/* Copyright (c) 2001-2016, The HSQL Development Group
 * 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 HSQL Development Group 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 HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * 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.hsqldb.lib;

import java.util.NoSuchElementException;

/**
 * A deque of long value. Implementation based on HsqlDeque class.
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version 2.3.4
 * @since 1.9.0
 */
public class LongDeque {

    private long[] list;
    private int    firstindex = 0;    // index of first list element
    private int    endindex   = 0;    // index of last list element + 1
    private int    elementCount;

    // can grow to fill list
    // if elementCount == 0 then firstindex == endindex
    private static final int DEFAULT_INITIAL_CAPACITY = 8;

    public LongDeque() {
        this(DEFAULT_INITIAL_CAPACITY);
    }

    public LongDeque(int capacity) {
        list = new long[capacity];
    }

    public int size() {
        return elementCount;
    }

    public boolean isEmpty() {
        return elementCount == 0;
    }

    public long getFirst() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        return list[firstindex];
    }

    public long getLast() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        return list[endindex - 1];
    }

    public long get(int i) throws IndexOutOfBoundsException {

        int index = getInternalIndex(i);

        return list[index];
    }

    public long removeFirst() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        long value = list[firstindex];

        list[firstindex] = 0;

        firstindex++;
        elementCount--;

        if (elementCount == 0) {
            firstindex = endindex = 0;
        } else if (firstindex == list.length) {
            firstindex = 0;
        }

        return value;
    }

    public long removeLast() throws NoSuchElementException {

        if (elementCount == 0) {
            throw new NoSuchElementException();
        }

        endindex--;

        long value = list[endindex];

        list[endindex] = 0;

        elementCount--;

        if (elementCount == 0) {
            firstindex = endindex = 0;
        } else if (endindex == 0) {
            endindex = list.length;
        }

        return value;
    }

    public boolean add(long value) {

        resetCapacity();

        if (endindex == list.length) {
            endindex = 0;
        }

        list[endindex] = value;

        elementCount++;
        endindex++;

        return true;
    }

    public boolean addLast(long value) {
        return add(value);
    }

    public boolean addFirst(long value) {

        resetCapacity();

        firstindex--;

        if (firstindex < 0) {
            firstindex = list.length - 1;

            if (endindex == 0) {
                endindex = list.length;
            }
        }

        list[firstindex] = value;

        elementCount++;

        return true;
    }

    public int addAll(LongDeque deque) {

        int count = 0;

        for (int i = 0; i < deque.size(); i++) {
            add(deque.get(i));

            count++;
        }

        return count;
    }

    public void clear() {

        if (elementCount == 0) {
            return;
        }

        firstindex = endindex = elementCount = 0;

        for (int i = 0; i < list.length; i++) {
            list[i] = 0;
        }
    }

    public void zeroSize() {
        firstindex = endindex = elementCount = 0;
    }

    public int indexOf(long value) {

        for (int i = 0; i < elementCount; i++) {
            int index = firstindex + i;

            if (index >= list.length) {
                index -= list.length;
            }

            if (list[index] == value) {
                return i;
            }
        }

        return -1;
    }

    public long remove(final int index) {

        int  target = getInternalIndex(index);
        long value  = list[target];

        if (target == firstindex) {
            list[firstindex] = 0;

            firstindex++;

            if (firstindex == list.length) {
                firstindex = 0;
            }
        } else if (target > firstindex) {
            System.arraycopy(list, firstindex, list, firstindex + 1,
                             target - firstindex);

            list[firstindex] = 0;

            firstindex++;

            if (firstindex == list.length) {
                firstindex = 0;
            }
        } else {
            System.arraycopy(list, target + 1, list, target,
                             endindex - target - 1);

            endindex--;

            list[endindex] = 0;

            if (endindex == 0) {
                endindex = list.length;
            }
        }

        elementCount--;

        if (elementCount == 0) {
            firstindex = endindex = 0;
        }

        return value;
    }

    public boolean contains(long value) {

        for (int i = 0; i < elementCount; i++) {
            int index = firstindex + i;

            if (index >= list.length) {
                index -= list.length;
            }

            if (list[index] == value) {
                return true;
            }
        }

        return false;
    }

    public void toArray(int[] array) {

        for (int i = 0; i < elementCount; i++) {
            array[i] = (int) get(i);
        }
    }

    public void toArray(long[] array) {

        for (int i = 0; i < elementCount; i++) {
            array[i] = get(i);
        }
    }

    private int getInternalIndex(int i) throws IndexOutOfBoundsException {

        if (i < 0 || i >= elementCount) {
            throw new IndexOutOfBoundsException();
        }

        int index = firstindex + i;

        if (index >= list.length) {
            index -= list.length;
        }

        return index;
    }

    private void resetCapacity() {

        if (elementCount < list.length) {
            return;
        }

        long[] newList = new long[list.length * 2];

        System.arraycopy(list, firstindex, newList, firstindex,
                         list.length - firstindex);

        if (endindex <= firstindex) {
            System.arraycopy(list, 0, newList, list.length, endindex);

            endindex = list.length + endindex;
        }

        list = newList;
    }
}
