/*
 * Copyright 2005-2006 The Apache Software Foundation.
 *
 * 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 org.apache.servicemix.components.validation;

import org.apache.servicemix.components.util.TransformComponentSupport;
import org.apache.servicemix.jbi.FaultException;
import org.apache.servicemix.jbi.jaxp.SourceTransformer;
import org.springframework.core.io.Resource;
import org.xml.sax.SAXException;

import javax.jbi.JBIException;
import javax.jbi.messaging.Fault;
import javax.jbi.messaging.MessageExchange;
import javax.jbi.messaging.MessagingException;
import javax.jbi.messaging.NormalizedMessage;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;
import java.io.IOException;

/**
 * This component performs a schema validation on the incoming document
 * and returning a fault if the document does not conform to the schema
 * otherwise the message is passed on its way.
 *
 * @version $Revision: 378288 $
 */
public class ValidateComponent extends TransformComponentSupport {
    private Schema schema;
    private String schemaLanguage = "http://www.w3.org/2001/XMLSchema";
    private Source schemaSource;
    private Resource schemaResource;

    public Schema getSchema() {
        return schema;
    }

    public void setSchema(Schema schema) {
        this.schema = schema;
    }

    public String getSchemaLanguage() {
        return schemaLanguage;
    }

    public void setSchemaLanguage(String schemaLanguage) {
        this.schemaLanguage = schemaLanguage;
    }

    public Source getSchemaSource() {
        return schemaSource;
    }

    public void setSchemaSource(Source schemaSource) {
        this.schemaSource = schemaSource;
    }

    public Resource getSchemaResource() {
        return schemaResource;
    }

    public void setSchemaResource(Resource schemaResource) {
        this.schemaResource = schemaResource;
    }
   
    protected void init() throws JBIException {
        super.init();

        try {
            if (schema == null) {
                SchemaFactory factory = SchemaFactory.newInstance(schemaLanguage);

                if (schemaSource == null) {
                    if (schemaResource == null) {
                        throw new JBIException("You must specify a schema, schemaSource or schemaResource property");
                    }
                    schemaSource = new StreamSource(schemaResource.getInputStream());
                }
                schema = factory.newSchema(schemaSource);
            }
        }
        catch (IOException e) {
            throw new JBIException("Failed to load schema: " + e, e);
        }
        catch (SAXException e) {
            throw new JBIException("Failed to load schema: " + e, e);
        }
    }

    protected boolean transform(MessageExchange exchange, NormalizedMessage in, NormalizedMessage out) throws MessagingException {
        Validator validator = schema.newValidator();

        CountingErrorHandler errorHandler = new CountingErrorHandler();
        validator.setErrorHandler(errorHandler);
        DOMResult result = new DOMResult();
        // Transform first so that the input source will be parsed only once
        // if it is a StreamSource
        getMessageTransformer().transform(exchange, in, out);
        try {
        	// Only DOMSource and SAXSource are allowed for validating
        	// See http://java.sun.com/j2se/1.5.0/docs/api/javax/xml/validation/Validator.html#validate(javax.xml.transform.Source,%20javax.xml.transform.Result)
        	// As we expect a DOMResult as output, we must ensure that the input is a 
        	// DOMSource
        	DOMSource src = new SourceTransformer().toDOMSource(out.getContent());
        	doValidation(validator,src,result);
            if (errorHandler.hasErrors()) {
                Fault fault = exchange.createFault();
                fault.setProperty("org.apache.servicemix.schema", schema);
                fault.setContent(new DOMSource(result.getNode(), result.getSystemId()));
                throw new FaultException("Failed to validate against schema: " + schema, exchange, fault);
            }
            else {
            	// Retrieve the ouput of the validation
            	// as it may have been changed by the validator
            	out.setContent(new DOMSource(result.getNode(), result.getSystemId()));
                return true;
             }
        }
        catch (SAXException e) {
            throw new MessagingException(e);
        }
        catch (IOException e) {
            throw new MessagingException(e);
        } 
        catch (ParserConfigurationException e) {
            throw new MessagingException(e);
		} 
        catch (TransformerException e) {
            throw new MessagingException(e);
		}
    }
    
    protected void doValidation(Validator validator, DOMSource src, DOMResult result) throws SAXException, IOException {
    	validator.validate(src,result);
    }
}
