/**
    * Copyright (C) 2014-2016 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.pure.validation.xpath;
  
  import java.util.List;
  import java.util.Map;
  
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  import javax.annotation.concurrent.NotThreadSafe;
  import javax.xml.xpath.XPathConstants;
  import javax.xml.xpath.XPathExpressionException;
  
  import org.oclc.purl.dsdl.svrl.ActivePattern;
  import org.oclc.purl.dsdl.svrl.DiagnosticReference;
  import org.oclc.purl.dsdl.svrl.FailedAssert;
  import org.oclc.purl.dsdl.svrl.FiredRule;
  import org.oclc.purl.dsdl.svrl.NsPrefixInAttributeValues;
  import org.oclc.purl.dsdl.svrl.SchematronOutputType;
  import org.oclc.purl.dsdl.svrl.SuccessfulReport;
  import org.w3c.dom.Node;
  
  import com.helger.commons.ValueEnforcer;
  import com.helger.commons.collection.CollectionHelper;
  import com.helger.commons.state.EContinue;
  import com.helger.schematron.pure.bound.xpath.PSXPathBoundAssertReport;
  import com.helger.schematron.pure.bound.xpath.PSXPathBoundDiagnostic;
  import com.helger.schematron.pure.bound.xpath.PSXPathBoundElement;
  import com.helger.schematron.pure.errorhandler.IPSErrorHandler;
  import com.helger.schematron.pure.model.IPSElement;
  import com.helger.schematron.pure.model.PSAssertReport;
  import com.helger.schematron.pure.model.PSDiagnostics;
  import com.helger.schematron.pure.model.PSDir;
  import com.helger.schematron.pure.model.PSEmph;
  import com.helger.schematron.pure.model.PSName;
  import com.helger.schematron.pure.model.PSPattern;
  import com.helger.schematron.pure.model.PSPhase;
  import com.helger.schematron.pure.model.PSRule;
  import com.helger.schematron.pure.model.PSSchema;
  import com.helger.schematron.pure.model.PSSpan;
  import com.helger.schematron.pure.model.PSTitle;
  import com.helger.schematron.pure.model.PSValueOf;
  import com.helger.schematron.pure.validation.PSValidationHandlerDefault;
  import com.helger.schematron.pure.validation.SchematronValidationException;
  import com.helger.xml.XMLHelper;
  
  /**
   * A special validation handler that creates an SVRL document. This class only
   * works for the XPath binding, as the special {@link PSXPathBoundAssertReport}
   * class is referenced!
   *
   * @author Philip Helger
   */
  @NotThreadSafe
  public class PSXPathValidationHandlerSVRL extends PSValidationHandlerDefault
  {
    private final IPSErrorHandler m_aErrorHandler;
    private SchematronOutputType m_aSchematronOutput;
    private PSSchema m_aSchema;
  
    /**
     * Constructor
     *
     * @param aErrorHandler
     *        The error handler to be used. May not be <code>null</code>.
     */
    public PSXPathValidationHandlerSVRL (@Nonnull final IPSErrorHandler aErrorHandler)
    {
      ValueEnforcer.notNull (aErrorHandler, "ErrorHandler");
      m_aErrorHandler = aErrorHandler;
    }
  
    private void _warn (@Nonnull final IPSElement aSourceElement, @Nonnull final String sMsg)
    {
      if (m_aSchema == null)
        throw new IllegalStateException ("No schema is present!");
  
      m_aErrorHandler.warn (m_aSchema.getResource (), aSourceElement, sMsg);
    }
  
    private void _error (@Nonnull final IPSElement aSourceElement, @Nonnull final String sMsg, @Nullable final Throwable t)
    {
      if (m_aSchema == null)
        throw new IllegalStateException ("No schema is present!");
  
     m_aErrorHandler.error (m_aSchema.getResource (), aSourceElement, sMsg, t);
   }
 
   @Nullable
   private static String _getTitleAsString (@Nullable final PSTitle aTitle) throws SchematronValidationException
   {
     if (aTitle == null)
       return null;
 
     final StringBuilder aSB = new StringBuilder ();
     for (final Object aContent : aTitle.getAllContentElements ())
     {
       if (aContent instanceof String)
         aSB.append ((String) aContent);
       else
         if (aContent instanceof PSDir)
           aSB.append (((PSDir) aContent).getAsText ());
         else
           throw new SchematronValidationException ("Unsupported title content element: " + aContent);
     }
     return aSB.toString ();
   }
 
   @Override
   public void onStart (@Nonnull final PSSchema aSchema, @Nullable final PSPhase aActivePhase) throws SchematronValidationException
   {
     final SchematronOutputType aSchematronOutput = new SchematronOutputType ();
     if (aActivePhase != null)
       aSchematronOutput.setPhase (aActivePhase.getID ());
     aSchematronOutput.setSchemaVersion (aSchema.getSchemaVersion ());
     aSchematronOutput.setTitle (_getTitleAsString (aSchema.getTitle ()));
 
     // Add namespace prefixes
     for (final Map.Entry <String, String> aEntry : aSchema.getAsNamespaceContext ()
                                                           .getPrefixToNamespaceURIMap ()
                                                           .entrySet ())
     {
       final NsPrefixInAttributeValues aNsPrefix = new NsPrefixInAttributeValues ();
       aNsPrefix.setPrefix (aEntry.getKey ());
       aNsPrefix.setUri (aEntry.getValue ());
       aSchematronOutput.getNsPrefixInAttributeValues ().add (aNsPrefix);
     }
     m_aSchematronOutput = aSchematronOutput;
     m_aSchema = aSchema;
   }
 
   @Override
   public void onPattern (@Nonnull final PSPattern aPattern)
   {
     final ActivePattern aRetPattern = new ActivePattern ();
     // TODO document
     aRetPattern.setId (aPattern.getID ());
     // TODO name
     // TODO role
     m_aSchematronOutput.getActivePatternAndFiredRuleAndFailedAssert ().add (aRetPattern);
   }
 
   @Override
   public void onRule (@Nonnull final PSRule aRule, @Nonnull final String sContext)
   {
     final FiredRule aRetRule = new FiredRule ();
     aRetRule.setContext (sContext);
     aRetRule.setFlag (aRule.getFlag ());
     aRetRule.setId (aRule.getID ());
     // TODO role
     m_aSchematronOutput.getActivePatternAndFiredRuleAndFailedAssert ().add (aRetRule);
   }
 
   /**
    * Get the error text from an assert or report element.
    *
    * @param aBoundContentElements
    *        The list of bound elements to be evaluated.
    * @param aSourceNode
    *        The XML node of the document currently validated.
    * @return A non-<code>null</code> String
    * @throws SchematronValidationException
    *         In case evaluating an XPath expression fails.
    */
   @Nonnull
   private String _getErrorText (@Nonnull final List <PSXPathBoundElement> aBoundContentElements,
                                 @Nonnull final Node aSourceNode) throws SchematronValidationException
   {
     final StringBuilder aSB = new StringBuilder ();
     for (final PSXPathBoundElement aBoundElement : aBoundContentElements)
     {
       final Object aContent = aBoundElement.getElement ();
       if (aContent instanceof String)
         aSB.append ((String) aContent);
       else
         if (aContent instanceof PSName)
         {
           final PSName aName = (PSName) aContent;
           if (aName.hasPath ())
           {
             // XPath present
             try
             {
               aSB.append ((String) aBoundElement.getBoundExpression ().evaluate (aSourceNode, XPathConstants.STRING));
             }
             catch (final XPathExpressionException ex)
             {
               _error (aName, "Failed to evaluate XPath expression to a string: '" +
                              aBoundElement.getExpression () +
                              "'", ex);
               // Append the path so that something is present in the output
               aSB.append (aName.getPath ());
             }
           }
           else
           {
             // No XPath present
             aSB.append (aSourceNode.getNodeName ());
           }
         }
         else
           if (aContent instanceof PSValueOf)
           {
             final PSValueOf aValueOf = (PSValueOf) aContent;
             try
             {
               aSB.append ((String) aBoundElement.getBoundExpression ().evaluate (aSourceNode, XPathConstants.STRING));
             }
             catch (final XPathExpressionException ex)
             {
               _error (aValueOf, "Failed to evaluate XPath expression to a string: '" +
                                 aBoundElement.getExpression () +
                                 "'", ex);
               // Append the path so that something is present in the output
               aSB.append (aValueOf.getSelect ());
             }
           }
           else
             if (aContent instanceof PSEmph)
               aSB.append (((PSEmph) aContent).getAsText ());
             else
               if (aContent instanceof PSDir)
                 aSB.append (((PSDir) aContent).getAsText ());
               else
                 if (aContent instanceof PSSpan)
                   aSB.append (((PSSpan) aContent).getAsText ());
                 else
                   throw new SchematronValidationException ("Unsupported assert/report content element: " + aContent);
     }
     return aSB.toString ();
   }
 
   /**
    * Handle the diagnostic references of a single assert/report element
    *
    * @param aSrcDiagnostics
    *        The list of diagnostic reference IDs in the source assert/report
    *        element. May be <code>null</code> if no diagnostic references are
    *        present
    * @param aDstList
    *        The diagnostic reference list of the SchematronOutput to be filled.
    *        May not be <code>null</code>.
    * @param aBoundAssertReport
    *        The bound assert report element. Never <code>null</code>.
    * @param aRuleMatchingNode
    *        The XML node of the XML document currently validated. Never
    *        <code>null</code>.
    * @throws SchematronValidationException
    */
   private void _handleDiagnosticReferences (@Nullable final List <String> aSrcDiagnostics,
                                             @Nonnull final List <DiagnosticReference> aDstList,
                                             @Nonnull final PSXPathBoundAssertReport aBoundAssertReport,
                                             @Nonnull final Node aRuleMatchingNode) throws SchematronValidationException
   {
     if (CollectionHelper.isNotEmpty (aSrcDiagnostics))
     {
       if (m_aSchema.hasDiagnostics ())
       {
         final PSDiagnostics aDiagnostics = m_aSchema.getDiagnostics ();
         for (final String sDiagnosticID : aSrcDiagnostics)
         {
           final PSXPathBoundDiagnostic aDiagnostic = aBoundAssertReport.getBoundDiagnosticOfID (sDiagnosticID);
           if (aDiagnostic == null)
             _warn (aDiagnostics, "Failed to resolve diagnostics with ID '" + sDiagnosticID + "'");
           else
           {
             // Create the SVRL diagnostic-reference element
             final DiagnosticReference aDR = new DiagnosticReference ();
             aDR.setDiagnostic (sDiagnosticID);
             aDR.setText (_getErrorText (aDiagnostic.getAllBoundContentElements (), aRuleMatchingNode));
             aDstList.add (aDR);
           }
         }
       }
       else
         _warn (m_aSchema, "Failed to resolve diagnostic because schema has no diagnostics");
     }
   }
 
   @Override
   @Nonnull
   public EContinue onFailedAssert (@Nonnull final PSAssertReport aAssertReport,
                                    @Nonnull final String sTestExpression,
                                    @Nonnull final Node aRuleMatchingNode,
                                    final int nNodeIndex,
                                    @Nullable final Object aContext) throws SchematronValidationException
   {
     if (!(aContext instanceof PSXPathBoundAssertReport))
       throw new SchematronValidationException ("The passed context must be an XPath object but is a " + aContext);
     final PSXPathBoundAssertReport aBoundAssertReport = (PSXPathBoundAssertReport) aContext;
 
     final FailedAssert aFailedAssert = new FailedAssert ();
     aFailedAssert.setFlag (aAssertReport.getFlag ());
     aFailedAssert.setId (aAssertReport.getID ());
     aFailedAssert.setLocation (XMLHelper.getPathToNode2 (aRuleMatchingNode));
     // TODO role
     aFailedAssert.setTest (sTestExpression);
     aFailedAssert.setText (_getErrorText (aBoundAssertReport.getAllBoundContentElements (), aRuleMatchingNode));
     _handleDiagnosticReferences (aAssertReport.getAllDiagnostics (),
                                  aFailedAssert.getDiagnosticReference (),
                                  aBoundAssertReport,
                                  aRuleMatchingNode);
     m_aSchematronOutput.getActivePatternAndFiredRuleAndFailedAssert ().add (aFailedAssert);
     return EContinue.CONTINUE;
   }
 
   @Override
   @Nonnull
   public EContinue onSuccessfulReport (@Nonnull final PSAssertReport aAssertReport,
                                        @Nonnull final String sTestExpression,
                                        @Nonnull final Node aRuleMatchingNode,
                                        final int nNodeIndex,
                                        @Nullable final Object aContext) throws SchematronValidationException
   {
     if (!(aContext instanceof PSXPathBoundAssertReport))
       throw new SchematronValidationException ("The passed context must be an XPath object but is a " + aContext);
     final PSXPathBoundAssertReport aBoundAssertReport = (PSXPathBoundAssertReport) aContext;
 
     final SuccessfulReport aSuccessfulReport = new SuccessfulReport ();
     aSuccessfulReport.setFlag (aAssertReport.getFlag ());
     aSuccessfulReport.setId (aAssertReport.getID ());
     aSuccessfulReport.setLocation (XMLHelper.getPathToNode2 (aRuleMatchingNode));
     // TODO role
     aSuccessfulReport.setTest (sTestExpression);
     aSuccessfulReport.setText (_getErrorText (aBoundAssertReport.getAllBoundContentElements (), aRuleMatchingNode));
     _handleDiagnosticReferences (aAssertReport.getAllDiagnostics (),
                                  aSuccessfulReport.getDiagnosticReference (),
                                  aBoundAssertReport,
                                  aRuleMatchingNode);
     m_aSchematronOutput.getActivePatternAndFiredRuleAndFailedAssert ().add (aSuccessfulReport);
     return EContinue.CONTINUE;
   }
 
   @Nullable
   public SchematronOutputType getSVRL ()
   {
     return m_aSchematronOutput;
   }
 }