/*-
 * ============LICENSE_START=======================================================
 * OSAM
 * ================================================================================
 * Copyright (C) 2018 AT&T
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 */



package org.onap.portalapp.filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;
import org.onap.portalapp.util.SecurityXssValidator;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.util.ContentCachingRequestWrapper;
import org.springframework.web.util.ContentCachingResponseWrapper;
import org.springframework.web.util.WebUtils;

public class SecurityXssFilter extends OncePerRequestFilter {

	private static final String BAD_REQUEST = "BAD_REQUEST";

	private SecurityXssValidator validator = SecurityXssValidator.getInstance();

	private static String getRequestData(final HttpServletRequest request) throws UnsupportedEncodingException {
		String payload = null;
		ContentCachingRequestWrapper wrapper = WebUtils.getNativeRequest(request, ContentCachingRequestWrapper.class);
		if (wrapper != null) {
			byte[] buf = wrapper.getContentAsByteArray();
			if (buf.length > 0) {
				payload = new String(buf, 0, buf.length, wrapper.getCharacterEncoding());
			}
		}
		return payload;
	}

	private static String getResponseData(final HttpServletResponse response) throws IOException {
		String payload = null;
		ContentCachingResponseWrapper wrapper = WebUtils.getNativeResponse(response,
				ContentCachingResponseWrapper.class);
		if (wrapper != null) {
			byte[] buf = wrapper.getContentAsByteArray();
			if (buf.length > 0) {
				payload = new String(buf, 0, buf.length, wrapper.getCharacterEncoding());
				wrapper.copyBodyToResponse();
			}
		}
		return payload;
	}

	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {

		if (request.getMethod().equalsIgnoreCase("POST") || request.getMethod().equalsIgnoreCase("PUT")) {

			HttpServletRequest requestToCache = new ContentCachingRequestWrapper(request);
			HttpServletResponse responseToCache = new ContentCachingResponseWrapper(response);
			filterChain.doFilter(requestToCache, responseToCache);
			String requestData = getRequestData(requestToCache);
			String responseData = getResponseData(responseToCache);
			if (StringUtils.isNotBlank(requestData) && validator.denyXSS(requestData)) {
				throw new SecurityException(BAD_REQUEST);
			}

		} else {
			filterChain.doFilter(request, response);
		}

	}
}