/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.collections.primitives;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
 * An {@link IntList} backed by an array of unsigned
 * <code>int</code> values.
 * This list stores <code>int</code> values
 * in the range [{@link #MIN_VALUE <code>0</code>},
 * {@link #MAX_VALUE <code>65535</code>}] in 16-bits 
 * per element.  Attempts to use elements outside this 
 * range may cause an 
 * {@link IllegalArgumentException IllegalArgumentException} 
 * to be thrown.
 * <p />
 * This implementation supports all optional methods.
 * 
 * @since Commons Primitives 1.0
 * @version $Revision: 480460 $ $Date: 2006-11-29 03:14:21 -0500 (Wed, 29 Nov 2006) $
 * 
 * @author Rodney Waldhoff 
 */
public class ArrayUnsignedIntList extends RandomAccessLongList implements LongList, Serializable {

    // constructors
    //-------------------------------------------------------------------------

    /** 
     * Construct an empty list with the default
     * initial capacity.
     */
    public ArrayUnsignedIntList() {
        this(8);
    }    

    /**
     * Construct an empty list with the given
     * initial capacity.
     * @throws IllegalArgumentException when <i>initialCapacity</i> is negative
     */
    public ArrayUnsignedIntList(int initialCapacity) {
        if(initialCapacity < 0) {
            throw new IllegalArgumentException("capacity " + initialCapacity);
        }
        _data = new int[initialCapacity];
        _size = 0;
    }    

    /** 
     * Constructs a list containing the elements of the given collection, 
     * in the order they are returned by that collection's iterator.
     * 
     * @see AbstractLongCollection#addAll(LongCollection)
     * @param that the non-<code>null</code> collection of <code>int</code>s 
     *        to add
     * @throws NullPointerException if <i>that</i> is <code>null</code>
     */
    public ArrayUnsignedIntList(LongCollection that) { 
        this(that.size());
        addAll(that);
    }    

    /**
     * Constructs a list by copying the specified array.
     * 
     * @param array  the array to initialize the collection with
     * @throws NullPointerException if the array is <code>null</code>
     */
    public ArrayUnsignedIntList(long[] array) { 
        this(array.length);
        for(int i=0;i<array.length;i++) {
            _data[i] = fromLong(array[i]);
        }
        _size = array.length;
    }
    
    // IntList methods
    //-------------------------------------------------------------------------

    /** 
     * Returns the element at the specified position within 
     * me. 
     * By construction, the returned value will be 
     * between {@link #MIN_VALUE} and {@link #MAX_VALUE}, inclusive.
     * 
     * @param index the index of the element to return
     * @return the value of the element at the specified position
     * @throws IndexOutOfBoundsException if the specified index is out of range
     */
    public long get(int index) {
        checkRange(index);
        return toLong(_data[index]);
    }
    
    public int size() {
        return _size;
    }
    
    /** 
     * Removes the element at the specified position in 
     * (optional operation).  Any subsequent elements 
     * are shifted to the left, subtracting one from their 
     * indices.  Returns the element that was removed.
     * By construction, the returned value will be 
     * between {@link #MIN_VALUE} and {@link #MAX_VALUE}, inclusive.
     * 
     * @param index the index of the element to remove
     * @return the value of the element that was removed
     * 
     * @throws UnsupportedOperationException when this operation is not 
     *         supported
     * @throws IndexOutOfBoundsException if the specified index is out of range
     */
    public long removeElementAt(int index) {
        checkRange(index);
        incrModCount();
        long oldval = toLong(_data[index]);
        int numtomove = _size - index - 1;
        if(numtomove > 0) {
            System.arraycopy(_data,index+1,_data,index,numtomove);
        }
        _size--;
        return oldval;
    }
    
    /** 
     * Replaces the element at the specified 
     * position in me with the specified element
     * (optional operation). 
     * Throws {@link IllegalArgumentException} if <i>element</i>
     * is less than {@link #MIN_VALUE} or greater than {@link #MAX_VALUE}.
     * 
     * @param index the index of the element to change
     * @param element the value to be stored at the specified position
     * @return the value previously stored at the specified position
     * 
     * @throws UnsupportedOperationException when this operation is not 
     *         supported
     * @throws IndexOutOfBoundsException if the specified index is out of range
     */
    public long set(int index, long element) {
        assertValidUnsignedInt(element);
        checkRange(index);
        incrModCount();
        long oldval = toLong(_data[index]);
        _data[index] = fromLong(element);
        return oldval;
    }
        
    /** 
     * Inserts the specified element at the specified position 
     * (optional operation). Shifts the element currently 
     * at that position (if any) and any subsequent elements to the 
     * right, increasing their indices.
     * Throws {@link IllegalArgumentException} if <i>element</i>
     * is less than {@link #MIN_VALUE} or greater than {@link #MAX_VALUE}.
     * 
     * @param index the index at which to insert the element
     * @param element the value to insert
     * 
     * @throws UnsupportedOperationException when this operation is not 
     *         supported
     * @throws IllegalArgumentException if some aspect of the specified element 
     *         prevents it from being added to me
     * @throws IndexOutOfBoundsException if the specified index is out of range
     */
    public void add(int index, long element) {
        assertValidUnsignedInt(element);
        checkRangeIncludingEndpoint(index);
        incrModCount();
        ensureCapacity(_size+1);
        int numtomove = _size-index;
        System.arraycopy(_data,index,_data,index+1,numtomove);
        _data[index] = fromLong(element);
        _size++;
    }

    public void clear() {
        incrModCount();
        _size = 0;
    }

    // capacity methods
    //-------------------------------------------------------------------------

    /** 
     * Increases my capacity, if necessary, to ensure that I can hold at 
     * least the number of elements specified by the minimum capacity 
     * argument without growing.
     */
    public void ensureCapacity(int mincap) {
        incrModCount();
        if(mincap > _data.length) {
            int newcap = (_data.length * 3)/2 + 1;
            int[] olddata = _data;
            _data = new int[newcap < mincap ? mincap : newcap];
            System.arraycopy(olddata,0,_data,0,_size);
        }
    }

    /** 
     * Reduce my capacity, if necessary, to match my
     * current {@link #size size}.
     */
    public void trimToSize() {
        incrModCount();
        if(_size < _data.length) {
            int[] olddata = _data;
            _data = new int[_size];
            System.arraycopy(olddata,0,_data,0,_size);
        }
    }

    // private methods
    //-------------------------------------------------------------------------

    private final long toLong(int value) { 
        return value & MAX_VALUE;
    }

    private final int fromLong(long value) {
        return (int)(value&MAX_VALUE);
    }

    private final void assertValidUnsignedInt(long value) throws IllegalArgumentException {
        if(value > MAX_VALUE) {
            throw new IllegalArgumentException(value + " > " + MAX_VALUE);
        }
        if(value < MIN_VALUE) {
            throw new IllegalArgumentException(value + " < " + MIN_VALUE);
        }
    }

    private void writeObject(ObjectOutputStream out) throws IOException{
        out.defaultWriteObject();
        out.writeInt(_data.length);
        for(int i=0;i<_size;i++) {
            out.writeInt(_data[i]);
        }
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        _data = new int[in.readInt()];
        for(int i=0;i<_size;i++) {
            _data[i] = in.readInt();
        }
    }
    
    private final void checkRange(int index) {
        if(index < 0 || index >= _size) {
            throw new IndexOutOfBoundsException("Should be at least 0 and less than " + _size + ", found " + index);
        }
    }

    private final void checkRangeIncludingEndpoint(int index) {
        if(index < 0 || index > _size) {
            throw new IndexOutOfBoundsException("Should be at least 0 and at most " + _size + ", found " + index);
        }
    }

    // attributes
    //-------------------------------------------------------------------------
    
    /**
     *  The maximum possible unsigned 32-bit value.
     */
    public static final long MAX_VALUE = 0xFFFFFFFFL;

    /**
     *  The minimum possible unsigned 32-bit value.
     */
    public static final long MIN_VALUE = 0L;

    private transient int[] _data = null;
    private int _size = 0;

}