Add combined ID class

[Sone.git] / src / main / java / net / pterodactylus / sone / data / Id.java

diff --git a/src/main/java/net/pterodactylus/sone/data/Id.java b/src/main/java/net/pterodactylus/sone/data/Id.java
new file mode 100644 (file)
index 0000000..bc875b9
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sone/data/Id.java
@@ -0,0 +1,66 @@
+package net.pterodactylus.sone.data;
+
+import com.google.common.base.Charsets;
+import com.google.common.base.Objects;
+import com.google.common.hash.HashFunction;
+import com.google.common.hash.Hashing;
+
+/**
+ * Container for a new, combined ID, originally computed from a {@link Sone}’s ID and an element’s ID.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class Id {
+
+       private static final HashFunction HASH_FUNCTION = Hashing.sha256();
+       public static final int LENGTH = HASH_FUNCTION.bits() / 4;
+
+       private final HashFunction sha256 = HASH_FUNCTION;
+       private final String soneId;
+       private final String elementId;
+
+       private Id(String soneId, String elementId) {
+               this.soneId = soneId;
+               this.elementId = elementId;
+       }
+
+       public String getSoneId() {
+               return soneId;
+       }
+
+       public String getElementId() {
+               return elementId;
+       }
+
+       public String getExternal() {
+               return sha256.newHasher()
+                               .putBytes(soneId.getBytes(Charsets.UTF_8))
+                               .putBytes(elementId.getBytes(Charsets.UTF_8))
+                               .hash().toString();
+       }
+
+       public static Id from(String soneId, String elementId) {
+               return new Id(soneId, elementId);
+       }
+
+       @Override
+       public boolean equals(Object o) {
+               if (o == null || getClass() != o.getClass()) {
+                       return false;
+               }
+               Id id = (Id) o;
+               return Objects.equal(soneId, id.soneId)
+                               && Objects.equal(elementId, id.elementId);
+       }
+
+       @Override
+       public int hashCode() {
+               return Objects.hashCode(soneId, elementId);
+       }
+
+       @Override
+       public String toString() {
+               return getExternal();
+       }
+
+}