Add trigger that detects new torrents.

diff --git a/src/main/java/net/pterodactylus/reactor/triggers/NewTorrentTrigger.java b/src/main/java/net/pterodactylus/reactor/triggers/NewTorrentTrigger.java
new file mode 100644 (file)
index 0000000..1eb2247
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+++ b/src/main/java/net/pterodactylus/reactor/triggers/NewTorrentTrigger.java
@@ -0,0 +1,69 @@
+/*
+ * Reactor - NewTorrentTrigger.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.reactor.triggers;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import java.util.List;
+
+import net.pterodactylus.reactor.State;
+import net.pterodactylus.reactor.Trigger;
+import net.pterodactylus.reactor.states.TorrentState;
+import net.pterodactylus.reactor.states.TorrentState.TorrentFile;
+
+import com.google.common.collect.Lists;
+
+/**
+ * {@link Trigger} implementation that is triggered by {@link TorrentFile}s that
+ * appear in the current {@link TorrentState} but not in the previous one.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class NewTorrentTrigger implements Trigger {
+
+       /** The newly detected torrent files. */
+       private List<TorrentFile> torrentFiles = Lists.newArrayList();
+
+       /**
+        * {@inheritDoc}
+        */
+       @Override
+       public boolean triggers(State currentState, State previousState) {
+               checkState(currentState instanceof TorrentState, "currentState is not a TorrentState but a %s", currentState.getClass().getName());
+               checkState(previousState instanceof TorrentState, "previousState is not a TorrentState but a %s", currentState.getClass().getName());
+               TorrentState currentTorrentState = (TorrentState) currentState;
+               TorrentState previousTorrentState = (TorrentState) previousState;
+               torrentFiles.clear();
+               for (TorrentFile torrentFile : currentTorrentState) {
+                       torrentFiles.add(torrentFile);
+               }
+               for (TorrentFile torrentFile : previousTorrentState) {
+                       torrentFiles.remove(torrentFile);
+               }
+               return !torrentFiles.isEmpty();
+       }
+
+       /**
+        * {@inheritDoc}
+        */
+       @Override
+       public Object trigger() {
+               return torrentFiles;
+       }
+
+}