/*******************************************************************************
 * Copyright 2014 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 *******************************************************************************/
package at.gv.egovernment.moa.id.configuration.auth.pvp2.servlets;

import java.io.IOException;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;

import org.joda.time.DateTime;
import org.opensaml.Configuration;
import org.opensaml.common.impl.SecureRandomIdentifierGenerator;
import org.opensaml.common.xml.SAMLConstants;
import org.opensaml.saml2.core.AuthnContextClassRef;
import org.opensaml.saml2.core.AuthnContextComparisonTypeEnumeration;
import org.opensaml.saml2.core.AuthnRequest;
import org.opensaml.saml2.core.Issuer;
import org.opensaml.saml2.core.NameID;
import org.opensaml.saml2.core.NameIDPolicy;
import org.opensaml.saml2.core.NameIDType;
import org.opensaml.saml2.core.RequestedAuthnContext;
import org.opensaml.saml2.core.Subject;
import org.opensaml.saml2.metadata.EntityDescriptor;
import org.opensaml.saml2.metadata.SingleSignOnService;
import org.opensaml.saml2.metadata.provider.HTTPMetadataProvider;
import org.opensaml.xml.XMLObject;
import org.opensaml.xml.io.Marshaller;
import org.opensaml.xml.io.MarshallingException;
import org.opensaml.xml.security.x509.X509Credential;
import org.opensaml.xml.signature.AbstractSignableXMLObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;

import at.gv.egovernment.moa.id.config.webgui.exception.ConfigurationException;
import at.gv.egovernment.moa.id.configuration.Constants;
import at.gv.egovernment.moa.id.configuration.auth.pvp2.PVP2Utils;
import at.gv.egovernment.moa.id.configuration.config.ConfigurationProvider;
import at.gv.egovernment.moa.id.configuration.utils.SAML2Utils;
import at.gv.egovernment.moa.util.MiscUtil;


/**
 * Servlet implementation class Authenticate
 */
public class Authenticate extends HttpServlet {
	private static final long serialVersionUID = 1L;

	private static final Logger log = LoggerFactory
			.getLogger(Authenticate.class);
	
	private static DocumentBuilderFactory factory = null;
	
	static {
		initialDocumentBuilderFactory();
	}
	
	synchronized private static void initialDocumentBuilderFactory() {
		factory = DocumentBuilderFactory.newInstance();
		factory.setNamespaceAware(true);
		
	}
	
	public Document asDOMDocument(XMLObject object) throws IOException,
			MarshallingException, TransformerException, ParserConfigurationException {		
		try {
			DocumentBuilder builder = null;
			synchronized (factory) {
				builder = factory.newDocumentBuilder();
					
			}	
			
			Document document = builder.newDocument();
			Marshaller out = Configuration.getMarshallerFactory().getMarshaller(
					object);
			out.marshall(object, document);
			return document;
			
		} catch (ParserConfigurationException e) {
			log.warn("PVP2 AuthenticationServlet can not be initialized.", e);
			throw e;
		}
		
	}
	
	protected void process(HttpServletRequest request,
			HttpServletResponse response, Map<String,String> legacyParameter) throws ServletException, IOException {
		try {
			
			ConfigurationProvider config = ConfigurationProvider.getInstance();
			config.initializePVP2Login();
			
			AuthnRequest authReq = SAML2Utils
					.createSAMLObject(AuthnRequest.class);
			SecureRandomIdentifierGenerator gen = new SecureRandomIdentifierGenerator();
			authReq.setID(gen.generateIdentifier());
			
			HttpSession session = request.getSession();
			if (session != null) {
				session.setAttribute(Constants.SESSION_PVP2REQUESTID, authReq.getID());
			}
			
			authReq.setAssertionConsumerServiceIndex(0);
			authReq.setAttributeConsumingServiceIndex(0);
			authReq.setIssueInstant(new DateTime());
			Subject subject = SAML2Utils.createSAMLObject(Subject.class);
			NameID name = SAML2Utils.createSAMLObject(NameID.class);
			Issuer issuer = SAML2Utils.createSAMLObject(Issuer.class);
			
			String serviceURL = config.getPublicUrlPreFix(request);
			if (!serviceURL.endsWith("/"))
				serviceURL = serviceURL + "/";
			name.setValue(serviceURL);
			issuer.setValue(serviceURL);

			subject.setNameID(name);
			authReq.setSubject(subject);
			issuer.setFormat(NameIDType.ENTITY);
			authReq.setIssuer(issuer);
			NameIDPolicy policy = SAML2Utils
					.createSAMLObject(NameIDPolicy.class);
			policy.setAllowCreate(true);
			policy.setFormat(NameID.PERSISTENT);
			authReq.setNameIDPolicy(policy);
			
			String entityname = config.getPVP2IDPMetadataEntityName();
			if (MiscUtil.isEmpty(entityname)) {
				log.info("No IDP EntityName configurated");
				throw new ConfigurationException("No IDP EntityName configurated");
			}
			
			HTTPMetadataProvider idpmetadata = config.getMetaDataProvier();
			EntityDescriptor idpEntity = idpmetadata.getEntityDescriptor(entityname);
			if (idpEntity == null) {
				log.info("IDP EntityName is not found in IDP Metadata");
				throw new ConfigurationException("IDP EntityName is not found in IDP Metadata");
			}
			
			SingleSignOnService redirectEndpoint = null;  
			for (SingleSignOnService sss : 
					idpEntity.getIDPSSODescriptor(SAMLConstants.SAML20P_NS).getSingleSignOnServices()) {
				
				//Get the service address for the binding you wish to use
				if (sss.getBinding().equals(SAMLConstants.SAML2_POST_BINDING_URI)) { 
					redirectEndpoint = sss;  
				}  
			}
			
			authReq.setDestination(redirectEndpoint.getLocation());
			
			RequestedAuthnContext reqAuthContext = 
					SAML2Utils.createSAMLObject(RequestedAuthnContext.class);
			
			AuthnContextClassRef authnClassRef = 
					SAML2Utils.createSAMLObject(AuthnContextClassRef.class);
			
			authnClassRef.setAuthnContextClassRef("http://www.stork.gov.eu/1.0/citizenQAALevel/4");

			reqAuthContext.setComparison(AuthnContextComparisonTypeEnumeration.MINIMUM);
			
			reqAuthContext.getAuthnContextClassRefs().add(authnClassRef);
			
			authReq.setRequestedAuthnContext(reqAuthContext);
			
			//sign Message
			X509Credential authcredential = PVP2Utils.signMessage((AbstractSignableXMLObject) authReq, config);
			
			//encode message
			PVP2Utils.postBindingEncoder(request, 
					response, 
					authReq, 
					authcredential, 
					redirectEndpoint.getLocation(), 
					null);
			
		} catch (Exception e) {
			log.warn("Authentication Request can not be generated", e);
			throw new ServletException("Authentication Request can not be generated.", e);
		}
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
				
		process(request, response, null);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		process(request, response, null);
	}

}