/*
 *                    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 org.biojava.nbio.structure.geometry.CalcPoint;
import java.util.Arrays;
import java.util.List;


public class Tetrahedron implements Polyhedron {
        private static double TETRAHEDRAL_ANGLE = Math.acos(-1.0/3.0);
        private static int[] lineLoop1 = {0,1,2,3,0,2};
        private static int[] lineLoop2 = {1,3};

        private double circumscribedRadius = 1.0;

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

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

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

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

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

        /**
         * Returns the vertices of an n-fold polygon of given radius and center
         * @return
         */
        @Override
        public  Point3d[] getVertices() {
                double x = getSideLengthFromCircumscribedRadius(circumscribedRadius)/2;
                double z = x/Math.sqrt(2);
                Point3d[] tetrahedron = new Point3d[4];
                tetrahedron[0] = new Point3d(-x,  0, -z);
                tetrahedron[1] = new Point3d( x,  0, -z);
                tetrahedron[2] = new Point3d( 0, -x,  z);
                tetrahedron[3] = new Point3d( 0,  x,  z);
                Point3d centroid = CalcPoint.centroid(tetrahedron);

                // rotate tetrahedron to align one vertex with the +z axis
                Matrix3d m = new Matrix3d();
                m.rotX(0.5 * TETRAHEDRAL_ANGLE);
                for (Point3d p: tetrahedron) {
                        p.sub(centroid);
                        m.transform(p);
                }
                return tetrahedron;
        };

        @Override
        public List<int[]> getLineLoops() {
                return Arrays.asList(lineLoop1, lineLoop2);
        }

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

        @Override
        public String getViewName(int index) {
                String name;
                switch (index) {
                case 0:  name = "Front 3-fold axis vertex-centered";
                break;
                case 1:  name = "Back 3-fold axis face-centered";
                break;
                case 2:  name = "Side 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(); // front vertex-centered
                break;
                case 1:  m.rotX(Math.PI); // back face-centered
                break;
                case 2: double angle = Math.PI - 0.5 * TETRAHEDRAL_ANGLE; // Side edge-centered
                m.rotX(angle);
                break;
                default: throw new IllegalArgumentException("getViewMatrix: index out of range:" + index);
                }
                return m;
        }

        private static double getSideLengthFromInscribedRadius(double radius) {
                return radius * Math.sqrt(24);
        }

        private static double getInscribedRadiusFromSideLength(double sideLength) {
                return sideLength / Math.sqrt(24);
        }

        private static double getSideLengthFromMiddleRadius(double radius) {
                return radius * Math.sqrt(8);
        }

        private static double getMiddleRadiusFromSideLength(double sideLength) {
                return sideLength / Math.sqrt(8);
        }

        private static double getSideLengthFromCircumscribedRadius(double radius) {
                return radius / Math.sqrt(3.0/8.0);
        }

        private static double getCircumscribedRadiusFromSideLength(double sideLength) {
                return sideLength * Math.sqrt(3.0/8.0);
        }

}