/*
 * 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.auth.modules.eIDAScentralAuth.tasks;

import java.io.IOException;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.TransformerException;

import org.apache.commons.lang3.StringUtils;
import org.opensaml.saml2.core.Response;
import org.opensaml.saml2.core.StatusCode;
import org.opensaml.ws.message.decoder.MessageDecodingException;
import org.opensaml.xml.io.MarshallingException;
import org.opensaml.xml.security.SecurityException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext;
import at.gv.egiz.eaaf.core.exceptions.EAAFStorageException;
import at.gv.egiz.eaaf.core.exceptions.InvalidProtocolRequestException;
import at.gv.egiz.eaaf.core.exceptions.TaskExecutionException;
import at.gv.egiz.eaaf.core.impl.idp.auth.modules.AbstractAuthServletTask;
import at.gv.egiz.eaaf.modules.pvp2.api.binding.IDecoder;
import at.gv.egiz.eaaf.modules.pvp2.exception.CredentialsNotAvailableException;
import at.gv.egiz.eaaf.modules.pvp2.impl.binding.PostBinding;
import at.gv.egiz.eaaf.modules.pvp2.impl.binding.RedirectBinding;
import at.gv.egiz.eaaf.modules.pvp2.impl.message.InboundMessage;
import at.gv.egiz.eaaf.modules.pvp2.impl.message.PVPSProfileResponse;
import at.gv.egiz.eaaf.modules.pvp2.impl.utils.SAML2Utils;
import at.gv.egiz.eaaf.modules.pvp2.impl.validation.EAAFURICompare;
import at.gv.egiz.eaaf.modules.pvp2.impl.validation.TrustEngineFactory;
import at.gv.egiz.eaaf.modules.pvp2.sp.exception.AssertionValidationExeption;
import at.gv.egiz.eaaf.modules.pvp2.sp.exception.AuthnResponseValidationException;
import at.gv.egiz.eaaf.modules.pvp2.sp.impl.utils.AssertionAttributeExtractor;
import at.gv.egovernment.moa.id.advancedlogging.MOAIDEventConstants;
import at.gv.egovernment.moa.id.auth.data.AuthenticationSessionWrapper;
import at.gv.egovernment.moa.id.auth.exception.BuildException;
import at.gv.egovernment.moa.id.auth.modules.eIDAScentralAuth.EidasCentralAuthConstants;
import at.gv.egovernment.moa.id.auth.modules.eIDAScentralAuth.utils.EidasCentralAuthCredentialProvider;
import at.gv.egovernment.moa.id.auth.modules.eIDAScentralAuth.utils.EidasCentralAuthMetadataProvider;
import at.gv.egovernment.moa.id.auth.modules.eIDAScentralAuth.utils.Utils;
import at.gv.egovernment.moa.id.commons.api.IOAAuthParameters;
import at.gv.egovernment.moa.id.commons.api.exceptions.ConfigurationException;
import at.gv.egovernment.moa.id.protocols.pvp2x.verification.SAMLVerificationEngineSP;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.MiscUtil;

/**
 * @author tlenz
 *
 */
@Component("ReceiveFederatedAuthnResponseTask")
public class ReceiveAuthnResponseTask extends AbstractAuthServletTask {

	@Autowired private SAMLVerificationEngineSP samlVerificationEngine;
	@Autowired private EidasCentralAuthCredentialProvider credentialProvider; 
	@Autowired(required=true) EidasCentralAuthMetadataProvider metadataProvider;
	
	
	/* (non-Javadoc)
	 * @see at.gv.egovernment.moa.id.auth.modules.AbstractAuthServletTask#execute(at.gv.egovernment.moa.id.process.api.ExecutionContext, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	 */
	@Override
	public void execute(ExecutionContext executionContext, HttpServletRequest request, HttpServletResponse response)
			throws TaskExecutionException {		
		InboundMessage msg = null;
		
		try {
			
			IDecoder decoder = null; 
			EAAFURICompare comperator = null;
			//select Response Binding
			if (request.getMethod().equalsIgnoreCase("POST")) {
				decoder = new PostBinding();
				comperator = new EAAFURICompare(pendingReq.getAuthURL() + EidasCentralAuthConstants.ENDPOINT_POST);
				Logger.trace("Receive PVP Response from 'ms-specific eIDAS node', by using POST-Binding.");
				
			}  else if (request.getMethod().equalsIgnoreCase("GET")) {
				decoder = new RedirectBinding();
				comperator = new EAAFURICompare(pendingReq.getAuthURL() + EidasCentralAuthConstants.ENDPOINT_REDIRECT);
				Logger.trace("Receive PVP Response from 'ms-specific eIDAS node', by using Redirect-Binding.");
				
			} else {
				Logger.warn("Receive PVP Response, but Binding (" 
						+ request.getMethod() + ") is not supported.");
				throw new AuthnResponseValidationException("sp.pvp2.03", new Object[] {EidasCentralAuthConstants.MODULE_NAME_FOR_LOGGING});
				
			}
			
			//decode PVP response object
			msg = (InboundMessage) decoder.decode(
					request, response, metadataProvider, true,
					comperator);
			
			if (MiscUtil.isEmpty(msg.getEntityID())) {
				throw new InvalidProtocolRequestException("sp.pvp2.04", 
						new Object[] {EidasCentralAuthConstants.MODULE_NAME_FOR_LOGGING});
				
			}

			//validate response signature
			if(!msg.isVerified()) {
				samlVerificationEngine.verify(msg, TrustEngineFactory.getSignatureKnownKeysTrustEngine(metadataProvider));
				msg.setVerified(true);
								
			}
						
			//validate assertion
			PVPSProfileResponse processedMsg = preProcessAuthResponse((PVPSProfileResponse) msg);
			
			//validate entityId of response
			String msNodeEntityID = Utils.getCentraleIDASNodeEntityId(pendingReq.getServiceProviderConfiguration(), authConfig);
			String respEntityId = msg.getEntityID();
			if (!msNodeEntityID.equals(respEntityId)) {
				Logger.warn("Response Issuer is not a 'ms-specific eIDAS node'. Stopping eIDAS authentication ...");
				throw new AuthnResponseValidationException("sp.pvp2.08", 
						new Object[] {EidasCentralAuthConstants.MODULE_NAME_FOR_LOGGING,
								msg.getEntityID()});
				
			}
									
			//initialize Attribute extractor
			AssertionAttributeExtractor extractor = 
					new AssertionAttributeExtractor((Response) processedMsg.getResponse());
															
			getAuthDataFromInterfederation(extractor, pendingReq.getServiceProviderConfiguration(IOAAuthParameters.class));	
							
			//store pending-request
			requestStoreage.storePendingRequest(pendingReq);
			
			//write log entries
			revisionsLogger.logEvent(pendingReq, MOAIDEventConstants.AUTHPROCESS_EIDAS_AT_CONNECTOR_MDS_VALID);				
			Logger.info("Receive a valid assertion from IDP " + msg.getEntityID()); 
											
		} catch (MessageDecodingException | SecurityException e) {
			String samlRequest = request.getParameter("SAMLRequest");			
			Logger.warn("Receive INVALID PVP Response from 'ms-specific eIDAS node': " + samlRequest, e);
			throw new TaskExecutionException(pendingReq, "Receive INVALID PVP Response from federated IDP", 
					new AuthnResponseValidationException("sp.pvp2.11", new Object[] {"'national central eIDASNode'"}, e));

		} catch (IOException | MarshallingException | TransformerException e) {
			Logger.warn("Processing PVP response from 'ms-specific eIDAS node' FAILED.", e);
			throw new TaskExecutionException(pendingReq, "Processing PVP response from 'ms-specific eIDAS node' FAILED.", 
					new AuthnResponseValidationException("sp.pvp2.12", new Object[] {"'national central eIDASNode'", e.getMessage()}, e));
			
		} catch (CredentialsNotAvailableException e) {
			Logger.error("PVP response decrytion FAILED. No credential found.", e);
			throw new TaskExecutionException(pendingReq, "PVP response decrytion FAILED. No credential found.", 
					new AuthnResponseValidationException("sp.pvp2.10", new Object[] {"'national central eIDASNode'"}, e));

		} catch (AssertionValidationExeption | AuthnResponseValidationException e) {
			Logger.info("PVP response validation FAILED. Msg:" + e.getMessage());			
			throw new TaskExecutionException(pendingReq, "PVP response validation FAILED.", 
					new AuthnResponseValidationException("sp.pvp2.10", new Object[] {"'national central eIDASNode'"}, e));
									
		} catch (Exception e) {
			Logger.warn("PVP response validation FAILED. Msg:" + e.getMessage(), e);			
			throw new TaskExecutionException(pendingReq, "PVP response validation FAILED.", 
					new AuthnResponseValidationException("sp.pvp2.12", new Object[] {"'national central eIDASNode'", e.getMessage()}, e));
			
		}

	}
	
	private void getAuthDataFromInterfederation(AssertionAttributeExtractor extractor, IOAAuthParameters spConfig) throws BuildException, ConfigurationException{		
		try {																		
			//check if all attributes are include
			if (!extractor.containsAllRequiredAttributes() 
					&& !extractor.containsAllRequiredAttributes(EidasCentralAuthConstants.DEFAULT_REQUIRED_PVP_ATTRIBUTE_NAMES)) {
				Logger.warn("PVP Response from 'ms-specific eIDAS node' contains not all requested attributes.");
				throw new AssertionValidationExeption("sp.pvp2.06", new Object[]{EidasCentralAuthConstants.MODULE_NAME_FOR_LOGGING});
				
			}
			
			//copy attributes into MOASession
			AuthenticationSessionWrapper session = pendingReq.getSessionData(AuthenticationSessionWrapper.class); 
			Set<String> includedAttrNames = extractor.getAllIncludeAttributeNames();
			for (String el : includedAttrNames) {
				String value = extractor.getSingleAttributeValue(el);				 				
				session.setGenericDataToSession(el, value);				
				Logger.debug("Add PVP-attribute " + el + " into MOASession");
				
			}
			
			//set foreigner flag
			session.setForeigner(true);
			if (extractor.getFullAssertion().getIssuer() != null && 
					StringUtils.isNotEmpty(extractor.getFullAssertion().getIssuer().getValue()))
				session.setBkuURL(extractor.getFullAssertion().getIssuer().getValue());
			else
				session.setBkuURL("eIDAS_Authentication");
			
												
		} catch (AssertionValidationExeption e) {
			throw new BuildException("builder.06", null, e);
			
		} catch (EAAFStorageException e) {
			throw new BuildException("builder.06", null, e);
			
		}
	}
		
	/**
	 * PreProcess AuthResponse and Assertion 
	 * @param msg
	 * @throws TransformerException 
	 * @throws MarshallingException 
	 * @throws IOException 
	 * @throws CredentialsNotAvailableException 
	 * @throws AssertionValidationExeption 
	 * @throws AuthnResponseValidationException 
	 */
	private PVPSProfileResponse preProcessAuthResponse(PVPSProfileResponse msg) throws IOException, MarshallingException, TransformerException, AssertionValidationExeption, CredentialsNotAvailableException, AuthnResponseValidationException {
		Logger.debug("Start PVP21 assertion processing... ");
		Response samlResp = (Response) msg.getResponse();

		// check SAML2 response status-code
		if (samlResp.getStatus().getStatusCode().getValue().equals(StatusCode.SUCCESS_URI)) {				
			//validate PVP 2.1 assertion
			samlVerificationEngine.validateAssertion(samlResp, true, 
					credentialProvider.getIDPAssertionEncryptionCredential(),
					pendingReq.getAuthURL() + EidasCentralAuthConstants.ENDPOINT_METADATA,
					EidasCentralAuthConstants.MODULE_NAME_FOR_LOGGING);

			msg.setSAMLMessage(SAML2Utils.asDOMDocument(samlResp).getDocumentElement());
			revisionsLogger.logEvent(pendingReq, 
					MOAIDEventConstants.AUTHPROCESS_EIDAS_AT_CONNECTOR_RECEIVED,
					samlResp.getID());
			return msg;
				
		} else {
			Logger.info("Receive StatusCode " + samlResp.getStatus().getStatusCode().getValue() 
				+ " from 'ms-specific eIDAS node'.");
			revisionsLogger.logEvent(pendingReq, 
					MOAIDEventConstants.AUTHPROCESS_EIDAS_AT_CONNECTOR_RECEIVED_ERROR);			
			throw new AuthnResponseValidationException("sp.pvp2.05", 
					new Object[]{EidasCentralAuthConstants.MODULE_NAME_FOR_LOGGING, 
									samlResp.getIssuer().getValue(), 
									samlResp.getStatus().getStatusCode().getValue(), 
									samlResp.getStatus().getStatusMessage().getMessage()});
					
		}
								
	}	

}