Extract a sensible ID from a torrent and use it for hashCode() and equals().

diff --git a/src/main/java/net/pterodactylus/reactor/states/TorrentState.java b/src/main/java/net/pterodactylus/reactor/states/TorrentState.java
index 915559a..0855195 100644 (file)
--- a/src/main/java/net/pterodactylus/reactor/states/TorrentState.java
+++ b/src/main/java/net/pterodactylus/reactor/states/TorrentState.java
@@ -17,12 +17,16 @@
 
 package net.pterodactylus.reactor.states;
 
+import java.nio.charset.Charset;
 import java.util.Iterator;
 import java.util.List;
 
 import net.pterodactylus.reactor.State;
 import net.pterodactylus.reactor.states.TorrentState.TorrentFile;
 
+import org.apache.http.NameValuePair;
+import org.apache.http.client.utils.URLEncodedUtils;
+
 import com.google.common.collect.Lists;
 
 /**
@@ -156,6 +160,51 @@ public class TorrentState extends AbstractState implements Iterable<TorrentFile>
                }
 
                //
+               // PRIVATE METHODS
+               //
+
+               /**
+                * Generates an ID for this file. If a {@link #magnetUri} is set, an ID
+                * is {@link #extractId(String) extracted} from it. Otherwise the magnet
+                * URI is used. If the {@link #magnetUri} is not set, the
+                * {@link #downloadUri} is used. If that is not set either, the name of
+                * the file is returned.
+                *
+                * @return The generated ID
+                */
+               private String generateId() {
+                       if (magnetUri != null) {
+                               String id = extractId(magnetUri);
+                               if (id != null) {
+                                       return id;
+                               }
+                               return magnetUri;
+                       }
+                       return (downloadUri != null) ? downloadUri : name;
+               }
+
+               //
+               // STATIC METHODS
+               //
+
+               /**
+                * Tries to extract the “exact target” of a magnet URI.
+                *
+                * @param magnetUri
+                *            The magnet URI to extract the “xt” from
+                * @return The extracted ID, or {@code null} if no ID could be found
+                */
+               private static String extractId(String magnetUri) {
+                       List<NameValuePair> parameters = URLEncodedUtils.parse(magnetUri.substring("magnet:?".length()), Charset.forName("UTF-8"));
+                       for (NameValuePair parameter : parameters) {
+                               if (parameter.getName().equals("xt")) {
+                                       return parameter.getValue();
+                               }
+                       }
+                       return null;
+               }
+
+               //
                // OBJECT METHODS
                //
 
@@ -163,6 +212,28 @@ public class TorrentState extends AbstractState implements Iterable<TorrentFile>
                 * {@inheritDoc}
                 */
                @Override
+               public int hashCode() {
+                       return (generateId() != null) ? generateId().hashCode() : 0;
+               }
+
+               /**
+                * {@inheritDoc}
+                */
+               @Override
+               public boolean equals(Object object) {
+                       if (!(object instanceof TorrentFile)) {
+                               return false;
+                       }
+                       if (generateId() != null) {
+                               return generateId().equals(((TorrentFile) object).generateId());
+                       }
+                       return false;
+               }
+
+               /**
+                * {@inheritDoc}
+                */
+               @Override
                public String toString() {
                        return String.format("%s(%s,%s,%s)", name(), size(), magnetUri(), downloadUri());
                }