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 static com.google.common.base.Optional.absent;
  21 import static com.google.common.base.Optional.fromNullable;
  22 import static com.google.common.base.Predicates.not;
  23 import static com.google.common.collect.FluentIterable.from;
  24
  25 import java.util.Collection;
  26 import java.util.Map;
  27 import java.util.Map.Entry;
  28
  29 import com.google.common.base.Optional;
  30 import com.google.common.base.Predicate;
  31 import com.google.common.collect.FluentIterable;
  32 import com.google.common.collect.ImmutableMap;
  33
  34 /**
  35  * Detects changes between two lists of {@link Identity}s. The detector can find
  36  * added and removed identities, and for identities that exist in both list
  37  * their contexts and properties are checked for added, removed, or (in case of
  38  * properties) changed values.
  39  */
  40 public class IdentityChangeDetector {
  41
  42         private final Map<String, Identity> oldIdentities;
  43         private Optional<IdentityProcessor> onNewIdentity = absent();
  44         private Optional<IdentityProcessor> onRemovedIdentity = absent();
  45         private Optional<IdentityProcessor> onChangedIdentity = absent();
  46         private Optional<IdentityProcessor> onUnchangedIdentity = absent();
  47
  48         public IdentityChangeDetector(Collection<? extends Identity> oldIdentities) {
  49                 this.oldIdentities = convertToMap(oldIdentities);
  50         }
  51
  52         public void onNewIdentity(IdentityProcessor onNewIdentity) {
  53                 this.onNewIdentity = fromNullable(onNewIdentity);
  54         }
  55
  56         public void onRemovedIdentity(IdentityProcessor onRemovedIdentity) {
  57                 this.onRemovedIdentity = fromNullable(onRemovedIdentity);
  58         }
  59
  60         public void onChangedIdentity(IdentityProcessor onChangedIdentity) {
  61                 this.onChangedIdentity = fromNullable(onChangedIdentity);
  62         }
  63
  64         public void onUnchangedIdentity(IdentityProcessor onUnchangedIdentity) {
  65                 this.onUnchangedIdentity = fromNullable(onUnchangedIdentity);
  66         }
  67
  68         public void detectChanges(final Collection<? extends Identity> newIdentities) {
  69                 notifyForRemovedIdentities(from(oldIdentities.values()).filter(notContainedIn(newIdentities)));
  70                 notifyForNewIdentities(from(newIdentities).filter(notContainedIn(oldIdentities.values())));
  71                 notifyForChangedIdentities(from(newIdentities).filter(containedIn(oldIdentities)).filter(hasChanged(oldIdentities)));
  72                 notifyForUnchangedIdentities(from(newIdentities).filter(containedIn(oldIdentities)).filter(not(hasChanged(oldIdentities))));
  73         }
  74
  75         private void notifyForRemovedIdentities(Iterable<Identity> identities) {
  76                 notify(onRemovedIdentity, identities);
  77         }
  78
  79         private void notifyForNewIdentities(FluentIterable<? extends Identity> newIdentities) {
  80                 notify(onNewIdentity, newIdentities);
  81         }
  82
  83         private void notifyForChangedIdentities(FluentIterable<? extends Identity> identities) {
  84                 notify(onChangedIdentity, identities);
  85         }
  86
  87         private void notifyForUnchangedIdentities(FluentIterable<? extends Identity> identities) {
  88                 notify(onUnchangedIdentity, identities);
  89         }
  90
  91         private void notify(Optional<IdentityProcessor> identityProcessor, Iterable<? extends Identity> identities) {
  92                 if (!identityProcessor.isPresent()) {
  93                         return;
  94                 }
  95                 for (Identity identity : identities) {
  96                         identityProcessor.get().processIdentity(identity);
  97                 }
  98         }
  99
 100         private static Predicate<Identity> hasChanged(final Map<String, Identity> oldIdentities) {
 101                 return new Predicate<Identity>() {
 102                         @Override
 103                         public boolean apply(Identity identity) {
 104                                 return (identity != null) && identityHasChanged(oldIdentities.get(identity.getId()), identity);
 105                         }
 106                 };
 107         }
 108
 109         private static boolean identityHasChanged(Identity oldIdentity, Identity newIdentity) {
 110                 return identityHasNewContexts(oldIdentity, newIdentity)
 111                                 || identityHasRemovedContexts(oldIdentity, newIdentity)
 112                                 || identityHasNewProperties(oldIdentity, newIdentity)
 113                                 || identityHasRemovedProperties(oldIdentity, newIdentity)
 114                                 || identityHasChangedProperties(oldIdentity, newIdentity);
 115         }
 116
 117         private static boolean identityHasNewContexts(Identity oldIdentity, Identity newIdentity) {
 118                 return newIdentity.getContexts().stream().anyMatch(notAContextOf(oldIdentity)::apply);
 119         }
 120
 121         private static boolean identityHasRemovedContexts(Identity oldIdentity, Identity newIdentity) {
 122                 return oldIdentity.getContexts().stream().anyMatch(notAContextOf(newIdentity)::apply);
 123         }
 124
 125         private static boolean identityHasNewProperties(Identity oldIdentity, Identity newIdentity) {
 126                 return newIdentity.getProperties().entrySet().stream().anyMatch(notAPropertyOf(oldIdentity)::apply);
 127         }
 128
 129         private static boolean identityHasRemovedProperties(Identity oldIdentity, Identity newIdentity) {
 130                 return oldIdentity.getProperties().entrySet().stream().anyMatch(notAPropertyOf(newIdentity)::apply);
 131         }
 132
 133         private static boolean identityHasChangedProperties(Identity oldIdentity, Identity newIdentity) {
 134                 return oldIdentity.getProperties().entrySet().stream().anyMatch(hasADifferentValueThanIn(newIdentity)::apply);
 135         }
 136
 137         private static Predicate<Identity> containedIn(final Map<String, Identity> identities) {
 138                 return new Predicate<Identity>() {
 139                         @Override
 140                         public boolean apply(Identity identity) {
 141                                 return (identity != null) && identities.containsKey(identity.getId());
 142                         }
 143                 };
 144         }
 145
 146         private static Predicate<String> notAContextOf(final Identity identity) {
 147                 return new Predicate<String>() {
 148                         @Override
 149                         public boolean apply(String context) {
 150                                 return (identity != null) && !identity.getContexts().contains(context);
 151                         }
 152                 };
 153         }
 154
 155         private static Predicate<Identity> notContainedIn(final Collection<? extends Identity> newIdentities) {
 156                 return new Predicate<Identity>() {
 157                         @Override
 158                         public boolean apply(Identity identity) {
 159                                 return (identity != null) && !newIdentities.contains(identity);
 160                         }
 161                 };
 162         }
 163
 164         private static Predicate<Entry<String, String>> notAPropertyOf(final Identity identity) {
 165                 return new Predicate<Entry<String, String>>() {
 166                         @Override
 167                         public boolean apply(Entry<String, String> property) {
 168                                 return (property != null) && !identity.getProperties().containsKey(property.getKey());
 169                         }
 170                 };
 171         }
 172
 173         private static Predicate<Entry<String, String>> hasADifferentValueThanIn(final Identity newIdentity) {
 174                 return new Predicate<Entry<String, String>>() {
 175                         @Override
 176                         public boolean apply(Entry<String, String> property) {
 177                                 return (property != null) && !newIdentity.getProperty(property.getKey()).equals(property.getValue());
 178                         }
 179                 };
 180         }
 181
 182         private static Map<String, Identity> convertToMap(Collection<? extends Identity> identities) {
 183                 ImmutableMap.Builder<String, Identity> mapBuilder = ImmutableMap.builder();
 184                 for (Identity identity : identities) {
 185                         mapBuilder.put(identity.getId(), identity);
 186                 }
 187                 return mapBuilder.build();
 188         }
 189
 190         public interface IdentityProcessor {
 191
 192                 void processIdentity(Identity identity);
 193
 194         }
 195
 196 }