source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/action/Action.java@ 26087

package org.greenstone.gsdl3.action;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;

import org.apache.log4j.Logger;
import org.greenstone.gsdl3.core.ModuleInterface;
import org.greenstone.gsdl3.util.GSConstants;
import org.greenstone.gsdl3.util.GSParams;
import org.greenstone.gsdl3.util.GSXML;
import org.greenstone.gsdl3.util.UserContext;
import org.greenstone.gsdl3.util.XMLConverter;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/** base class for Actions */
abstract public class Action
{

    /** the system set up variables */
    protected HashMap<String, Comparable> config_params = null;
    /** container Document to create XML Nodes */
    protected Document doc = null;
    /** a converter class to parse XML and create Docs */
    protected XMLConverter converter = null;
    /**
     * a reference to the message router that it must talk to to get info. it
     * may be a communicator acting as a proxy, but it doesn't care about that
     */
    protected ModuleInterface mr = null;

    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.action.Action.class.getName());

    public Action()
    {
        this.converter = new XMLConverter();
        this.doc = this.converter.newDOM();
    }

    /** the config variables must be set before configure is called */
    public void setConfigParams(HashMap<String, Comparable> params)
    {
        this.config_params = params;
    }

    /** sets the message router */
    public void setMessageRouter(ModuleInterface m)
    {
        this.mr = m;
    }

    public boolean configure()
    {
        // does nothing yet
        return true;
    }

    /**
     * process takes an xml representation of cgi args and returns the page of
     * results - may be in html/xml/other depending on the output att of the
     * request
     */
    public String process(String xml_in)
    {

        Document message_doc = this.converter.getDOM(xml_in);
        if (message_doc == null)
        {
            logger.error("Couldn't parse request");
            logger.error(xml_in);
            return null;
        }
        Node result = process(message_doc);
        return this.converter.getString(result);
    }

    /** the main process method - must be implemented in subclass */
    abstract public Node process(Node xml_in);

    /**
     * tell the param class what its arguments are if an action has its own
     * arguments, this should add them to the params object - particularly
     * important for args that should not be saved
     */
    public boolean addActionParameters(GSParams params)
    {
        return true;
    }

    protected void getRequiredMetadataNames(Element format, HashSet<String> meta_names)
    {
        extractMetadataNames(format, meta_names);
        addLinkMetadataNames(format, meta_names);
    }

  // should change to metadataList?? and use attributes for select rather than
  // prepending parent_ etc
  protected void extractMetadataNames(Element format, HashSet<String> meta_names)
    {

      NodeList metadata_nodes = format.getElementsByTagNameNS(GSXML.GSF_NAMESPACE, "metadata");
      for (int i = 0; i < metadata_nodes.getLength(); i++)
        {
          Element elem = (Element) metadata_nodes.item(i);
          String name = elem.getAttribute("name");
          String select = elem.getAttribute("select");

          if (!select.equals("")) {
        name = select+GSConstants.META_RELATION_SEP+name;
          }
          meta_names.add(name);
        }
          
    }

    protected void addLinkMetadataNames(Element format, HashSet<String> meta_names)
    {
        // The XSL tranform for
        //   gsf:link type="source" 
        // makes use of 'assocfilepath' so need to make sure it's asked for

        boolean getEquivLinkMeta = false;

        NodeList link_nodes = format.getElementsByTagNameNS(GSXML.GSF_NAMESPACE, "link");
        for (int i = 0; i < link_nodes.getLength(); i++)
        {
            Element elem = (Element) link_nodes.item(i);
            String type = elem.getAttribute("type");
            if (type.equals("source"))
            {
                meta_names.add("assocfilepath");
                meta_names.add("srclinkFile");
            }
            else if (type.equals("web"))
            {
                meta_names.add("weblink");
                meta_names.add("webicon");
                meta_names.add("/weblink");
            }
            else if (type.equals("equivdoc"))
            {
                getEquivLinkMeta = true;
            }
        }

        // get all the metadata necessary for when the user has used "gsf:equivlink"
        // so that we can build up the equivlink from the metadata components it needs
        link_nodes = format.getElementsByTagNameNS(GSXML.GSF_NAMESPACE, "equivlinkgs3");
        if (getEquivLinkMeta || link_nodes.getLength() > 0)
        {
            String[] equivlink_metanames = { "equivDocIcon", "equivDocLink", "/equivDocLink" };

            for (int i = 0; i < equivlink_metanames.length; i++)
            {
                StringBuffer metadata = new StringBuffer();
                metadata.append("all"); // this means the attr multiple = true;
                metadata.append(GSConstants.META_RELATION_SEP);

                metadata.append(GSConstants.META_SEPARATOR_SEP);
                metadata.append(','); // attr separator = ","
                metadata.append(GSConstants.META_SEPARATOR_SEP);
                metadata.append(GSConstants.META_RELATION_SEP);

                // the name of the metadata we're retrieving
                metadata.append(equivlink_metanames[i]);
                meta_names.add(metadata.toString());
            }
        }

        if (format.getElementsByTagNameNS(GSXML.GSF_NAMESPACE, "image").getLength() > 0)
        {
            meta_names.add("Thumb");
            meta_names.add("Screen");
            meta_names.add("SourceFile");
        }
    }

    protected Element createMetadataParamList(HashSet<String> metadata_names)
    {
        Element param_list = this.doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);

        Element param = null;
        Iterator<String> i = metadata_names.iterator();
        while (i.hasNext())
        {
            String name = i.next();
            param = this.doc.createElement(GSXML.PARAM_ELEM);
            param_list.appendChild(param);
            param.setAttribute(GSXML.NAME_ATT, "metadata");
            param.setAttribute(GSXML.VALUE_ATT, name);

        }
        return param_list;
    }

    protected boolean processErrorElements(Element message, Element page)
    {
        NodeList error_nodes = message.getElementsByTagName(GSXML.ERROR_ELEM);
        if (error_nodes.getLength() == 0)
        {
            return false;
        }
        Document owner = page.getOwnerDocument();
        for (int i = 0; i < error_nodes.getLength(); i++)
        {
            page.appendChild(owner.importNode(error_nodes.item(i), true));
        }
        return true;
    }

    /**
     * Takes an XML element and adds the metadata of the current site to it.
     * Useful for adding the current site's metadata to a response before
     * sending it
     * 
     * @param element
     *            the element to add site metadata to
     * @param lang
     *            the current language
     * @param uid
     *            the current user id
     */
    protected void addSiteMetadata(Element element, UserContext userContext)
    {
        //ADD SITE METADATA
        Element metadata_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_DESCRIBE, "", userContext);
        //create a hashmap of params
        HashMap subset_params = new HashMap(1);
        subset_params.put(GSXML.SUBSET_PARAM, GSXML.METADATA_ELEM + GSXML.LIST_MODIFIER);
        //create the element to put the params in
        Element param_list = this.doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
        //put them in
        GSXML.addParametersToList(this.doc, param_list, subset_params);
        metadata_request.appendChild(param_list);
        //create the message
        Element metadata_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
        metadata_message.appendChild(metadata_request);
        //get response
        Element metadata_response_message = (Element) this.mr.process(metadata_message);
        //drill down to response
        Element metadata_response = (Element) GSXML.getChildByTagName(metadata_response_message, GSXML.RESPONSE_ELEM);
        //merge in metadata
        GSXML.mergeMetadataLists(element, metadata_response);
    }

    protected void addInterfaceOptions(Element elem)
    {
        Element documentOptionList = this.doc.createElement("interfaceOptions");
        for (Object key : this.config_params.keySet())
        {
            Element option = this.doc.createElement("option");
            option.setAttribute(GSXML.NAME_ATT, (String) key);
            option.setAttribute(GSXML.VALUE_ATT, this.config_params.get(key).toString());
            documentOptionList.appendChild(option);
        }
        elem.appendChild(elem.getOwnerDocument().importNode(documentOptionList, true));
    }
}