/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.
   *
   */
  package org.opencastproject.external.endpoint;
  
  import static org.apache.commons.lang3.StringUtils.isBlank;
  import static org.apache.commons.lang3.StringUtils.isNotBlank;
  import static org.opencastproject.util.DateTimeSupport.fromUTC;
  import static org.opencastproject.util.DateTimeSupport.toUTC;
  import static org.opencastproject.util.doc.rest.RestParameter.Type.STRING;
  
  import org.opencastproject.external.common.ApiMediaType;
  import org.opencastproject.external.common.ApiResponseBuilder;
  import org.opencastproject.security.urlsigning.exception.UrlSigningException;
  import org.opencastproject.security.urlsigning.service.UrlSigningService;
  import org.opencastproject.util.DateTimeSupport;
  import org.opencastproject.util.OsgiUtil;
  import org.opencastproject.util.RestUtil.R;
  import org.opencastproject.util.doc.rest.RestParameter;
  import org.opencastproject.util.doc.rest.RestQuery;
  import org.opencastproject.util.doc.rest.RestResponse;
  import org.opencastproject.util.doc.rest.RestService;
  
  import com.google.gson.JsonObject;
  
  import org.joda.time.DateTime;
  import org.joda.time.DateTimeConstants;
  import org.osgi.service.cm.ConfigurationException;
  import org.osgi.service.cm.ManagedService;
  import org.osgi.service.component.annotations.Activate;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  import org.osgi.service.jaxrs.whiteboard.propertytypes.JaxrsResource;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.text.ParseException;
  import java.util.Date;
  import java.util.Dictionary;
  import java.util.Optional;
  
  import javax.servlet.http.HttpServletResponse;
  import javax.ws.rs.FormParam;
  import javax.ws.rs.HeaderParam;
  import javax.ws.rs.POST;
  import javax.ws.rs.Path;
  import javax.ws.rs.Produces;
  import javax.ws.rs.core.Response;
  
  @Path("/api/security")
  @Produces({ ApiMediaType.JSON, ApiMediaType.VERSION_1_0_0, ApiMediaType.VERSION_1_1_0, ApiMediaType.VERSION_1_2_0,
              ApiMediaType.VERSION_1_3_0, ApiMediaType.VERSION_1_4_0, ApiMediaType.VERSION_1_5_0,
              ApiMediaType.VERSION_1_6_0, ApiMediaType.VERSION_1_7_0, ApiMediaType.VERSION_1_8_0,
              ApiMediaType.VERSION_1_9_0, ApiMediaType.VERSION_1_10_0, ApiMediaType.VERSION_1_11_0 })
  @RestService(
      name = "externalapisecurity",
      title = "External API Security Service",
      notes = {},
      abstractText = "Provides security operations related to the external API"
  )
  @Component(
      immediate = true,
      service = { SecurityEndpoint.class,ManagedService.class },
      property = {
          "service.description=External API - Security Endpoint",
          "opencast.service.type=org.opencastproject.external.security",
          "opencast.service.path=/api/security"
      }
  )
  @JaxrsResource
  public class SecurityEndpoint implements ManagedService {
  
    protected static final String URL_SIGNING_EXPIRES_DURATION_SECONDS_KEY = "url.signing.expires.seconds";
  
    /** The default time before a piece of signed content expires. 2 Hours. */
    protected static final long DEFAULT_URL_SIGNING_EXPIRE_DURATION = 2 * 60 * 60;
  
    /** The logging facility */
    private static final Logger log = LoggerFactory.getLogger(SecurityEndpoint.class);
  
    private long expireSeconds = DEFAULT_URL_SIGNING_EXPIRE_DURATION;
  
   /* OSGi service references */
   private UrlSigningService urlSigningService;
 
   /** OSGi DI */
   @Reference
   void setUrlSigningService(UrlSigningService urlSigningService) {
     this.urlSigningService = urlSigningService;
   }
 
   /** OSGi activation method */
   @Activate
   void activate() {
     log.info("Activating External API - Security Endpoint");
   }
 
   @Override
   public void updated(Dictionary<String, ?> properties) throws ConfigurationException {
     if (properties == null) {
       log.info("No configuration available, using defaults");
       return;
     }
 
     Optional<Long> expiration = OsgiUtil.getOptCfg(properties, URL_SIGNING_EXPIRES_DURATION_SECONDS_KEY)
             .map(Long::parseLong);
     if (expiration.isPresent()) {
       expireSeconds = expiration.get();
       log.info("The property {} has been configured to expire signed URLs in {}.",
               URL_SIGNING_EXPIRES_DURATION_SECONDS_KEY, DateTimeSupport.humanReadableTime(expireSeconds));
     } else {
       expireSeconds = DEFAULT_URL_SIGNING_EXPIRE_DURATION;
       log.info("The property {} has not been configured, so the default is being used to expire signed URLs in {}.",
               URL_SIGNING_EXPIRES_DURATION_SECONDS_KEY, DateTimeSupport.humanReadableTime(expireSeconds));
     }
   }
 
   @POST
   @Path("sign")
   @RestQuery(
       name = "signurl",
       description = "Returns a signed URL that can be played back for the indicated period of time, while access is "
           + "optionally restricted to the specified IP address.",
       returnDescription = "",
       restParameters = {
           @RestParameter(name = "url", isRequired = true, description = "The linke to encode.", type = STRING),
           @RestParameter(name = "valid-until", description = "Until when is the signed url valid", isRequired = false,
               type = STRING),
           @RestParameter(name = "valid-source", description = "The IP address from which the url can be accessed",
               isRequired = false, type = STRING)
       },
       responses = {
           @RestResponse(description = "The signed URL is returned.", responseCode = HttpServletResponse.SC_OK),
           @RestResponse(description = "The caller is not authorized to have the link signed.",
               responseCode = HttpServletResponse.SC_UNAUTHORIZED)
       })
   public Response signUrl(@HeaderParam("Accept") String acceptHeader, @FormParam("url") String url,
           @FormParam("valid-until") String validUntilUtc, @FormParam("valid-source") String validSource) {
     if (isBlank(url)) {
       return R.badRequest("Query parameter 'url' is mandatory");
     }
 
     final DateTime validUntil;
     if (isNotBlank(validUntilUtc)) {
       try {
         validUntil = new DateTime(fromUTC(validUntilUtc));
       } catch (IllegalStateException | ParseException e) {
         return R.badRequest("Query parameter 'valid-until' is not a valid ISO-8601 date string");
       }
     } else {
       validUntil = new DateTime(new Date().getTime() + expireSeconds * DateTimeConstants.MILLIS_PER_SECOND);
     }
 
     if (urlSigningService.accepts(url)) {
       String signedUrl = "";
       try {
         signedUrl = urlSigningService.sign(url, validUntil, null, validSource);
       } catch (UrlSigningException e) {
         log.warn("Error while trying to sign url '{}':", url, e);
         JsonObject errorJson = new JsonObject();
         errorJson.addProperty("error", "Error while signing url");
         return ApiResponseBuilder.Json.ok(acceptHeader, errorJson);
       }
 
       JsonObject successJson = new JsonObject();
       successJson.addProperty("url", signedUrl);
       successJson.addProperty("valid-until", toUTC(validUntil.getMillis()));
       return ApiResponseBuilder.Json.ok(acceptHeader, successJson);
     } else {
       JsonObject errorJson = new JsonObject();
       errorJson.addProperty("error", "Given URL cannot be signed");
       return ApiResponseBuilder.Json.ok(acceptHeader, errorJson);
     }
   }
 }