opendaylight/networkconfiguration/neutron/northbound/src/main/java/org/opendaylight/controller/networkconfig/neutron/northbound/PaginatedRequestFactory.java

   1 /*
   2  * Copyright (C) 2014 Red Hat, Inc.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  *
   8  *  Authors : Dave Tucker
   9  */
  10
  11 package org.opendaylight.controller.networkconfig.neutron.northbound;
  12
  13 import java.util.ArrayList;
  14 import java.util.Collections;
  15 import java.util.Comparator;
  16 import java.util.List;
  17 import javax.ws.rs.core.UriInfo;
  18 import org.opendaylight.controller.networkconfig.neutron.INeutronObject;
  19 import org.opendaylight.controller.networkconfig.neutron.NeutronNetwork;
  20 import org.opendaylight.controller.networkconfig.neutron.NeutronPort;
  21 import org.opendaylight.controller.networkconfig.neutron.NeutronSubnet;
  22 import org.opendaylight.controller.northbound.commons.exception.BadRequestException;
  23 import org.opendaylight.controller.northbound.commons.exception.ResourceNotFoundException;
  24
  25 public class PaginatedRequestFactory {
  26     private static final Comparator<INeutronObject> NEUTRON_OBJECT_COMPARATOR = new Comparator<INeutronObject>() {
  27         @Override
  28         public int compare(INeutronObject o1, INeutronObject o2) {
  29             return o1.getID().compareTo(o2.getID());
  30         }
  31     };
  32
  33     public static class PaginationResults<T extends INeutronObject> {
  34         List<T> collection;
  35         List<NeutronPageLink> links;
  36
  37         public PaginationResults(List<T> collection, List<NeutronPageLink> links) {
  38             this.collection = collection;
  39             this.links = links;
  40         }
  41     }
  42
  43     private static final class MarkerObject implements INeutronObject {
  44         private final String id;
  45
  46         MarkerObject(String id) {
  47             this.id = id;
  48         }
  49
  50         @Override
  51         public String getID() {
  52             return id;
  53         }
  54
  55         @Override
  56         public void setID(String id) {
  57             throw new UnsupportedOperationException("Marker has constant ID");
  58         }
  59     }
  60
  61     /*
  62      * SuppressWarnings is needed because the compiler does not understand that we
  63      * are actually safe here.
  64      *
  65      * FIXME: the only caller performs a cast back, so this is not actually necessary.
  66      */
  67     @SuppressWarnings("unchecked")
  68     public static <T extends INeutronObject> INeutronRequest<T> createRequest(Integer limit, String marker,
  69                                                                            Boolean pageReverse,
  70                                                                            UriInfo uriInfo,
  71                                                                            List<T> collection,
  72                                                                            Class<T> clazz) {
  73         PaginationResults<T> results = _paginate(limit, marker, pageReverse, uriInfo, collection);
  74
  75         if (clazz.equals(NeutronNetwork.class)){
  76             return (INeutronRequest<T>) new NeutronNetworkRequest((List<NeutronNetwork>) results.collection, results.links);
  77         }
  78         if (clazz.equals(NeutronSubnet.class)){
  79             return (INeutronRequest<T>) new NeutronSubnetRequest((List<NeutronSubnet>) results.collection, results.links);
  80         }
  81         if (clazz.equals(NeutronPort.class)){
  82             return (INeutronRequest<T>) new NeutronPortRequest((List<NeutronPort>) results.collection, results.links);
  83         }
  84         return null;
  85     }
  86
  87     private static <T extends INeutronObject> PaginationResults<T> _paginate(Integer limit, String marker, Boolean pageReverse, UriInfo uriInfo, List<T> collection) {
  88         List<NeutronPageLink> links = new ArrayList<>();
  89         final int startPos;
  90         String startMarker;
  91         String endMarker;
  92         Boolean firstPage = false;
  93         Boolean lastPage = false;
  94
  95         Collections.sort(collection, NEUTRON_OBJECT_COMPARATOR);
  96
  97         if (marker != null) {
  98             int offset = Collections.binarySearch(collection, new MarkerObject(marker), NEUTRON_OBJECT_COMPARATOR);
  99             if (offset < 0) {
 100                 throw new ResourceNotFoundException("UUID for marker: " + marker + " could not be found");
 101             }
 102
 103             if (!pageReverse) {
 104                 startPos = offset + 1;
 105             }
 106             else {
 107                 startPos = offset - limit;
 108             }
 109         }
 110         else {
 111             startPos = 0;
 112         }
 113
 114         if (startPos == 0){
 115             firstPage = true;
 116         }
 117
 118         if (startPos + limit >= collection.size()) {
 119             collection = collection.subList(startPos, collection.size());
 120             startMarker = collection.get(0).getID();
 121             endMarker = collection.get(collection.size() - 1).getID();
 122             lastPage = true;
 123         }
 124         else if (startPos < 0) {
 125             if (startPos + limit > 0) {
 126                 collection = collection.subList(0, startPos + limit);
 127                 startMarker = collection.get(0).getID();
 128                 endMarker = collection.get(collection.size() - 1).getID();
 129                 firstPage = true;
 130             }
 131             else {
 132                 throw new BadRequestException("Requested page is out of bounds. Please check the supplied limit and marker");
 133             }
 134         }
 135         else {
 136             collection = collection.subList(startPos, startPos + limit);
 137             startMarker = collection.get(0).getID();
 138             endMarker = collection.get(limit-1).getID();
 139         }
 140
 141         if (!lastPage) {
 142             NeutronPageLink next = new NeutronPageLink();
 143             next.setRef("next");
 144             next.setHref(uriInfo.getAbsolutePath().toString() + "?limit=" + limit.toString() + "&marker=" + endMarker);
 145             links.add(next);
 146         }
 147
 148         if (!firstPage) {
 149             NeutronPageLink previous = new NeutronPageLink();
 150             previous.setRef("previous");
 151             previous.setHref(uriInfo.getAbsolutePath().toString() + "?limit=" + limit.toString() + "&marker=" + startMarker + "&page_reverse=True");
 152             links.add(previous);
 153         }
 154
 155         return new PaginationResults<T>(collection, links);
 156     }
 157 }