package rebelsky.newvec;

import java.io.PrintWriter;

/**
 * Something that willingly helps with a variety of tasks.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of September 2004
 */
public class GraduateAssistant
{
// +--------+--------------------------------------------------
// | Fields |
// +--------+

	/** 
	 * The pen the assistant uses to write everything.
	 */
	PrintWriter pen;

// +--------------+--------------------------------------------
// | Constructors |
// +--------------+

	/**
	 * Create a new assistant that uses a particular pen.
	 */
	public GraduateAssistant(PrintWriter _pen)
	{
		this.pen = _pen;
	} // GraduateAssistant(PrintWriter)

// +---------+-------------------------------------------------
// | Methods |
// +---------+

	/**
	 * Print a message that depends on the closeness of a vector
	 * to the origin.
	 */
	public void checkClose(Vec2D vec)
	{
		if ((Math.abs(vec.getX()) > 0.1) ||
			(Math.abs(vec.getY()) > 0.1)) {
			pen.println("Not near the origin.");
		}
		else {
			pen.println("Near the origin.");
		}
	} // checkClose(Vec2D)
	
	/**
	 * Describe a two dimensional vector.
	 */
	public void describe(Vec2D vec)
	{
		pen.println("Self description: " + vec.toString());
		pen.println("(x,y): (" + vec.getX() + "," + vec.getY() +")");
		pen.println("theta: " + vec.getAngle());
		pen.println("radius: " + vec.getRadius());
	} // describe(Vec2D)

	/**
	 * Describe something that can be expressed as a real number.
	 */
	public void describeR(CanBeExpressedAsARealNumber r)
	{
		pen.println(r.toString() + " can be expressed as " + r.asReal());
	} // describeR(CanBeExpressedAsARealNumber)
	
	/**
	 * Test a two dimensional vector in a variety of ways.
	 */
	public void test(Vec2D vec)
	{
		pen.println("*** Original ***");
		this.describe(vec);
		pen.println("***** Unit *****");
		this.describe(vec.unitVector());
		pen.println("** Rotate pi/4 **");
		this.describe(vec.rotate(Math.PI/4.0));
		pen.println("** Rotate pi/2 **");
		this.describe(vec.rotate(Math.PI/2.0));
		pen.println("*** Rotate pi ***");
		this.describe(vec.rotate(Math.PI));
	} // test(Vec2D)

} // class GraduateAssistant