JsiGenerator.java

package com.cognifide.cq.includefilter.generator.types;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URL;

import org.apache.commons.lang.StringEscapeUtils;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Service;
import org.osgi.service.component.ComponentContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.cognifide.cq.includefilter.generator.IncludeGenerator;

/**
 * Client side include generator - using Ajax/JQuery.
 * 
 * @author tomasz.rekawek
 */
@Component
@Service
public class JsiGenerator implements IncludeGenerator {
	private static final String TEMPLATE_FILENAME = "generators/jquery.html";

	private static final String UUID_FIELD = "${uniqueId}";

	private static final String URL_FIELD = "${url}";

	private static final Logger LOG = LoggerFactory.getLogger(JsiGenerator.class);
	
	private static final String GENERATOR_NAME = "JSI";

	private volatile int divId = 1000;

	private String template;

	@Activate
	public void activate(ComponentContext ctx) {
		URL url = ctx.getBundleContext().getBundle().getResource(TEMPLATE_FILENAME);
		if (url == null) {
			LOG.error("File " + TEMPLATE_FILENAME + " not found in bundle.");
			return;
		}
		readTemplateFromUrl(url);
	}
	
	@Override
	public String getType() {
		return GENERATOR_NAME;
	}
	
	@Override
	public String getInclude(String url) {
		if (template == null) {
			throw new IllegalStateException("JSI generator hasn't be initialized");
		}

		String divName;
		synchronized (this) {
			divName = "dynamic_include_filter_div_" + divId++;
		}
		
		return template
				.replace(UUID_FIELD, divName)
				.replace(URL_FIELD, StringEscapeUtils.escapeJavaScript(url));
	}


	private void readTemplateFromUrl(URL url) {
		BufferedReader br = null;
		try {
			InputStream in = url.openStream();
			br = new BufferedReader(new InputStreamReader(in, "UTF-8"));
			StringBuilder builder = new StringBuilder();
			String line;
			while ((line = br.readLine()) != null) {
				builder.append(line).append('\n');
			}
			template = builder.toString();
		} catch (UnsupportedEncodingException e) {
			LOG.error("Error while reading template", e);
		} catch (IOException e) {
			LOG.error("Error while reading template", e);
		} finally {
			try {
				if (br != null) {
					br.close();
				}
			} catch (Exception e) {
				LOG.error("Error while closing reader", e);
			}
		}
	}

}