/*
 *                    BioJava development code
 *
 * This code may be freely distributed and modified under the
 * terms of the GNU Lesser General Public Licence.  This should
 * be distributed with the code.  If you do not have a copy,
 * see:
 *
 *      http://www.gnu.org/copyleft/lesser.html
 *
 * Copyright for this code is held jointly by the individual
 * authors.  These should be listed in @author doc comments.
 *
 * For more information on the BioJava project and its aims,
 * or to join the biojava-l mailing list, visit the home page
 * at:
 *
 *      http://www.biojava.org/
 *
 */
package org.biojava.nbio.structure.symmetry.geometry;

import javax.vecmath.Matrix3d;
import javax.vecmath.Point3d;
import java.util.Arrays;
import java.util.List;


public class Octahedron implements Polyhedron {
        private static double TETRAHEDRAL_ANGLE = Math.acos(-1.0/3.0);
        private static int[] lineLoop1 = {2,4,3,5,2,1,3,0,5,1,4,0,2};
        private double cirumscribedRadius = 1.0;

        /**
         * Returns the radius of a circumscribed sphere, that goes
         * through all vertices
         * @return the cirumscribedRadius
         */
        @Override
        public double getCirumscribedRadius() {
                return cirumscribedRadius;
        }

        /**
         * Set the radius of a circumscribed sphere, that goes
         * through all vertices
         * @param cirumscribedRadius the cirumscribedRadius to set
         */
        public void setCirumscribedRadius(double cirumscribedRadius) {
                this.cirumscribedRadius = cirumscribedRadius;
        }
        /**
         * Returns the radius of an inscribed sphere, that is tangent to each
         * of the octahedron's faces
         * @return the inscribedRadius
         */
        public double getInscribedRadius() {
                double side = getSideLengthFromCircumscribedRadius(cirumscribedRadius);
                return getInscribedRadiusFromSideLength(side);
        }

        /**
         * Sets the radius of an inscribed sphere, that is tangent to each
         * of the octahedron's faces
         * @param radius the inscribedRadius to set
         */
        public void setInscribedRadius(double radius) {
                double side = getSideLengthFromInscribedRadius(radius);
                this.cirumscribedRadius = getCircumscribedRadiusFromSideLength(side);
        }

        /**
         * Returns the radius of a sphere, that is tangent to each
         * of the octahedron's edges
         *
         * @return the midRadius
         */
        public double getMidRadius() {
                double side = getSideLengthFromCircumscribedRadius(cirumscribedRadius);
                return getMiddleRadiusFromSideLength(side);
        }

        /**
         * Sets the radius of radius of a sphere, that is tangent to each
         * of the octahedron's edges
         * @param radius the midRadius to set
         */
        public void setMidRadius(double radius) {
                double side = getSideLengthFromMiddleRadius(radius);
                this.cirumscribedRadius = getCircumscribedRadiusFromSideLength(side);
        }

        /**
         * Returns the vertices of an n-fold polygon of given radius and center
         * @return
         */
        @Override
        public Point3d[] getVertices() {
                Point3d[] octahedron = new Point3d[6];
            octahedron[0] = new Point3d(-cirumscribedRadius, 0, 0);
            octahedron[1] = new Point3d( cirumscribedRadius, 0, 0);
            octahedron[2] = new Point3d(0, -cirumscribedRadius, 0);
            octahedron[3] = new Point3d(0,  cirumscribedRadius, 0);
            octahedron[4] = new Point3d(0, 0, -cirumscribedRadius);
            octahedron[5] = new Point3d(0, 0,  cirumscribedRadius);

                return octahedron;
        };

        @Override
        public List<int[]> getLineLoops() {
                return Arrays.asList(lineLoop1);
        }

        public Point3d getC4Axis(double scale) {
                return new Point3d(0, 0, cirumscribedRadius*scale);
        }
        public Point3d getC3Axis(double scale) {
                double s = 1/Math.sqrt(1 + Math.sqrt(2));
                return new Point3d(cirumscribedRadius*scale*s, cirumscribedRadius*scale*s, cirumscribedRadius*scale*s);
        }
        public Point3d getC2Axis(double scale) {
                double s = 1/Math.sqrt(2);
                return new Point3d(cirumscribedRadius*scale*s, cirumscribedRadius*scale*s, 0);
        }

        @Override
        public int getViewCount() {
                return 3;
        }

        @Override
        public String getViewName(int index) {
                String name;
                switch (index) {
                case 0:  name = "4-fold axis vertex-centered";
                break;
                case 1:  name = "3-fold axis face-centered";
                break;
                case 2:  name = "2-fold axis edge-centered";
                break;
                default: throw new IllegalArgumentException("getViewMatrix: index out of range:" + index);
                }
                return name;
        }

        @Override
        public Matrix3d getViewMatrix(int index) {
                Matrix3d m = new Matrix3d();
                switch (index) {
                case 0:
                        m.setIdentity(); // C4 vertex-centered
                        break;
                case 1:
                        m.rotX(-0.5 * TETRAHEDRAL_ANGLE); // C3 face-centered  2.0*Math.PI/3
                        Matrix3d m1 = new Matrix3d();
                        m1.rotZ(Math.PI/4);
                        m.mul(m1);
                        break;
                case 2:
                        m.rotY(Math.PI/4); // side face-centered
                        break;
                default:
                        throw new IllegalArgumentException("getViewMatrix: index out of range:" + index);
                }
                return m;
        }

        private static double getSideLengthFromInscribedRadius(double radius) {
                return radius * 6 / Math.sqrt(6);
        }

        private static double getInscribedRadiusFromSideLength(double sideLength) {
                return sideLength / 6 * Math.sqrt(6);
        }

        private static double getSideLengthFromMiddleRadius(double radius) {
                return radius * 2;
        }

        private static double getMiddleRadiusFromSideLength(double sideLength) {
                return sideLength / 2;
        }

        private static double getSideLengthFromCircumscribedRadius(double radius) {
                return radius * 2 / Math.sqrt(2);
        }

        private static double getCircumscribedRadiusFromSideLength(double sideLength) {
                return sideLength / 2 * Math.sqrt(2);
        }
}