StaxParser.java

package feed.parser;

import java.io.Reader;
import java.util.HashMap;
import java.util.Map;
import java.util.Stack;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import org.apache.commons.lang3.StringUtils;
import org.caudexorigo.ErrorAnalyser;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class StaxParser
{
	private static final Logger log = LoggerFactory.getLogger(StaxParser.class);

	private static final XMLInputFactory factory = XMLInputFactory.newInstance();

	private static Map<String, String> ns_aliases = new HashMap<String, String>();

	private static Map<String, FeedChannelProcessor> feed_channel_processors = new HashMap<String, FeedChannelProcessor>();

	private static Map<String, FeedEntryProcessor> feed_entry_processors = new HashMap<String, FeedEntryProcessor>();

	private boolean stripHtml;

	static
	{
		ns_aliases.put("http://a9.com/-/spec/opensearchrss/1.0/", "opensearch");
		ns_aliases.put("http://backend.userland.com/blogChannelModule", "blogChannel");
		ns_aliases.put("http://backend.userland.com/creativeCommonsRssModule", "creativeCommons");
		ns_aliases.put("http://example.com/dtds/podcast-1.0.dtd", "itunes");
		ns_aliases.put("http://freshmeat.net/rss/fm/", "fm");
		ns_aliases.put("http://hacks.benhammersley.com/rss/streaming/", "str");
		ns_aliases.put("http://madskills.com/public/xml/rss/module/pingback/", "pingback");
		ns_aliases.put("http://madskills.com/public/xml/rss/module/trackback/", "trackback");
		ns_aliases.put("http://media.tangent.org/rss/1.0/", "audio");
		ns_aliases.put("http://my.theinfo.org/changed/1.0/rss/", "cp");
		ns_aliases.put("http://postneo.com/icbm/", "icbm");
		ns_aliases.put("http://prismstandard.org/namespaces/1.2/basic/", "prism");
		ns_aliases.put("http://purl.org/dc/elements/1.1/", "dc");
		ns_aliases.put("http://purl.org/dc/terms/", "dcterms");
		ns_aliases.put("http://purl.org/rss/1.0/modules/aggregation/", "ag");
		ns_aliases.put("http://purl.org/rss/1.0/modules/annotate/", "annotate");
		ns_aliases.put("http://purl.org/rss/1.0/modules/company", "co");
		ns_aliases.put("http://purl.org/rss/1.0/modules/content/", "content");
		ns_aliases.put("http://purl.org/rss/1.0/modules/email/", "email");
		ns_aliases.put("http://purl.org/rss/1.0/modules/event/", "ev");
		ns_aliases.put("http://purl.org/rss/1.0/modules/image/", "image");
		ns_aliases.put("http://purl.org/rss/1.0/modules/link/", "l");
		ns_aliases.put("http://purl.org/rss/1.0/modules/reference/", "ref");
		ns_aliases.put("http://purl.org/rss/1.0/modules/richequiv/", "reqv");
		ns_aliases.put("http://purl.org/rss/1.0/modules/search/", "search");
		ns_aliases.put("http://purl.org/rss/1.0/modules/servicestatus/", "ss");
		ns_aliases.put("http://purl.org/rss/1.0/modules/slash/", "slash");
		ns_aliases.put("http://purl.org/rss/1.0/modules/subscription/", "sub");
		ns_aliases.put("http://purl.org/rss/1.0/modules/syndication/", "sy");
		ns_aliases.put("http://purl.org/rss/1.0/modules/taxonomy/", "taxo");
		ns_aliases.put("http://purl.org/rss/1.0/modules/textinput/", "ti");
		ns_aliases.put("http://purl.org/rss/1.0/modules/threading/", "thr");
		ns_aliases.put("http://purl.org/rss/1.0/modules/wiki/", "wiki");
		ns_aliases.put("http://purl.org/rss/1.0/", "rdf");
		ns_aliases.put("http://rssnamespace.org/feedburner/ext/1.0", "feedburner");

		ns_aliases.put("http://schemas.xmlsoap.org/soap/envelope/", "soap");
		ns_aliases.put("http://webns.net/mvcb/", "admin");
		ns_aliases.put("http://web.resource.org/cc/", "cc");
		ns_aliases.put("http://wellformedweb.org/commentapi/", "wfw");
		ns_aliases.put("http://www.georss.org/georss", "georss");
		ns_aliases.put("http://www.itunes.com/dtds/podcast-1.0.dtd", "itunes");
		ns_aliases.put("http://www.w3.org/1999/02/22-rdf-syntax-ns#", "rdf");
		ns_aliases.put("http://www.w3.org/1999/xhtml", "xhtml");
		ns_aliases.put("http://www.w3.org/2000/01/rdf-schema#", "rdfs");
		ns_aliases.put("http://www.w3.org/2003/01/geo/wgs84_pos#", "wgs84");
		ns_aliases.put("http://www.w3.org/2005/atom", "atom");
		ns_aliases.put("http://www.w3.org/XML/1998/namespace", "xml");
		ns_aliases.put("http://xmlns.com/foaf/0.1/", "foaf");
		ns_aliases.put("http://search.yahoo.com/mrss/", "media");
		ns_aliases.put("", "rss");

		feed_channel_processors.put("/rss:rss/rss:channel/rss:title", new SimpleFeedChannelProcessor("title"));
		feed_channel_processors.put("/rss:rss/rss:channel/rss:link", new SimpleFeedChannelProcessor("link"));
		feed_channel_processors.put("/rss:rss/rss:channel/rss:description", new SimpleFeedChannelProcessor("description"));
		feed_channel_processors.put("/rss:rss/rss:channel/rss:language", new SimpleFeedChannelProcessor("language"));
		feed_channel_processors.put("/rss:rss/rss:channel/rss:item", new AddFeedEntryProcessor());

		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:title", new SimpleFeedEntryProcessor("title"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:author", new SimpleFeedEntryProcessor("author"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:guid", new GuidProcessor());
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:pubdate", new SimpleFeedEntryProcessor("pubdate"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:description", new SimpleFeedEntryProcessor("body"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/atom:summary", new SimpleFeedEntryProcessor("body"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:link", new SimpleFeedEntryProcessor("link"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/feedburner:origlink", new SimpleFeedEntryProcessor("origlink"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:category", new CategoryProcessor());
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:tag", new CategoryProcessor());
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:subject", new CategoryProcessor());
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:subtitle", new CategoryProcessor());
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/dc:subject", new CategoryProcessor());
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/dc:date", new SimpleFeedEntryProcessor("pubdate"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/dc:creator", new SimpleFeedEntryProcessor("author"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/content:encoded", new SimpleFeedEntryProcessor("body"));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/rss:enclosure", new EnclosureProcessor(Enclosure.Type.RSS));
		feed_entry_processors.put("/rss:rss/rss:channel/rss:item/media:content", new EnclosureProcessor(Enclosure.Type.YAHOO_MEDIA));

		feed_channel_processors.put("/rdf:rdf/rdf:channel/rdf:title", new SimpleFeedChannelProcessor("title"));
		feed_channel_processors.put("/rdf:rdf/rdf:channel/rdf:link", new SimpleFeedChannelProcessor("link"));
		feed_channel_processors.put("/rdf:rdf/rdf:channel/rdf:description", new SimpleFeedChannelProcessor("description"));
		feed_channel_processors.put("/rdf:rdf/rdf:item", new AddFeedEntryProcessor());
		feed_entry_processors.put("/rdf:rdf/rdf:item/rdf:title", new SimpleFeedEntryProcessor("title"));
		feed_entry_processors.put("/rdf:rdf/rdf:item/dc:subject", new CategoryProcessor());
		feed_entry_processors.put("/rdf:rdf/rdf:item/rdf:link", new SimpleFeedEntryProcessor("link"));
		feed_entry_processors.put("/rdf:rdf/rdf:item/feedburner:origlink", new SimpleFeedEntryProcessor("origlink"));
		feed_entry_processors.put("/rdf:rdf/rdf:item/dc:creator", new SimpleFeedEntryProcessor("author"));
		feed_entry_processors.put("/rdf:rdf/rdf:item/dc:date", new SimpleFeedEntryProcessor("pubdate"));
		feed_entry_processors.put("/rdf:rdf/rdf:item/rdf:description", new SimpleFeedEntryProcessor("body"));

		feed_channel_processors.put("/atom:feed/atom:title", new SimpleFeedChannelProcessor("title"));
		feed_channel_processors.put("/atom:feed/atom:subtitle", new SimpleFeedChannelProcessor("description"));
		feed_channel_processors.put("/atom:feed/atom:link", new AtomFeedChannelLinkProcessor("service.feed", "application/x.atom+xml"));
		feed_channel_processors.put("/atom:feed/atom:entry", new AddFeedEntryProcessor());
		feed_entry_processors.put("/atom:feed/atom:entry/atom:title", new SimpleFeedEntryProcessor("title"));
		feed_entry_processors.put("/atom:feed/atom:entry/feedburner:origlink", new SimpleFeedEntryProcessor("origlink"));
		feed_entry_processors.put("/atom:feed/atom:entry/atom:id", new GuidProcessor());
		feed_entry_processors.put("/atom:feed/atom:entry/atom:link", new AtomFeedEntryLinkProcessor("alternate", "text/html"));
		feed_entry_processors.put("/atom:feed/atom:entry/atom:author/atom:name", new SimpleFeedEntryProcessor("author"));
		feed_entry_processors.put("/atom:feed/atom:entry/atom:published", new SimpleFeedEntryProcessor("pubdate"));
		feed_entry_processors.put("/atom:feed/atom:entry/atom:category", new CategoryProcessor());
		feed_entry_processors.put("/atom:feed/atom:entry/atom:content", new AtomContentProcessor());

	}

	public StaxParser()
	{
		super();
	}

	// public FeedChannel parse(InputStream stream)
	// {
	// return parse(stream, true);
	// }
	//
	// public FeedChannel parse(InputStream stream, boolean failOnError)
	// {
	// try
	// {
	// XMLStreamReader staxXmlReader = factory.createXMLStreamReader(stream,
	// "UTF-8");
	// return _parse(staxXmlReader, failOnError);
	// }
	// catch (Throwable t)
	// {
	// if (failOnError)
	// {
	// throw new RuntimeException(t);
	// }
	// else
	// {
	// Throwable r = ErrorAnalyser.findRootCause(t);
	// log.error(r.getMessage(), r);
	// return new FeedChannel();
	// }
	// }
	// }

	public FeedChannel parse(Reader reader)
	{
		return parse(reader, true, false);
	}

	public FeedChannel parse(Reader reader, boolean failOnError, boolean stripHtml)
	{
		this.stripHtml = stripHtml;
		try
		{
			XMLStreamReader staxXmlReader = factory.createXMLStreamReader(reader);
			return _parse(staxXmlReader, failOnError);
		}
		catch (Throwable t)
		{
			if (failOnError)
			{
				throw new RuntimeException(t);
			}
			else
			{
				Throwable r = ErrorAnalyser.findRootCause(t);
				log.error(r.getMessage(), r);
				return new FeedChannel(stripHtml);
			}
		}
	}

	private FeedChannel _parse(XMLStreamReader staxXmlReader, boolean failOnError) throws Throwable
	{
		int eventType = staxXmlReader.getEventType();

		Stack<FeedXmlElement> stack = new Stack<FeedXmlElement>();
		FeedChannel feed_channel = new FeedChannel(stripHtml);

		do
		{
			try
			{
				if (eventType == XMLStreamConstants.START_ELEMENT)
				{
					String ns = StringUtils.isBlank(staxXmlReader.getNamespaceURI()) ? "" : staxXmlReader.getNamespaceURI().toLowerCase();
					String lname = staxXmlReader.getLocalName().toLowerCase();
					String alias_prefix = ns_aliases.get(ns);

					FeedXmlElement fxe = new FeedXmlElement(alias_prefix, lname);
					stack.push(fxe);

					String path = buildPath(stack);

					if (log.isDebugEnabled())
					{
						log.debug("Xml element path: {}", path);
					}

					FeedChannelProcessor fc_proc = feed_channel_processors.get(path);

					if (fc_proc != null)
					{
						fc_proc.process(feed_channel, staxXmlReader);
					}

					FeedEntryProcessor fe_proc = feed_entry_processors.get(path);

					if (fe_proc != null)
					{
						try
						{
							fe_proc.process(feed_channel, staxXmlReader);
						}
						catch (Throwable t)
						{
							Throwable r = ErrorAnalyser.findRootCause(t);

							if (r instanceof XMLStreamException)
							{
								log.error("Invalid feed element", r);
								continue;
							}
							else
							{
								throw new RuntimeException(r);
							}
						}
					}

					eventType = staxXmlReader.getEventType();
				}

				if (eventType == XMLStreamConstants.END_ELEMENT)
				{
					stack.pop();
				}
			}
			catch (Throwable t)
			{
				if (failOnError)
				{
					throw new RuntimeException(t);
				}
				else
				{
					Throwable r = ErrorAnalyser.findRootCause(t);
					log.error(r.getMessage(), r);
				}
			}

			eventType = staxXmlReader.next();
		}
		while (eventType != XMLStreamConstants.END_DOCUMENT);

		return feed_channel;
	}

	private String buildPath(Stack<FeedXmlElement> stack)
	{
		StringBuilder sb = new StringBuilder();
		sb.append("/");
		int s = stack.size();
		for (FeedXmlElement fxe : stack)
		{
			sb.append(fxe.toString());
			if (--s > 0)
			{
				sb.append("/");
			}
		}
		return sb.toString();
	}
}