/*****************************************************************************
 * Copyright (C) Codehaus.org                                                *
 * ------------------------------------------------------------------------- *
 * Licensed 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 net.ion.rosetta.util;

import net.ion.rosetta.annotations.Private;

/**
 * A simple, efficient and dynamic int list.
 * 
 * <p>
 * Not thread-safe.
 * 
 * @author Ben Yu.
 */
public final class IntList {
	private int[] buf;
	private int len = 0;

	/** Creates a {@code int[]} object with all the elements. */
	public int[] toArray() {
		int[] ret = new int[len];
		for (int i = 0; i < len; i++) {
			ret[i] = buf[i];
		}
		return ret;
	}

	/**
	 * Creates an {@link IntList} object with initial capacity equal to
	 * {@code capacity}.
	 */
	public IntList(int capacity) {
		this.buf = new int[capacity];
	}

	/** Creates an empty {@link IntList} object. */
	public IntList() {
		this(10);
	}

	/** Gets the number of int values stored. */
	public int size() {
		return len;
	}

	private void checkIndex(int i) {
		if (i < 0 || i >= len)
			throw new ArrayIndexOutOfBoundsException(i);
	}

	/**
	 * Gets the int value at a index {@code i}.
	 * 
	 * @param i
	 *            the 0 - based index of the value.
	 * @return the int value.
	 * @throws ArrayIndexOutOfBoundsException
	 *             if {@code i < 0 or i >= size()}.
	 */
	public int get(int i) {
		checkIndex(i);
		return buf[i];
	}

	/**
	 * Sets the value at index {@code i} to {@code val}.
	 * 
	 * @param i
	 *            the 0 - based index.
	 * @param val
	 *            the new value.
	 * @return the old value.
	 * @throws ArrayIndexOutOfBoundsException
	 *             if {@code i < 0 or i >= size()}.
	 */
	public int set(int i, int val) {
		checkIndex(i);
		int old = buf[i];
		buf[i] = val;
		return old;
	}

	@Private
	static int calcSize(int expectedSize, int factor) {
		int rem = expectedSize % factor;
		return expectedSize / factor * factor + (rem > 0 ? factor : 0);
	}

	/**
	 * Ensures that there is at least {@code l} capacity.
	 * 
	 * @param capacity
	 *            the minimal capacity.
	 */
	public void ensureCapacity(int capacity) {
		if (capacity > buf.length) {
			int factor = buf.length / 2 + 1;
			grow(calcSize(capacity - buf.length, factor));
		}
	}

	private void grow(int l) {
		int[] nbuf = new int[buf.length + l];
		for (int i = 0; i < buf.length; i++) {
			nbuf[i] = buf[i];
		}
		buf = nbuf;
	}

	/**
	 * Adds {@code i} into the array.
	 * 
	 * @param i
	 *            the int value.
	 * @return this object.
	 */
	public IntList add(int i) {
		ensureCapacity(len + 1);
		buf[len++] = i;
		return this;
	}
}