/*******************************************************************************
 * ============LICENSE_START==================================================
 * * org.onap.dmaap
 * * ===========================================================================
 * * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
 * * ===========================================================================
 * * 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====================================================
 * *
 * * ECOMP is a trademark and service mark of AT&T Intellectual Property.
 * *
 ******************************************************************************/
package org.onap.dmaap.datarouter.subscriber;

import org.apache.commons.codec.binary.Base64;
import org.apache.log4j.Logger;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

public class SampleSubscriberServlet extends HttpServlet {

  private static Logger logger =
      Logger.getLogger("org.onap.dmaap.datarouter.subscriber.SampleSubscriberServlet");
  private String outputDirectory;
  private String basicAuth;

  /**
   * Configure the SampleSubscriberServlet.
   *
   * <ul>
   *   <li>Login - The login expected in the Authorization header (default "LOGIN").
   *   <li>Password - The password expected in the Authorization header (default "PASSWORD").
   *   <li>outputDirectory - The directory where files are placed (default
   *       "/opt/app/subscriber/delivery").
   * </ul>
   */
  @Override
  public void init() {
    SubscriberProps props = SubscriberProps.getInstance();
    String login = props.getValue("org.onap.dmaap.datarouter.subscriber.auth.user", "LOGIN");
    String password =
        props.getValue("org.onap.dmaap.datarouter.subscriber.auth.password", "PASSWORD");
    outputDirectory =
        props.getValue(
            "org.onap.dmaap.datarouter.subscriber.delivery.dir", "/opt/app/subscriber/delivery");
    try {
      Files.createDirectory(Paths.get(outputDirectory));
    } catch (IOException e) {
      logger.info("SubServlet: Failed to create delivery dir: " + e.getMessage());
    }
    basicAuth = "Basic " + Base64.encodeBase64String((login + ":" + password).getBytes());
  }

  @Override
  protected void doPut(HttpServletRequest req, HttpServletResponse resp) {
    try {
      common(req, resp, false);
    } catch (IOException e) {
      logger.info(
          "SampleSubServlet: Failed to doPut: " + req.getRemoteAddr() + " : " + req.getPathInfo(),
          e);
    }
  }

  @Override
  protected void doDelete(HttpServletRequest req, HttpServletResponse resp) {
    try {
      common(req, resp, true);
    } catch (IOException e) {
      logger.info(
          "SampleSubServlet: Failed to doDelete: "
              + req.getRemoteAddr()
              + " : "
              + req.getPathInfo(),
          e);
    }
  }
  /**
   * Process a PUT or DELETE request.
   *
   * <ol>
   *   <li>Verify that the request contains an Authorization header or else UNAUTHORIZED.
   *   <li>Verify that the Authorization header matches the configured Login and Password or else
   *       FORBIDDEN.
   *   <li>If the request is PUT, store the message body as a file in the configured outputDirectory
   *       directory protecting against evil characters in the received FileID. The file is created
   *       initially with its name prefixed with a ".", and once it is complete, it is renamed to
   *       remove the leading "." character.
   *   <li>If the request is DELETE, instead delete the file (if it exists) from the configured
   *       outputDirectory directory.
   *   <li>Respond with NO_CONTENT.
   * </ol>
   */
  private void common(HttpServletRequest req, HttpServletResponse resp, boolean isdelete)
      throws IOException {
    String authHeader = req.getHeader("Authorization");
    if (authHeader == null) {
      logger.info(
          "SampleSubServlet: Rejecting request with no Authorization header from "
              + req.getRemoteAddr()
              + ": "
              + req.getPathInfo());
      resp.sendError(HttpServletResponse.SC_UNAUTHORIZED);
      return;
    }
    if (!basicAuth.equals(authHeader)) {
      logger.info(
          "SampleSubServlet: Rejecting request with incorrect Authorization header from "
              + req.getRemoteAddr()
              + ": "
              + req.getPathInfo());
      resp.sendError(HttpServletResponse.SC_FORBIDDEN);
      return;
    }
    String fileid = req.getPathInfo();
    fileid = fileid.substring(fileid.lastIndexOf('/') + 1);
    String queryString = req.getQueryString();
    if (queryString != null) {
      fileid = fileid + "?" + queryString;
    }
    String publishid = req.getHeader("X-ATT-DR-PUBLISH-ID");
    String filename =
        URLEncoder.encode(fileid, "UTF-8").replaceAll("^\\.", "%2E").replaceAll("\\*", "%2A");
    String fullPath = outputDirectory + "/" + filename;
    String tmpPath = outputDirectory + "/." + filename;
    try {
      if (isdelete) {
        Files.deleteIfExists(Paths.get(fullPath));
        logger.info(
            "SampleSubServlet: Received delete for file id "
                + fileid
                + " from "
                + req.getRemoteAddr()
                + " publish id "
                + publishid
                + " as "
                + fullPath);
      } else {
        new File(tmpPath).createNewFile();
        try (InputStream is = req.getInputStream();
            OutputStream os = new FileOutputStream(tmpPath)) {
          byte[] buf = new byte[65536];
          int i;
          while ((i = is.read(buf)) > 0) {
            os.write(buf, 0, i);
          }
        }
        Files.move(Paths.get(tmpPath), Paths.get(fullPath), StandardCopyOption.REPLACE_EXISTING);
        logger.info(
            "SampleSubServlet: Received file id "
                + fileid
                + " from "
                + req.getRemoteAddr()
                + " publish id "
                + publishid
                + " as "
                + fullPath);
        resp.setStatus(HttpServletResponse.SC_NO_CONTENT);
      }
      resp.setStatus(HttpServletResponse.SC_NO_CONTENT);
    } catch (IOException ioe) {
      Files.deleteIfExists(Paths.get(tmpPath));
      logger.info(
          "SampleSubServlet: Failed to process file "
              + fullPath
              + " from "
              + req.getRemoteAddr()
              + ": "
              + req.getPathInfo());
      throw ioe;
    }
  }
}