package student_classes;

/**
 * Objects of this class prompt the user for the number of points 
 * they earned on a particular exam and the total number of points
 * that are available for that exam. If the user enters the String
 * "quit", the dialog exits and the average is printed.
 * For example:
 * >>>Enter your raw score: 20
 * >>>Out of ? : 25
 * >>>Enter your raw score: 40
 * >>>Out of ? : 40
 * >>>Enter your raw score: -1
 * >>>Your average is 92.3.
 * 
 * Note: the client may provide any flavor of Scanner they'd prefer to 
 * provide the interaction. A default, which uses the Console, is provided by the
 * default ctor.
 * @author tomr55
 *
 */
import java.util.Scanner;

public class AverageCalculator {
// properties:
	private Scanner myReader;
	/* these variables provide a location in this object's
	 * "private" memory where the raw scores and the total
	 * points that the user enters can be accumulated.
	 */
	private double  raw_points_accumulator; // default = 0.0
	private double  total_points_accumulator; // default = 0.0
	
// ctor(s):
	public AverageCalculator( Scanner preferred_reader ) {
		this.myReader = preferred_reader;
	}
	
	/**
	 * default ctor .... uses System.in for the Scanner's stream.
	 */
	public AverageCalculator() {
		// complete this method!!
	}
// public methods (user interface)
	/**
	 * Only method that uses needs ... starts the dialog that is 
	 * terminated with any negative integer.
	 */
	public void start() { 
		/* notice how we use a method call at this point
		 * to serve two purposes at the same time:
		 * (1) to provide a "guard" for the while 
		 * loop (in other words, to provide a way to 
		 * control when we repeat and when we terminate
		 * the loop); and 
		 * (2) to delegate control to the method that
		 * creates the dialog.
		 */
		System.out.println("Type quit at this point, or enter to continue inputting data. ");
		String response = this.myReader.next();
		while( ! (response.equalsIgnoreCase("quit" ))) {
			/* ask the user for raw score and total points */
			showDialog();
			/* offer the user a way out. */
			System.out.println("Type quit at this point, or enter to continue inputting data. ");
			response = this.myReader.next();
		}
		return;
	}
	/**
	 * Call this method to obtain a printed report of the grade point average.
	 */
	public void report() {
		double average = this.computeAvg();
		System.out.println("Average is " + average );
	}
// overrides:
	public String toString() { 
		return "<AverageCalculator>";
	}


// private methods.
	/* We will have lots of these! Ideally, we would like to 
	 * create a suite of private methods that manage the interaction
	 * with the client. If we are successful, our "main" program
	 * basically creates an AverageCalculator and the client
	 * calls start(); to begin.
	 */
	/** although we don't usually document private methods, this one's important:
	 * The sole purpose of this method is to collect data from the user and to
	 * use that data to update the private instance variables on this object.
	 */
	private void showDialog() {
		// TODO Auto-generated method stub
		
	}
	
	private double promptDouble( String msg ) {
		System.out.println( msg );
		return this.myReader.nextDouble();
	}
	
	/** Again: although this is a private method, we document it because its logic
	 * is essential to the success of the object.
	 */
	private double computeAvg() {
		if( this.total_points_accumulator <= 0.0 ) {
			// later: we will replace this code with code that raises an 
			// exception, which is the right thing to do... .
			System.err.println("No average computation possible because the total points is < 0.");
			return 0.0;
		} else { 
			return this.raw_points_accumulator/this.total_points_accumulator;
		}
	}
// main entry point:
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// Create an instance of this class ... asking the
		// user for their preferences re: the Scanner.
		
		
		// call the start method.
		
		// call the report method.
	}

}