/*
 *                    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.core;

import org.biojava.nbio.structure.symmetry.geometry.MomentsOfInertia;
import org.biojava.nbio.structure.symmetry.geometry.SuperPosition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.vecmath.*;
import java.util.*;

public class HelixAxisAligner extends AxisAligner {
        
        private static final Logger LOGGER = LoggerFactory.getLogger(HelixAxisAligner.class);
        
        private static final Vector3d Y_AXIS = new Vector3d(0,1,0);
        private static final Vector3d Z_AXIS = new Vector3d(0,0,1);

        private Subunits subunits = null;
        private HelixLayers helixLayers = null;

        private Matrix4d transformationMatrix = new Matrix4d();
        private Matrix4d reverseTransformationMatrix = new Matrix4d();
        private Vector3d referenceVector = new Vector3d();
        private Vector3d principalRotationVector = new Vector3d();
        private Vector3d[] principalAxesOfInertia = null;
        private List<List<Integer>> alignedOrbits = null;

        private Vector3d minBoundary = new Vector3d();
        private Vector3d maxBoundary = new Vector3d();
        private double xzRadiusMax = Double.MIN_VALUE;

        boolean modified = true;

        public HelixAxisAligner(QuatSymmetryResults results) {
                this.subunits = results.getSubunits();
                this.helixLayers = results.getHelixLayers();
                if (subunits == null) {
                        throw new IllegalArgumentException("HelixAxisTransformation: Subunits are null");
                } else if (helixLayers == null) {
                        throw new IllegalArgumentException("HelixAxisTransformation: HelixLayers is null");
                } else if (subunits.getSubunitCount() == 0) {
                        throw new IllegalArgumentException("HelixAxisTransformation: Subunits is empty");
                } else if (helixLayers.size() == 0) {
                        throw new IllegalArgumentException("HelixAxisTransformation: HelixLayers is empty");
                }
        }


        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getTransformation()
         */
        @Override
        public String getSymmetry() {
                run();
                return "H";
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getTransformation()
         */
        @Override
        public Matrix4d getTransformation() {
                run();
                return transformationMatrix;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getRotationMatrix()
         */
        @Override
        public Matrix3d getRotationMatrix() {
                run();
                Matrix3d m = new Matrix3d();
                transformationMatrix.getRotationScale(m);
                return m;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getReverseTransformation()
         */
        @Override
        public Matrix4d getReverseTransformation() {
                run();
                return reverseTransformationMatrix;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getPrincipalRotationAxis()
         */
        @Override
        public Vector3d getPrincipalRotationAxis() {
                run();
                return principalRotationVector;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getRotationReferenceAxis()
         */
        @Override
        public Vector3d getRotationReferenceAxis() {
                run();
                return referenceVector;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getPrincipalAxesOfInertia()
         */
        @Override
        public Vector3d[] getPrincipalAxesOfInertia() {
                run();
                return principalAxesOfInertia;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getDimension()
         */
        @Override
        public Vector3d getDimension() {
                run();
                Vector3d dimension = new Vector3d();
                dimension.sub(maxBoundary, minBoundary);
                dimension.scale(0.5);
                return dimension;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getXYRadius()
         */
        @Override
        public double getRadius() {
                run();
                return xzRadiusMax;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getGeometicCenterTransformation()
         */
        @Override
        public Matrix4d getGeometicCenterTransformation() {
                run();

                Matrix4d geometricCentered = new Matrix4d(reverseTransformationMatrix);
                geometricCentered.setTranslation(new Vector3d(getGeometricCenter()));

                return geometricCentered;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getGeometricCenter()
         */
        @Override
        public Point3d getGeometricCenter() {
                run();

                Point3d geometricCenter = new Point3d();
                Vector3d translation = new Vector3d();
//              reverseTransformationMatrix.get(translation);

                // TODO does this apply to the helic case?
                // calculate adjustment around z-axis and transform adjustment to
                //  original coordinate frame with the reverse transformation

//              Vector3d corr = new Vector3d(0,minBoundary.y+getDimension().y, 0);
//              reverseTransformationMatrix.transform(corr);
//              geometricCenter.set(corr);

                reverseTransformationMatrix.transform(translation);
                geometricCenter.add(translation);
                return geometricCenter;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getCentroid()
         */
        @Override
        public Point3d getCentroid() {
                return new Point3d(subunits.getCentroid());
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getSubunits()
         */
        @Override
        public Subunits getSubunits() {
                return subunits;
        }

        public HelixLayers getHelixLayers() {
                run();
                return helixLayers;
        }

        /* (non-Javadoc)
         * @see org.biojava.nbio.structure.quaternary.core.AxisAligner#getOrbits()
         */
        @Override
        public List<List<Integer>> getOrbits() {
                run();
                return alignedOrbits;
        }

        /**
         * @return
         */

        private void run () {
                if (modified) {
                        calcPrincipalRotationVector();
                        calcPrincipalAxes();
                        calcReferenceVector();
                        calcTransformation();
                        // orient helix along Y axis by rotating 90 degrees around X-axis
                        transformationMatrix = reorientHelix(0);

                        calcReverseTransformation();
                        calcBoundaries();
                        calcAlignedOrbits();
                        calcCenterOfRotation();

                        // orient helix along Y axis by rotating 90 degrees around X-axis
//                      transformationMatrix = reorientHelix(0);
//                      calcReverseTransformation();

                        modified = false;
                }
        }

        public Point3d calcCenterOfRotation() {
                List<Integer> line = getLongestLayerLine();

                // can't determine center of rotation if there are only 2 points
                // TODO does this ever happen??
                if (line.size() < 3) {
                        return subunits.getCentroid();
                }

                Point3d centerOfRotation = new Point3d();
                List<Point3d> centers = subunits.getOriginalCenters();

                // calculate helix mid points for each set of 3 adjacent subunits
                for (int i = 0; i < line.size()-2; i++) {
                        Point3d p1 = new Point3d(centers.get(line.get(i)));
                        Point3d p2 = new Point3d(centers.get(line.get(i+1)));
                        Point3d p3 = new Point3d(centers.get(line.get(i+2)));
                        transformationMatrix.transform(p1);
                        transformationMatrix.transform(p2);
                        transformationMatrix.transform(p3);
                        centerOfRotation.add(getMidPoint(p1, p2, p3));
                }

                // average over all midpoints to find best center of rotation
                centerOfRotation.scale(1/(line.size()-2));
                // since helix is aligned along the y-axis, with an origin at y = 0, place the center of rotation there
                centerOfRotation.y = 0;
                // transform center of rotation to the original coordinate frame
                reverseTransformationMatrix.transform(centerOfRotation);
//              System.out.println("center of rotation: " + centerOfRotation);
                return centerOfRotation;
        }

        private List<Integer> getLongestLayerLine() {
                int len = 0;
                int index = 0;

                Helix helix = helixLayers.getByLargestContacts();
                List<List<Integer>> layerLines = helix.getLayerLines();
                for (int i = 0; i < layerLines.size(); i++) {
                        if (layerLines.get(i).size() > len) {
                                len = layerLines.get(i).size();
                                index = i;
                        }
                }
                return layerLines.get(index);
        }

        /**
         * Return a midpoint of a helix, calculated from three positions
         * of three adjacent subunit centers.
         * @param p1 center of first subunit
         * @param p2 center of second subunit
         * @param p3 center of third subunit
         * @return midpoint of helix
         */
        private Point3d getMidPoint(Point3d p1, Point3d p2, Point3d p3) {
                Vector3d v1 = new Vector3d();
                v1.sub(p1, p2);
                Vector3d v2 = new Vector3d();
                v2.sub(p3, p2);
                Vector3d v3 = new Vector3d();
                v3.add(v1);
                v3.add(v2);
                v3.normalize();

                // calculat the total distance between to subunits
                double dTotal = v1.length();
                // calculate the rise along the y-axis. The helix axis is aligned with y-axis,
                // therfore, the rise between subunits is the y-distance
                double rise = p2.y - p1.y;
                // use phythagorean theoremm to calculate chord length between two subunit centers
                double chord = Math.sqrt(dTotal*dTotal - rise*rise);
//              System.out.println("Chord d: " + dTotal + " rise: " + rise + "chord: " + chord);
                double angle = helixLayers.getByLargestContacts().getAxisAngle().angle;

                // using the axis angle and the chord length, we can calculate the radius of the helix
                // http://en.wikipedia.org/wiki/Chord_%28geometry%29
                double radius = chord/Math.sin(angle/2)/2; // can this go to zero?
//              System.out.println("Radius: " + radius);

                // project the radius onto the vector that points toward the helix axis
                v3.scale(radius);
                v3.add(p2);
//              System.out.println("Angle: " + Math.toDegrees(helixLayers.getByLowestAngle().getAxisAngle().angle));
                Point3d cor = new Point3d(v3);
                return cor;
        }

        private Matrix4d reorientHelix(int index) {
                Matrix4d matrix = new Matrix4d();
                matrix.setIdentity();
                matrix.setRotation(new AxisAngle4d(1,0,0,Math.PI/2*(index+1)));
                matrix.mul(transformationMatrix);
        return matrix;
        }

        /**
         * Returns a list of orbits (an orbit is a cyclic permutation of subunit indices that are related
         * by a rotation around the principal rotation axis) ordered from the +z direction to the -z direction (z-depth).
         * Within an orbit, subunit indices are ordered with a clockwise rotation around the z-axis.
         * @return list of orbits ordered by z-depth
         */
        private void calcAlignedOrbits() {
                Map<Double, List<Integer>> depthMap = new TreeMap<Double, List<Integer>>();
                double[] depth = getSubunitZDepth();
                alignedOrbits = calcOrbits();

                // calculate the mean depth of orbit along z-axis
                for (List<Integer> orbit: alignedOrbits) {
                        // calculate the mean depth along z-axis for each orbit
                        double meanDepth = 0;
                        for (int subunit: orbit) {
                                meanDepth += depth[subunit];
                        }
                        meanDepth /= orbit.size();

                        if (depthMap.get(meanDepth) != null) {
                                meanDepth += 0.01;
                        }
//                      System.out.println("calcAlignedOrbits: " + meanDepth + " orbit: " + orbit);
                        depthMap.put(meanDepth, orbit);
                }

                // now fill orbits back into list ordered by depth
                alignedOrbits.clear();
                for (List<Integer> orbit: depthMap.values()) {
                        // order subunit in a clockwise rotation around the z-axis
                        /// starting at the 12 O-clock position (+y position)
                        // TODO how should this be aligned??
        //              alignWithReferenceAxis(orbit);
                        alignedOrbits.add(orbit);
                }
        }


        private void calcTransformation() {
                calcTransformationBySymmetryAxes();
                // make sure this value is zero. On Linux this value is 0.
                transformationMatrix.setElement(3, 3, 1.0);
        }

        private void calcReverseTransformation() {
                reverseTransformationMatrix.invert(transformationMatrix);
        }

        private void calcTransformationBySymmetryAxes() {
                Vector3d[] axisVectors = new Vector3d[2];
                axisVectors[0] = new Vector3d(principalRotationVector);
                axisVectors[1] = new Vector3d(referenceVector);

                //  y,z axis centered at the centroid of the subunits
                Vector3d[] referenceVectors = new Vector3d[2];
                referenceVectors[0] = new Vector3d(Z_AXIS);
                referenceVectors[1] = new Vector3d(Y_AXIS);

                transformationMatrix = alignAxes(axisVectors, referenceVectors);

                // combine with translation
                Matrix4d combined = new Matrix4d();
                combined.setIdentity();
                Vector3d trans = new Vector3d(subunits.getCentroid());
                trans.negate();
                combined.setTranslation(trans);
                transformationMatrix.mul(combined);

                // for helical geometry, set a canonical view for the Z direction
                calcZDirection();
        }

        /**
         * Returns a transformation matrix that rotates refPoints to match
         * coordPoints
         * @param refPoints the points to be aligned
         * @param referenceVectors
         * @return
         */
        private Matrix4d alignAxes(Vector3d[] axisVectors, Vector3d[] referenceVectors) {
                Matrix4d m1 = new Matrix4d();
                AxisAngle4d a = new AxisAngle4d();
                Vector3d axis = new Vector3d();

                // calculate rotation matrix to rotate refPoints[0] into coordPoints[0]
                Vector3d v1 = new Vector3d(axisVectors[0]);
                Vector3d v2 = new Vector3d(referenceVectors[0]);
                double dot = v1.dot(v2);
                if (Math.abs(dot) < 0.999) {
                        axis.cross(v1,v2);
                        axis.normalize();
                        a.set(axis, v1.angle(v2));
                        m1.set(a);
                        // make sure matrix element m33 is 1.0. It's 0 on Linux.
                        m1.setElement(3,  3, 1.0);
                } else if (dot > 0) {
                        // parallel axis, nothing to do -> identity matrix
                        m1.setIdentity();
                } else if (dot < 0) {
                        // anti-parallel axis, flip around x-axis
                        m1.set(flipX());
                }

                // apply transformation matrix to all refPoints
                m1.transform(axisVectors[0]);
                m1.transform(axisVectors[1]);

                // calculate rotation matrix to rotate refPoints[1] into coordPoints[1]
                v1 = new Vector3d(axisVectors[1]);
                v2 = new Vector3d(referenceVectors[1]);
                Matrix4d m2 = new Matrix4d();
                dot = v1.dot(v2);
                if (Math.abs(dot) < 0.999) {
                        axis.cross(v1,v2);
                        axis.normalize();
                        a.set(axis, v1.angle(v2));
                        m2.set(a);
                        // make sure matrix element m33 is 1.0. It's 0 on Linux.
                        m2.setElement(3,  3, 1.0);
                } else if (dot > 0) {
                        // parallel axis, nothing to do -> identity matrix
                        m2.setIdentity();
                } else if (dot < 0) {
                        // anti-parallel axis, flip around z-axis
                        m2.set(flipZ());
                }

                // apply transformation matrix to all refPoints
                m2.transform(axisVectors[0]);
                m2.transform(axisVectors[1]);

                // combine the two rotation matrices
                m2.mul(m1);

                // the RMSD should be close to zero
                Point3d[] axes = new Point3d[2];
                axes[0] = new Point3d(axisVectors[0]);
                axes[1] = new Point3d(axisVectors[1]);
                Point3d[] ref = new Point3d[2];
                ref[0] = new Point3d(referenceVectors[0]);
                ref[1] = new Point3d(referenceVectors[1]);
                if (SuperPosition.rmsd(axes, ref) > 0.1) {
                        LOGGER.info("AxisTransformation: axes alignment is off. RMSD: " + SuperPosition.rmsd(axes, ref));
                }

                return m2;
        }

        private void calcPrincipalAxes() {
                MomentsOfInertia moi = new MomentsOfInertia();

                for (Point3d[] list: subunits.getTraces()) {
                        for (Point3d p: list) {
                                moi.addPoint(p, 1.0);
                        }
                }
                principalAxesOfInertia = moi.getPrincipalAxes();
        }

        /**
         * Calculates the min and max boundaries of the structure after it has been
         * transformed into its canonical orientation.
         */
        private void calcBoundaries() {
                minBoundary.x = Double.MAX_VALUE;
                maxBoundary.x = Double.MIN_VALUE;
                minBoundary.y = Double.MAX_VALUE;
                maxBoundary.x = Double.MIN_VALUE;
                minBoundary.z = Double.MAX_VALUE;
                maxBoundary.z = Double.MIN_VALUE;
                xzRadiusMax = Double.MIN_VALUE;

                Point3d probe = new Point3d();

                for (Point3d[] list: subunits.getTraces()) {
                        for (Point3d p: list) {
                                probe.set(p);
                                transformationMatrix.transform(probe);

                                minBoundary.x = Math.min(minBoundary.x, probe.x);
                                maxBoundary.x = Math.max(maxBoundary.x, probe.x);
                                minBoundary.y = Math.min(minBoundary.y, probe.y);
                                maxBoundary.y = Math.max(maxBoundary.y, probe.y);
                                minBoundary.z = Math.min(minBoundary.z, probe.z);
                                maxBoundary.z = Math.max(maxBoundary.z, probe.z);
                                xzRadiusMax = Math.max(xzRadiusMax, Math.sqrt(probe.x*probe.x + probe.z * probe.z));
                        }
                }
//              System.out.println("MinBoundary: " + minBoundary);
//              System.out.println("MaxBoundary: " + maxBoundary);
//              System.out.println("zxRadius: " + xzRadiusMax);
        }

        /*
         * Modifies the rotation part of the transformation axis for
         * a Cn symmetric complex, so that the narrower end faces the
         * viewer, and the wider end faces away from the viewer. Example: 3LSV
         */
        private void calcZDirection() {
                calcBoundaries();

                // if the longer part of the structure faces towards the back (-z direction),
                // rotate around y-axis so the longer part faces the viewer (+z direction)
                if (Math.abs(minBoundary.z) > Math.abs(maxBoundary.z)) {
                        Matrix4d rot = flipY();
                        rot.mul(transformationMatrix);
                        transformationMatrix.set(rot);
                }
        }

        private double[] getSubunitZDepth() {
                int n = subunits.getSubunitCount();
                double[] depth = new double[n];
                Point3d probe = new Point3d();

                // transform subunit centers into z-aligned position and calculate
                // z-coordinates (depth) along the z-axis.
                for (int i = 0; i < n; i++) {
                        Point3d p= subunits.getCenters().get(i);
                        probe.set(p);
                        transformationMatrix.transform(probe);
                        depth[i] = probe.z;
                }
                return depth;
        }

        /**
         * Returns a list of list of subunit ids that form an "orbit", i.e. they
         * are transformed into each other during a rotation around the principal symmetry axis (z-axis)
         * @return
         */
        private List<List<Integer>> calcOrbits() {
                int n = subunits.getSubunitCount();

                List<List<Integer>> orbits = new ArrayList<List<Integer>>();
                for (int i = 0; i < n; i++) {
                        orbits.add(Collections.singletonList(i));
                }

                return orbits;
        }

        /**
         * Returns a vector along the principal rotation axis for the
         * alignment of structures along the z-axis
         * @return principal rotation vector
         */
        private void calcPrincipalRotationVector() {
//              AxisAngle4d axisAngle = helixLayers.getByLowestAngle().getAxisAngle();
                AxisAngle4d axisAngle = helixLayers.getByLargestContacts().getAxisAngle();
                principalRotationVector = new Vector3d(axisAngle.x, axisAngle.y, axisAngle.z);
        }

        /**
         * Returns a vector perpendicular to the principal rotation vector
         * for the alignment of structures in the xy-plane
         * @return reference vector
         */
        private void calcReferenceVector() {
                referenceVector = getReferenceAxisCylic();

                if (referenceVector == null) {
                        LOGGER.warn("no reference vector found. Using y-axis.");
                        referenceVector = new Vector3d(Y_AXIS);
                }
                // make sure reference vector is perpendicular principal roation vector
                referenceVector = orthogonalize(principalRotationVector, referenceVector);
        }

        private Vector3d orthogonalize(Vector3d vector1, Vector3d vector2) {
                double dot = vector1.dot(vector2);
                Vector3d ref = new Vector3d(vector2);
//              System.out.println("p.r: " + dot);
//              System.out.println("Orig refVector: " + referenceVector);
                if (dot < 0) {
                        vector2.negate();
                }
                if (Math.abs(dot) < 0.00001) {
                        LOGGER.info("HelixAxisAligner: reference axis parallel");
                }
                vector2.cross(vector1, vector2);
//              System.out.println("Intermed. refVector: " + vector2);
                vector2.normalize();
//              referenceVector.cross(referenceVector, principalRotationVector);
                vector2.cross(vector1, vector2);
                vector2.normalize();
                if (ref.dot(vector2) < 0) {
                        vector2.negate();
                }
//              System.out.println("Mod. refVector: " + vector2);
                return vector2;
        }
        /**
         * Returns the default reference vector for the alignment of Cn structures
         * @return
         */
        private Vector3d getReferenceAxisCylic() {
                // get principal axis vector that is perpendicular to the principal
                // rotation vector
                Vector3d vmin = null;
                double dotMin = 1.0;
                for (Vector3d v: principalAxesOfInertia) {
                        if (Math.abs(principalRotationVector.dot(v)) < dotMin) {
                                dotMin = Math.abs(principalRotationVector.dot(v));
                                vmin = new Vector3d(v);
                        }
                }
                if (principalRotationVector.dot(vmin) < 0) {
                        vmin.negate();
                }

                return vmin;
        }

        private static Matrix4d flipX() {
                Matrix4d rot = new Matrix4d();
                rot.m00 = 1;
                rot.m11 = -1;
                rot.m22 = -1;
                rot.m33 = 1;
                return rot;
        }

        private static Matrix4d flipY() {
                Matrix4d rot = new Matrix4d();
                rot.m00 = -1;
                rot.m11 = 1;
                rot.m22 = -1;
                rot.m33 = 1;
                return rot;
        }

        private static Matrix4d flipZ() {
                Matrix4d rot = new Matrix4d();
                rot.m00 = -1;
                rot.m11 = -1;
                rot.m22 = 1;
                rot.m33 = 1;
                return rot;
        }

}