/**
    * Copyright (C) 2014-2017 Philip Helger (www.helger.com)
    * philip[at]helger[dot]com
    *
    * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
   *
   * 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 com.helger.schematron;
  
  import java.io.IOException;
  
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  import javax.annotation.concurrent.Immutable;
  import javax.xml.transform.Source;
  import javax.xml.transform.dom.DOMSource;
  
  import org.oclc.purl.dsdl.svrl.SchematronOutputType;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.w3c.dom.Node;
  import org.xml.sax.InputSource;
  
  import com.helger.commons.ValueEnforcer;
  import com.helger.commons.annotation.PresentForCodeCoverage;
  import com.helger.commons.error.list.ErrorList;
  import com.helger.commons.error.list.IErrorList;
  import com.helger.commons.hierarchy.visit.ChildrenProviderHierarchyVisitor;
  import com.helger.commons.hierarchy.visit.DefaultHierarchyVisitorCallback;
  import com.helger.commons.hierarchy.visit.EHierarchyVisitorReturn;
  import com.helger.commons.io.resource.IReadableResource;
  import com.helger.commons.state.ESuccess;
  import com.helger.commons.wrapper.Wrapper;
  import com.helger.schematron.pure.errorhandler.IPSErrorHandler;
  import com.helger.schematron.pure.errorhandler.LoggingPSErrorHandler;
  import com.helger.schematron.resolve.DefaultSchematronIncludeResolver;
  import com.helger.schematron.svrl.SVRLFailedAssert;
  import com.helger.schematron.svrl.SVRLHelper;
  import com.helger.schematron.svrl.SVRLResourceError;
  import com.helger.xml.microdom.IMicroDocument;
  import com.helger.xml.microdom.IMicroElement;
  import com.helger.xml.microdom.IMicroNode;
  import com.helger.xml.microdom.serialize.MicroReader;
  import com.helger.xml.sax.InputSourceFactory;
  import com.helger.xml.serialize.read.ISAXReaderSettings;
  
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  
  /**
   * This is a helper class that provides a way to easily apply an Schematron
   * resource on an XML resource.
   *
   * @author Philip Helger
   */
  @Immutable
  public final class SchematronHelper
  {
    private static final Logger s_aLogger = LoggerFactory.getLogger (SchematronHelper.class);
  
    @PresentForCodeCoverage
    private static final SchematronHelper s_aInstance = new SchematronHelper ();
  
    private SchematronHelper ()
    {}
  
    /**
     * Apply the passed schematron on the passed XML resource using a custom error
     * handler.
     *
     * @param aSchematron
     *        The Schematron resource. May not be <code>null</code>.
     * @param aXML
     *        The XML resource. May not be <code>null</code>.
     * @return <code>null</code> if either the Schematron or the XML could not be
     *         read.
     * @throws IllegalStateException
     *         if the processing throws an unexpected exception.
     */
    @Nullable
    public static SchematronOutputType applySchematron (@Nonnull final ISchematronResource aSchematron,
                                                        @Nonnull final IReadableResource aXML)
    {
      ValueEnforcer.notNull (aSchematron, "SchematronResource");
      ValueEnforcer.notNull (aXML, "XMLSource");
  
      try
      {
        // Apply Schematron on XML
        return aSchematron.applySchematronValidationToSVRL (aXML);
      }
     catch (final Exception ex)
     {
       throw new IllegalArgumentException ("Failed to apply Schematron " +
                                           aSchematron.getID () +
                                           " onto XML resource " +
                                           aXML.getResourceID (),
                                           ex);
     }
   }
 
   /**
    * Apply the passed schematron on the passed XML resource.
    *
    * @param aSchematron
    *        The Schematron resource. May not be <code>null</code>.
    * @param aXML
    *        The XML resource. May not be <code>null</code>.
    * @return <code>null</code> if either the Schematron or the XML could not be
    *         read.
    * @throws IllegalStateException
    *         if the processing throws an unexpected exception.
    */
   @Nullable
   public static SchematronOutputType applySchematron (@Nonnull final ISchematronResource aSchematron,
                                                       @Nonnull final Source aXML)
   {
     ValueEnforcer.notNull (aSchematron, "SchematronResource");
     ValueEnforcer.notNull (aXML, "XMLSource");
 
     try
     {
       // Apply Schematron on XML.
       return aSchematron.applySchematronValidationToSVRL (aXML);
     }
     catch (final Exception ex)
     {
       throw new IllegalArgumentException ("Failed to apply Schematron " +
                                           aSchematron.getID () +
                                           " onto XML source " +
                                           aXML,
                                           ex);
     }
   }
 
   /**
    * Apply the passed schematron on the passed XML node.
    *
    * @param aSchematron
    *        The Schematron resource. May not be <code>null</code>.
    * @param aNode
    *        The XML node. May not be <code>null</code>.
    * @return <code>null</code> if either the Schematron or the XML could not be
    *         read.
    * @throws IllegalStateException
    *         if the processing throws an unexpected exception.
    */
   @Nullable
   public static SchematronOutputType applySchematron (@Nonnull final ISchematronResource aSchematron,
                                                       @Nonnull final Node aNode)
   {
     ValueEnforcer.notNull (aSchematron, "SchematronResource");
     ValueEnforcer.notNull (aNode, "Node");
 
     return applySchematron (aSchematron, new DOMSource (aNode));
   }
 
   /**
    * Convert a {@link SchematronOutputType} to an {@link IErrorList}.
    *
    * @param aSchematronOutput
    *        The result of Schematron validation
    * @param sResourceName
    *        The name of the resource that was validated (may be a file path
    *        etc.)
    * @return List non-<code>null</code> error list of {@link SVRLResourceError}
    *         objects.
    */
   @Nonnull
   public static IErrorList convertToErrorList (@Nonnull final SchematronOutputType aSchematronOutput,
                                                @Nullable final String sResourceName)
   {
     ValueEnforcer.notNull (aSchematronOutput, "SchematronOutput");
 
     final ErrorList ret = new ErrorList ();
     for (final SVRLFailedAssert aFailedAssert : SVRLHelper.getAllFailedAssertions (aSchematronOutput))
       ret.add (aFailedAssert.getAsResourceError (sResourceName));
     return ret;
   }
 
   @SuppressFBWarnings ("RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE")
   @Nonnull
   private static ESuccess _recursiveResolveAllSchematronIncludes (@Nonnull final IMicroElement eRoot,
                                                                   @Nonnull final IReadableResource aResource,
                                                                   @Nullable final ISAXReaderSettings aSettings,
                                                                   @Nonnull final IPSErrorHandler aErrorHandler)
   {
     if (eRoot != null)
     {
       final DefaultSchematronIncludeResolver aIncludeResolver = new DefaultSchematronIncludeResolver (aResource);
 
       for (final IMicroElement aElement : eRoot.getAllChildElementsRecursive ())
         if (CSchematron.NAMESPACE_SCHEMATRON.equals (aElement.getNamespaceURI ()) &&
             aElement.getLocalName ().equals (CSchematronXML.ELEMENT_INCLUDE))
         {
           String sHref = aElement.getAttributeValue (CSchematronXML.ATTR_HREF);
           try
           {
             final int nHashIndex = sHref.indexOf ('#');
             String sAnchor = null;
             if (nHashIndex >= 0)
             {
               sAnchor = sHref.substring (nHashIndex + 1);
               sHref = sHref.substring (0, nHashIndex);
             }
 
             final IReadableResource aIncludeRes = aIncludeResolver.getResolvedSchematronResource (sHref);
             if (aIncludeRes == null)
             {
               aErrorHandler.error (aResource, null, "Failed to resolve include '" + sHref + "'", null);
               return ESuccess.FAILURE;
             }
 
             if (s_aLogger.isDebugEnabled ())
               s_aLogger.debug ("Resolved '" +
                                sHref +
                                "' relative to '" +
                                aIncludeResolver.getBaseHref () +
                                "' as '" +
                                aIncludeRes.getPath () +
                                "'");
 
             // Read XML to be included
             final IMicroDocument aIncludedDoc = MicroReader.readMicroXML (aIncludeRes, aSettings);
             if (aIncludedDoc == null)
             {
               aErrorHandler.error (aResource, null, "Failed to parse include " + aIncludeRes, null);
               return ESuccess.FAILURE;
             }
 
             IMicroElement aIncludedContent;
             if (sAnchor == null)
             {
               // no anchor present - include the whole document
 
               // Return the document element
               aIncludedContent = aIncludedDoc.getDocumentElement ();
             }
             else
             {
               final String sFinalAnchor = sAnchor;
               final Wrapper <IMicroElement> aMatch = new Wrapper <> ();
               // Also include the root element in the search
               ChildrenProviderHierarchyVisitor.visitFrom (aIncludedDoc.getDocumentElement (),
                                                           new DefaultHierarchyVisitorCallback <IMicroNode> ()
                                                           {
                                                             @Override
                                                             public EHierarchyVisitorReturn onItemBeforeChildren (final IMicroNode aItem)
                                                             {
                                                               if (aItem.isElement ())
                                                               {
                                                                 final IMicroElement aCurElement = (IMicroElement) aItem;
                                                                 final String sID = aCurElement.getAttributeValue ("id");
                                                                 if (sFinalAnchor.equals (sID))
                                                                   aMatch.set (aCurElement);
                                                               }
                                                               return EHierarchyVisitorReturn.CONTINUE;
                                                             }
                                                           },
                                                           true);
               aIncludedContent = aMatch.get ();
               if (aIncludedContent == null)
               {
                 aErrorHandler.warn (aResource,
                                     null,
                                     "Failed to resolve an element with the ID '" +
                                           sAnchor +
                                           "' in " +
                                           aIncludeRes +
                                           "! Therefore including the whole document!");
                 aIncludedContent = aIncludedDoc.getDocumentElement ();
               }
             }
 
             // Important to detach from parent!
             aIncludedContent.detachFromParent ();
 
             // Check for correct namespace URI of included content
             if (!CSchematron.NAMESPACE_SCHEMATRON.equals (aIncludedContent.getNamespaceURI ()))
             {
               aErrorHandler.error (aResource,
                                    null,
                                    "The included resource " +
                                          aIncludeRes +
                                          " contains the wrong XML namespace URI '" +
                                          aIncludedContent.getNamespaceURI () +
                                          "' but was expected to have '" +
                                          CSchematron.NAMESPACE_SCHEMATRON +
                                          "'",
                                    null);
               return ESuccess.FAILURE;
             }
 
             // Check that not a whole Schema but only a part is included
             if (CSchematronXML.ELEMENT_SCHEMA.equals (aIncludedContent.getLocalName ()))
             {
               aErrorHandler.warn (aResource,
                                   null,
                                   "The included resource " +
                                         aIncludeRes +
                                         " seems to be a complete schema. To includes parts of a schema the respective element must be the root element of the included resource.");
             }
 
             // Recursive resolve includes
             if (_recursiveResolveAllSchematronIncludes (aIncludedContent,
                                                         aIncludeRes,
                                                         aSettings,
                                                         aErrorHandler).isFailure ())
               return ESuccess.FAILURE;
 
             // Now replace "include" element with content in MicroDOM
             aElement.getParent ().replaceChild (aElement, aIncludedContent);
           }
           catch (final IOException ex)
           {
             aErrorHandler.error (aResource, null, "Failed to read include '" + sHref + "'", ex);
             return ESuccess.FAILURE;
           }
         }
     }
     return ESuccess.SUCCESS;
   }
 
   /**
    * Resolve all Schematron includes of the passed resource.
    *
    * @param aResource
    *        The Schematron resource to read. May not be <code>null</code>.
    * @return <code>null</code> if the passed resource could not be read as XML
    *         document
    */
   @Nullable
   public static IMicroDocument getWithResolvedSchematronIncludes (@Nonnull final IReadableResource aResource)
   {
     return getWithResolvedSchematronIncludes (aResource, (ISAXReaderSettings) null, new LoggingPSErrorHandler ());
   }
 
   /**
    * Resolve all Schematron includes of the passed resource.
    *
    * @param aResource
    *        The Schematron resource to read. May not be <code>null</code>.
    * @param aSettings
    *        The SAX reader settings to be used. May be <code>null</code> to use
    *        the default settings.
    * @param aErrorHandler
    *        The error handler to be used. May not be <code>null</code>.
    * @return <code>null</code> if the passed resource could not be read as XML
    *         document
    */
   @Nullable
   public static IMicroDocument getWithResolvedSchematronIncludes (@Nonnull final IReadableResource aResource,
                                                                   @Nullable final ISAXReaderSettings aSettings,
                                                                   @Nonnull final IPSErrorHandler aErrorHandler)
   {
     final InputSource aIS = InputSourceFactory.create (aResource);
     final IMicroDocument aDoc = MicroReader.readMicroXML (aIS, aSettings);
     if (aDoc != null)
     {
       // Resolve all Schematron includes
       if (_recursiveResolveAllSchematronIncludes (aDoc.getDocumentElement (),
                                                   aResource,
                                                   aSettings,
                                                   aErrorHandler).isFailure ())
       {
         // Error resolving includes
         return null;
       }
     }
     return aDoc;
   }
 }