package com.evanhoffman.interest;

import java.text.DecimalFormat;
import java.text.NumberFormat;

public class InterestCalculator {

	static final NumberFormat df = new DecimalFormat("##0.00");

	
	static double getAmountWithInterest(double initialPrincipal, double interestRate, int periodsPerYear, int totalYears) {
		
		double p = initialPrincipal * Math.pow((1 + (interestRate / periodsPerYear)),(periodsPerYear*totalYears));
		return p;
	}
	
	static double getAmountWithContinuouslyCompoundedInterest(double initialPrincipal, double interestRate, int totalYears) {
		double p = initialPrincipal * Math.pow(Math.E,(interestRate *totalYears));
		return p;
	}
	
	static void printAmountWithInterest(double initialPrincipal, double interestRate, int periodsPerYear, int totalYears, double annualAddition) {

		double v = initialPrincipal;
		double periodicRate = interestRate / periodsPerYear;
		
		for (int currentYear = 1; currentYear <= totalYears; currentYear++) {
			System.out.println("Starting year "+currentYear+" with $"+df.format(v));
			for (int currentPeriod = 1; currentPeriod <= periodsPerYear; currentPeriod++) {
				double periodInterest = v *  periodicRate;
				v = v + periodInterest;
				System.out.println("Year "+currentYear+", period "+currentPeriod+", accrued $"+df.format(periodInterest)+", value is now: $"+df.format(v));
			}
			v += annualAddition;
			System.out.println("Added $"+df.format(annualAddition)+" for the end of year "+currentYear+", total is now: "+df.format(v));
		}
		
		System.out.println("Final value: $"+df.format(v));
		
//		double p = initialPrincipal * Math.pow((1 + (interestRate / periodsPerYear)),(periodsPerYear*totalYears));
	}
	

	
	static final int pIndex = 0;
	static final int rIndex = 1;
	static final int nIndex = 2;
	static final int tIndex = 3;
	static final int aIndex = 4;
	
	
	public static void main(String args[]) {
		double p = Double.parseDouble(args[pIndex]);
		double r = Double.parseDouble(args[rIndex]);
		int n = Integer.parseInt(args[nIndex]);
		int t = Integer.parseInt(args[tIndex]);
		double a = Double.parseDouble(args[aIndex]);
		
		System.out.println("Initial principal: "+df.format(p));
		System.out.println("Interest rate:     "+df.format(r)+" ("+df.format(r*100)+"%)");
		System.out.println("# of ann. periods: "+n);
		System.out.println("Total years:       "+t);
		System.out.println("Annual Addition:   "+a);
//		System.out.println("Total with finite compounding:     "+df.format(getAmountWithInterest(p, r, n, t)));
//		System.out.println("Total with continuous compounding: "+df.format(getAmountWithContinuouslyCompoundedInterest(p, r, t)));
		printAmountWithInterest(p, r, n, t, a);
	}
}