/*
 * 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.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringEscapeUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.ExceptionHandler;

import com.google.common.net.MediaType;

import at.gv.egovernment.moa.id.advancedlogging.IStatisticLogger;
import at.gv.egovernment.moa.id.advancedlogging.MOAIDEventConstants;
import at.gv.egovernment.moa.id.advancedlogging.MOAReversionLogger;
import at.gv.egovernment.moa.id.auth.exception.InvalidProtocolRequestException;
import at.gv.egovernment.moa.id.auth.exception.ProtocolNotActiveException;
import at.gv.egovernment.moa.id.auth.frontend.builder.DefaultGUIFormBuilderConfiguration;
import at.gv.egovernment.moa.id.auth.frontend.builder.IGUIFormBuilder;
import at.gv.egovernment.moa.id.auth.frontend.exception.GUIBuildException;
import at.gv.egovernment.moa.id.auth.modules.TaskExecutionException;
import at.gv.egovernment.moa.id.commons.MOAIDAuthConstants;
import at.gv.egovernment.moa.id.commons.api.AuthConfiguration;
import at.gv.egovernment.moa.id.commons.api.IRequest;
import at.gv.egovernment.moa.id.commons.api.exceptions.ConfigurationException;
import at.gv.egovernment.moa.id.commons.api.exceptions.MOAIDException;
import at.gv.egovernment.moa.id.commons.utils.MOAIDMessageProvider;
import at.gv.egovernment.moa.id.data.ExceptionContainer;
import at.gv.egovernment.moa.id.moduls.IRequestStorage;
import at.gv.egovernment.moa.id.process.ProcessExecutionException;
import at.gv.egovernment.moa.id.protocols.AbstractAuthProtocolModulController;
import at.gv.egovernment.moa.id.protocols.pvp2x.exceptions.AuthnRequestValidatorException;
import at.gv.egovernment.moa.id.storage.ITransactionStorage;
import at.gv.egovernment.moa.id.util.ErrorResponseUtils;
import at.gv.egovernment.moa.id.util.HTTPUtils;
import at.gv.egovernment.moa.id.util.Random;
import at.gv.egovernment.moa.id.util.ServletUtils;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.MiscUtil;

/**
 * @author tlenz
 *
 */
public abstract class AbstractController extends MOAIDAuthConstants {

	public static final String ERROR_CODE_PARAM = "errorid";
	
	@Autowired protected IStatisticLogger statisticLogger;
	@Autowired protected IRequestStorage requestStorage;
	@Autowired protected ITransactionStorage transactionStorage;
	@Autowired protected MOAReversionLogger revisionsLogger;
	@Autowired protected AuthConfiguration authConfig;
	@Autowired protected IGUIFormBuilder guiBuilder;
	
	@ExceptionHandler({MOAIDException.class})
	public void MOAIDExceptionHandler(HttpServletRequest req, HttpServletResponse resp, Exception e) throws IOException {				
		Logger.error(e.getMessage() , e);
		internalMOAIDExceptionHandler(req, resp, e, true);
		
	}
	
	@ExceptionHandler({Exception.class})
	public void GenericExceptionHandler(HttpServletResponse resp, Exception exception) throws IOException {
		Logger.error("Internel Server Error." , exception);
		resp.setContentType(MediaType.HTML_UTF_8.toString());
		resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Internal Server Error!" +
				"(Errorcode=9199"
				+" | Description="+ StringEscapeUtils.escapeHtml(exception.getMessage()) + ")");
		return;
		
	}
	
	@ExceptionHandler({IOException.class})
	public void IOExceptionHandler(HttpServletResponse resp, Throwable exception) {
		Logger.error("Internel Server Error." , exception);
		resp.setContentType(MediaType.HTML_UTF_8.toString());
		resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
		return;
		
	}
	
	protected void handleError(String errorMessage, Throwable exceptionThrown,
			HttpServletRequest req, HttpServletResponse resp, IRequest pendingReq) throws IOException {

		String pendingRequestID = null;
		if (pendingReq != null)
			pendingRequestID = pendingReq.getRequestID();
		
		Throwable loggedException = null;
		Throwable extractedException = extractOriginalExceptionFromProcessException(exceptionThrown);
		
		//extract pendingRequestID and originalException if it was a TaskExecutionException
		if (extractedException instanceof TaskExecutionException) {
			//set original exception
			loggedException = ((TaskExecutionException) extractedException).getOriginalException();
			
			//use TaskExecutionException directly, if no Original Exeception is included
			if (loggedException == null)
				loggedException = exceptionThrown;
			
			//set pending-request ID if it is set
			String reqID = ((TaskExecutionException) extractedException).getPendingRequestID();
			if (MiscUtil.isNotEmpty(reqID))
				pendingRequestID = reqID; 
						
		} else
			loggedException = exceptionThrown;
					
		try {			
			//switch to protocol-finalize method to generate a protocol-specific error message
							
			//put exception into transaction store for redirect
			String key = Random.nextLongRandom();
			if (pendingReq != null) {
				revisionsLogger.logEvent(pendingReq, MOAIDEventConstants.TRANSACTION_ERROR);
				transactionStorage.put(key, 
						new ExceptionContainer(pendingReq, loggedException),-1);
			
			} else {
				transactionStorage.put(key, 
						new ExceptionContainer(null, loggedException),-1);
				
			}
				
			//build up redirect URL
			String redirectURL = null;
			redirectURL = ServletUtils.getBaseUrl(req);	
			redirectURL += "/"+AbstractAuthProtocolModulController.FINALIZEPROTOCOL_ENDPOINT 
					+ "?" + ERROR_CODE_PARAM + "=" + key;
			
			//only add pending-request Id if it exists 
			if (MiscUtil.isNotEmpty(pendingRequestID))							
				redirectURL += "&" + MOAIDAuthConstants.PARAM_TARGET_PENDINGREQUESTID + "=" + pendingRequestID;

			resp.setContentType("text/html");
			resp.setStatus(302);

			resp.addHeader("Location", redirectURL);		
			Logger.debug("REDIRECT TO: " + redirectURL);	

			return;
					
		} catch (Exception e) {
			Logger.warn("Default error-handling FAILED. Exception can not be stored to Database.", e);
			Logger.info("Switch to generic generic backup error-handling ... ");
			handleErrorNoRedirect(loggedException, req, resp, true);
			
		}

	}
		
	/**
	 * Handles all exceptions with no pending request.
	 * Therefore, the error is written to the users browser
	 * 
	 * @param throwable
	 * @param req
	 * @param resp
	 * @throws IOException 
	 */
	protected void handleErrorNoRedirect(Throwable throwable, HttpServletRequest req, 
			HttpServletResponse resp, boolean writeExceptionToStatisticLog) throws IOException {
		
		//log Exception into statistic database
		if (writeExceptionToStatisticLog)
			statisticLogger.logErrorOperation(throwable);
		
		//write errror to console
		logExceptionToTechnicalLog(throwable);
		
		//return error to Web browser
		if (throwable instanceof MOAIDException || throwable instanceof ProcessExecutionException)
			internalMOAIDExceptionHandler(req, resp, (Exception)throwable, false);
		
		else {
			//write generic message for general exceptions
			String msg = MOAIDMessageProvider.getInstance().getMessage("internal.00", null);			
			writeHTMLErrorResponse(req, resp, msg, "9199", (Exception) throwable);
			
		}
			
	}
	
	/**
	 * Write a Exception to the MOA-ID-Auth internal technical log
	 * 
	 * @param loggedException Exception to log
	 */	
	protected void logExceptionToTechnicalLog(Throwable loggedException) {
		if (!( loggedException instanceof MOAIDException 
				 || loggedException instanceof ProcessExecutionException )) {
			Logger.error("Receive an internal error: Message=" + loggedException.getMessage(), loggedException);
	
		} else {
			if (Logger.isDebugEnabled() || Logger.isTraceEnabled()) {
				Logger.warn(loggedException.getMessage(), loggedException);
	
			} else {
				Logger.warn(loggedException.getMessage());
	
			}			
		}		
	}
		
	private void writeBadRequestErrorResponse(HttpServletRequest req, HttpServletResponse resp, MOAIDException e) throws IOException {
		ErrorResponseUtils utils = ErrorResponseUtils.getInstance();
		String code = utils.mapInternalErrorToExternalError(
				((InvalidProtocolRequestException)e).getMessageId());
		String descr = StringEscapeUtils.escapeHtml(e.getMessage());
		resp.setContentType(MediaType.HTML_UTF_8.toString());
		resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "Protocol validation FAILED!" +
				"(Errorcode=" + code +
				" | Description=" + descr + ")");
		
	}
	
	private void writeHTMLErrorResponse(HttpServletRequest req, HttpServletResponse httpResp, String msg, String errorCode, Exception error) throws IOException {

		try {
			DefaultGUIFormBuilderConfiguration config = new DefaultGUIFormBuilderConfiguration(
					HTTPUtils.extractAuthURLFromRequest(req), 
					DefaultGUIFormBuilderConfiguration.VIEW_ERRORMESSAGE, 
					null);
				
			//add errorcode and errormessage
			config.putCustomParameter("errorMsg", StringEscapeUtils.escapeHtml(msg));
			config.putCustomParameter("errorCode", errorCode);
		
			//add stacktrace if debug is enabled
			if (Logger.isTraceEnabled()) {
				config.putCustomParameter("stacktrace", 
						StringEscapeUtils.escapeHtml(getStacktraceFromException(error)));
			
			}
			
			guiBuilder.build(httpResp, config, "Error-Message");
			
		} catch (GUIBuildException e) {
			Logger.warn("Can not build error-message GUI.", e);
			GenericExceptionHandler(httpResp, e);
			
		}
		
	}
	
	private void writeHTMLErrorResponse(HttpServletRequest req, HttpServletResponse httpResp, Exception error) throws IOException {				
		writeHTMLErrorResponse(req, httpResp, 
				error.getMessage(), 
				ErrorResponseUtils.getInstance().getResponseErrorCode(error), 
				error);		
	}
	
	
	private String getStacktraceFromException(Exception ex) {
		StringWriter errors = new StringWriter();
	    ex.printStackTrace(new PrintWriter(errors));
	    return errors.toString();
	    
	}
		
	/**
	 * Extracts a TaskExecutionException of a ProcessExecutionExeception Stacktrace.
	 * 
	 * @param exception 
	 * @return Return the latest TaskExecutionExecption if exists, otherwise the latest ProcessExecutionException
	 */
	private Throwable extractOriginalExceptionFromProcessException(Throwable exception) {
		Throwable exholder = exception;
		TaskExecutionException taskExc = null;
		
		while(exholder != null 
				&& exholder instanceof ProcessExecutionException) {
			ProcessExecutionException procExc = (ProcessExecutionException) exholder;
			if (procExc.getCause() != null && 
					procExc.getCause() instanceof TaskExecutionException) {
				taskExc = (TaskExecutionException) procExc.getCause();
				exholder = taskExc.getOriginalException();
			
			} else
				break;
			
		}
				
		if (taskExc == null)
			return exholder;
		
		else
			return taskExc;
	}
	
	private void internalMOAIDExceptionHandler(HttpServletRequest req, HttpServletResponse resp, Exception e, boolean writeExceptionToStatisicLog) throws IOException {				
		if (e instanceof ProtocolNotActiveException) {
			resp.getWriter().write(e.getMessage());
			resp.setContentType(MediaType.HTML_UTF_8.toString());
			resp.sendError(HttpServletResponse.SC_FORBIDDEN, StringEscapeUtils.escapeHtml(e.getMessage()));
		
		} else if (e instanceof AuthnRequestValidatorException) {
			AuthnRequestValidatorException ex = (AuthnRequestValidatorException)e;
			//log Error Message
			if (writeExceptionToStatisicLog)
				statisticLogger.logErrorOperation(ex, ex.getErrorRequest());
			
			//write error message
			writeBadRequestErrorResponse(req, resp, (MOAIDException) e);			
		
		} else if (e instanceof InvalidProtocolRequestException) {		
			//send error response
			writeBadRequestErrorResponse(req, resp, (MOAIDException) e);
			
		} else if (e instanceof ConfigurationException) {
			//send HTML formated error message
			writeHTMLErrorResponse(req, resp, (MOAIDException) e);
		
		} else if (e instanceof MOAIDException) {
			//send HTML formated error message
			writeHTMLErrorResponse(req, resp, e);
					
		} else if (e instanceof ProcessExecutionException) {
			//send HTML formated error message
			writeHTMLErrorResponse(req, resp, e);
					
		}
		
	}
	
}