	  */
	 string stringvalue;
	 double value;

	 /* define functions & procedures used */
	 bool isReal(string instring);


	 while (true)
	 {
		 cout << "\nEnter the " << type ;
		 cin >> stringvalue;

		 if (isReal(stringvalue))
		 {
		  /* Converting the string to char array[] (with c_str()) and then
		   * convert to floating value variable with (stdlib::atof())
		   */
		   value = atof(stringvalue.c_str());
		   if (value>0)
		   { break;  }
		 }

		 cout << "#Error - The value entered MUST be positive double value!\n";

	 }

     return value;
}



/* this function computes the Payment according to the formula. We have split it into three
 * segments for readability.
 */
double computePayment(double principal, double interest, double length)
{

	double mpr = interest / (100 * 12);

	double sub_calc =  1 / ( pow(1+mpr, length*12) );

	return (mpr * principal / (1 - sub_calc));
}



/* This procedure outputs a row (with the dollar sign) for the given values */
void printMoneyRow(string label, double value1, double value2)
{
	int shift_val = COLSPAN - label.size();

	//Sets the format flags. 2 decimal points precision.
	cout <<  setprecision(2) << setiosflags(ios::fixed | ios::showpoint);

	/* Print first column - add spaces required to align 2nd column */
	cout << label << setw(shift_val);

	cout << '$';

	// Set extra format flag. Sets a value to be used as the field width for the next insertion operation.
	cout << setw(COLSPANB) << value1 << ' ' << "  $" << setw(COLSPANB) << value2 << ' ' << endl;

	//Reset the format flags.
	cout << resetiosflags (ios::fixed | ios::showpoint);
	cout << setprecision(0);
}


/* This procedure outputs a row (with the percentage sign) for the given values */
void printPercentageRow(string label, double value1, double value2)
{
	int shift_val = COLSPAN - label.size();

	/* Print first column - add spaces required to align 2nd column */
	cout << label << setw(shift_val);

	cout << ' ';

	// Set extra format flag. Sets a value to be used as the field width for the next insertion operation.
	cout << setw(COLSPANB-1) << value1 << '%' << "   " << setw(COLSPANB) << value2 << '%' << endl;

}


/* This procedure outputs a row (without any sign) for the given values */
void printNormalRow(string label, double value1, double value2)
{
	int shift_val = COLSPAN - label.size();

	/* Print first column - add spaces required to align 2nd column */
	cout << label << setw(shift_val);

	cout << ' ';

	// Set extra format flag. Sets a value to be used as the field width for the next insertion operation.
	cout << setw(COLSPANB) << value1 << ' ' << "   " << setw(COLSPANB)  << value2 << ' ' << endl;

}


/* Output the data & results */
void printOutput(string firstname, string lastname,
				double principal1, double principal2,
				double interest1, double interest2,
				double length1, double length2,
				double result1, double result2)
{

	/* define functions & procedures used */
	void printNormalRow(string label, double value1, double value2);
	void printPercentageRow(string label, double value1, double value2);
	void printMoneyRow(string label, double value1, double value2);

		/* print-out intro */
	cout << "\n\n" << firstname << " " << lastname << " here is your comparison data \n\n";

	/* print-out data */
	printMoneyRow("Principal", principal1, principal2);
	printPercentageRow("Annual interest rate", interest1, interest2);
	printNormalRow("Years", length1, length2);
	cout << endl;

	/* print-out results */
	printMoneyRow("Monthly payment", result1, result2);


}



void main()
{
	/* define variables */
	string firstname;			 /* The firstame of the user  */
	string lastname;			 /* The lastname of the user  */

	double principal1, principal2; /* The amounts borrowed	  */
	double interest1, interest2;   /* The yearly interest	  */
	double length1, length2;	   /* The length of loan	  */

	double result1, result2;	   /* The payment			  */

	/* define functions & procedures used */
	string getName(string type);
	double getRealNumber(string type);
	void printOutput(string firstname, string lastname, double principal1, double principal2,
					 double interest1, double interest2,	double length1, double length2amount,
					 double result1, double result2);
	


	/* print intro */
	cout << "Calculator of the monthly payment of a fully amortized loan.\n";
	cout << "by Demetris Zeinalipour : cs10 #24.\n\n";

	/* get Values from user  */
	firstname = getName("First Name");
    lastname  = getName("Last Name");

	principal1 = getRealNumber("The #1 Principal Amount borrowed : $");
	principal2 = getRealNumber("The #2 Principal Amount borrowed : $");

	interest1 = getRealNumber("The #1 Annual interest rate : %");
	interest2 = getRealNumber("The #2 Annual interest rate : %");

	length1 = getRealNumber("The #1 Length of the loan (in years) : ");
	length2 = getRealNumber("The #2 Length of the loan (in years) : ");

	/* making the calculation of the payment */
	result1 = computePayment(principal1, interest1, length1);
	result2 = computePayment(principal2, interest2, length2);

	//prints the output of the program
	printOutput(firstname, lastname, principal1, principal2,
				interest1, interest2, length1, length2, result1, result2);
	
	char empty;
	cout << "Press 'q' to exit!";
	cin >> empty;

}