// CSE 142, Spring 2010, Marty Stepp
// This program computes two people's body mass index (BMI) and
// compares them.  The code uses Scanner for input, and parameters/returns.
// It is also useful as an example of procedural design decisions.

import java.util.*;  // so that I can use Scanner

public class BMI {
    public static void main(String[] args) {
        System.out.println("This program reads ... (etc.)");
        Scanner console = new Scanner(System.in);
        double bmi1 = processPerson(console);
        double bmi2 = processPerson(console);
        
        double difference = Math.abs(bmi1 - bmi2);
        System.out.printf("Difference = %.2f\n", difference);
    }
    
    // Reads and computes the body mass data for one person.
    // Returns the person's body mass index (BMI).
    public static double processPerson(Scanner console) {
        double height = doHeight(console);
        double weight = doWeight(console);
        double bmi = doBMI(weight, height);
        doWeightClass(bmi);
        return bmi;
    }

    // Reads and returns a person's height.
    public static double doHeight(Scanner console) {
        System.out.println("Enter next person's information:");
        System.out.print("height (in inches)? ");
        double height = console.nextDouble();
        return height;
    }

    // Reads and returns a person's weight.
    public static double doWeight(Scanner console) {
        System.out.print("weight (in pounds)? ");
        double weight = console.nextDouble();
        return weight;
    }

    // Computes and returns a person's body mass index (BMI) based
    // on the given weight and height.
    public static double doBMI(double weight, double height) {     
        double bmi = weight * 703 / height / height;
        System.out.printf("Person #1 BMI = %.2f\n", bmi);
        return bmi;
    }
    
    // Outputs the person's general weight class as specified by the US CDC
    // based on the given body mass index.
    public static void doWeightClass(double bmi) {
        if (bmi < 18.5) {
            System.out.println("underweight");
        } else if (bmi < 25) {
            System.out.println("normal");
        } else if (bmi < 30) {
            System.out.println("overweight");
        } else {
            System.out.println("obese");
        }
    }
}