/*
 *                    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.contact;

import java.io.Serializable;
import java.util.*;

import org.biojava.nbio.core.util.SingleLinkageClusterer;
import org.biojava.nbio.structure.Atom;
import org.biojava.nbio.structure.Structure;
import org.biojava.nbio.structure.asa.AsaCalculator;
import org.biojava.nbio.structure.xtal.CrystalBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * A list of interfaces between 2 molecules (2 sets of atoms)
 *
 * @author duarte_j
 *
 */
public class StructureInterfaceList implements Serializable, Iterable<StructureInterface> {

        private static final Logger logger = LoggerFactory.getLogger(StructureInterfaceList.class);

        /**
         * Default minimum area for a contact between two chains to be considered a
         * valid interface.
         * @see #removeInterfacesBelowArea(double);
         */
        public static final double DEFAULT_MINIMUM_INTERFACE_AREA = 35.0;
        /**
         * Default number of points to use when calculating ASAs
         * @see #calcAsas(int, int, int)
         */
        public static final int DEFAULT_ASA_SPHERE_POINTS = 3000;
        /**
         * Default minimum size of cofactor molecule (non-chain HET atoms) that will be used
         * @see #calcAsas(int, int, int)
         */
        public static final int DEFAULT_MIN_COFACTOR_SIZE = 40;

        /**
         * Any 2 interfaces with contact overlap score larger than this value
         * will be considered to be clustered
         */
        public static final double DEFAULT_CONTACT_OVERLAP_SCORE_CLUSTER_CUTOFF = 0.2;

        private static final long serialVersionUID = 1L;

        private List<StructureInterface> list;

        private List<StructureInterfaceCluster> clusters = null;
        private List<StructureInterfaceCluster> clustersNcs = null;

        public StructureInterfaceList() {
                this.list = new ArrayList<>();
        }

        public void add(StructureInterface interf) {
                this.list.add(interf);
        }

        public int size() {
                return this.list.size();
        }

        /**
         * Gets the interface corresponding to given id.
         * The ids go from 1 to n
         * If {@link #sort()} was called then the order is descendent by area.
         * @param id
         * @return
         */
        public StructureInterface get(int id) {
                return list.get(id-1);
        }

        /**
         * Calculates ASAs for all interfaces in list, both for the unbound
         * chains and for the complex of the two chains together.
         * Also sorts the interfaces based on calculated BSA areas (descending).
         *
         * <p>Uses default parameters
         */
        public void calcAsas() {
                calcAsas( DEFAULT_ASA_SPHERE_POINTS,
                                Runtime.getRuntime().availableProcessors(),
                                DEFAULT_MIN_COFACTOR_SIZE );
        }
        /**
         * Calculates ASAs for all interfaces in list, both for the unbound
         * chains and for the complex of the two chains together.
         * Also sorts the interfaces based on calculated BSA areas (descending)
         * @param nSpherePoints
         * @param nThreads
         * @param cofactorSizeToUse the minimum size of cofactor molecule (non-chain HET atoms) that will be used
         */
        public void calcAsas(int nSpherePoints, int nThreads, int cofactorSizeToUse) {

                // asa/bsa calculation
                // NOTE in principle it is more efficient to calculate asas only once per unique chain
                // BUT! the rolling ball algorithm gives slightly different values for same molecule in different
                // rotations (due to sampling depending on orientation of axes grid).
                // Both NACCESS and our own implementation behave like that.
                // That's why we calculate ASAs for each rotation-unique molecule, otherwise
                // we get discrepancies (not very big but annoying) which lead to things like negative (small) bsa values


                Map<String, Atom[]> uniqAsaChains = new TreeMap<String, Atom[]>();
                Map<String, double[]> chainAsas = new TreeMap<String, double[]>();

                // first we gather rotation-unique chains (in terms of AU id and transform id)
                for (StructureInterface interf:list) {
                        String molecId1 = interf.getMoleculeIds().getFirst()+interf.getTransforms().getFirst().getTransformId();
                        String molecId2 = interf.getMoleculeIds().getSecond()+interf.getTransforms().getSecond().getTransformId();

                        uniqAsaChains.put(molecId1, interf.getFirstAtomsForAsa(cofactorSizeToUse));
                        uniqAsaChains.put(molecId2, interf.getSecondAtomsForAsa(cofactorSizeToUse));
                }

                long start = System.currentTimeMillis();

                // we only need to calculate ASA for that subset (any translation of those will have same values)
                for (String molecId:uniqAsaChains.keySet()) {

                        AsaCalculator asaCalc = new AsaCalculator(uniqAsaChains.get(molecId),
                                        AsaCalculator.DEFAULT_PROBE_SIZE, nSpherePoints, nThreads);

                        double[] atomAsas = asaCalc.calculateAsas();

                        chainAsas.put(molecId, atomAsas);

                }
                long end = System.currentTimeMillis();

                logger.debug("Calculated uncomplexed ASA for "+uniqAsaChains.size()+" orientation-unique chains. "
                                        + "Time: "+((end-start)/1000.0)+" s");

                start = System.currentTimeMillis();

                // now we calculate the ASAs for each of the complexes
                for (StructureInterface interf:list) {

                        String molecId1 = interf.getMoleculeIds().getFirst()+interf.getTransforms().getFirst().getTransformId();
                        String molecId2 = interf.getMoleculeIds().getSecond()+interf.getTransforms().getSecond().getTransformId();

                        interf.setAsas(chainAsas.get(molecId1), chainAsas.get(molecId2), nSpherePoints, nThreads, cofactorSizeToUse);

                }
                end = System.currentTimeMillis();

                logger.debug("Calculated complexes ASA for "+list.size()+" pairwise complexes. "
                                        + "Time: "+((end-start)/1000.0)+" s");


                // finally we sort based on the ChainInterface.comparable() (based in interfaceArea)
                sort();
        }

        /**
         * Sorts the interface list and reassigns ids based on new sorting
         */
        public void sort() {
                Collections.sort(list);
                int i=1;
                for (StructureInterface interf:list) {
                        interf.setId(i);
                        i++;
                }
        }

        /**
         * Get the interface clusters for this StructureInterfaceList grouped by NCS-equivalence.
         * This means that for any two interfaces in the same cluster:
         * 1. The chains forming the first interface are NCS-copies of the chains forming the second interface, in any order.
         * 2. Relative orientation of the chains is preserved, i.e. the contacts are identical.
         * @return list of {@link StructureInterfaceCluster} objects.
         * @since 5.0.0
         */
        public List<StructureInterfaceCluster> getClustersNcs() {
                return clustersNcs;
        }

        /**
         * Add an interface to the list, possibly defining it as NCS-equivalent to an interface already in the list.
         * Used to build up the NCS clustering.
         * @param interfaceNew
         *          an interface to be added to the list.
         * @param interfaceRef
         *          interfaceNew will be added to the cluster which contains interfaceRef.
         *          If interfaceRef is null, new cluster will be created for interfaceNew.
         * @since 5.0.0
         */
        public void addNcsEquivalent(StructureInterface interfaceNew, StructureInterface interfaceRef) {

                this.add(interfaceNew);
                if (clustersNcs == null) {
                        clustersNcs = new ArrayList<>();
                }

                if (interfaceRef == null) {
                        StructureInterfaceCluster newCluster = new StructureInterfaceCluster();
                        newCluster.addMember(interfaceNew);
                        clustersNcs.add(newCluster);
                        return;
                }

                Optional<StructureInterfaceCluster> clusterRef =
                                clustersNcs.stream().
                                        filter(r->r.getMembers().stream().
                                                anyMatch(c -> c.equals(interfaceRef))).
                                                findFirst();

                if (clusterRef.isPresent()) {
                        clusterRef.get().addMember(interfaceNew);
                        return;
                }

                logger.warn("The specified reference interface, if not null, should have been added to this set previously. " +
                                "Creating new cluster and adding both interfaces. This is likely a bug.");
                this.add(interfaceRef);
                StructureInterfaceCluster newCluster = new StructureInterfaceCluster();
                newCluster.addMember(interfaceRef);
                newCluster.addMember(interfaceNew);
                clustersNcs.add(newCluster);
        }

        /**
         * Removes from this interface list all interfaces with areas
         * below the default cutoff area
         * @see #DEFAULT_MINIMUM_INTERFACE_AREA
         */
        public void removeInterfacesBelowArea() {
                removeInterfacesBelowArea(DEFAULT_MINIMUM_INTERFACE_AREA);
        }

        /**
         * Removes from this interface list all interfaces with areas
         * below the given cutoff area
         * @param area
         */
        public void removeInterfacesBelowArea(double area) {
                Iterator<StructureInterface> it = iterator();
                while (it.hasNext()) {
                        StructureInterface interf = it.next();
                        if (interf.getTotalArea()<area) {
                                it.remove();
                        }
                }
        }

        /**
         * Calculate the interface clusters for this StructureInterfaceList
         * using a contact overlap score to measure the similarity of interfaces.
         * Subsequent calls will use the cached value without recomputing the clusters.
         * The contact overlap score cutoff to consider a pair in the same cluster is
         * the value {@link #DEFAULT_CONTACT_OVERLAP_SCORE_CLUSTER_CUTOFF}
         * @return
         */
        public List<StructureInterfaceCluster> getClusters() {
                return getClusters(DEFAULT_CONTACT_OVERLAP_SCORE_CLUSTER_CUTOFF);
        }

        /**
         * Calculate the interface clusters for this StructureInterfaceList
         * using a contact overlap score to measure the similarity of interfaces.
         * Subsequent calls will use the cached value without recomputing the clusters.
         * @param contactOverlapScoreClusterCutoff the contact overlap score above which a pair will be
         * clustered
         * @return
         */
        public List<StructureInterfaceCluster> getClusters(double contactOverlapScoreClusterCutoff) {
                if (clusters!=null) {
                        return clusters;
                }

                clusters = new ArrayList<StructureInterfaceCluster>();

                // nothing to do if we have no interfaces
                if (list.size()==0) return clusters;

                double[][] matrix = new double[list.size()][list.size()];

                for (int i=0;i<list.size();i++) {
                        for (int j=i+1;j<list.size();j++) {
                                StructureInterface iInterf = list.get(i);
                                StructureInterface jInterf = list.get(j);

                                double scoreDirect = iInterf.getContactOverlapScore(jInterf, false);
                                double scoreInvert = iInterf.getContactOverlapScore(jInterf, true);

                                double maxScore = Math.max(scoreDirect, scoreInvert);

                                matrix[i][j] = maxScore;
                        }

                }

                SingleLinkageClusterer slc = new SingleLinkageClusterer(matrix, true);

                Map<Integer,Set<Integer>> clusteredIndices = slc.getClusters(contactOverlapScoreClusterCutoff);
                for (int clusterIdx:clusteredIndices.keySet()) {
                        List<StructureInterface> members = new ArrayList<StructureInterface>();
                        for (int idx:clusteredIndices.get(clusterIdx)) {
                                members.add(list.get(idx));
                        }
                        StructureInterfaceCluster cluster = new StructureInterfaceCluster();
                        cluster.setMembers(members);
                        double averageScore = 0.0;
                        int countPairs = 0;
                        for (int i=0;i<members.size();i++) {
                                for (int j=i+1;j<members.size();j++) {
                                        averageScore += matrix[members.get(i).getId()-1][members.get(j).getId()-1];
                                        countPairs++;
                                }
                        }
                        if (countPairs>0) {
                                averageScore = averageScore/countPairs;
                        } else {
                                // if only one interface in cluster we set the score to the maximum
                                averageScore = 1.0;
                        }
                        cluster.setAverageScore(averageScore);
                        clusters.add(cluster);
                }

                // finally we have to set the back-references in each StructureInterface
                for (StructureInterfaceCluster cluster:clusters) {
                        for (StructureInterface interf:cluster.getMembers()) {
                                interf.setCluster(cluster);
                        }
                }

                // now we sort by areas (descending) and assign ids based on that sorting
                Collections.sort(clusters, new Comparator<StructureInterfaceCluster>() {
                        @Override
                        public int compare(StructureInterfaceCluster o1, StructureInterfaceCluster o2) {
                                return Double.compare(o2.getTotalArea(), o1.getTotalArea()); //note we invert so that sorting is descending
                        }
                });
                int id = 1;
                for (StructureInterfaceCluster cluster:clusters) {
                        cluster.setId(id);
                        id++;
                }


                return clusters;
        }

        @Override
        public Iterator<StructureInterface> iterator() {
                return list.iterator();
        }

        @Override
        public String toString() {
                return list.toString();
        }

        /**
         * Calculates the interfaces for a structure using default parameters
         * @param struc
         * @return
         */
        public static StructureInterfaceList calculateInterfaces(Structure struc) {
                CrystalBuilder builder = new CrystalBuilder(struc);
                StructureInterfaceList interfaces = builder.getUniqueInterfaces();
                logger.debug("Calculating ASA for "+interfaces.size()+" potential interfaces");
                interfaces.calcAsas(StructureInterfaceList.DEFAULT_ASA_SPHERE_POINTS, //fewer for performance
                                Runtime.getRuntime().availableProcessors(),
                                StructureInterfaceList.DEFAULT_MIN_COFACTOR_SIZE);
                interfaces.removeInterfacesBelowArea();
                interfaces.getClusters();
                logger.debug("Found "+interfaces.size()+" interfaces");
                return interfaces;
        }

}