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

   1 /*
   2  * Sone - IdentityChangeDetector.java - Copyright © 2013 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 import static net.pterodactylus.sone.freenet.wot.Identity.TO_CONTEXTS;
  25 import static net.pterodactylus.sone.freenet.wot.Identity.TO_PROPERTIES;
  26
  27 import java.util.Collection;
  28 import java.util.Map;
  29 import java.util.Map.Entry;
  30
  31 import com.google.common.base.Optional;
  32 import com.google.common.base.Predicate;
  33 import com.google.common.collect.FluentIterable;
  34 import com.google.common.collect.ImmutableMap;
  35
  36 /**
  37  * Detects changes between two lists of {@link Identity}s. The detector can find
  38  * added and removed identities, and for identities that exist in both list
  39  * their contexts and properties are checked for added, removed, or (in case of
  40  * properties) changed values.
  41  *
  42  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  43  */
  44 public class IdentityChangeDetector {
  45
  46         private final Map<String, Identity> oldIdentities;
  47         private Optional<IdentityProcessor> onNewIdentity = absent();
  48         private Optional<IdentityProcessor> onRemovedIdentity = absent();
  49         private Optional<IdentityProcessor> onChangedIdentity = absent();
  50         private Optional<IdentityProcessor> onUnchangedIdentity = absent();
  51
  52         public IdentityChangeDetector(Collection<? extends Identity> oldIdentities) {
  53                 this.oldIdentities = convertToMap(oldIdentities);
  54         }
  55
  56         public void onNewIdentity(IdentityProcessor onNewIdentity) {
  57                 this.onNewIdentity = fromNullable(onNewIdentity);
  58         }
  59
  60         public void onRemovedIdentity(IdentityProcessor onRemovedIdentity) {
  61                 this.onRemovedIdentity = fromNullable(onRemovedIdentity);
  62         }
  63
  64         public void onChangedIdentity(IdentityProcessor onChangedIdentity) {
  65                 this.onChangedIdentity = fromNullable(onChangedIdentity);
  66         }
  67
  68         public void onUnchangedIdentity(IdentityProcessor onUnchangedIdentity) {
  69                 this.onUnchangedIdentity = fromNullable(onUnchangedIdentity);
  70         }
  71
  72         public void detectChanges(final Collection<? extends Identity> newIdentities) {
  73                 notifyForRemovedIdentities(from(oldIdentities.values()).filter(notContainedIn(newIdentities)));
  74                 notifyForNewIdentities(from(newIdentities).filter(notContainedIn(oldIdentities.values())));
  75                 notifyForChangedIdentities(from(newIdentities).filter(containedIn(oldIdentities)).filter(hasChanged(oldIdentities)));
  76                 notifyForUnchangedIdentities(from(newIdentities).filter(containedIn(oldIdentities)).filter(not(hasChanged(oldIdentities))));
  77         }
  78
  79         private void notifyForRemovedIdentities(Iterable<Identity> identities) {
  80                 notify(onRemovedIdentity, identities);
  81         }
  82
  83         private void notifyForNewIdentities(FluentIterable<? extends Identity> newIdentities) {
  84                 notify(onNewIdentity, newIdentities);
  85         }
  86
  87         private void notifyForChangedIdentities(FluentIterable<? extends Identity> identities) {
  88                 notify(onChangedIdentity, identities);
  89         }
  90
  91         private void notifyForUnchangedIdentities(FluentIterable<? extends Identity> identities) {
  92                 notify(onUnchangedIdentity, identities);
  93         }
  94
  95         private void notify(Optional<IdentityProcessor> identityProcessor, Iterable<? extends Identity> identities) {
  96                 if (!identityProcessor.isPresent()) {
  97                         return;
  98                 }
  99                 for (Identity identity : identities) {
 100                         identityProcessor.get().processIdentity(identity);
 101                 }
 102         }
 103
 104         private static Predicate<Identity> hasChanged(final Map<String, Identity> oldIdentities) {
 105                 return new Predicate<Identity>() {
 106                         @Override
 107                         public boolean apply(Identity identity) {
 108                                 return (identity == null) ? false : identityHasChanged(oldIdentities.get(identity.getId()), identity);
 109                         }
 110                 };
 111         }
 112
 113         private static boolean identityHasChanged(Identity oldIdentity, Identity newIdentity) {
 114                 return identityHasNewContexts(oldIdentity, newIdentity)
 115                                 || identityHasRemovedContexts(oldIdentity, newIdentity)
 116                                 || identityHasNewProperties(oldIdentity, newIdentity)
 117                                 || identityHasRemovedProperties(oldIdentity, newIdentity)
 118                                 || identityHasChangedProperties(oldIdentity, newIdentity);
 119         }
 120
 121         private static boolean identityHasNewContexts(Identity oldIdentity, Identity newIdentity) {
 122                 return from(TO_CONTEXTS.apply(newIdentity)).anyMatch(notAContextOf(oldIdentity));
 123         }
 124
 125         private static boolean identityHasRemovedContexts(Identity oldIdentity, Identity newIdentity) {
 126                 return from(TO_CONTEXTS.apply(oldIdentity)).anyMatch(notAContextOf(newIdentity));
 127         }
 128
 129         private static boolean identityHasNewProperties(Identity oldIdentity, Identity newIdentity) {
 130                 return from(TO_PROPERTIES.apply(newIdentity).entrySet()).anyMatch(notAPropertyOf(oldIdentity));
 131         }
 132
 133         private static boolean identityHasRemovedProperties(Identity oldIdentity, Identity newIdentity) {
 134                 return from(TO_PROPERTIES.apply(oldIdentity).entrySet()).anyMatch(notAPropertyOf(newIdentity));
 135         }
 136
 137         private static boolean identityHasChangedProperties(Identity oldIdentity, Identity newIdentity) {
 138                 return from(TO_PROPERTIES.apply(oldIdentity).entrySet()).anyMatch(hasADifferentValueThanIn(newIdentity));
 139         }
 140
 141         private static Predicate<Identity> containedIn(final Map<String, Identity> identities) {
 142                 return new Predicate<Identity>() {
 143                         @Override
 144                         public boolean apply(Identity identity) {
 145                                 return identities.containsKey(identity.getId());
 146                         }
 147                 };
 148         }
 149
 150         private static Predicate<String> notAContextOf(final Identity identity) {
 151                 return new Predicate<String>() {
 152                         @Override
 153                         public boolean apply(String context) {
 154                                 return (identity == null) ? false : !identity.getContexts().contains(context);
 155                         }
 156                 };
 157         }
 158
 159         private static Predicate<Identity> notContainedIn(final Collection<? extends Identity> newIdentities) {
 160                 return new Predicate<Identity>() {
 161                         @Override
 162                         public boolean apply(Identity identity) {
 163                                 return (identity == null) ? false : !newIdentities.contains(identity);
 164                         }
 165                 };
 166         }
 167
 168         private static Predicate<Entry<String, String>> notAPropertyOf(final Identity identity) {
 169                 return new Predicate<Entry<String, String>>() {
 170                         @Override
 171                         public boolean apply(Entry<String, String> property) {
 172                                 return (property == null) ? false : !identity.getProperties().containsKey(property.getKey());
 173                         }
 174                 };
 175         }
 176
 177         private static Predicate<Entry<String, String>> hasADifferentValueThanIn(final Identity newIdentity) {
 178                 return new Predicate<Entry<String, String>>() {
 179                         @Override
 180                         public boolean apply(Entry<String, String> property) {
 181                                 return (property == null) ? false : !newIdentity.getProperty(property.getKey()).equals(property.getValue());
 182                         }
 183                 };
 184         }
 185
 186         private static Map<String, Identity> convertToMap(Collection<? extends Identity> identities) {
 187                 ImmutableMap.Builder<String, Identity> mapBuilder = ImmutableMap.builder();
 188                 for (Identity identity : identities) {
 189                         mapBuilder.put(identity.getId(), identity);
 190                 }
 191                 return mapBuilder.build();
 192         }
 193
 194         public interface IdentityProcessor {
 195
 196                 void processIdentity(Identity identity);
 197
 198         }
 199
 200 }