/* ServletLabelLocator.java

	Purpose:
		
	Description:
		
	History:
		Sat Apr  8 19:51:08     2006, Created by tomyeh

Copyright (C) 2006 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under LGPL Version 2.1 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.util.resource;

import java.io.IOException;
import java.net.URL;
import java.util.Locale;

import javax.servlet.ServletContext;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.zkoss.lang.Library;
import org.zkoss.lang.Objects;
import org.zkoss.util.resource.LabelLocator;
import org.zkoss.web.servlet.Servlets;

/**
 * Used by Labels to load labels from a servlet context.
 *
 * @author tomyeh
 */
public class ServletLabelLocator implements LabelLocator {
	private static final Logger log = LoggerFactory.getLogger(ServletLabelLocator.class);

	private final ServletContext _ctx;
	private final String _path;

	/** Constructs a locator where the properties file is decided
	 * by the library property called org.zkoss.util.label.web.location.
	 * If not defined, /WEB-INF/zk-label.properties is assumed
	 */
	public ServletLabelLocator(ServletContext ctx) {
		this(ctx, null);
	}

	/** Constructs a locator for the given path.
	 * @param path the path of the properties file<br/>
	 * Notice that <code>file://path</code> is supported (but not http://).
	 * @since 5.0.7
	 */
	public ServletLabelLocator(ServletContext ctx, String path) {
		if (ctx == null)
			throw new IllegalArgumentException("null");
		_ctx = ctx;
		_path = path;
	}

	//-- LabelLocator --//
	public URL locate(Locale locale) throws IOException {
		boolean fallback = false;
		String path;
		if (_path != null) {
			path = _path;
		} else {
			path = Library.getProperty("org.zkoss.util.label.web.location");
			if (path == null) {
				path = "/WEB-INF/zk-label.properties";
				fallback = true;
			}
		}
		URL url = locate0(path, locale);
		if (url == null)
			if (fallback)
				url = locate0("/WEB-INF/i3-label.properties", locale);
			else if (locale == null)
				log.error("File not found in " + _ctx.getServletContextName() + ": " + path);
		//error is shown only if locale, since zh_TW will load zh_TW and zh
		//while users won't prepare zh
		return url;
	}

	private URL locate0(String path, Locale locale) throws IOException {
		final int j = path.lastIndexOf('.');
		final String prefix = j >= 0 ? path.substring(0, j) : path;
		final String suffix = j >= 0 ? path.substring(j) : "";
		path = locale == null ? prefix + suffix : prefix + '_' + locale + suffix;
		return path.toLowerCase(java.util.Locale.ENGLISH).startsWith("file://") ? Servlets.getResource(_ctx, path)
				: _ctx.getResource(path);
		//we don't accept http:// since we cannot detect if it exists
	}

	//-- Object --//
	public int hashCode() {
		return _ctx.hashCode() + Objects.hashCode(_path);
	}

	public boolean equals(Object o) {
		if (this == o)
			return true;
		return o instanceof ServletLabelLocator && ((ServletLabelLocator) o)._ctx.equals(_ctx)
				&& Objects.equals(((ServletLabelLocator) o)._path, _path);
	}

	public String toString() {
		return "ServletLabelLocator" + (_path != null ? ": " + _path : "");
	}
}