/**
    * Copyright (C) 2014-2015 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;
  
  import java.io.File;
  import java.io.InputStream;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.nio.charset.Charset;
  
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  import javax.annotation.concurrent.NotThreadSafe;
  import javax.xml.transform.Source;
  import javax.xml.xpath.XPathFunctionResolver;
  import javax.xml.xpath.XPathVariableResolver;
  
  import org.oclc.purl.dsdl.svrl.SchematronOutputType;
  import org.w3c.dom.Document;
  import org.w3c.dom.Node;
  
  import com.helger.commons.ValueEnforcer;
  import com.helger.commons.annotation.Nonempty;
  import com.helger.commons.charset.CharsetManager;
  import com.helger.commons.io.IHasInputStream;
  import com.helger.commons.io.resource.ClassPathResource;
  import com.helger.commons.io.resource.FileSystemResource;
  import com.helger.commons.io.resource.IReadableResource;
  import com.helger.commons.io.resource.URLResource;
  import com.helger.commons.io.resource.inmemory.AbstractMemoryReadableResource;
  import com.helger.commons.io.resource.inmemory.ReadableResourceByteArray;
  import com.helger.commons.io.resource.inmemory.ReadableResourceInputStream;
  import com.helger.commons.state.EValidity;
  import com.helger.commons.xml.serialize.read.DOMReader;
  import com.helger.commons.xml.serialize.write.XMLWriterSettings;
  import com.helger.schematron.AbstractSchematronResource;
  import com.helger.schematron.SchematronException;
  import com.helger.schematron.SchematronResourceHelper;
  import com.helger.schematron.pure.bound.IPSBoundSchema;
  import com.helger.schematron.pure.bound.PSBoundSchemaCache;
  import com.helger.schematron.pure.bound.PSBoundSchemaCacheKey;
  import com.helger.schematron.pure.errorhandler.DoNothingPSErrorHandler;
  import com.helger.schematron.pure.errorhandler.IPSErrorHandler;
  import com.helger.schematron.pure.exchange.PSWriter;
  import com.helger.schematron.pure.model.PSSchema;
  import com.helger.schematron.svrl.SVRLWriter;
  
  /**
   * A Schematron resource that is not XSLT based but using the pure (native Java)
   * implementation. This class itself is not thread safe, but the underlying
   * cache is thread safe. So once you configured this object fully (with all the
   * setter), it can be considered thread safe.<br>
   * <b>Important:</b> This class can <u>only</u> handle XPath expressions but no
   * XSLT functions in Schematron asserts and reports!
   *
   * @author Philip Helger
   */
  @NotThreadSafe
  public class SchematronResourcePure extends AbstractSchematronResource
  {
    private String m_sPhase;
    private IPSErrorHandler m_aErrorHandler;
    private XPathVariableResolver m_aVariableResolver;
    private XPathFunctionResolver m_aFunctionResolver;
    // Status var
    private IPSBoundSchema m_aBoundSchema;
  
    public SchematronResourcePure (@Nonnull final IReadableResource aResource)
    {
      this (aResource, (String) null, (IPSErrorHandler) null);
    }
  
    public SchematronResourcePure (@Nonnull final IReadableResource aResource,
                                   @Nullable final String sPhase,
                                   @Nullable final IPSErrorHandler aErrorHandler)
    {
      super (aResource);
      setPhase (sPhase);
      setErrorHandler (aErrorHandler);
    }
  
    /**
     * @return The phase to be used. May be <code>null</code>.
     */
    @Nullable
   public String getPhase ()
   {
     return m_sPhase;
   }
 
   /**
    * Set the Schematron phase to be evaluated. Changing the phase will result in
    * a newly bound schema!
    *
    * @param sPhase
    *        The name of the phase to use. May be <code>null</code> which means
    *        all phases.
    * @return this
    */
   @Nonnull
   public SchematronResourcePure setPhase (@Nullable final String sPhase)
   {
     if (m_aBoundSchema != null)
       throw new IllegalStateException ("Schematron was already bound and can therefore not be altered!");
     m_sPhase = sPhase;
     return this;
   }
 
   /**
    * @return The error handler to be used to bind the schema. May be
    *         <code>null</code>.
    */
   @Nullable
   public IPSErrorHandler getErrorHandler ()
   {
     return m_aErrorHandler;
   }
 
   /**
    * Set the error handler to be used during binding.
    *
    * @param aErrorHandler
    *        The error handler. May be <code>null</code>.
    * @return this
    */
   @Nonnull
   public SchematronResourcePure setErrorHandler (@Nullable final IPSErrorHandler aErrorHandler)
   {
     if (m_aBoundSchema != null)
       throw new IllegalStateException ("Schematron was already bound and can therefore not be altered!");
     m_aErrorHandler = aErrorHandler;
     return this;
   }
 
   /**
    * @return The variable resolver to be used. May be <code>null</code>.
    */
   @Nullable
   public XPathVariableResolver getVariableResolver ()
   {
     return m_aVariableResolver;
   }
 
   /**
    * Set the variable resolver to be used in the XPath statements. This can only
    * be set before the Schematron is bound. If it is already bound an exception
    * is thrown to indicate the unnecessity of the call.
    *
    * @param aVariableResolver
    *        The variable resolver to set. May be <code>null</code>.
    * @return this
    */
   @Nonnull
   public SchematronResourcePure setVariableResolver (@Nullable final XPathVariableResolver aVariableResolver)
   {
     if (m_aBoundSchema != null)
       throw new IllegalStateException ("Schematron was already bound and can therefore not be altered!");
     m_aVariableResolver = aVariableResolver;
     return this;
   }
 
   /**
    * @return The function resolver to be used. May be <code>null</code>.
    */
   @Nullable
   public XPathFunctionResolver getFunctionResolver ()
   {
     return m_aFunctionResolver;
   }
 
   /**
    * Set the function resolver to be used in the XPath statements. This can only
    * be set before the Schematron is bound. If it is already bound an exception
    * is thrown to indicate the unnecessity of the call.
    *
    * @param aFunctionResolver
    *        The function resolver to set. May be <code>null</code>.
    * @return this
    */
   @Nonnull
   public SchematronResourcePure setFunctionResolver (@Nullable final XPathFunctionResolver aFunctionResolver)
   {
     if (m_aBoundSchema != null)
       throw new IllegalStateException ("Schematron was already bound and can therefore not be altered!");
     m_aFunctionResolver = aFunctionResolver;
     return this;
   }
 
   @Nonnull
   protected IPSBoundSchema createBoundSchema ()
   {
     final IReadableResource aResource = getResource ();
     final IPSErrorHandler aErrorHandler = getErrorHandler ();
     final PSBoundSchemaCacheKey aCacheKey = new PSBoundSchemaCacheKey (aResource,
                                                                        getPhase (),
                                                                        aErrorHandler,
                                                                        getVariableResolver (),
                                                                        getFunctionResolver ());
     if (aResource instanceof AbstractMemoryReadableResource)
     {
       // No need to cache anything for memory resources
       try
       {
         return aCacheKey.createBoundSchema ();
       }
       catch (final SchematronException ex)
       {
         // Convert to runtime exception
         throw new IllegalStateException ("Failed to bind Schematron", ex);
       }
     }
 
     // Resolve from cache - inside the cacheKey the reading and binding
     // happens
     return PSBoundSchemaCache.getInstance ().getFromCache (aCacheKey);
   }
 
   @Nonnull
   protected IPSBoundSchema getOrCreateBoundSchema ()
   {
     if (m_aBoundSchema == null)
       try
       {
         m_aBoundSchema = createBoundSchema ();
       }
       catch (final RuntimeException ex)
       {
         if (m_aErrorHandler != null)
           m_aErrorHandler.error (getResource (), null, "Error creating bound schema", ex);
         throw ex;
       }
 
     return m_aBoundSchema;
   }
 
   public boolean isValidSchematron ()
   {
     // Use the provided error handler (if any)
     try
     {
       final IPSErrorHandler aErrorHandler = m_aErrorHandler != null ? m_aErrorHandler : new DoNothingPSErrorHandler ();
       return getOrCreateBoundSchema ().getOriginalSchema ().isValid (aErrorHandler);
     }
     catch (final RuntimeException ex)
     {
       // May happen when XPath errors are contained
       return false;
     }
   }
 
   /**
    * Use the internal error handler to validate all elements in the schematron.
    * It tries to catch as many errors as possible.
    */
   public void validateCompletely ()
   {
     // Use the provided error handler (if any)
     final IPSErrorHandler aErrorHandler = m_aErrorHandler != null ? m_aErrorHandler : new DoNothingPSErrorHandler ();
     validateCompletely (aErrorHandler);
   }
 
   /**
    * Use the provided error handler to validate all elements in the schematron.
    * It tries to catch as many errors as possible.
    *
    * @param aErrorHandler
    *        The error handler to use. May not be <code>null</code>.
    */
   public void validateCompletely (@Nonnull final IPSErrorHandler aErrorHandler)
   {
     ValueEnforcer.notNull (aErrorHandler, "ErrorHandler");
 
     try
     {
       getOrCreateBoundSchema ().getOriginalSchema ().validateCompletely (aErrorHandler);
     }
     catch (final RuntimeException ex)
     {
       // May happen when XPath errors are contained
     }
   }
 
   /**
    * The main method to convert a node to an SVRL document.
    *
    * @param aXMLNode
    *        The source node to be validated. May not be <code>null</code>.
    * @return The SVRL document. Never <code>null</code>.
    * @throws SchematronException
    *         in case of a sever error validating the schema
    */
   @Nonnull
   public SchematronOutputType applySchematronValidationToSVRL (@Nonnull final Node aXMLNode) throws SchematronException
   {
     return getOrCreateBoundSchema ().validateComplete (aXMLNode);
   }
 
   @Nonnull
   public EValidity getSchematronValidity (@Nonnull final IHasInputStream aXMLResource) throws Exception
   {
     if (!isValidSchematron ())
       return EValidity.INVALID;
 
     final Document aDoc = DOMReader.readXMLDOM (aXMLResource.getInputStream ());
     if (aDoc == null)
       throw new IllegalArgumentException ("Failed to read resource " + aXMLResource + " as XML");
 
     return getOrCreateBoundSchema ().validatePartially (aDoc);
   }
 
   @Nonnull
   public EValidity getSchematronValidity (@Nonnull final Source aXMLSource) throws Exception
   {
     if (!isValidSchematron ())
       return EValidity.INVALID;
 
     // Convert Source to Node
     final Node aNode = SchematronResourceHelper.getNodeOfSource (aXMLSource);
     if (aNode == null)
       return EValidity.INVALID;
 
     return getOrCreateBoundSchema ().validatePartially (aNode);
   }
 
   @Nullable
   public Document applySchematronValidation (@Nonnull final IHasInputStream aXMLResource) throws Exception
   {
     final SchematronOutputType aSO = applySchematronValidationToSVRL (aXMLResource);
     return aSO == null ? null : SVRLWriter.createXML (aSO);
   }
 
   @Nullable
   public Document applySchematronValidation (@Nonnull final Source aXMLSource) throws Exception
   {
     final SchematronOutputType aSO = applySchematronValidationToSVRL (aXMLSource);
     return aSO == null ? null : SVRLWriter.createXML (aSO);
   }
 
   @Nullable
   public SchematronOutputType applySchematronValidationToSVRL (@Nonnull final IHasInputStream aXMLResource) throws Exception
   {
     ValueEnforcer.notNull (aXMLResource, "XMLResource");
 
     if (!isValidSchematron ())
       return null;
 
     final InputStream aIS = aXMLResource.getInputStream ();
     if (aIS == null)
       return null;
 
     final Document aDoc = DOMReader.readXMLDOM (aIS);
     if (aDoc == null)
       throw new IllegalArgumentException ("Failed to read resource " + aXMLResource + " as XML");
 
     return applySchematronValidationToSVRL (aDoc);
   }
 
   @Nullable
   public SchematronOutputType applySchematronValidationToSVRL (@Nonnull final Source aXMLSource) throws Exception
   {
     ValueEnforcer.notNull (aXMLSource, "XMLSource");
 
     if (!isValidSchematron ())
       return null;
 
     // Convert to Node
     final Node aNode = SchematronResourceHelper.getNodeOfSource (aXMLSource);
     if (aNode == null)
       return null;
 
     return applySchematronValidationToSVRL (aNode);
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from a Classpath Schematron
    * rules
    *
    * @param sSCHPath
    *        The classpath relative path to the Schematron rules.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromClassPath (@Nonnull @Nonempty final String sSCHPath)
   {
     return new SchematronResourcePure (new ClassPathResource (sSCHPath));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from file system Schematron
    * rules
    *
    * @param sSCHPath
    *        The file system path to the Schematron rules.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromFile (@Nonnull @Nonempty final String sSCHPath)
   {
     return new SchematronResourcePure (new FileSystemResource (sSCHPath));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from file system Schematron
    * rules
    *
    * @param aSCHFile
    *        The file system path to the Schematron rules.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromFile (@Nonnull final File aSCHFile)
   {
     return new SchematronResourcePure (new FileSystemResource (aSCHFile));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from Schematron rules provided
    * at a URL
    *
    * @param sSCHURL
    *        The URL to the Schematron rules. May neither be <code>null</code>
    *        nor empty.
    * @return Never <code>null</code>.
    * @throws MalformedURLException
    *         In case an invalid URL is provided
    */
   @Nonnull
   public static SchematronResourcePure fromURL (@Nonnull @Nonempty final String sSCHURL) throws MalformedURLException
   {
     return new SchematronResourcePure (new URLResource (sSCHURL));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from Schematron rules provided
    * at a URL
    *
    * @param aSCHURL
    *        The URL to the Schematron rules. May not be <code>null</code>.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromURL (@Nonnull final URL aSCHURL)
   {
     return new SchematronResourcePure (new URLResource (aSCHURL));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from Schematron rules provided
    * by an arbitrary {@link InputStream}.<br>
    * <b>Important:</b> in this case, no include resolution will be performed!!
    *
    * @param aSchematronIS
    *        The {@link InputStream} to read the Schematron rules from. May not
    *        be <code>null</code>.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromInputStream (@Nonnull final InputStream aSchematronIS)
   {
     return new SchematronResourcePure (new ReadableResourceInputStream (aSchematronIS));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from Schematron rules provided
    * by an arbitrary byte array.<br>
    * <b>Important:</b> in this case, no include resolution will be performed!!
    *
    * @param aSchematron
    *        The byte array representing the Schematron. May not be
    *        <code>null</code>.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromByteArray (@Nonnull final byte [] aSchematron)
   {
     return new SchematronResourcePure (new ReadableResourceByteArray (aSchematron));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from Schematron rules provided
    * by an arbitrary String.<br>
    * <b>Important:</b> in this case, no include resolution will be performed!!
    *
    * @param sSchematron
    *        The String representing the Schematron. May not be <code>null</code>
    *        .
    * @param aCharset
    *        The charset to be used to convert the String to a byte array.
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromString (@Nonnull final String sSchematron, @Nonnull final Charset aCharset)
   {
     return fromByteArray (CharsetManager.getAsBytes (sSchematron, aCharset));
   }
 
   /**
    * Create a new {@link SchematronResourcePure} from Schematron rules provided
    * by a domain model.<br>
    * <b>Important:</b> in this case, no include resolution will be performed!!
    *
    * @param aSchematron
    *        The Schematron model to be used. May not be <code>null</code> .
    * @return Never <code>null</code>.
    */
   @Nonnull
   public static SchematronResourcePure fromSchema (@Nonnull final PSSchema aSchematron)
   {
     return fromString (new PSWriter ().getXMLString (aSchematron), XMLWriterSettings.DEFAULT_XML_CHARSET_OBJ);
   }
 }