source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/service/RSSRetrieve.java@ 27087

package org.greenstone.gsdl3.service;


// Greenstone classes
import org.greenstone.gsdl3.util.*;
import org.greenstone.gsdl3.collection.Collection;
import org.greenstone.util.GlobalProperties;

// XML classes
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.Attr;
import org.w3c.dom.Text;
import org.w3c.dom.NodeList;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.ProcessingInstruction;

// General Java classes
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.Serializable;
import java.util.Vector;
import java.util.HashMap;
import java.util.Date;
import java.text.SimpleDateFormat;
import org.apache.log4j.*;

public class RSSRetrieve extends ServiceRack {

    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.service.RSSRetrieve.class.getName());
    protected static final String RSS_SERVICE = "RSSFeed";

    public boolean configure(Element info, Element extra_info) {
    if (!super.configure(info, extra_info)){
        return false;
    }
    logger.info("configuring RSSRetrieve...");  
    
    // set up short_service_info_ - for now just has name and type
    Element rss_service = this.doc.createElement(GSXML.SERVICE_ELEM);
    rss_service.setAttribute(GSXML.TYPE_ATT, GSXML.SERVICE_TYPE_RETRIEVE);
    rss_service.setAttribute(GSXML.NAME_ATT, RSS_SERVICE);
    this.short_service_info.appendChild(rss_service);

    return true;
    }

    // this may get called but is not useful in the case of retrieve services
    protected Element getServiceDescription(String service_id, String lang, String subset) {

    Element rss_service = this.doc.createElement(GSXML.SERVICE_ELEM);
    rss_service.setAttribute(GSXML.TYPE_ATT, GSXML.SERVICE_TYPE_RETRIEVE);
    rss_service.setAttribute(GSXML.NAME_ATT, service_id);
    return rss_service;
    }
    
    // Sends off a collection 'describe' message and returns the <collection> element of the response.
    // This contains the collection meta from collectionConfig.xml. Used to construct header of RSS feed
    protected Element getCollMetadata(UserContext userContext) {
    Element mr_request_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
    String to = this.cluster_name;
    Element meta_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_DESCRIBE, to, userContext);
    mr_request_message.appendChild(meta_request);
    Element meta_response = (Element) this.router.process(mr_request_message);
    meta_response = (Element) GSXML.getChildByTagName(meta_response, GSXML.RESPONSE_ELEM);

    NodeList nl = meta_response.getElementsByTagName(GSXML.COLLECTION_ELEM);
    Element collectionEl = (Element) nl.item(0);
    return collectionEl;
    }


    /**
       Generates the RSS feed XML by creating the header and footer with the contents
       of the the collection's index/rss-items.rdf file embedded in the middle.       
       @return the RSS feed XML.
       @see http://cyber.law.harvard.edu/rss/rss.html
     */
    protected Element processRSSFeed(Element request) {

    // Ask the MessageRouter for this collection's colConfig metadata 
    // from which the RSS header values will be constructed
    UserContext userContext = new UserContext(request);
    Element collMeta = getCollMetadata(userContext);
    
    //logger.error("**** collection metadata:");
    //GSXML.elementToLogAsString(collMeta, true);

    // work out some commonly used variables such as lang and url_prefix
    String lang = request.getAttribute("lang");
    if(lang.equals("")) {
        lang = "en";
    }

    // url_prefix is of the form http://domain/greenstone3/library/collection/_colname_/
    String url_prefix = GlobalProperties.getFullGSDL3WebAddress()+"/"+this.library_name+"/collection/"+this.cluster_name;


    // generate the header and footer
    Document rssDoc = this.doc;
    
    Element rssNode = rssDoc.createElement("rss"); // rootnode
    rssNode.setAttribute("version", "2.0");

    String namespace_url = "http://www.w3.org/2000/xmlns/";
    rssNode.setAttributeNS(namespace_url, "xmlns:content", "http://purl.org/rss/1.0/modules/content/");
    rssNode.setAttributeNS(namespace_url, "xmlns:taxo", "http://purl.org/rss/1.0/modules/taxonomy/");
    rssNode.setAttributeNS(namespace_url, "xmlns:dc", "http://purl.org/dc/elements/1.1/");
    rssNode.setAttributeNS(namespace_url, "xmlns:syn", "http://purl.org/rss/1.0/modules/syndication/");
    rssNode.setAttributeNS(namespace_url, "xmlns:admin", "http://webns.net/mvcb/");
    rssDoc.appendChild(rssNode);

    // Setting the preproccessing header line (Utf-8) will be done in web/interfaces' rss.xsl
    //ProcessingInstruction procInstruction = doc.createProcessingInstruction("xml","version=\"1.0\"");
    //rssDoc.appendChild(procInstruction);
    
    Element channelNode = rssDoc.createElement("channel");
    rssNode.appendChild(channelNode);
    
    Element childNode = rssDoc.createElement("title");
    GSXML.setNodeText(childNode, this.cluster_name); //_collectionname_
    channelNode.appendChild(childNode);

    // _httppageabout_: of form http://domain/greenstone3/library/collection/_colname_/page/about
    childNode = rssDoc.createElement("link");   
    GSXML.setNodeText(childNode, url_prefix+"/page/about"); // _httppageabout_
    channelNode.appendChild(childNode);

    // get the description string for the requested language, else fallback on en description if present
    childNode = rssDoc.createElement("description");
    NodeList descriptions = GSXML.getNamedElements(collMeta, GSXML.DISPLAY_TEXT_ELEM, GSXML.NAME_ATT, GSXML.DISPLAY_TEXT_DESCRIPTION);
    //Element descriptEl = GSXML.getNamedElement(collMeta, GSXML.DISPLAY_TEXT_ELEM, GSXML.NAME_ATT, GSXML.DISPLAY_TEXT_DESCRIPTION);
    Element descriptEl = null;
    if(descriptions != null) {
        for (int i = 0; i < descriptions.getLength(); i++) {
        Element e = (Element) descriptions.item(i);
        if(e.getAttribute("lang").equals(lang)) {
            descriptEl = e;
            break; // found the description for the requested language, finish loop
        } else if(e.getAttribute("lang").equals("en")) {
            descriptEl = e; // at least found english fall-back description, continue loop
        }
        }
    }
    String description = (descriptEl == null) ? "none" : GSXML.getNodeText(descriptEl);
    GSXML.setNodeText(childNode, description); //_collectionextra_
    channelNode.appendChild(childNode);

    childNode = rssDoc.createElement("language");
    GSXML.setNodeText(childNode, lang); //_cgiargl_
    channelNode.appendChild(childNode);


    // RSS specification: http://cyber.law.harvard.edu/rss/rss.html
    // pubDate is date of first publication of the item. Use collection.getEarliestDatestamp()
    // lastBuildDate is the date the item was last modified. Use collection.getLastmodified()

    //HashMap<String, ModuleInterface> module_map = this.router.getModuleMap();
    //Collection coll = (Collection)module_map.get(this.cluster_name);
    Collection coll = (Collection)serviceCluster;
    SimpleDateFormat dateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z");

    childNode = rssDoc.createElement("pubDate");
    Date date = new Date(coll.getEarliestDatestamp()); // "Thu, 23 Aug 1999 07:00:00 GMT"
    GSXML.setNodeText(childNode, dateFormat.format(date));
    channelNode.appendChild(childNode);

    childNode = rssDoc.createElement("lastBuildDate");
    date = new Date(coll.getLastmodified()); // "Thu, 23 Aug 1999 16:20:26 GMT" 
    GSXML.setNodeText(childNode, dateFormat.format(date));
    channelNode.appendChild(childNode);

    childNode = rssDoc.createElement("managingEditor");
    Element e = GSXML.getNamedElement(collMeta, GSXML.DISPLAY_TEXT_ELEM, GSXML.NAME_ATT, "creator");
    String value = (e == null) ? "unknown" : GSXML.getNodeText(e);
    GSXML.setNodeText(childNode, value); //_creator_
    channelNode.appendChild(childNode);

    childNode = rssDoc.createElement("webMaster");
    e = GSXML.getNamedElement(collMeta, GSXML.DISPLAY_TEXT_ELEM, GSXML.NAME_ATT, "maintainer");
    value = (e == null) ? "unknown" : GSXML.getNodeText(e);
    GSXML.setNodeText(childNode, value); //_maintainer_
    channelNode.appendChild(childNode);


    // <image> child of <channel> has title, url, link and description children
    Element collIcon = GSXML.getNamedElement(collMeta, GSXML.DISPLAY_TEXT_ELEM, GSXML.NAME_ATT, "icon");
    if(collIcon != null) { // since there is a collection image, create an imageNode
        
        Node imageNode = rssDoc.createElement("image");
        channelNode.appendChild(imageNode); 

        childNode = rssDoc.createElement("title");
        GSXML.setNodeText(childNode, this.cluster_name); //_collectionname_
        imageNode.appendChild(childNode);

        // need full URL for collection icon. Its name is in <displayItem name="icon_name.ext"/>
        // URL is of the form domain/servlet/sites/localsite/collect/lucene-jdbm-demo/images/icon_name.ext
        childNode = rssDoc.createElement("url");        
        String domain = GlobalProperties.getFullGSDL3WebAddress(); // remove servlet as it's included in site_http_address
        domain = domain.substring(0, domain.lastIndexOf("/"));
        String image_url = GSXML.getNodeText(collIcon); // name of image file
        image_url = domain+"/"+this.site_http_address+"/"+"/collect/"+this.cluster_name+"/images/"+image_url;
        GSXML.setNodeText(childNode, image_url); // _iconcollection_
        imageNode.appendChild(childNode);

        childNode = rssDoc.createElement("link");
        GSXML.setNodeText(childNode, url_prefix+"/page/about"); // _httppageabout_
        imageNode.appendChild(childNode);

        childNode = rssDoc.createElement("description");
        GSXML.setNodeText(childNode, description); //_collectionextra_
        imageNode.appendChild(childNode);
    }


    // now add the contents of rss-items.rdf as a child of channel, 
    // passing in url_prefix for url resolution
    Element rss_raw_data = loadDocument("rss-items.rdf", url_prefix);
    if(rss_raw_data != null) {
        NodeList rss_items = rss_raw_data.getElementsByTagName("item");
        for(int i = 0; i < rss_items.getLength(); i++) {
        channelNode.appendChild(rssDoc.importNode(rss_items.item(i), true));
        }
    }

    // generate the GS3 response message containing the RSS xml
    Element result = this.doc.createElement(GSXML.RESPONSE_ELEM);
    result.setAttribute(GSXML.FROM_ATT, RSS_SERVICE);
    result.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_PROCESS);
    result.appendChild(rssNode); // body of <response> is simply the <rss> root element of the RSS feed
    return result;
    
    }

    // load contents of rss-items.rdf file into an XML doc in memory, after doing the url_prefix replacements
    protected Element loadDocument(String doc_name, String url_prefix) {
    String document_encoding = "UTF-8";

    // try to find the document
    File doc_file = new File(GSFile.collectionIndexDir(this.site_home, this.cluster_name)+File.separator+doc_name);
        
    if (!doc_file.exists()) {
        logger.info("couldn't find file in coll "+this.cluster_name +", file "+doc_name);
        return null;
    }

    // the rss-items.rdf file has no root element, only multiple <item> elements (and subelements)
    // Without a root element, it can't be read into a DOM object. So we read it into a regular String,
    // then bookend the contents with temporary <rssrawdata></rssrawdata> elements to provide a root 
    // element and can read in that String as a DOM object.

    StringBuffer contents = new StringBuffer("<rssrawdata>\n");
    try {
        BufferedReader in = new BufferedReader(new FileReader(doc_file));       
        String line = null;
        while((line = in.readLine()) != null) {
        //line = line.replace("_httpcollection_", "/"+this.cluster_name);
        line = line.replace("_httpdomain__httpcollection_", url_prefix);
        contents.append(line);
        }
        contents.append("</rssrawdata>");
        in.close(); // close the fileread handle

    } catch (Exception e) {
        e.printStackTrace();
        contents.append("couldn't read ");
        contents.append(doc_file);
        contents.append("\n</rssrawdata>");
    }


    Document the_doc = null;
    try {
        the_doc = this.converter.getDOM(contents.toString()); // String input converted to DOM
    } catch (Exception e) {
        logger.error("couldn't create a DOM from file "+doc_file.getPath());
        return null;
    }
    
    return the_doc.getDocumentElement();

    }

    
}