/* Lesley Hogan
 * July 15th 2003
 * MathVariables.java
 * Some common-ish math functions
 * Homework from:
 * http://teachertech.rice.edu/Participants/marilynt/Lessons/Exeter/Programming/mathlab.html
 */

package net.bunnie.dos;

import java.text.DecimalFormat;
import net.bunnie.*;

public class MathVariables {
    public static void main (String[] args) {

		// temperature variables
		double degreesF = 0;
		double degreesC = 0;
		String degreesCString;
		String continues = "";

		// km to school variables
		double averageSpeed = 0;
		double minutesToSchool = 0;

		// e=mc^2 variables
		double mass;
		double energy;
		double bulbs;

		// sleep variables
		int day;
		int month;
		int year;
		int tDay;
		int tMonth;
		int tYear;
		int alive;
		int sHours;
		double sDays;

		// general variables
		KeyboardReader r = new KeyboardReader();
		DecimalFormat dec = new DecimalFormat("#.##");
		boolean loop = false;
		boolean fullLoop = true;
		int switchInt = 0;

		// array of options
		String[] optionList = new String[6];
		String optionString = "";
		int options = optionList.length - 1;
		optionList[0] = "0: View this menu";
		optionList[1] = "1: Convert a temperature from F to C";
		optionList[2] = "2: Calculate the time it will take for you to get to school";
		optionList[3] = "3: Calculate energy using E=MC^2";
		optionList[4] = "4: Calculate how long you have slept in your life";
		optionList[options] = "" + options + ": Press " + options + " to escape";

		int i = 0;
		do {
			optionString += optionList[i];
			optionString += "\n";
			i++;
		}
		while (i < optionList.length);

		// welcome message
		System.out.print("-----------------------------------\n");
		System.out.print("    M A T H   V A R I A B L E S    \n");
		System.out.print("          L .   H O G A N          \n");
		System.out.print("                 _______           \n");
		System.out.print("       |    |       |        |     \n");
		System.out.print("       |    |       |        |     \n");
		System.out.print("       |____|       |        |     \n");
		System.out.print("       |    |       |        |     \n");
		System.out.print("       |    |       |              \n");
		System.out.print("       |    |    ___|___     +     \n\n");
		System.out.print("-----------------------------------\n\n\n");

		// print out list of options and let user choose
		// what they want to do in the program
		do {
			switch(switchInt) {
			case 0:
				// show menu
				System.out.print("What would you like to do today?\n");
				System.out.print(optionString + "\n");
				switchInt = r.readInt();
				break;
			case 1:
				// temperature conversion, in loop for ease of repeat
				do {
				    System.out.print("Enter the temperature in Farenheit: ");
				    degreesF = r.readDouble();

				    degreesC = (5.0 / 9.0) * (degreesF - 32.0);
				    degreesCString = dec.format(degreesC);
				    System.out.print("The temperature in Celsius is " + degreesCString + " degrees.\n\n");

				    System.out.print("Would you like to convert another number? Y/N\n");
				    continues = r.readLine().toLowerCase();
				    if ((continues.equals("y")) || (continues.equals("yes"))) {
						loop = true;
					}
					else {
						loop = false;
					}
					System.out.print('\n');
				}
				while (loop == true);
				switchInt = 0;
				break;
			case 2:
				// time to get to school
				System.out.print("Enter your average speed, in km per hour: ");
				averageSpeed = r.readDouble();

				minutesToSchool = 60 * (32.0 / averageSpeed);
				System.out.print("The trip to school will take " + dec.format(minutesToSchool) + " minutes.\n\n");

				switchInt = 0;
				break;
			case 3:
				// e = mc^2
				System.out.print("Enter the mass in kg: ");
				mass = r.readDouble();

				energy = mass * Math.pow((3.0 * Math.pow(10,8)), 2);
				System.out.print("This mass could produce " + energy + " Joules of energy.\n");

				bulbs = energy / 360000.0;
				System.out.print("It could power " + bulbs + " 100-watt light bulbs for an hour.\n\n");

				switchInt = 0;
				break;
			case 4:
				// how long have you slept
				System.out.print("Enter your birthdate (using number for months):\n");
				System.out.print("Month: ");
				month = r.readInt();
				System.out.print("Day: ");
				day = r.readInt();
				System.out.print("Year: ");
				year = r.readInt();
				System.out.print("\n\nEnter today's date (using numbers for months):\n");
				System.out.print("Month: ");
				tMonth = r.readInt();
				System.out.print("Day: ");
				tDay = r.readInt();
				System.out.print("Year: ");
				tYear = r.readInt();

				alive = ((tYear - year) * 365) + ((tMonth - month) * 30) + (tDay - day);
				sHours = alive * 8;
				sDays = sHours / 24.0;

				System.out.print("\n\nYou have been alive for " + alive + " days.\n");
				System.out.print("You have slept " + dec.format(sHours) + " hours.\n");
				System.out.print("You have slept " + dec.format(sDays) + " days.\n\n");

				switchInt = 0;
				break;
			default:
				// exit program
				fullLoop = false;
				break;
			}
		}
		while (fullLoop == true);
	}
}