src/main/java/net/pterodactylus/sone/freenet/wot/IdentityChangeDetector.java

   1 /*
   2  * Sone - IdentityChangeDetector.java - Copyright © 2013–2019 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.sone.freenet.wot;
  19
  20 import java.util.*;
  21 import java.util.Map.*;
  22 import java.util.function.*;
  23 import java.util.stream.*;
  24
  25 import com.google.common.collect.*;
  26
  27 /**
  28  * Detects changes between two lists of {@link Identity}s. The detector can find
  29  * added and removed identities, and for identities that exist in both list
  30  * their contexts and properties are checked for added, removed, or (in case of
  31  * properties) changed values.
  32  */
  33 public class IdentityChangeDetector {
  34
  35         private final Map<String, Identity> oldIdentities;
  36         private IdentityProcessor onNewIdentity;
  37         private IdentityProcessor onRemovedIdentity;
  38         private IdentityProcessor onChangedIdentity;
  39         private IdentityProcessor onUnchangedIdentity;
  40
  41         public IdentityChangeDetector(Collection<? extends Identity> oldIdentities) {
  42                 this.oldIdentities = convertToMap(oldIdentities);
  43         }
  44
  45         public void onNewIdentity(IdentityProcessor onNewIdentity) {
  46                 this.onNewIdentity = onNewIdentity;
  47         }
  48
  49         public void onRemovedIdentity(IdentityProcessor onRemovedIdentity) {
  50                 this.onRemovedIdentity = onRemovedIdentity;
  51         }
  52
  53         public void onChangedIdentity(IdentityProcessor onChangedIdentity) {
  54                 this.onChangedIdentity = onChangedIdentity;
  55         }
  56
  57         public void onUnchangedIdentity(IdentityProcessor onUnchangedIdentity) {
  58                 this.onUnchangedIdentity = onUnchangedIdentity;
  59         }
  60
  61         public void detectChanges(final Collection<? extends Identity> newIdentities) {
  62                 notifyForRemovedIdentities(oldIdentities.values().stream().filter(notContainedIn(newIdentities)).collect(Collectors.toList()));
  63                 notifyForNewIdentities(newIdentities.stream().filter(notContainedIn(oldIdentities.values())).collect(Collectors.toList()));
  64                 notifyForChangedIdentities(newIdentities.stream().filter(containedIn(oldIdentities)).filter(hasChanged(oldIdentities)).collect(Collectors.toList()));
  65                 notifyForUnchangedIdentities(newIdentities.stream().filter(containedIn(oldIdentities)).filter(hasChanged(oldIdentities).negate()).collect(Collectors.toList()));
  66         }
  67
  68         private void notifyForRemovedIdentities(Iterable<Identity> identities) {
  69                 notify(onRemovedIdentity, identities);
  70         }
  71
  72         private void notifyForNewIdentities(Iterable<? extends Identity> newIdentities) {
  73                 notify(onNewIdentity, newIdentities);
  74         }
  75
  76         private void notifyForChangedIdentities(Iterable<? extends Identity> identities) {
  77                 notify(onChangedIdentity, identities);
  78         }
  79
  80         private void notifyForUnchangedIdentities(Iterable<? extends Identity> identities) {
  81                 notify(onUnchangedIdentity, identities);
  82         }
  83
  84         private void notify(IdentityProcessor identityProcessor, Iterable<? extends Identity> identities) {
  85                 if (identityProcessor == null) {
  86                         return;
  87                 }
  88                 for (Identity identity : identities) {
  89                         identityProcessor.processIdentity(identity);
  90                 }
  91         }
  92
  93         private static Predicate<Identity> hasChanged(final Map<String, Identity> oldIdentities) {
  94                 return identity -> (identity != null) && identityHasChanged(oldIdentities.get(identity.getId()), identity);
  95         }
  96
  97         private static boolean identityHasChanged(Identity oldIdentity, Identity newIdentity) {
  98                 return identityHasNewContexts(oldIdentity, newIdentity)
  99                                 || identityHasRemovedContexts(oldIdentity, newIdentity)
 100                                 || identityHasNewProperties(oldIdentity, newIdentity)
 101                                 || identityHasRemovedProperties(oldIdentity, newIdentity)
 102                                 || identityHasChangedProperties(oldIdentity, newIdentity);
 103         }
 104
 105         private static boolean identityHasNewContexts(Identity oldIdentity, Identity newIdentity) {
 106                 return newIdentity.getContexts().stream().anyMatch(notAContextOf(oldIdentity));
 107         }
 108
 109         private static boolean identityHasRemovedContexts(Identity oldIdentity, Identity newIdentity) {
 110                 return oldIdentity.getContexts().stream().anyMatch(notAContextOf(newIdentity));
 111         }
 112
 113         private static boolean identityHasNewProperties(Identity oldIdentity, Identity newIdentity) {
 114                 return newIdentity.getProperties().entrySet().stream().anyMatch(notAPropertyOf(oldIdentity));
 115         }
 116
 117         private static boolean identityHasRemovedProperties(Identity oldIdentity, Identity newIdentity) {
 118                 return oldIdentity.getProperties().entrySet().stream().anyMatch(notAPropertyOf(newIdentity));
 119         }
 120
 121         private static boolean identityHasChangedProperties(Identity oldIdentity, Identity newIdentity) {
 122                 return oldIdentity.getProperties().entrySet().stream().anyMatch(hasADifferentValueThanIn(newIdentity));
 123         }
 124
 125         private static Predicate<Identity> containedIn(final Map<String, Identity> identities) {
 126                 return identity -> (identity != null) && identities.containsKey(identity.getId());
 127         }
 128
 129         private static Predicate<String> notAContextOf(final Identity identity) {
 130                 return context -> (identity != null) && !identity.getContexts().contains(context);
 131         }
 132
 133         private static Predicate<Identity> notContainedIn(final Collection<? extends Identity> newIdentities) {
 134                 return identity -> (identity != null) && !newIdentities.contains(identity);
 135         }
 136
 137         private static Predicate<Entry<String, String>> notAPropertyOf(final Identity identity) {
 138                 return property -> (property != null) && !identity.getProperties().containsKey(property.getKey());
 139         }
 140
 141         private static Predicate<Entry<String, String>> hasADifferentValueThanIn(final Identity newIdentity) {
 142                 return property -> (property != null) && !newIdentity.getProperty(property.getKey()).equals(property.getValue());
 143         }
 144
 145         private static Map<String, Identity> convertToMap(Collection<? extends Identity> identities) {
 146                 ImmutableMap.Builder<String, Identity> mapBuilder = ImmutableMap.builder();
 147                 for (Identity identity : identities) {
 148                         mapBuilder.put(identity.getId(), identity);
 149                 }
 150                 return mapBuilder.build();
 151         }
 152
 153         public interface IdentityProcessor {
 154
 155                 void processIdentity(Identity identity);
 156
 157         }
 158
 159 }