// Helene Martin, CSE 142
// This program computes two people's body mass index.

// to see bad versions of this program and why they are bad,
// read "procedural design heuristics" on page 291

import java.util.*;  // for Scanner

public class BMICalculator {
   public static void main(String[] args) {
      Scanner console = new Scanner(System.in);
      
      introduction();
      
      double bmi1 = calculateBMI(console);
      double bmi2 = calculateBMI(console);
      
      reportResults(bmi1, bmi2);
      
      System.out.println("Difference = " + round(Math.abs(bmi1 - bmi2), 2));
   }
   
   // Prints an introduction for the program.
   public static void introduction() {
      System.out.println("This program reads in data for two people and");
      System.out.println("computes their body mass index (BMI)");
      System.out.println();
   }
   
   // Prompts for height and weight then calculates and returns
   // body mass index.
   public static double calculateBMI(Scanner console) {
      System.out.println("Enter next person's information:");
      System.out.print("height (in inches)? ");
      double height = console.nextDouble();
      System.out.print("weight (in pounds)? ");
      double weight = console.nextDouble();
      
      double bmi = bmiFor(weight, height);
      return bmi;
   }
   
   // Calculates and returns body mass index for specified weight and height
   public static double bmiFor(double weight, double height) {
      return weight / Math.pow(height, 2) * 703;
   }
   
   // Calculates and returns the bmi class based on a
   // chart published by the Centers for Disease Control and Prevention
   public static String calculateWeightClass(double bmi) {
      if (bmi < 18.5) {
         return "underweight";
      } else if (bmi < 25) {
         return "normal";
      } else if (bmi < 30) {
         return "overweight";
      } else {
         return "obese";
      }
   }
   
   // Reports the bmi and weight class for two people on the console
   public static void reportResults(double bmi1, double bmi2) {
      System.out.println("Person 1 BMI = " + bmi1);
      System.out.println(calculateWeightClass(bmi1));
      
      System.out.println("Person 2 BMI = " + bmi2);
      System.out.println(calculateWeightClass(bmi2));
   }
   
   // Rounds a value to a given number of digits.
   public static double round(double value, int digits) {
      return Math.round(value * Math.pow(10, digits)) / Math.pow(10, digits);
   }
}