LabelUtils.java

/**
 * Copyright (c) 2011-2012 Optimax Software Ltd.
 * 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 Optimax Software, ElasticInbox, 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 com.elasticinbox.core.utils;

import java.util.Random;
import java.util.Set;

import com.elasticinbox.core.ExistingLabelException;
import com.elasticinbox.core.IllegalLabelException;
import com.elasticinbox.core.model.Label;
import com.elasticinbox.core.model.LabelConstants;
import com.elasticinbox.core.model.LabelMap;
import com.elasticinbox.core.model.ReservedLabels;

public final class LabelUtils
{
	private final static Random random = new Random();
	private final static int MAX_NEW_LABEL_ID_ATTEMPTS = 200;

	/**
	 * Generate random label ID
	 * 
	 * @return
	 */
	private static int getNewLabelId()
	{
		// New label ID whould be greater than reserved label IDs and within
		// allowed range (less than MAX_LABEL_ID).
		int labelId = LabelConstants.MAX_RESERVED_LABEL_ID
				+ random.nextInt(LabelConstants.MAX_LABEL_ID - LabelConstants.MAX_RESERVED_LABEL_ID);
		return labelId;
	}
	
	/**
	 * Generates new label ID which does not exist in the given list
	 * 
	 * @param existingLabels
	 * @return
	 */
	public static int getNewLabelId(Set<Integer> existingLabels)
	{
		// generate new unique label id
		int labelId = LabelUtils.getNewLabelId();
		int attempts = 1;
		while (existingLabels.contains(labelId))
		{
			if (attempts > MAX_NEW_LABEL_ID_ATTEMPTS)
			{
				// too many attempts to get new random id! too many labels?
				throw new IllegalLabelException("Too many labels");
			}

			labelId = LabelUtils.getNewLabelId();
			attempts++;
		}
		
		return labelId;
	}

	/**
	 * Validate label name and check within existing labels
	 * 
	 * @param labelName
	 */
	public static void validateLabelName(final String labelName, final LabelMap existingLabels)
	{
		// check total length of label
		if (labelName.length() > LabelConstants.MAX_LABEL_NAME_LENGTH) {
			throw new IllegalLabelException("Label name exceeds maximum allowed length");
		}

		// check if label already exists
		if (existingLabels.containsName(labelName)) {
			throw new ExistingLabelException("Label with this name already exists");
		}

		// check if starts with reserved label
		for (Label l : ReservedLabels.getAll())
		{
			if (labelName.startsWith(l.getName() + LabelConstants.NESTED_LABEL_SEPARATOR.toString()))
				throw new IllegalLabelException("Netsted labels are not allowed under reserved labels");
		}

		if (labelName.contains(LabelConstants.NESTED_LABEL_SEPARATOR.toString() + LabelConstants.NESTED_LABEL_SEPARATOR.toString()))
		{
			throw new IllegalLabelException("Illegal use of nested label separator");
		}

		// check special symbols? for now we allow any symbol
	}
}