Tags.java

/*
 * Copyright (c) 2006-2009 by Dirk Riehle, http://dirkriehle.com
 *
 * This file is part of the Wahlzeit photo rating application.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 */

package org.wahlzeit.model;

import org.wahlzeit.utils.StringUtil;

import java.io.Serializable;
import java.util.Set;
import java.util.TreeSet;

/**
 * A Tags instance represents a set of tags; each tag ist just a string.
 * All tags are maintained lowercase and without whitespace. 
 * For example, "Captain America" turns into "captainamerica".
 */
public class Tags implements Serializable {

	/**
	 *
	 */
	public static final char SEPARATOR_CHAR = ',';

	/**
	 *
	 */
	public static final int MAX_NO_TAGS = 32;

	/**
	 *
	 */
	public static final Tags EMPTY_TAGS = new Tags();

	/**
	 *
	 */
	private final char separator;

	/**
	 *
	 */
	protected Set<String> tags = new TreeSet<String>();

	/**
	 *
	 */
	public Tags() {
		// do nothing
		this.separator = SEPARATOR_CHAR;
	}

	/**
	 *
	 */
	public Tags(String myTags) {
		this.separator = SEPARATOR_CHAR;
		this.tags = asTagSetFromString(myTags);
	}

	/**
	 *
	 */
	public Tags(String myTags, char separator) {
		this.separator = separator;
		this.tags = asTagSetFromString(myTags, separator);
	}

	/**
	 * @methodtype boolean-query
	 */
	@Override
	public int hashCode() {
		return (tags == null) ? super.hashCode() : tags.hashCode();
	}

	/**
	 *
	 */
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (!(obj instanceof Tags))
			return false;

		Tags other = (Tags) obj;
		return isEqual(other);
	}

	/**
	 *
	 */
	public boolean isEqual(Tags other) {
		if (tags == null) {
			return other.tags == null;
		}

		return tags.equals(other.tags);
	}

	/**
	 *
	 */
	public boolean hasTag(String tag) {
		return (null != tag) && tags.contains(tag);
	}

	/**
	 * @methodtype get
	 */
	public int getSize() {
		return tags.size();
	}

	/**
	 * @methodtype conversion
	 */
	public String asString() {
		return asString(false, separator);
	}

	/**
	 *
	 */
	public String asString(boolean lead, char sep) {
		StringBuffer result = new StringBuffer();
		String seps = (lead ? " " : "") + sep + " ";
		String[] myTags = asArray();
		for (int i = 0; i < myTags.length; i++) {
			if (i != 0)
				result.append(seps);
			result.append(myTags[i]);
		}
		return result.toString();
	}

	/**
	 *
	 */
	public String[] asArray() {
		return tags.toArray(new String[tags.size()]);
	}

	/**
	 * @methodtype conversion
	 * @methodproperties convenience, class
	 */
	public static Set<String> asTagSetFromString(String tags) {
		return asTagSetFromString(tags, SEPARATOR_CHAR);
	}

	/**
	 * @methodtype conversion
	 * @methodproperties class
	 */
	public static Set<String> asTagSetFromString(String tags, char separator) {
		Set<String> result = new TreeSet<String>();

		if (tags != null) {
			int i = 0;
			int j = 0;
			for (; i < tags.length(); i = j) {
				for (; ((i < tags.length()) && (tags.charAt(i) == separator)); ) {
					i++;
				}

				for (j = i; ((j < tags.length()) && (tags.charAt(j) != separator)); ) {
					j++;
				}

				if (i != j) {
					String tag = asTag(tags.substring(i, j));
					if (!StringUtil.isNullOrEmptyString(tag)) {
						result.add(tag);
					}
				}
			}
		}

		return result;
	}

	/**
	 *
	 */
	public static String asTag(String n) {
		StringBuffer result = new StringBuffer(n.length());

		for (int i = 0; i < n.length(); i++) {
			char c = n.charAt(i);
			if (Character.isLetter(c)) {
				result.append(Character.toLowerCase(c));
			} else if (Character.isDigit(c)) {
				result.append(c);
			}
		}

		return result.toString();
	}

}