/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.tuscany.sca.implementation.bpel.impl;

import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;

import java.io.InputStream;
import java.net.URI;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import javax.wsdl.Definition;
import javax.wsdl.PortType;
import javax.wsdl.extensions.ExtensibilityElement;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamReader;

import org.apache.tuscany.sca.assembly.builder.impl.ProblemImpl;
import org.apache.tuscany.sca.contribution.ModelFactoryExtensionPoint;
import org.apache.tuscany.sca.contribution.processor.BaseStAXArtifactProcessor;
import org.apache.tuscany.sca.contribution.processor.URLArtifactProcessor;
import org.apache.tuscany.sca.contribution.resolver.ModelResolver;
import org.apache.tuscany.sca.contribution.service.ContributionReadException;
import org.apache.tuscany.sca.contribution.service.ContributionResolveException;
import org.apache.tuscany.sca.implementation.bpel.BPELFactory;
import org.apache.tuscany.sca.implementation.bpel.BPELProcessDefinition;
import org.apache.tuscany.sca.implementation.bpel.xml.BPELImportElement;
import org.apache.tuscany.sca.implementation.bpel.xml.BPELPartnerLinkElement;
import org.apache.tuscany.sca.implementation.bpel.xml.BPELPartnerLinkTypeElement;
import org.apache.tuscany.sca.interfacedef.InvalidInterfaceException;
import org.apache.tuscany.sca.interfacedef.wsdl.WSDLDefinition;
import org.apache.tuscany.sca.interfacedef.wsdl.WSDLFactory;
import org.apache.tuscany.sca.interfacedef.wsdl.WSDLInterface;
import org.apache.tuscany.sca.interfacedef.wsdl.WSDLObject;
import org.apache.tuscany.sca.interfacedef.wsdl.xml.BPELPartnerLinkTypeExt;
import org.apache.tuscany.sca.monitor.Monitor;
import org.apache.tuscany.sca.monitor.Problem;
import org.apache.tuscany.sca.monitor.Problem.Severity;

/**
 * BPEL document processor responsible for reading a BPEL file and producing necessary model info about it
 * 
 * TODO: The namespaces for WS-BPEL include 2 versions - only the earlier BPEL 1.1 versions are
 * supported at present - the BPEL 2.0 namespaces also need support.  This will require inspection
 * of both BPEL process files and of WSDL files for their BPEL namespaces
 * @version $Rev$ $Date$
 */
public class BPELDocumentProcessor extends BaseStAXArtifactProcessor implements URLArtifactProcessor<BPELProcessDefinition> {
    public final static QName BPEL_PROCESS_DEFINITION = new QName("http://schemas.xmlsoap.org/ws/2004/03/business-process/", "process");
    public final static QName BPEL_EXECUTABLE_DEFINITION = new QName("http://docs.oasis-open.org/wsbpel/2.0/process/executable", "process");
    private static final String SCA_BPEL_NS = "http://docs.oasis-open.org/ns/opencsa/sca-bpel/200801";
    private static final String BPEL_NS = "http://schemas.xmlsoap.org/ws/2004/03/business-process/";
    private static final String BPEL_PLINK_NS = "http://schemas.xmlsoap.org/ws/2004/03/partner-link/";
    private static final QName PROCESS_ELEMENT = new QName(BPEL_NS, "process");
    private static final QName PARTNERLINK_ELEMENT = new QName(BPEL_NS, "partnerLink");
    private static final QName ONEVENT_ELEMENT = new QName(BPEL_NS, "onEvent");
    private static final QName RECEIVE_ELEMENT = new QName(BPEL_NS, "receive");
    private static final QName ONMESSAGE_ELEMENT = new QName(BPEL_NS, "onMessage");
    private static final QName INVOKE_ELEMENT = new QName(BPEL_NS, "invoke");
    private static final QName IMPORT_ELEMENT = new QName(BPEL_NS, "import");
    private static final String LINKTYPE_NAME = "partnerLinkType";
    private static final QName LINKTYPE_ELEMENT = new QName(BPEL_PLINK_NS, LINKTYPE_NAME);

    public final static String NAME_ELEMENT = "name";
    
    private final static XMLInputFactory inputFactory = XMLInputFactory.newInstance();
    
    private final BPELFactory factory;
    private WSDLFactory WSDLfactory;
    private Monitor monitor;

    public BPELDocumentProcessor(ModelFactoryExtensionPoint modelFactories, Monitor monitor) {
        this.factory     = modelFactories.getFactory(BPELFactory.class);
        this.WSDLfactory = modelFactories.getFactory(WSDLFactory.class);
        this.monitor = monitor;
    }
    
    /**
     * Report a warning.
     * 
     * @param problems
     * @param message
     * @param model
     */
     private void warning(String message, Object model, Object... messageParameters) {
         if (monitor != null) {
             Problem problem = new ProblemImpl(this.getClass().getName(), "impl-bpel-validation-messages", Severity.WARNING, model, message, (Object[])messageParameters);
             monitor.problem(problem);
         }
     }
     
     /**
      * Report a error.
      * 
      * @param problems
      * @param message
      * @param model
      */
      private void error(String message, Object model, Object... messageParameters) {
          if (monitor != null) {
              Problem problem = new ProblemImpl(this.getClass().getName(), "impl-bpel-validation-messages", Severity.ERROR, model, message, (Object[])messageParameters);
              monitor.problem(problem);
          }
      }
    
    /**
     * Report a exception.
     * 
     * @param problems
     * @param message
     * @param model
     */
     private void error(String message, Object model, Exception ex) {
         if (monitor != null) {
             Problem problem = new ProblemImpl(this.getClass().getName(), "impl-bpel-validation-messages", Severity.ERROR, model, message, ex);
             monitor.problem(problem);
         }        
     }
            
    
    public String getArtifactType() {
        return "*.bpel";
    }    

    public Class<BPELProcessDefinition> getModelType() {
        return BPELProcessDefinition.class;
    }

    public BPELProcessDefinition read(URL contributionURL, URI artifactURI, URL artifactURL) throws ContributionReadException {
        BPELProcessDefinition processDefinition = null;
        try {
            //for now we are just using process name
            //and relying on componentType file for service definition
            //so it's OK to set resolved for now
            processDefinition = indexRead2(artifactURL);
            processDefinition.setURI(artifactURI);
            processDefinition.setUnresolved(false);
        } catch (Exception e) {
        	ContributionReadException ce = new ContributionReadException(e);
        	error("ContributionReadException", artifactURL, ce);
            //throw ce;
        }
        
        return processDefinition;
    }

    /**
     * Resolve the BPEL process
     * - one of the things that needs doing is to pin down the WSDLs that are being used by
     * the process, in particular the partnerLinkType and the related PortType definitions
     */
    public void resolve(BPELProcessDefinition model, ModelResolver resolver) 
    	throws ContributionResolveException {
        // FIXME - serious resolving needs to happen here
    	
    	// Step 1 is to resolve the WSDL files referenced from this BPEL process
    	// - one complexity here is that the WSDL definitions hold BPEL extension elements for
    	// the partnerLinkType declarations - and these must be used in later steps
    	//
    	// Step 2 is to take all the partnerLink definitions and establish the PortType being
    	// used, by tracing through the related partnerLinkType declarations - the PortType is
    	// effectively a definition of the interface used by the partnerLink.
    	// - another consideration here is that each partnerLink can involve 2 interfaces, one
    	// for the forward calls to the process, the other for calls from the process - depending
    	// on whether the partnerLink is a reference or a service, one of these interfaces is a
    	// callback interface.
    	
    	List<BPELImportElement> theImports = model.getImports();
    	for ( BPELImportElement theImport : theImports ) {
    		// Deal with WSDL imports
    		if ( theImport.getImportType().equals("http://schemas.xmlsoap.org/wsdl/") ) {
    			String WSDLLocation = theImport.getLocation();
    			String WSDLNamespace = theImport.getNamespace();
    			
    			// Resolve the WSDL definition
                WSDLDefinition proxy = WSDLfactory.createWSDLDefinition();
                proxy.setUnresolved(true);
                proxy.setNamespace(WSDLNamespace);
                if ( WSDLLocation != null ) proxy.setLocation(URI.create(WSDLLocation));
                WSDLDefinition resolved = resolver.resolveModel(WSDLDefinition.class, proxy);
                if (resolved != null && !resolved.isUnresolved()) {
                    theImport.setWSDLDefinition( resolved );
                } else {
                    error("CannotResolveWSDLReference", resolver, WSDLLocation, WSDLNamespace);
                    //throw new ContributionResolveException("BPELDocumentProcessor:resolve -" +
                			//" unable to resolve WSDL referenced by BPEL import" +
                			//"WSDL location: " + WSDLLocation + " WSDLNamespace: " +
                			//WSDLNamespace );
                    return;
                } // end if	
    		} // end if
    	} // end for
    	
    	// Fetch the sets of partner links, port types and interfaces
    	List<BPELPartnerLinkTypeElement> thePLinkTypes = getPartnerLinkTypes( theImports );
    	Collection<WSDLInterface> theInterfaces = (Collection<WSDLInterface>)new ArrayList<WSDLInterface>();
    	Collection<PortType> thePortTypes = getAllPortTypes( theImports, theInterfaces, resolver );
    	
    	// Store the Port Types and the Interfaces for later calculation of the component type...
    	model.setPortTypes(thePortTypes);
    	model.setInterfaces(theInterfaces);
    	
    	// Now, for each partnerLink in the BPEL process, find the related partnerLinkType
    	// element 
    	List<BPELPartnerLinkElement> thePartnerLinks = model.getPartnerLinks();
    	for ( BPELPartnerLinkElement thePartnerLink : thePartnerLinks ) {
    		QName partnerLinkType = thePartnerLink.getPartnerLinkType();
    		BPELPartnerLinkTypeElement pLinkType = 
    			findPartnerLinkType( partnerLinkType, thePLinkTypes );
    		if( pLinkType == null ) {
    		    error("PartnerLinkNoMatchingType", thePartnerLink, thePartnerLink.getName());
    		    //throw new ContributionResolveException( "PartnerLink " 
    		        //+ thePartnerLink.getName() + " has no matching partner link type");
    		} else    					
    		    thePartnerLink.setPartnerLinkType(pLinkType);
    	} // end for
    	
    } // end resolve
    
    /*
     * Retrieve all the Partner Link types defined in the imported WSDL files
     */
    private List<BPELPartnerLinkTypeElement> getPartnerLinkTypes( List<BPELImportElement> theImports )
    	throws ContributionResolveException {
    	
    	List<BPELPartnerLinkTypeElement> thePLinks = 
    		new ArrayList<BPELPartnerLinkTypeElement>();
    		
    	// We must find the partner link type elements from amongst the imported WSDLs
    	for ( BPELImportElement theImport : theImports ){
    		WSDLDefinition theWSDL = theImport.getWSDLDefinition();
    		Definition WSDLDefinition = theWSDL.getDefinition();
    		// The BPEL partnerLinkType elements are extension elements within the WSDL
    		List<ExtensibilityElement> extensibilityElements = WSDLDefinition.getExtensibilityElements();
    		
    		for ( ExtensibilityElement theElement : extensibilityElements ) {
    			QName elementType = theElement.getElementType();
    			if ( elementType.equals( LINKTYPE_ELEMENT ) ) {
    				BPELPartnerLinkTypeExt pLinkExt = (BPELPartnerLinkTypeExt)theElement;
    				// Fetch the name of the partnerLinkType
    				String name = pLinkExt.getName();
    				QName qName = new QName( WSDLDefinition.getTargetNamespace(), name );
    				BPELPartnerLinkTypeElement pLinkElement = new BPELPartnerLinkTypeElement( qName );
    				
    				// The partnerLinkType must have one and may have 2 role child elements
    				int count = 0;
    				for( int i = 0; i < 2; i++ ) {
    					if(pLinkExt.getRoleName(i) == null ) continue;
    					PortType pType = WSDLDefinition.getPortType(pLinkExt.getRolePortType(i));
    					if ( count == 0 ) {
    						pLinkElement.setRole1(pLinkExt.getRoleName(i),
    								              pLinkExt.getRolePortType(i),
    								              pType );
    						count++;
    					} else if (count == 1) {
    						pLinkElement.setRole2(pLinkExt.getRoleName(i),
						                          pLinkExt.getRolePortType(i),
						                          pType );
    						count++;
    					} else {
    						break;
    					} // end if 
    				} // end for
    				if( count == 0 ) {
    				    error("PartnerLinkTypeNoRoles", theElement, pLinkElement.getName());
    				    throw new ContributionResolveException( "partnerLinkType " +
    				        pLinkElement.getName() +" has no Roles defined" );
    				} else    						                         
    				    thePLinks.add( pLinkElement );
    			} // end if
    			
    		} // end for
    	} // end for
    	return thePLinks;
    } // end getPartnerLinkTypes
    
    protected Collection<PortType> getAllPortTypes( List<BPELImportElement> theImports,
    												Collection<WSDLInterface> theInterfaces,
    												ModelResolver resolver) 
    				throws ContributionResolveException {
    	
    	Collection<PortType> thePortTypes = (Collection<PortType>)new ArrayList<PortType>();
    	for ( BPELImportElement theImport : theImports ){
    		WSDLDefinition theWSDL = theImport.getWSDLDefinition();
    		Definition wsdlDefinition = theWSDL.getDefinition();
    		
    		Collection<PortType> portTypes = (Collection<PortType>)wsdlDefinition.getPortTypes().values();
    		thePortTypes.addAll( portTypes );
    		
    		// Create WSDLInterface elements for each PortType found
    		for( PortType portType : portTypes ) {
    			WSDLObject<PortType> wsdlPortType = theWSDL.getWSDLObject(PortType.class, portType.getQName() );
    			WSDLInterface wsdlInterface;
                if (wsdlPortType != null) {      
                    // Introspect the WSDL portType and add the resulting
                    // WSDLInterface to the resolver
                    try {
                        theWSDL.setDefinition( wsdlPortType.getDefinition() );
                        wsdlInterface = WSDLfactory.createWSDLInterface(wsdlPortType.getElement(), 
                        		theWSDL, resolver);
                        wsdlInterface.setWsdlDefinition(theWSDL);
                    } catch (InvalidInterfaceException e) {
                    	ContributionResolveException ce = new ContributionResolveException(e);
                    	error("ContributionResolveException", resolver, ce);
                        throw ce;
                    } // end try
                    resolver.addModel(wsdlInterface);
                    theInterfaces.add(wsdlInterface);
                } // end if
            } // end for
      
    		//-----------------------
    		
    	} // end for
    	
    	return thePortTypes;
    } // end getAllPortTypes
    
    /**
     * Returns a QName from a string.  
     * @param definition - a WSDL Definition
     * @param value - the String from which to form the QName in the form "pref:localName"
     * @return
     */
    protected QName getQNameValue(Definition definition, String value) {
        if (value != null && definition != null) {
            int index = value.indexOf(':');
            String prefix = index == -1 ? "" : value.substring(0, index);
            String localName = index == -1 ? value : value.substring(index + 1);
            String ns = definition.getNamespace(prefix);
            if (ns == null) {
                ns = "";
            }
            return new QName(ns, localName, prefix);
        } else {
            return null;
        }
    } // end getQNameValue

    
    /*
     * Method which finds a partnerLinkType definition within the WSDLs imported by the BPEL
     * process.
     * @param partnerLinkTypeName - the name of the partnerLinkType
     * @param theImports a list of the WSDL import declarations
     * @returns a BPELPartnerLinkTypeElement for the partnerLinkType or null if it cannot be
     * found
     */
    private BPELPartnerLinkTypeElement findPartnerLinkType( QName partnerLinkTypeName,
    										List<BPELPartnerLinkTypeElement> thePLinkTypes) {
    	// We must find the partner link type element from amongst the imported WSDLs
    	for ( BPELPartnerLinkTypeElement thePLinkType : thePLinkTypes ){
    		if( thePLinkType.getName().equals(partnerLinkTypeName) ) return thePLinkType;
     	} // end for
    	return null;
    } // end findPartnerLinkType
    
    

    protected BPELProcessDefinition indexRead2(URL doc) throws Exception {
        BPELProcessDefinition processDefinition = factory.createBPELProcessDefinition();
        processDefinition.setUnresolved(true);
        processDefinition.setLocation(doc);

        InputStream is = doc.openStream();
        XMLStreamReader reader = null;
        try {
            reader = inputFactory.createXMLStreamReader(is);
            /*
             * The principle here is to look for partnerLink elements, which form either services
             * or references.  A partnerLink can be EITHER - the algorithm for deciding is:
             * 1) Explicit marking with sca:reference or sca:service attribute
             * 2) "first use" of the partnerLink by specific BPEL activity elements:
             * <onEvent../>, <receive../> or <pick../> elements imply a service
             * <invoke../> implies a reference
             */
            // TODO - need to handle <scope../> elements as kind of "nested" processes
            // - and scopes introduce the possibility of partnerLinks with the same name at
            // different levels of scope.... (yuk!!)
            boolean completed = false;
            while (!completed) {
                switch (reader.next()) {
                    case START_ELEMENT:
                        QName qname = reader.getName();
                        //System.out.println("BPEL TypeLoader - found element with name: " + qname.toString());
                        if (BPEL_PROCESS_DEFINITION.equals(qname) || 
                        	BPEL_EXECUTABLE_DEFINITION.equals(qname)) {
                            QName processName = new QName(getString(reader, org.apache.tuscany.sca.assembly.xml.Constants.TARGET_NAMESPACE), 
                            		                      getString(reader, NAME_ELEMENT));
                            processDefinition.setName(processName);
                		} else if (PARTNERLINK_ELEMENT.equals(qname)) { 
                            processDefinition.getPartnerLinks().add(processPartnerLinkElement( reader ));
                        } else if (ONEVENT_ELEMENT.equals(qname) || 
                        		   RECEIVE_ELEMENT.equals(qname) ||
                        		   ONMESSAGE_ELEMENT.equals(qname) ) {
                        	processPartnerLinkAsService( reader.getAttributeValue(null, "partnerLink"), processDefinition.getPartnerLinks() );
                        } else if (INVOKE_ELEMENT.equals(qname)) { 
                        	processPartnerLinkAsReference( reader.getAttributeValue(null, "partnerLink"), processDefinition.getPartnerLinks() );
                        } else if (IMPORT_ELEMENT.equals(qname)) {
                        	processDefinition.getImports().add( processImportElement( reader ) );
                        } // end if
                        break;
                    case END_ELEMENT:
                        if (PROCESS_ELEMENT.equals(reader.getName())) {
                            //System.out.println("BPEL TypeLoader - finished read of process file");
                            completed = true;
                            break;
                        } // end if
                } // end switch
            } // end while
        } finally {
            if(reader != null) reader.close();
            is.close();
        } // end try
        
        return processDefinition;
    } // end indexRead2

	/*
	 * Processes a partnerLink element from the BPEL process and creates a
	 * BPELPartnerLink object
	 */
	private BPELPartnerLinkElement processPartnerLinkElement( XMLStreamReader reader ) 
					throws ContributionReadException {
		BPELPartnerLinkElement partnerLink = new BPELPartnerLinkElement(
	    		reader.getAttributeValue(null, "name"), 
	    		getQNameValue(reader, reader.getAttributeValue(null, "partnerLinkType") ),
	    		reader.getAttributeValue(null, "myRole"),
	    		reader.getAttributeValue(null, "partnerRole"));
	    // See if there are any SCA extension attributes
	    String scaService = reader.getAttributeValue( SCA_BPEL_NS, "service");
	    String scaReference = reader.getAttributeValue( SCA_BPEL_NS, "reference");
	    if( (scaService != null) && (scaReference != null) ) {
	    	// It is incorrect to set both service & reference attributes
	        error("PartnerLinkHasBothAttr", partnerLink, reader.getAttributeValue(null, "name"));
	    	throw new ContributionReadException( "BPEL PartnerLink " 
	    			+ reader.getAttributeValue(null, "name") + 
	    			" has both sca:reference and sca:service attributes set" );
	    }
	    // Set the SCA type and the related name, if present
	    if( scaService != null ) partnerLink.setAsService( scaService );
	    else if ( scaReference != null ) partnerLink.setAsReference( scaReference );
	    return partnerLink;
	} // end processPartnerLinkElement

	/*
	 * Processes an <import../> element from the BPEL process and creates a 
	 * BPELImportElement object
	 */
	private BPELImportElement processImportElement( XMLStreamReader reader ) {
		return ( new BPELImportElement( reader.getAttributeValue(null, "location"),
				                        reader.getAttributeValue(null, "importType"),
				                        reader.getAttributeValue(null, "namespace") ));
	} // end processImportElement

	/*
	 * Mark a named partnerLink as a Service, unless it is already marked as a Reference
	 */
	private void processPartnerLinkAsService( String partnerLinkName, 
										List<BPELPartnerLinkElement> partnerLinks ) {
		BPELPartnerLinkElement partnerLink = findPartnerLinkByName( partnerLinks, partnerLinkName );
		if( partnerLink == null ) {
		    warning("ReferencePartnerLinkNotInList", partnerLinkName, partnerLinkName);
		} else {
			// Set the type of the partnerLink to "service" if not already set...
			if( !partnerLink.isSCATyped() ) partnerLink.setAsService( partnerLinkName );
		} // endif
	} // end processPartnerLinkAsReference

	/*
	 * Mark a named partnerLink as a Reference, unless it is already marked as a Service
	 */
	private void processPartnerLinkAsReference( String partnerLinkName, 
			List<BPELPartnerLinkElement> partnerLinks ) {
		BPELPartnerLinkElement partnerLink = findPartnerLinkByName( partnerLinks, partnerLinkName );
		if( partnerLink == null ) {
		    warning("ReferencePartnerLinkNotInList", partnerLinkName, partnerLinkName);
		} else {
			// Set the type of the partnerLink to "service" if not already set...
			if( !partnerLink.isSCATyped() ) partnerLink.setAsReference( partnerLinkName );
		} // endif
	} // end processPartnerLinkAsReference

	/*
	 * Finds a PartnerLink by name from a List of PartnerLinks
	 * 
	 * returns null if there is no partnerLink with a matching name
	 * - returns the PartnerLink with a matching name
	 */
	private BPELPartnerLinkElement findPartnerLinkByName( List<BPELPartnerLinkElement> partnerLinks, 
														  String partnerLinkName ) {
		// Scan the list looking for a partner link with the supplied name
		Iterator<BPELPartnerLinkElement> it = partnerLinks.iterator();
		while( it.hasNext() ) {
			BPELPartnerLinkElement thePartnerLink = it.next();
			if( thePartnerLink.getName().equals(partnerLinkName) ) return thePartnerLink;
		}
		return null;
	} // end method findPartnerLinkByName


}