/**

  * Copyright 2005-2011 The Kuali Foundation

  *

  * Licensed under the Educational Community License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  * http://www.opensource.org/licenses/ecl2.php

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.kuali.rice.core.impl.impex.xml;

 import java.io.IOException;

 import java.util.Collection;

 import java.util.LinkedHashSet;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Set;

 import javax.xml.XMLConstants;

 import javax.xml.parsers.DocumentBuilder;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import org.apache.commons.lang.exception.ExceptionUtils;

 import org.apache.log4j.Logger;

 import org.kuali.rice.core.api.impex.xml.XmlDoc;

 import org.kuali.rice.core.api.impex.xml.XmlDocCollection;

 import org.kuali.rice.core.api.impex.xml.XmlIngesterService;

 import org.kuali.rice.core.framework.impex.xml.XmlImpexRegistry;

 import org.kuali.rice.core.framework.impex.xml.XmlLoader;

 import org.xml.sax.EntityResolver;

 import org.xml.sax.ErrorHandler;

 import org.xml.sax.SAXException;

 import org.xml.sax.SAXParseException;

 /**

  * XmlIngesterService implementation which delegates to XmlDigesterService.

  * This implementation goes through some pains to ensure that the types of

  * xml doc (determined by file name convention) are issued to the XmlDigesterService

  * in a pre-ordained order in an effort to avoid dependency problems.  This implementation

  * is not responsible for knowing about the mappings between types and services, but

  * only the ordering of types, for the moment.

  * NOTE: when types are merged into a universal document, we need to decide how to handle

  * rollback if any specific type <i>in</i> that document fails, given that the current,

  * legacy implementation assumes that a given XmlDoc consists of one and only one type

  * and as such can be rolled back atomically.  For instance, if universal doc now contains

  * types A, B, and C, and it invokes ServiceA, ServiceB, and ServiceC in succession on the

  * entire document, and ServiceB throws an exception attempting to parse B content...

  * is it sufficient to rollback only that entry, or do we rollback the whole document

  * and consider it "tainted"? (not to mention whether we should roll back the entire collection

  * of which the document is a part - for now we do NOT rollback a collection or workflow data doc,

  * but it is merely moved to a "problem" directory by the poller.  the implementation does not yet

  * specifically note which document or type (and potentially eventually which entry) failed in the

  * collection or workflow data doc)

  *

  * NOTE: this service must be invoked only after all other services have initialized

  * this <i>should</i> be the case since the LifeCycle is kicked off after contextInitialized,

  * which <i>should</i> occur after Spring is actually done initializing.  But is it, considering

  * we are asynchronously initializing Spring?  There is a 30 second built-in delay before

  * XmlPoller is first run, but suffice it to say there is a possible race condition.

  *

  * @see org.kuali.rice.core.api.impex.xml.batch.XmlIngesterService

  * @see org.kuali.rice.core.impl.impex.xml.batch.XmlDigesterServiceImpl

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class XmlIngesterServiceImpl implements XmlIngesterService {

     private static final Logger LOG = Logger.getLogger(XmlIngesterServiceImpl.class);

     /**

      * The entity resolver to use during validation

      */

     private EntityResolver resolver = new ClassLoaderEntityResolver();

     private XmlDigesterService digesterService;

     private XmlImpexRegistry xmlImpexRegistry;

     /**

      * Whether to validate at all

      */

     private boolean validate = true;

     // ---- bean properties

     public void setXmlDigesterService(XmlDigesterService digesterService) {

         this.digesterService = digesterService;

     }

     public void setXmlImpexRegistry(XmlImpexRegistry xmlImpexRegistry) {

             this.xmlImpexRegistry = xmlImpexRegistry;

     }

     public void setEntityResolver(EntityResolver resolver) {

         this.resolver = resolver;

     }

     public void setValidate(boolean b) {

         validate = b;

     }

     // ---- implementation

     private static void addProcessingException(XmlDoc xmlDoc, String message, Throwable t) {

         String msg = xmlDoc.getProcessingMessage();

         if (msg == null) {

             msg = "";

         }

         msg += message + "\n" + ExceptionUtils.getFullStackTrace(t);

         xmlDoc.setProcessingMessage(msg);

     }

     private static void validate(final XmlDoc xmlDoc, EntityResolver resolver) throws ParserConfigurationException, IOException, SAXException {

         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

         dbf.setValidating(true);

         dbf.setNamespaceAware( true );

         dbf.setAttribute("http://java.sun.com/xml/jaxp/properties/schemaLanguage", XMLConstants.W3C_XML_SCHEMA_NS_URI);

         DocumentBuilder db = dbf.newDocumentBuilder();

         db.setEntityResolver(resolver);

         db.setErrorHandler(new ErrorHandler() {

             public void warning(SAXParseException se) {

                 LOG.warn("Warning parsing xml doc " + xmlDoc, se);

                 addProcessingException(xmlDoc, "Warning parsing xml doc " + xmlDoc, se);

             }

             public void error(SAXParseException se) throws SAXException {

                 LOG.error("Error parsing xml doc " + xmlDoc, se);

                 addProcessingException(xmlDoc, "Error parsing xml doc " + xmlDoc, se);

                 throw se;

             }

             public void fatalError(SAXParseException se) throws SAXException {

                 LOG.error("Fatal error parsing xml doc " + xmlDoc, se);

                 addProcessingException(xmlDoc, "Fatal error parsing xml doc " + xmlDoc, se);

                 throw se;

             }

         });

         db.parse(xmlDoc.getStream());

     }

     /**

      * Validates (if possible) all XmlDocs, and accumulates only those

      * which either were not possible to validate, or passed validation.

      * @param collections collection of XmlDocCollection

      * @param resolver the entity resolver to use

      * @param successful xmldoccollections in which all docs successfully validated

      * @param failed xmldoccollections in which one or more docs failed validation

      */

     private static void validate(List<XmlDocCollection> collections, EntityResolver resolver, Set<XmlDocCollection> successful, Set<XmlDocCollection> failed) {

         // for every collection, validate all docs

         for (XmlDocCollection collection : collections)

         {

             // for every xml doc in the collection, try to validate it

             for (XmlDoc xmlDoc : collection.getXmlDocs())

             {

                 try

                 {

                     validate(xmlDoc, resolver);

                 } catch (Exception e)

                 {

                     LOG.error("Error validating doc: " + xmlDoc, e);

                     addProcessingException(xmlDoc, "Error validating doc: " + xmlDoc, e);

                     // validation failed, so add collection to successful set

                     // do not break here, so that we can attempt validation on all

                     // docs in a collection; since validation has no side-effects

                     // we might as well validate all the docs now instead of forcing

                     // the user to continually re-submit

                     failed.add(collection);

                 }

             }

             // all files validated, so add collection to successful set

             successful.add(collection);

         }

     }

     private void ingest(XmlLoader xmlLoader, Collection<XmlDocCollection> xmlDocCollections, String principalId, Set<Object> successful, Set<XmlDocCollection> failed) {

         for (XmlDocCollection xmlDocCollection : xmlDocCollections)

         {

             if (failed.contains(xmlDocCollection))

             {

                 LOG.debug("Skipping " + xmlDocCollection.getFile() + "...");

                 continue;

             }

             try

             {

                 digesterService.digest(xmlLoader, xmlDocCollection, principalId);

             } catch (Exception e)

             {

                 LOG.error("Caught Exception loading xml data from " + xmlDocCollection.getFile() + ".  Will move associated file to problem dir.", e);

                 failed.add(xmlDocCollection);

             }

         }

     }

     public Collection<XmlDocCollection> ingest(List<XmlDocCollection> collections) throws Exception {

         return ingest(collections, null);

     }

     private void ingestThroughOrderedLoaders(Collection<XmlDocCollection> xmlDocCollections, String principalId, Set<Object> successful, Set<XmlDocCollection> failed) {

         LOG.debug("Ingesting through ordered XmlLoaders");

         List<XmlLoader> xmlLoaders = xmlImpexRegistry.getLoaders();

         for (XmlLoader xmlLoader : xmlLoaders) {

                 LOG.debug("Ingesting through ordered XmlLoader: " + xmlLoader);

                 ingest(xmlLoader, xmlDocCollections, principalId, successful, failed);

         }

     }

     public Collection<XmlDocCollection> ingest(List<XmlDocCollection> collections, String principalId) {

         Set<XmlDocCollection> failed = new LinkedHashSet<XmlDocCollection>();

         // validate all the docs up-front because we will be iterating over them

         // multiple times: one for each XmlLoader.  If we delegated validation to

         // XmlDigesterService then the docs would re-validated over and over again,

         // for each XmlLoader

         if (validate) {

             Set<XmlDocCollection> successful = new LinkedHashSet<XmlDocCollection>();

             validate(collections, resolver, successful, failed);

             collections = new LinkedList<XmlDocCollection>(successful);

         }

         Set<Object> successful = new LinkedHashSet<Object>();

         // ingest docs first by ordered services

         ingestThroughOrderedLoaders(collections, principalId, successful, failed);

         // then by unordered services

 //        collections = new LinkedList(successful);

         //ingestThroughUnorderedLoaders(collections, user, successful, failed);

         return failed;

     }

 }