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/*
 * Copyright (c) 2009-2020 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.jme3.math;

import com.jme3.export.*;
import com.jme3.util.BufferUtils;
import com.jme3.util.TempVars;
import java.io.IOException;
import java.nio.FloatBuffer;

/**
 * Line defines a line. Where a line is defined as infinite along
 * two points. The two points of the line are defined as the origin and direction.
 *
 * @author Mark Powell
 * @author Joshua Slack
 */
public class Line implements Savable, Cloneable, java.io.Serializable {
    static final long serialVersionUID = 1;

    private Vector3f origin;
    private Vector3f direction;

    /**
     * Constructor instantiates a new Line object. The origin and
     * direction both default to (0,0,0).
     *
     */
    public Line() {
        origin = new Vector3f();
        direction = new Vector3f();
    }

    /**
     * Constructor instantiates a new Line object. The origin
     * and direction are set via the parameters.
     *
     * @param origin the origin of the line.
     * @param direction the direction of the line.
     */
    public Line(Vector3f origin, Vector3f direction) {
        this.origin = origin;
        this.direction = direction;
    }

    /**
     * getOrigin returns the origin of the line.
     *
     * @return the origin of the line.
     */
    public Vector3f getOrigin() {
        return origin;
    }

    /**
     * setOrigin sets the origin of the line.
     *
     * @param origin the origin of the line.
     */
    public void setOrigin(Vector3f origin) {
        this.origin = origin;
    }

    /**
     * getDirection returns the direction of the line.
     *
     * @return the direction of the line.
     */
    public Vector3f getDirection() {
        return direction;
    }

    /**
     * setDirection sets the direction of the line.
     *
     * @param direction the direction of the line.
     */
    public void setDirection(Vector3f direction) {
        this.direction = direction;
    }

    /**
     * Calculate the squared distance from this line to the specified point.
     *
     * @param point location vector of the input point (not null, unaffected)
     * @return the square of the minimum distance (≥0)
     */
    public float distanceSquared(Vector3f point) {
        TempVars vars = TempVars.get();

        Vector3f compVec1 = vars.vect1;
        Vector3f compVec2 = vars.vect2;

        point.subtract(origin, compVec1);
        float lineParameter = direction.dot(compVec1);
        origin.add(direction.mult(lineParameter, compVec2), compVec2);
        compVec2.subtract(point, compVec1);
        float len = compVec1.lengthSquared();
        vars.release();
        return len;
    }

    /**
     * Calculate the distance from this line to the specified point.
     *
     * @param point location vector of the input point (not null, unaffected)
     * @return the minimum distance (≥0)
     */
    public float distance(Vector3f point) {
        return FastMath.sqrt(distanceSquared(point));
    }

    /**
     * Fit this line to the specified points.
     *
     * @param points a buffer containing location vectors, or null
     */
    public void orthogonalLineFit(FloatBuffer points) {
        if (points == null) {
            return;
        }

        TempVars vars = TempVars.get();

        Vector3f compVec1 = vars.vect1;
        Vector3f compVec2 = vars.vect2;
        Matrix3f compMat1 = vars.tempMat3;
        Eigen3f compEigen1 = vars.eigen;

        points.rewind();

        // compute average of points
        int length = points.remaining() / 3;

        BufferUtils.populateFromBuffer(origin, points, 0);
        for (int i = 1; i < length; i++) {
            BufferUtils.populateFromBuffer(compVec1, points, i);
            origin.addLocal(compVec1);
        }

        origin.multLocal(1f / length);

        // compute sums of products
        float sumXX = 0.0f, sumXY = 0.0f, sumXZ = 0.0f;
        float sumYY = 0.0f, sumYZ = 0.0f, sumZZ = 0.0f;

        points.rewind();
        for (int i = 0; i < length; i++) {
            BufferUtils.populateFromBuffer(compVec1, points, i);
            compVec1.subtract(origin, compVec2);
            sumXX += compVec2.x * compVec2.x;
            sumXY += compVec2.x * compVec2.y;
            sumXZ += compVec2.x * compVec2.z;
            sumYY += compVec2.y * compVec2.y;
            sumYZ += compVec2.y * compVec2.z;
            sumZZ += compVec2.z * compVec2.z;
        }

        //find the smallest eigen vector for the direction vector
        compMat1.m00 = sumYY + sumZZ;
        compMat1.m01 = -sumXY;
        compMat1.m02 = -sumXZ;
        compMat1.m10 = -sumXY;
        compMat1.m11 = sumXX + sumZZ;
        compMat1.m12 = -sumYZ;
        compMat1.m20 = -sumXZ;
        compMat1.m21 = -sumYZ;
        compMat1.m22 = sumXX + sumYY;

        compEigen1.calculateEigen(compMat1);
        direction = compEigen1.getEigenVector(0);

        vars.release();
    }

    /**
     * random determines a random point along the line.
     *
     * @return a random point on the line.
     */
    public Vector3f random() {
        return random(null);
    }

    /**
     * random determines a random point along the line.
     *
     * @param result Vector to store result in
     * @return a random point on the line.
     */
    public Vector3f random(Vector3f result) {
        if (result == null) {
            result = new Vector3f();
        }
        float rand = (float) Math.random();

        result.x = (origin.x * (1 - rand)) + (direction.x * rand);
        result.y = (origin.y * (1 - rand)) + (direction.y * rand);
        result.z = (origin.z * (1 - rand)) + (direction.z * rand);

        return result;
    }

    /**
     * Serialize this line to the specified exporter, for example when
     * saving to a J3O file.
     *
     * @param e (not null)
     * @throws IOException from the exporter
     */
    @Override
    public void write(JmeExporter e) throws IOException {
        OutputCapsule capsule = e.getCapsule(this);
        capsule.write(origin, "origin", Vector3f.ZERO);
        capsule.write(direction, "direction", Vector3f.ZERO);
    }

    /**
     * De-serialize this line from the specified importer, for example when
     * loading from a J3O file.
     *
     * @param importer (not null)
     * @throws IOException from the importer
     */
    @Override
    public void read(JmeImporter importer) throws IOException {
        InputCapsule capsule = importer.getCapsule(this);
        origin = (Vector3f) capsule.readSavable("origin", Vector3f.ZERO.clone());
        direction = (Vector3f) capsule.readSavable("direction", Vector3f.ZERO.clone());
    }

    /**
     * Create a copy of this line.
     *
     * @return a new instance, equivalent to this one
     */
    @Override
    public Line clone() {
        try {
            Line line = (Line) super.clone();
            line.direction = direction.clone();
            line.origin = origin.clone();
            return line;
        } catch (CloneNotSupportedException e) {
            throw new AssertionError();
        }
    }
}