package cse1030.test2;

import cse1030.drawing.Point2D;

/**
 * A class for finding two dimensional points that are strictly within a square
 * neighbourhood surrounding a point.
 * 
 * @author CSE1030_F13_14
 * 
 */
public class PointInSquare extends PointMatcher {

  private double h;

  /**
   * Creates an object that matches all points strictly within a square
   * neighbourhood surrounding the point <code>p</code>. The size of the square
   * is determined by the parameter <code>halfLength</code> which is one half of
   * the length of the side of the square (see figure below).
   * 
   * <p>
   * <img src="./pointinsquare.png" />
   * </p>
   * 
   * @param p
   *          the point at the center of the square neighbourhood
   * @param halfLength
   *          half the length of the side of the square
   */
  public PointInSquare(Point2D p, double halfLength) {
    super(p);
    if (halfLength < 0) {
      throw new IllegalArgumentException("half length is less than zero");
    }
    this.h = halfLength;
  }
  
  /**
   * Returns the size of the square neighbourhood used for matching.
   * The size is equal to one-half of the length of the side of the square.
   * 
   * @return the half length of the side of the square neighbourhood
   */
  public double getHalfLength() {
    return this.h;
  }

  /**
   * Checks if the point <code>other</code> is strictly inside the square
   * neighbourhood surrounding the point held by this matcher. If
   * <code>other</code> has coordinates <code>(x, y)</code>, and the point held by
   * this matcher has coordinates <code>(px, py)</code>, and the half length of
   * the square neighbourhood is <code>h</code>, then the result is
   * <code>true</code> if and only if:
   * 
   * <p>
   * <code>| px - x | < h</code> &nbsp;is&nbsp; <code>true</code>
   * 
   * <p>
   * AND
   * 
   * <p>
   * <code>| py - y | < h</code> &nbsp;is&nbsp; <code>true</code>
   * 
   * @param other
   *          the point to check for a match
   * @return <code>true</code> if <code>other</code> is strictly inside the
   *         square neighbourhood surround the point held by this matcher
   * @see cse1030.test2.PointMatcher#matches(cse1030.drawing.Point2D)
   */
  @Override
  public boolean matches(Point2D other) {
    return Math.abs(this.point.getX() - other.getX()) < this.h
        && Math.abs(this.point.getY() - other.getY()) < this.h;
  }
}