Add Sone modification detector.

[Sone.git] / src / main / java / net / pterodactylus / sone / core / SoneModificationDetector.java

diff --git a/src/main/java/net/pterodactylus/sone/core/SoneModificationDetector.java b/src/main/java/net/pterodactylus/sone/core/SoneModificationDetector.java
new file mode 100644 (file)
index 0000000..0a26e9e
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sone/core/SoneModificationDetector.java
@@ -0,0 +1,77 @@
+package net.pterodactylus.sone.core;
+
+import static com.google.common.base.Optional.absent;
+import static com.google.common.base.Optional.of;
+import static com.google.common.base.Ticker.systemTicker;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import net.pterodactylus.sone.data.Sone;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Optional;
+import com.google.common.base.Ticker;
+
+/**
+ * Class that detects {@link Sone} modifications (as per their {@link
+ * Sone#getFingerprint() fingerprints} and determines when a modified Sone may
+ * be inserted.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+class SoneModificationDetector {
+
+       private final Ticker ticker;
+       private final Core core;
+       private final Sone sone;
+       private final AtomicInteger insertionDelay;
+       private Optional<Long> lastModificationTime;
+       private String originalFingerprint;
+       private String lastFingerprint;
+
+       SoneModificationDetector(Core core, Sone sone, AtomicInteger insertionDelay) {
+               this(systemTicker(), core, sone, insertionDelay);
+       }
+
+       @VisibleForTesting
+       SoneModificationDetector(Ticker ticker, Core core, Sone sone, AtomicInteger insertionDelay) {
+               this.ticker = ticker;
+               this.core = core;
+               this.sone = sone;
+               this.insertionDelay = insertionDelay;
+               originalFingerprint = sone.getFingerprint();
+               lastFingerprint = originalFingerprint;
+       }
+
+       public boolean isEligibleForInsert() {
+               if (core.isLocked(sone)) {
+                       lastModificationTime = absent();
+                       lastFingerprint = "";
+                       return false;
+               }
+               String fingerprint = sone.getFingerprint();
+               if (originalFingerprint.equals(fingerprint)) {
+                       lastModificationTime = absent();
+                       lastFingerprint = fingerprint;
+                       return false;
+               }
+               if (!lastFingerprint.equals(fingerprint)) {
+                       lastModificationTime = of(ticker.read());
+                       lastFingerprint = fingerprint;
+                       return false;
+               }
+               return insertionDelayHasPassed();
+       }
+
+       public void setFingerprint(String fingerprint) {
+               originalFingerprint = fingerprint;
+               lastFingerprint = originalFingerprint;
+               lastModificationTime = absent();
+       }
+
+       private boolean insertionDelayHasPassed() {
+               return lastModificationTime.isPresent() && (NANOSECONDS.toSeconds(ticker.read() - lastModificationTime.get()) >= insertionDelay.get());
+       }
+
+}