content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.
   */
  
  package org.apache.ambari.server.api.handlers;
  
  import java.util.Map;
  
  import org.apache.ambari.server.api.query.Query;
  import org.apache.ambari.server.api.services.Request;
  import org.apache.ambari.server.api.services.RequestBody;
  import org.apache.ambari.server.api.services.Result;
  import org.apache.ambari.server.api.services.ResultImpl;
  import org.apache.ambari.server.api.services.ResultStatus;
  import org.apache.ambari.server.controller.spi.NoSuchParentResourceException;
  import org.apache.ambari.server.controller.spi.NoSuchResourceException;
  import org.apache.ambari.server.controller.spi.Predicate;
  import org.apache.ambari.server.controller.spi.SystemException;
  import org.apache.ambari.server.controller.spi.TemporalInfo;
  import org.apache.ambari.server.controller.spi.UnsupportedPropertyException;
  import org.apache.ambari.server.security.authorization.AuthorizationException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Responsible for read requests.
   */
  public class ReadHandler implements RequestHandler {
  
    /**
     * Logger instance.
     */
    private final static Logger LOG =
        LoggerFactory.getLogger(ReadHandler.class);
  
    @Override
    public Result handleRequest(Request request) {
      Query query = request.getResource().getQuery();
  
      query.setPageRequest(request.getPageRequest());
      query.setSortRequest(request.getSortRequest());
      query.setRenderer(request.getRenderer());
  
      // If the request body exists, copy the requstInfoProperties from it.  This map should contain
      // the _directives_ specified in the request.
      RequestBody body = request.getBody();
      if(body != null) {
        query.setRequestInfoProps(body.getRequestInfoProperties());
      }
  
      try {
        addFieldsToQuery(request, query);
      } catch (IllegalArgumentException e) {
        return new ResultImpl(new ResultStatus(ResultStatus.STATUS.BAD_REQUEST, e.getMessage()));
      }
  
      Result result;
      Predicate p = null;
      try {
        p = request.getQueryPredicate();
        query.setUserPredicate(p);
  
        result = query.execute();
        result.setResultStatus(new ResultStatus(ResultStatus.STATUS.OK));
      } catch (AuthorizationException e) {
        result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.FORBIDDEN, e.getMessage()));
      } catch (SystemException e) {
        result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.SERVER_ERROR, e));
      } catch (NoSuchParentResourceException e) {
        result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.NOT_FOUND, e.getMessage()));
      } catch (UnsupportedPropertyException e) {
        result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.BAD_REQUEST, e.getMessage()));
      } catch (NoSuchResourceException e) {
        if (p == null) {
          // no predicate specified, resource requested by id
          result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.NOT_FOUND, e.getMessage()));
        } else {
          // resource(s) requested using predicate
          result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.OK, e));
          result.getResultTree().setProperty("isCollection", "true");
        }
      } catch (IllegalArgumentException e) {
        result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.BAD_REQUEST,
            "Invalid Request: " + e.getMessage()));
        LOG.error("Bad request: ", e);
      }  catch (RuntimeException e) {
        if (LOG.isErrorEnabled()) {
          LOG.error("Caught a runtime exception executing a query", e);
        }
        //result = new ResultImpl(new ResultStatus(ResultStatus.STATUS.SERVER_ERROR, e));
        throw e;
      }
      return result;
    }
  
    /**
     * Add partial response fields to the provided query.
     *
     * @param request  the current request
     * @param query    the associated query
     */
    private void addFieldsToQuery(Request request, Query query) {
      //Partial response
      for (Map.Entry<String, TemporalInfo> entry : request.getFields().entrySet()) {
        // Iterate over map and add props/temporalInfo
        String propertyId = entry.getKey();
        query.addProperty(propertyId, entry.getValue());
      }
    }
  }
  