/**
 * 
 */
package org.vamsas.client;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;
import java.lang.reflect.Field;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Vector;

import org.exolab.castor.mapping.FieldHandler;
import org.exolab.castor.mapping.GeneralizedFieldHandler;
import org.exolab.castor.mapping.ValidityException;
import org.exolab.castor.xml.IDResolver;
import org.exolab.castor.xml.MarshalException;
import org.exolab.castor.xml.MarshalListener;
import org.exolab.castor.xml.Marshaller;
import org.exolab.castor.xml.UnmarshalListener;
import org.exolab.castor.xml.Unmarshaller;
import org.exolab.castor.xml.ValidationException;
import org.vamsas.objects.core.VamsasDocument;
/**
 * Implements the Vamsas object ID machinery for translating 
 * between non-volatile XML IDs and object references. Use the
 * marshalling and unmarshalling methods in this class in order
 * to avoid validation exceptions when marshalling new objects
 * into the vamsas document.
 */
public class VorbaXmlBinder implements UnmarshalListener {
  private final IVorbaIdFactory vorbafactory;

  private final Vector obj;

  private final Hashtable objrefs;

  public VorbaXmlBinder(IVorbaIdFactory vorbafactory, Vector obj, Hashtable objrefs) {
    this.vorbafactory = vorbafactory;
    this.obj = obj;
    this.objrefs = objrefs;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.exolab.castor.xml.UnmarshalListener#attributesProcessed(java.lang.Object)
   */
  public void attributesProcessed(Object object) {
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.exolab.castor.xml.UnmarshalListener#fieldAdded(java.lang.String,
   *      java.lang.Object, java.lang.Object)
   */
  public void fieldAdded(String fieldName, Object parent, Object child) {
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.exolab.castor.xml.UnmarshalListener#initialized(java.lang.Object)
   */
  public void initialized(Object object) {
  }
  
  /*
   * Check if the object has an 'id' field - if it does, copy the value into
   * the VorbaId field of object, and add the object to the VorbaId hash.
   * 
   * @see org.exolab.castor.xml.UnmarshalListener#unmarshalled(java.lang.Object)
   */
  public void unmarshalled(Object newobj) {
    if (newobj instanceof object) {
      object nobj = (object) newobj;
      nobj.set__stored_in_document(true);
      Field fd = null;
      try {
        if (nobj.isRegisterable()) {
          // look for the id field (should be an NCName string)
          nobj.__vorba = vorbafactory;
          fd = nobj.getClass().getField("id");
          String idstring;
          if (fd.get(nobj) != null) {
            idstring = (String) fd.get(nobj);
            if (idstring.length() > 0) {
              if (!objrefs.containsKey(idstring)) {
                objrefs.put(idstring, nobj);
                nobj.setVorbaId(VorbaId.newId(idstring));
              } else {
                System.err.println("Serious problem : duplicate id '"+idstring+"' found! expect badness.");
                // TODO: HANDLE duplicate XML ids correctly
              }
            } else {
              // add to list of objects without a valid vorbaId
              obj.add(nobj);
            }
          } else {
            // add to list of objects without a valid vorbaId
            obj.add(nobj);
          }
          
        nobj.doHash();
      }
      } catch (Exception e) {
        return;
      };
      
    }
  }

  /**
   * writes the VamsasDocument to the given stream.
   * TODO: ensure that (at least) default provenance entries are written for objects.
   * @param outstream
   * @param vorba valid VorbaIdFactory to construct any missing IDs 
   * @param doc
   * @throws IOException
   * @throws MarshalException
   * @throws ValidationException
   */
  public static void putVamsasDocument(PrintWriter outstream, VorbaIdFactory vorba, VamsasDocument doc)
      throws IOException, MarshalException, ValidationException {
    // Ensure references
    if (vorba==null)
      throw new Error("Null VorbaIdVactory Parameter");
    if (doc.__vorba==null)
      doc.__vorba = vorba;
    doc.__ensure_instance_ids(); // this may take a while. Do we allow for cyclic references ? 
    doc.marshal(outstream);
  }

  private static boolean ensure_references(Vector unrefed, Hashtable objrefs) {
    boolean sync=true;
    if (unrefed.size()>0) {
      sync=false; // document is out of sync - ids have been created.
      java.util.Iterator newobj = unrefed.listIterator();
      while (newobj.hasNext()) {
        object o = (object) newobj.next();
        // forces registration and id field update.
        VorbaId id = o.getVorbaId();
        if (!objrefs.containsKey(id)) {
          objrefs.put(id.id, o);
        } else {
          throw new Error("Serious! Duplicate reference made by vorbaIdFactory!");
        }
      }
    }
    return sync;
  }
  /**
     * Unmarshals a vamsasDocument object from a stream, registers
     * unregistered objects, records existing VorbaIds, and completes 
     * the org.vamsas.client.object housekeeping fields.
     * For a valid unmarshalling, the array of returned objects also includes
     * a <return>sync</return> parameter which is true if new VorbaIds
     * were created. If sync is false, then the caller should ensure that the
     * vamsasDocument is written back to disk to propagate the new VorbaIds.
     *  TODO: ensure that provenance is correct for newly registered objects
     * @param instream - the XML input stream 
   * @param factory - the SimpleClient's properly configured VorbaId factory to make new references.
   * @param root the root element's org.vamsas.objects.core object.
     * @return null or {(Object) VamsasDocument object, (Object) Hashtable of object references, (Object) Boolean(sync) }
     */
  public static Object[] getVamsasObjects(Reader instream,
        IVorbaIdFactory factory, object root) {
      Unmarshaller unmarshaller = new Unmarshaller(root);
      unmarshaller.setIDResolver(new IDResolver() {
        public Object resolve(String id) {
          System.err.println("Warning - id " + id
              + " is not found in the VamsasDocument!");
          return null;
        }
      });
      Hashtable refbase = new Hashtable();
      Vector unrefed = new Vector();
      final Hashtable objrefs = refbase;
      final IVorbaIdFactory vorbafactory = factory;
      final Vector unrefedObj =  unrefed;
      unmarshaller.setUnmarshalListener(new VorbaXmlBinder(vorbafactory, unrefedObj, objrefs));
      // Call the unmarshaller.
      try {
        while (instream.ready()) {
          Object obj = unmarshaller.unmarshal(instream);
          boolean sync=ensure_references(unrefed, objrefs);
          if (!(obj instanceof object))
            return null;
          return new Object[] { obj, objrefs, new Boolean(sync)};
          }
      } catch (MarshalException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      } catch (ValidationException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      return null;
    }
}