/*
    * Copyright (C) 2017 Alberto Irurueta Carro (alberto@irurueta.com)
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *         http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.irurueta.geometry;
  
  import java.io.Serializable;
  import java.util.Objects;
  
  /**
   * Subclass of Point2D defining an inhomogeneous 2D point.
   * An inhomogeneous 2D point is defined by two coordinates: (x, y), where x and
   * y are the horizontal and vertical coordinates, respectively.
   * Homogeneous 2D points can be transformed into inhomogeneous ones by
   * normalizing both x and y coordinates by the w factor as follows:
   * Homogeneous 2d point (x,y,w) -< Inhomogeneous 2D point (x/w,y/w).
   * Note that if and homogeneous 2D point is at infinity (w=0), its corresponding
   * inhomogeneous point will be at infinity by setting (x=inf,y=inf). Because of
   * this, and because of machine precision, usually Homogeneous points are better
   * suited when working at far distances or for numerical purposes, and their
   * inhomogeneous counterparts are better suited when computing Euclidean
   * distances, etc.
   */
  public class InhomogeneousPoint2D extends Point2D implements Serializable {
  
      /**
       * Defines the X coordinate of an inhomogeneous 2D point.
       */
      private double x;
  
      /**
       * Defines the Y coordinate of an inhomogeneous 2D point.
       */
      private double y;
  
      /**
       * Empty constructor.
       */
      public InhomogeneousPoint2D() {
          super();
          x = y = 0.0;
      }
  
      /**
       * Constructor of this class. This constructor sets a new inhomogeneous v
       * array containing the coordinates X and Y of the given point.
       *
       * @param v Array of length 2 containing the 2D coordinates of an
       *          inhomogeneous point.
       * @throws IllegalArgumentException Raised when the size of the array is not
       *                                  2.
       */
      public InhomogeneousPoint2D(final double[] v) {
          super();
          setCoordinates(v);
      }
  
      /**
       * Constructor of this class. This constructor sets a new inhomogeneous 2D
       * point using the coordinates x and y of the given point.
       *
       * @param x X coordinate of the given 2D point.
       * @param y Y coordinate of the given 2D point.
       */
      public InhomogeneousPoint2D(final double x, final double y) {
          this.x = x;
          this.y = y;
      }
  
      /**
       * This constructor sets a new inhomogeneous 2D point using as
       * initialization provided Point2D instance.
       *
       * @param point Point to initialize new instance to.
       */
      public InhomogeneousPoint2D(final Point2D point) {
          setCoordinates(point);
      }
  
      /**
       * Returns the X coordinate of the given homogeneous 2D point instance.
       *
       * @return X coordinate.
       */
      public double getX() {
          return x;
      }
 
     /**
      * Sets the X coordinate of this homogeneous point.
      *
      * @param x X coordinate.
      */
     public void setX(final double x) {
         this.x = x;
     }
 
     /**
      * Returns the Y coordinate of the given homogeneous 2D point instance.
      *
      * @return Y coordinate.
      */
     public double getY() {
         return y;
     }
 
     /**
      * Sets the Y coordinate of this homogeneous point.
      *
      * @param y Y coordinate.
      */
     public void setY(final double y) {
         this.y = y;
     }
 
     /**
      * Sets the coordinates of this inhomogeneous 2D point by using provided X
      * and Y coordinates.
      *
      * @param x X coordinate.
      * @param y Y coordinate.
      */
     public void setCoordinates(final double x, final double y) {
         this.x = x;
         this.y = y;
     }
 
     /**
      * Sets the coordinates of a 2D point using an array containing its
      * coordinates.
      *
      * @param v Array containing the coordinates of the point.
      * @throws IllegalArgumentException Raised if provided array does not have a
      *                                  valid size.
      */
     @Override
     public final void setCoordinates(final double[] v) {
         if (v.length != POINT2D_INHOMOGENEOUS_COORDINATES_LENGTH) {
             throw new IllegalArgumentException();
         } else {
             x = v[0];
             y = v[1];
         }
     }
 
     /**
      * Sets coordinates of this instance using the coordinates of provided 2D
      * point.
      *
      * @param point Input point.
      */
     @Override
     public final void setCoordinates(final Point2D point) {
         switch (point.getType()) {
             case INHOMOGENEOUS_COORDINATES:
                 final var inhomPoint = (InhomogeneousPoint2D) point;
                 x = inhomPoint.getX();
                 y = inhomPoint.getY();
                 break;
             case HOMOGENEOUS_COORDINATES:
             default:
                 final var homPoint = (HomogeneousPoint2D) point;
                 x = homPoint.getInhomX();
                 y = homPoint.getInhomY();
                 break;
         }
     }
 
     /**
      * Returns X homogeneous coordinate of this 2d point.
      *
      * @return X homogeneous coordinate.
      */
     @Override
     public double getHomX() {
         return getX();
     }
 
     /**
      * Returns Y homogeneous coordinate of this 2d point.
      *
      * @return Y homogeneous coordinate.
      */
     @Override
     public double getHomY() {
         return getY();
     }
 
     /**
      * Returns W homogeneous coordinate of this 2d point.
      *
      * @return W homogeneous coordinate.
      */
     @Override
     public double getHomW() {
         return 1.0;
     }
 
     /**
      * Sets coordinates of this 2d point instance using provided homogeneous
      * coordinates.
      *
      * @param homX x homogeneous coordinate.
      * @param homY y homogeneous coordinate.
      * @param homW w homogeneous coordinate.
      */
     @Override
     public void setHomogeneousCoordinates(final double homX, final double homY, final double homW) {
         x = homX / homW;
         y = homY / homW;
     }
 
     /**
      * Returns X inhomogeneous coordinate of this 2d point.
      *
      * @return X inhomogeneous coordinate.
      */
     @Override
     public double getInhomX() {
         return getX();
     }
 
     /**
      * Sets X inhomogeneous coordinate of this 2d point.
      *
      * @param inhomX inhomogeneous coordinate.
      */
     @Override
     public void setInhomX(final double inhomX) {
         x = inhomX;
     }
 
     /**
      * Returns Y inhomogeneous coordinate of this 2d point.
      *
      * @return Y inhomogeneous coordinate.
      */
     @Override
     public double getInhomY() {
         return getY();
     }
 
     /**
      * Sets Y inhomogeneous coordinate of this 2d point.
      *
      * @param inhomY Y inhomogeneous coordinate.
      */
     @Override
     public void setInhomY(final double inhomY) {
         y = inhomY;
     }
 
     /**
      * Sets coordinates of this 2d point instance using provided inhomogeneous
      * coordinates.
      *
      * @param inhomX x inhomogeneous coordinate.
      * @param inhomY y inhomogeneous coordinate.
      */
     @Override
     public void setInhomogeneousCoordinates(final double inhomX, final double inhomY) {
         setCoordinates(inhomX, inhomY);
     }
 
     /**
      * Checks if provided object equals current 2D point.
      *
      * @param obj Object to compare.
      * @return True if both objects are considered to be equal, false otherwise.
      */
     @Override
     public boolean equals(final Object obj) {
         if (!(obj instanceof Point2D point)) {
             return false;
         }
         if (obj == this) {
             return true;
         }
 
         return equals(point);
     }
 
     /**
      * Returns hash code value.
      *
      * @return Hash code value.
      */
     @Override
     public int hashCode() {
         return Objects.hash(x, y, 1.0);
     }
 
     /**
      * Checks if the homogeneous 2d point described by this instance equals the
      * input {@link Point2D} (using a comparison threshold).
      *
      * @param point     Point that will be compared to.
      * @param threshold threshold grade of tolerance to determine whether the
      *                  points are equal or not. It is used because due to machine precision, the
      *                  values might not be exactly equal (if not provided
      *                  DEFAULT_COMPARISON_THRESHOLD is used).
      * @return True if current point and input point are the same, false
      * otherwise.
      * @throws IllegalArgumentException Raised if threshold is negative.
      */
     @Override
     public boolean equals(final Point2D point, final double threshold) {
         if (point.getType() == CoordinatesType.INHOMOGENEOUS_COORDINATES) {
             return equals((InhomogeneousPoint2D) point, threshold);
         } else {
             return equals((HomogeneousPoint2D) point, threshold);
         }
     }
 
     /**
      * Checks if the homogeneous 2d point described by this instance equals the
      * input HomogeneousPoint2d (using a comparison threshold).
      *
      * @param point     Point that will be compared to.
      * @param threshold threshold grade of tolerance to determine whether the
      *                  points are equal or not. It is used because due to machine precision, the
      *                  values might not be exactly equal (if not provided
      *                  DEFAULT_COMPARISON_THRESHOLD is used).
      * @return True if current point and input point are the same, false
      * otherwise.
      * @throws IllegalArgumentException Raised if threshold is negative.
      */
     public boolean equals(final HomogeneousPoint2D point, final double threshold) {
         if (threshold < MIN_THRESHOLD) {
             throw new IllegalArgumentException();
         }
 
         final var dX = Math.abs((point.getX() / point.getW()) - x) <= threshold;
         final var dY = Math.abs((point.getY() / point.getW()) - y) <= threshold;
 
         return (dX && dY);
     }
 
     /**
      * Checks if the homogeneous 2d point described by this instance equals the
      * input HomogeneousPoint2d (using a comparison threshold).
      *
      * @param point Point that will be compared to.
      * @return True if current point and input point are the same, false
      * otherwise.
      */
     public boolean equals(final HomogeneousPoint2D point) {
         return equals(point, DEFAULT_COMPARISON_THRESHOLD);
     }
 
     /**
      * Checks if the homogeneous 2d point described by this instance equals the
      * input InhomogeneousPoint2d (using a comparison threshold).
      *
      * @param point     Point that will be compared to.
      * @param threshold threshold grade of tolerance to determine whether the
      *                  points are equal or not. It is used because due to machine precision, the
      *                  values might not be exactly equal (if not provided
      *                  DEFAULT_COMPARISON_THRESHOLD is used).
      * @return True if current point and input point are the same, false
      * otherwise.
      * @throws IllegalArgumentException Raised if threshold is negative.
      */
     public boolean equals(final InhomogeneousPoint2D point, final double threshold) {
         if (threshold < MIN_THRESHOLD) {
             throw new IllegalArgumentException();
         }
 
         final var dX = Math.abs(point.getX() - x) <= threshold;
         final var dY = Math.abs(point.getY() - y) <= threshold;
 
         return (dX && dY);
     }
 
     /**
      * Checks if the homogeneous 2d point described by this instance equals the
      * input InhomogeneousPoint2d (using a comparison threshold).
      *
      * @param point Point that will be compared to.
      * @return True if current point and input point are the same, false
      * otherwise.
      */
     public boolean equals(final InhomogeneousPoint2D point) {
         return equals(point, DEFAULT_COMPARISON_THRESHOLD);
     }
 
     /**
      * Checks whether this Point2D is at infinity or not.
      *
      * @return True if the point is at infinity. False otherwise.
      */
     @Override
     public boolean isAtInfinity() {
         return (Double.isInfinite(x) || Double.isNaN(x) || Double.isInfinite(y) || Double.isNaN(y));
     }
 
     /**
      * Returns the type of coordinates used to represent a Point2D.
      *
      * @return Type of coordinates of this 2d point.
      */
     @Override
     public CoordinatesType getType() {
         return CoordinatesType.INHOMOGENEOUS_COORDINATES;
     }
 
     /**
      * Converts this instance into an homogeneous 2D point and returns the
      * result as a new homogeneous 2D point instance.
      *
      * @return Converts and returns this point as an homogeneous 2D point.
      */
     public HomogeneousPoint2D toHomogeneous() {
         return new HomogeneousPoint2D(x, y, 1.0);
     }
 
     /**
      * Returns an array containing the coordinates of this Point2D.
      *
      * @return Array containing coordinates of this Point2D.
      */
     @Override
     public double[] asArray() {
         final var out = new double[POINT2D_INHOMOGENEOUS_COORDINATES_LENGTH];
         asArray(out);
         return out;
     }
 
     /**
      * Uses provided array to store the coordinates of this InhomogeneousPoint2D
      *
      * @param array Array where coordinates will be stored.
      * @throws IllegalArgumentException Raised if length of array is not 2.
      */
     @Override
     public void asArray(final double[] array) {
         if (array.length != POINT2D_INHOMOGENEOUS_COORDINATES_LENGTH) {
             throw new IllegalArgumentException();
         }
         array[0] = x;
         array[1] = y;
     }
 }