/*
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*/
/**
 * 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;
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.util.array;

import gnu.trove.iterator.TIntShortIterator;
import gnu.trove.map.hash.TIntShortHashMap;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * A {@link SparseShortArray} implementation based on a
 * {@link TIntShortHashMap}. Unlike the {@link SparseBinSearchShortArray}
 * implementation, this class should be good for the case
 * where random insertion is used frequently (O(1) insert complexity).
 * In the worst-case search is O(n), although in practice it should be better.
 * <p>
 * Note that the {@link #entries()} method will in general not return
 * the entries in index order. 
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 *
 */
public class SparseHashedShortArray extends SparseShortArray {
        TIntShortHashMap data;
        
        /**
         * @param values
         */
        public SparseHashedShortArray(short[] values) {
                this(values.length);
                
                for (int i=0; i<values.length; i++) {
                        if (values[i] != 0) set(i, values[i]);
                }
        }

        /**
         * Construct the array with the given length
         * @param length the length
         */
        public SparseHashedShortArray(int length) {
                this(length, DEFAULT_CAPACITY);
        }

        /**
         * Construct the array with the given length and capacity for non-zero elements
         * @param length the length
         * @param capacity the capacity
         */
        public SparseHashedShortArray(int length, int capacity) {
                if (length < 0) throw new IllegalArgumentException("length must be >= 0");
                if (capacity <= 0) throw new IllegalArgumentException("capacity must be > 0");
        
                this.length = length;
                this.data = new TIntShortHashMap(capacity);
        }

        /**
         * Construct the array with the given length and expected density
         * @param length the length
         * @param density the density
         */
        public SparseHashedShortArray(int length, float density) {
                if (length < 0) throw new IllegalArgumentException("length must be >= 0");
                if (density <= 0 || density > 1) throw new IllegalArgumentException("density must be > 0 and < 1");
                
                this.length = length;
                int capacity = (int) (density * length);
                this.data = new TIntShortHashMap(capacity);
        }
        
        @Override
        public short increment(int key, short value) {
                return data.adjustOrPutValue(key, value, value);
        }

        @Override
        public int[] indices() {
                return data.keys();
        }

        @Override
        public short[] values() {
                return data.values();
        }

        /* (non-Javadoc)
         * @see org.openimaj.util.array.SparseShortArray#entries()
         */
        @Override
        public Iterable<Entry> entries() {
                return new Iterable<Entry>() {
                        @Override
                        public Iterator<Entry> iterator() {
                                return new Iterator<Entry>() {
                                        private Entry entry = new Entry();
                                        private TIntShortIterator iterator = data.iterator();

                                        @Override
                                        public boolean hasNext() {
                                                return iterator.hasNext();
                                        }

                                        @Override
                                        public Entry next() {
                                                if (!hasNext()) throw new NoSuchElementException();
                                                iterator.advance();
                                                entry.index = iterator.key();
                                                entry.value = iterator.value();
                                                
                                                return entry;
                                        }

                                        @Override
                                        public void remove() {
                                                throw new UnsupportedOperationException();
                                        }
                                };
                        }
                };
        }

        @Override
        public boolean equals(Object obj) {
                if (!(obj instanceof SparseHashedShortArray)) return false;
                
                return length == ((SparseHashedShortArray)obj).length &&
                                data.equals(((SparseHashedShortArray)obj).data);
        }

        @Override
        public short get(int key) {
                if (key < 0 || key >= length) throw new IndexOutOfBoundsException(Integer.toString(key)); 
                return data.get(key);
        }

        @Override
        public int hashCode() {
                return length ^ data.hashCode();
        }

        @Override
        public boolean isUsed(int key) {
                return data.contains(key);
        }

        @Override
        public short set(int key, short value) {
                return data.put(key, value);
        }

        @Override
        public int used() {
                return data.size();
        }

        @Override
        public void compact() {
                data.compact();
        }
        
        /* (non-Javadoc)
         * @see org.openimaj.util.array.SparseDoubleArray#copy()
         */
        @Override
        public SparseShortArray copy() {
                SparseHashedShortArray copy = new SparseHashedShortArray(length);
                
                copy.data = new TIntShortHashMap(data);
                
                return copy;
        }

        /* (non-Javadoc)
         * @see org.openimaj.util.array.SparseDoubleArray#reverse()
         */
        @Override
        public SparseShortArray reverse() {
                //TODO: this could be more efficient and avoid the copy
                TIntShortHashMap tmp = new TIntShortHashMap(data.size());

                for (Entry e : entries())
                        tmp.put(length - e.index, e.value);
                
                this.data = tmp;
                
                return this;
        }
}