/*
 * 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.ssotransfer.task;

import java.math.BigInteger;
import java.security.PrivateKey;

import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.DHPublicKeySpec;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import at.gv.egiz.eaaf.core.api.gui.IGUIFormBuilder;
import at.gv.egiz.eaaf.core.api.idp.process.ExecutionContext;
import at.gv.egiz.eaaf.core.exceptions.TaskExecutionException;
import at.gv.egiz.eaaf.core.impl.idp.auth.modules.AbstractAuthServletTask;
import at.gv.egiz.eaaf.core.impl.utils.HTTPUtils;
import at.gv.egiz.eaaf.core.impl.utils.Random;
import at.gv.egovernment.moa.id.auth.modules.ssotransfer.SSOTransferConstants;
import at.gv.egovernment.moa.id.auth.modules.ssotransfer.data.Pair;
import at.gv.egovernment.moa.id.auth.modules.ssotransfer.data.SSOTransferContainer;
import at.gv.egovernment.moa.id.auth.modules.ssotransfer.utils.GUIUtils;
import at.gv.egovernment.moa.id.auth.modules.ssotransfer.utils.SSOContainerUtils;
import at.gv.egovernment.moa.id.commons.api.exceptions.MOAIDException;
import at.gv.egovernment.moa.id.config.auth.AuthConfigurationProviderFactory;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.Base64Utils;

/**
 * @author tlenz
 *
 */
@Component("InitializeRestoreSSOSessionTask")
public class InitializeRestoreSSOSessionTask extends AbstractAuthServletTask {
	
	@Autowired IGUIFormBuilder guiBuilder;
	@Autowired SSOContainerUtils ssoTransferUtils;
	
	/* (non-Javadoc)
	 * @see at.gv.egovernment.moa.id.process.springweb.MoaIdTask#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 {

		try {
			//create first step of SSO Transfer GUI
			String authURL = HTTPUtils.extractAuthURLFromRequest(request);
			if (!AuthConfigurationProviderFactory.getInstance().getPublicURLPrefix().
					contains(authURL)) {						
				Logger.warn("Requested URL is not allowed.");;
				response.sendError(500, "Requested URL is not allowed.");
				
			}

			//use predefined parameters
			BigInteger prime = new BigInteger(Base64Utils.decode(SSOTransferConstants.DH_PRIME_BASE64, false));
			BigInteger generator = new BigInteger(Base64Utils.decode(SSOTransferConstants.DH_GENERATOR_BASE64, false));
			DHParameterSpec dhSpec = new DHParameterSpec(prime, generator, 1024);
								
			Pair<DHPublicKeySpec, PrivateKey> dhKeyIDP = ssoTransferUtils.createSpecificKey(dhSpec.getP(), dhSpec.getG());
			String nonce = Random.nextLongRandom();
			
			GUIUtils.buildSSOTransferGUI(guiBuilder, response, authURL, 
					pendingReq.getPendingRequestId(), nonce, dhKeyIDP.getF());
			
			//store DH params and nonce to pending-request
			SSOTransferContainer container = new SSOTransferContainer();
			container.setDhParams(dhKeyIDP);
			pendingReq.setRawDataToTransaction(SSOTransferConstants.PENDINGREQ_DH, container);
			pendingReq.setRawDataToTransaction(SSOTransferConstants.PENDINGREQ_NONCE, nonce);
						
			//store pending-request
			requestStoreage.storePendingRequest(pendingReq);
			
			//set flag
			executionContext.put("sessionRestoreFinished", false);
									
		} catch (MOAIDException e) {
			throw new TaskExecutionException(pendingReq, e.getMessage(), e);

		} catch (Exception e) {
			Logger.error(this.getClass().getName() + " has an interal Error.", e);
			throw new TaskExecutionException(pendingReq, this.getClass().getName() + " has an interal Error.", e);
			
		}
		

	}

}