CountryTag.java

/*******************************************************************************
 *   Gisgraphy Project 
 * 
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 * 
 *   This library 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
 *   Lesser General Public License for more details.
 * 
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
 * 
 *  Copyright 2008  Gisgraphy project 
 *  David Masclet <davidmasclet@gisgraphy.com>
 *  
 *  
 *******************************************************************************/
package com.gisgraphy.webapp.taglib;

import java.io.IOException;
import java.text.Collator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

import org.displaytag.tags.el.ExpressionEvaluator;

import com.gisgraphy.model.LabelValue;

/**
 * Tag for creating multiple <select> options for displaying a list of
 * country names.
 * <p>
 * <b>NOTE</b> - This tag requires a Java2 (JDK 1.2 or later) platform.
 * </p>
 * 
 * @author Jens Fischer, Matt Raible
 * @version $Revision: 1.4.2.1 $ $Date: 2006-06-10 08:00:48 -0600 (Sat, 10 Jun
 *          2006) $
 */
public class CountryTag extends TagSupport {
    private static final long serialVersionUID = 3905528206810167095L;

    private String name;

    private String prompt;

    private String scope;

    private String selected;

    public void setName(String name) {
	this.name = name;
    }

    public void setPrompt(String prompt) {
	this.prompt = prompt;
    }

    public void setDefault(String selected) {
	this.selected = selected;
    }

    public void setToScope(String scope) {
	this.scope = scope;
    }

    /**
     * Process the start of this tag.
     * 
     * @return int status
     * @exception JspException
     *                    if a JSP exception has occurred
     * @see javax.servlet.jsp.tagext.Tag#doStartTag()
     */
    @Override
    public int doStartTag() throws JspException {
	ExpressionEvaluator eval = new ExpressionEvaluator(this, pageContext);

	if (selected != null) {
	    selected = eval.evalString("default", selected);
	}

	Locale userLocale = pageContext.getRequest().getLocale();
	List<LabelValue> countries = this.buildCountryList(userLocale);

	if (scope != null) {
	    if (scope.equals("page")) {
		pageContext.setAttribute(name, countries);
	    } else if (scope.equals("request")) {
		pageContext.getRequest().setAttribute(name, countries);
	    } else if (scope.equals("session")) {
		pageContext.getSession().setAttribute(name, countries);
	    } else if (scope.equals("application")) {
		pageContext.getServletContext().setAttribute(name, countries);
	    } else {
		throw new JspException(
			"Attribute 'scope' must be: page, request, session or application");
	    }
	} else {
	    StringBuffer sb = new StringBuffer();
	    sb.append("<select name=\"").append(name).append("\" id=\"")
		    .append(name).append("\" class=\"select\">\n");

	    if (prompt != null) {
		sb.append("    <option value=\"\" selected=\"selected\">");
		sb.append(eval.evalString("prompt", prompt)).append(
			"</option>\n");
	    }

	    for (Object country1 : countries) {
		LabelValue country = (LabelValue) country1;
		sb.append("    <option value=\"").append(country.getValue())
			.append("\"");

		if ((selected != null) && selected.equals(country.getValue())) {
		    sb.append(" selected=\"selected\"");
		}

		sb.append(">").append(country.getLabel()).append("</option>\n");
	    }

	    sb.append("</select>");

	    try {
		pageContext.getOut().write(sb.toString());
	    } catch (IOException io) {
		throw new JspException(io);
	    }
	}

	return super.doStartTag();
    }

    /**
     * Release aquired resources to enable tag reusage.
     * 
     * @see javax.servlet.jsp.tagext.Tag#release()
     */
    @Override
    public void release() {
	super.release();
    }

    /**
     * Build a List of LabelValues for all the available countries. Uses the two
     * letter uppercase ISO name of the country as the value and the localized
     * country name as the label.
     * 
     * @param locale
     *                The Locale used to localize the country names.
     * @return List of LabelValues for all available countries.
     */
    @SuppressWarnings("unchecked")
    protected List<LabelValue> buildCountryList(Locale locale) {
	final Locale[] available = Locale.getAvailableLocales();

	List<LabelValue> countries = new ArrayList<LabelValue>();

	for (Locale anAvailable : available) {
	    final String iso = anAvailable.getCountry();
	    final String name = anAvailable.getDisplayCountry(locale);

	    if (!"".equals(iso) && !"".equals(name)) {
		LabelValue country = new LabelValue(name, iso);

		if (!countries.contains(country)) {
		    countries.add(new LabelValue(name, iso));
		}
	    }
	}

	Collections.sort(countries, new LabelValueComparator(locale));

	return countries;
    }

    /**
     * Class to compare LabelValues using their labels with locale-sensitive
     * behaviour.
     */
    @SuppressWarnings("unchecked")
    public class LabelValueComparator implements Comparator {
	private Comparator c;

	/**
	 * Creates a new LabelValueComparator object.
	 * 
	 * @param locale
	 *                The Locale used for localized String comparison.
	 */
	public LabelValueComparator(final Locale locale) {
	    c = Collator.getInstance(locale);
	}

	/**
	 * Compares the localized labels of two LabelValues.
	 * 
	 * @param o1
	 *                The first LabelValue to compare.
	 * @param o2
	 *                The second LabelValue to compare.
	 * @return The value returned by comparing the localized labels.
	 */
	@SuppressWarnings("unchecked")
	public final int compare(Object o1, Object o2) {
	    LabelValue lhs = (LabelValue) o1;
	    LabelValue rhs = (LabelValue) o2;

	    return c.compare(lhs.getLabel(), rhs.getLabel());
	}
    }
}