/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * 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 the University of Southampton 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 org.openimaj.ml.clustering;

import gnu.trove.list.array.TIntArrayList;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;

import org.openimaj.io.IOUtils;

/**
 * Interface to describe objects that are the result of the clustering where the
 * training data is implicitly clustered
 * 
 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
 */
public class IndexClusters implements Clusters {
        protected int[][] clusters;
        protected int nEntries;

        /**
         * Used only to initailise for {@link IOUtils}
         */
        public IndexClusters() {
        }

        /**
         * @param clusters
         *            the clusters
         * @param nEntries
         *            the number of entries
         */
        public IndexClusters(int[][] clusters, int nEntries) {
                this.nEntries = nEntries;
                this.clusters = clusters;
        }

        /**
         * @param clusters
         *            the clusters
         */
        public IndexClusters(int[][] clusters) {
                this.nEntries = 0;
                this.clusters = clusters;
                for (int i = 0; i < clusters.length; i++) {
                        this.nEntries += clusters[i].length;
                }
        }

        /**
         * @param assignments
         *            convert a list of cluster assignments to a 2D array to cluster
         *            to assignments
         */
        public IndexClusters(int[] assignments) {
                this.nEntries = assignments.length;
                final Map<Integer, TIntArrayList> clusters = new HashMap<Integer, TIntArrayList>();
                for (int i = 0; i < assignments.length; i++) {
                        final int ass = assignments[i];
                        TIntArrayList current = clusters.get(ass);
                        if (current == null) {
                                clusters.put(ass, current = new TIntArrayList());
                        }
                        current.add(i);
                }
                int clustersSeen = 0;
                this.clusters = new int[clusters.size()][];
                for (final Entry<Integer, TIntArrayList> i : clusters.entrySet()) {
                        this.clusters[clustersSeen] = i.getValue().toArray();
                        clustersSeen++;
                }
        }

        public IndexClusters(List<int[]> completedClusters) {
                this.nEntries = 0;
                this.clusters = new int[completedClusters.size()][];
                for (int i = 0; i < clusters.length; i++) {
                        clusters[i] = completedClusters.get(i);
                        this.nEntries += clusters[i].length;
                }
        }

        /**
         * Get the number of clusters.
         * 
         * @return number of clusters.
         */
        public int[][] clusters() {
                return clusters;
        }

        /**
         * Get the number of data entries
         * 
         * @return the number of data entries.
         */
        public int numEntries() {
                return nEntries;
        }

        /**
         * Get the number of clusters.
         * 
         * @return number of clusters.
         */
        public int numClusters() {
                return this.clusters.length;
        }

        @Override
        public void readASCII(Scanner in) throws IOException {
                this.clusters = new int[in.nextInt()][];
                this.nEntries = in.nextInt();
                for (int i = 0; i < this.nEntries;) {
                        final int cluster = in.nextInt();
                        final int count = in.nextInt();
                        i += count;
                        this.clusters[cluster] = new int[count];
                        for (int j = 0; j < count; j++) {
                                this.clusters[cluster][j] = in.nextInt();
                        }
                }
        }

        @Override
        public String asciiHeader() {
                return "IDX" + CLUSTER_HEADER;
        }

        @Override
        public void readBinary(DataInput in) throws IOException {
                this.clusters = new int[in.readInt()][];
                this.nEntries = in.readInt();
                for (int i = 0; i < this.nEntries;) {
                        final int cluster = in.readInt();
                        final int count = in.readInt();
                        i += count;
                        this.clusters[cluster] = new int[count];
                        for (int j = 0; j < count; j++) {
                                this.clusters[cluster][j] = in.readInt();
                        }
                }
        }

        @Override
        public byte[] binaryHeader() {
                return asciiHeader().getBytes();
        }

        @Override
        public void writeASCII(PrintWriter out) throws IOException {
                out.println(this.numClusters());
                out.println(this.nEntries);
                for (int i = 0; i < this.clusters.length; i++) {
                        final int[] cluster = this.clusters[i];
                        out.println(i);
                        out.println(cluster.length);
                        for (int j = 0; j < cluster.length; j++) {
                                out.println(cluster[j]);
                        }
                }
        }

        @Override
        public void writeBinary(DataOutput out) throws IOException {
                out.writeInt(this.numClusters());
                out.writeInt(nEntries);
                for (int i = 0; i < this.clusters.length; i++) {
                        final int[] cluster = this.clusters[i];
                        out.writeInt(i);
                        out.writeInt(cluster.length);
                        for (int j = 0; j < cluster.length; j++) {
                                out.writeInt(cluster[j]);
                        }
                }
        }

        @Override
        public String toString() {
                final int[][] clusters = this.clusters();
                int i = 0;
                final StringWriter sw = new StringWriter();
                final PrintWriter out = new PrintWriter(sw);
                out.println("N-Clusters: " + this.numClusters());
                out.println("Entities: " + this.numEntries());
                String str = sw.toString();
                for (final int[] member : clusters) {
                        str += String.format("%d %s\n", i++, Arrays.toString(member));
                }
                return str;
        }
}