/* JQueryRenderPatch.java

	Purpose:
		
	Description:
		
	History:
		Sun Jan 17 11:48:04 TST 2010, Created by tomyeh

Copyright (C) 2010 Potix Corporation. All Rights Reserved.

*/
package org.zkoss.zkplus.liferay;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

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

import org.zkoss.lang.Library;
import org.zkoss.lang.Strings;
import org.zkoss.zk.ui.Page;
import org.zkoss.zk.ui.sys.PageRenderPatch;
import org.zkoss.zk.ui.sys.RequestInfo;

/**
 * Used to patch the rendering result of a ZK portlet for Liferay.
 * When using ZK portlets with Liferay under Internet Explorer, we have
 * to delay the processing at the client a bit.
 *
 * <p>To use it, you have to specify a library property called
 * ""org.zkoss.zk.portlet.PageRenderPatch.class" with this class's name
 * ("org.zkoss.zkplus.liferay.JQueryRenderPatch").
 *
 * <p>You can further control the behavior of this patch by use of
 * a library property called "org.zkoss.zkplus.liferary.jQueryPatch"
 * (refer to {@link #JQUERY_PATCH} for details).
 *
 * @author tomyeh, sam
 * @since 5.0.0
 */
public class JQueryRenderPatch implements PageRenderPatch {
	private static final Logger log = LoggerFactory.getLogger(JQueryRenderPatch.class);

	/** A library property to indicate how to apply the so-called jQuery patch.
	 * <p>Default: "500" (it means 500 milliseconds)
	 *
	 * <p>You can specify a number to indicate how many milliseconds to wait
	 * before replacing with the correct content.
	 * If negative, the patch is ignored.
	 */
	public static final String JQUERY_PATCH = "org.zkoss.zkplus.liferary.jQueryPatch";

	private int _delay = -1;

	public JQueryRenderPatch() {
		final String val = Library.getProperty(JQUERY_PATCH);
		try {
			_delay = Integer.parseInt(val);
		} catch (Throwable ex) {
			log.warn("Ignored delay time specified in " + JQUERY_PATCH + ": " + val);
		}
	}

	/** Returns the number of milliseconds to wait before replacing with
	 * the correct content.
	 * <p>Default: depends on the value defined in the {@link #JQUERY_PATCH}
	 * library property.
	 */
	public int getDelay() {
		return _delay;
	}

	/** Sets the number of milliseconds to wait before replacing with
	 * the correct content.
	 * @see #JQUERY_PATCH
	 */
	public void setDelay(int delay) {
		_delay = delay;
	}

	/** It returns an instance of StringWriter if {@link #getDelay} is non-negative,
	 * or null if negative (means no patch).
	 */
	public Writer beforeRender(RequestInfo reqInfo) {
		return _delay >= 0 ? new StringWriter() : null;
		//we cannot retrieve HTTP request's header so no need to
		//apply the patch for particular browsers, such as ie
	}

	public void patchRender(RequestInfo reqInfo, Page page, Writer result, Writer out) throws IOException {
		final String extid = page.getUuid() + "-ext";
		String[] html = processHtml(((StringWriter) result).toString());
		//we have to process CSS and append it to HEAD
		out.write(html[0]);
		out.write("<div id=\"");
		out.write(extid);
		out.write("\"></div><script>setTimeout(function(){\njQuery('#");
		out.write(extid);
		out.write("').append('");
		//we have to use append() since it is evaluated synchronously
		//while replaceWith() is not
		out.write(Strings.escape(html[1], Strings.ESCAPE_JAVASCRIPT));
		out.write("');},");
		out.write("" + getBrowserDelay());
		out.write(");</script>");
	}

	protected String getBrowserDelay() {
		return "" + _delay;
	}

	protected String[] processHtml(String html) {
		boolean isAppendCSS = false;
		StringBuffer script = new StringBuffer(
				"<script>function _zkCSS(uri){var e=document.createElement(\"LINK\");e.rel=\"stylesheet\";e.type=\"text/css\";e.href=uri;document.getElementsByTagName(\"HEAD\")[0].appendChild(e);};");
		Pattern p = Pattern.compile("<link[^>]+href=[\"']?([^'\"> ]+)[\"']?[^>]*>");

		StringBuffer buffer = new StringBuffer();
		int parseStart = 0, scriptStart = 0, scriptEnd = 0;
		for (scriptStart = html.indexOf("<script"); scriptStart != -1;) {
			if (parseStart < scriptStart) {
				Matcher m = p.matcher(html.substring(parseStart, scriptStart));
				while (m.find()) {
					isAppendCSS = true;
					String uri = m.group(1);
					script.append("_zkCSS('" + uri + "');");
					m.appendReplacement(buffer, "");
				}
				m.appendTail(buffer);
			}
			scriptEnd = html.indexOf("</script>", scriptStart);
			if (scriptEnd == -1)
				break;
			scriptEnd += "</script>".length();
			buffer.append(html.subSequence(scriptStart, scriptEnd));
			if ((scriptStart = html.indexOf("<script", scriptEnd)) != -1)
				parseStart = scriptEnd;
			else {
				buffer.append(html.substring(scriptEnd, html.length()));
				break;
			}
		}

		String[] ret = { "", html };
		if (isAppendCSS) {
			script.append("</script>");
			ret[0] = script.toString();
			ret[1] = buffer.toString();
		}
		return ret;
	}
}