// Doing computations in java
import java.util.Scanner; // for the input
import javax.swing.JOptionPane; //for the dialog boxes

/**
 * A MakingCoasters object has a rectangular piece of fabric, defined by its
 * width and length.<br>
 * It can compute the number of coasters of a certain radius that can be cut out
 * of that piece of fabric and the percentage of fabric that goes unused
 */

public class MakingCoasters {
	// instance variables
	// Dimensions of the piece of fabric (in feet)
	private int width;

	private int length;

	// Note: using the same name for more than one method (here for
	// the constructors) is an example of overloading.

	/**
	 * Default constructor for objects of type MakingCoasters.<br>
	 * The dimensions of the piece of fabric are input by the user.<br>
	 * If any input is negative or 0, the corresponding dimension is set to 1
	 * foot.
	 */
	public MakingCoasters() {
		// Initialize the dimensions of the piece of fabric
		// Input from the user via an Scanner object
		Scanner input = new Scanner(System.in);
		System.out.print("Width of the piece of fabric: ");
		width = input.nextInt();
		System.out.print("Length of the piece of fabric: ");
		length = input.nextInt();

		/*
		 * Could also do: Input input = new Input(); width =
		 * input.nextInt("Width of the piece of fabric: "); length =
		 * input.nextInt("Length of the piece of fabric: ");
		 * 
		 * Requires importing the Input class import uwcse.io.Input;
		 */

		// Check that the input is valid (dimension>0)
		// Use a method checkWidthAndLength()
		// (we will use it again in the other constructor)
		checkWidthAndLength();
	}

	/**
	 * MakingCoasters constructor<br>
	 * Width and length are set to w and l if w and l are positive integers.<br>
	 * If any of them is negative or zero, the corresponding dimension is set to
	 * one foot.
	 * 
	 * @param w
	 *            the width of the piece of fabric
	 * @param l
	 *            the length of the piece of fabric
	 */
	public MakingCoasters(int w, int l) {
		width = w;
		length = l;
		checkWidthAndLength();
	}

	/**
	 * Compute the number of coasters of a given radius that can be cut out of
	 * the piece of fabric.
	 * 
	 * @param radius
	 *            the radius of one coaster in feet.
	 */
	public int computeNumberOfCoasters(int radius) {
		// If the radius is negative or 0, no coaster is cut out
		// Display an error message and return 0
		if (radius <= 0) {
			// Note: you can't write a String in Java on several lines, i.e.
			// "Hello,
			// how are you?" gives an error
			// But you can write
			// "Hello, "+
			// "how are you?"
			JOptionPane.showMessageDialog(null, "Can't compute a number of "
					+ "coasters of non positive radius",
					"computeNumberOfCoasters error", JOptionPane.ERROR_MESSAGE);
			return 0;
		} else {
			// Multiply the number of coasters that fit along the length by the
			// number of coasters that fit along the width
			// IMPORTANT NOTE: / between integers is the integer division
			// 50/3 is 16 (not 16.6666)
			int nl = length / (2 * radius);
			int nw = width / (2 * radius);
			int number = nl * nw;
			return number;
			// Could have written
			// return (length/(2*radius))*(width/(2*radius));
			// but not
			// return length/(2*radius)*width/(2*radius);
			// which is syntactically correct, but is not the same expression!
			// e.g. try length is 10, width is 1 and radius is 1
			// (length/(2*radius))*(width/(2*radius)) is 0
			// length/(2*radius)*width/(2*radius) is 2
		}
	}

	/**
	 * Compute the percentage of fabric that goes unused when cutting out
	 * coasters of a given radius
	 * 
	 * @param radius
	 *            the radius of one coaster in feet
	 */
	public double computePercentageUnused(int radius) {
		// If the radius is negative or 0, no coaster is cut out
		if (radius <= 0) {
			JOptionPane.showMessageDialog(null, "Can't have coasters with "
					+ "a non positive radius", "computePercentageUnused error",
					JOptionPane.ERROR_MESSAGE);
			return 100.0; // . is not necessary. Just to make it obvious that
			// a double is returned.
		} else {
			// Area of the piece of fabric
			double fabricArea = width * length;
			// compute the area used for the coasters
			// Math.PI is a constant within the Math class (=3.1415...)
			// There is no exponent in Java. To square radius, write
			// radius*radius
			// (for higher exponents, use the Math.pow method)
			double usedArea = computeNumberOfCoasters(radius) * Math.PI
					* radius * radius;
			// area unused
			double unusedArea = fabricArea - usedArea;
			// return it as a percentage
			return unusedArea / fabricArea * 100.0;
		}
	}

	/**
	 * Check that the width and length are positive integers.<br>
	 * Set to one foot any of them that is negative or 0 and display an error
	 * message.
	 */
	private void checkWidthAndLength() {
		if (width <= 0) {
			width = 1;
			JOptionPane.showMessageDialog(null, "Invalid value for the width."
					+ "\nThe width is set to 1 ft", "Input error",
					JOptionPane.ERROR_MESSAGE);
		}
		if (length <= 0) {
			length = 1;
			JOptionPane.showMessageDialog(null, "Invalid value for the length."
					+ "\nThe length is set to 1 ft", "Input error",
					JOptionPane.ERROR_MESSAGE);
		}
	}

}