From 25eccb52bf670342982c1f87c85b191cf4ae56cd Mon Sep 17 00:00:00 2001
From: =?utf8?q?David=20=E2=80=98Bombe=E2=80=99=20Roden?=
 <bombe@pterodactylus.net>
Date: Wed, 7 Oct 2015 19:15:44 +0200
Subject: [PATCH] Add combined ID class

---
 src/main/java/net/pterodactylus/sone/data/Id.java  | 66 ++++++++++++++++++++
 .../java/net/pterodactylus/sone/data/IdTest.java   | 71 ++++++++++++++++++++++
 2 files changed, 137 insertions(+)
 create mode 100644 src/main/java/net/pterodactylus/sone/data/Id.java
 create mode 100644 src/test/java/net/pterodactylus/sone/data/IdTest.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
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();
+	}
+
+}
diff --git a/src/test/java/net/pterodactylus/sone/data/IdTest.java b/src/test/java/net/pterodactylus/sone/data/IdTest.java
new file mode 100644
index 0000000..082f65b
--- /dev/null
+++ b/src/test/java/net/pterodactylus/sone/data/IdTest.java
@@ -0,0 +1,71 @@
+package net.pterodactylus.sone.data;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+
+import org.junit.Test;
+
+/**
+ * Unit test for {@link Id}.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class IdTest {
+
+	private static final String SONE_ID = "~Yp72VX0c6FLDvgIzip5wIvaGIIrjKcKvnX~pTaMKXs";
+	private static final String ELEMENT_ID = "88CC70AE-E853-4EEE-B245-E4C55F40DDDF";
+	private static final String EXPECTED_ID = "139a629a13f6a2c4191fb19ecead7e57335ea3deb2a971b88d5e004378c4daad";
+	private final Id id = Id.from(SONE_ID, ELEMENT_ID);
+
+	@Test
+	public void idBuilderBuildsCorrectIds() {
+		assertThat(id.getSoneId(), is(SONE_ID));
+		assertThat(id.getElementId(), is(ELEMENT_ID));
+		assertThat(id.getExternal(), is(EXPECTED_ID));
+	}
+
+	@Test
+	public void twoIdsAreNotEqualIfSoneIdIsDifferent() {
+		Id id2 = Id.from(SONE_ID + "1", ELEMENT_ID);
+		assertThat(id2, not(equalTo(id)));
+		assertThat(id, not(equalTo(id2)));
+	}
+
+	@Test
+	public void twoIdsAreNotEqualIfElementIdIsDifferent() {
+		Id id2 = Id.from(SONE_ID, ELEMENT_ID + "1");
+		assertThat(id2, not(equalTo(id)));
+		assertThat(id, not(equalTo(id2)));
+	}
+
+	@Test
+	public void twoIdsAreEqualIfSoneAndElementIdIsEqual() {
+		Id id2 = Id.from(SONE_ID, ELEMENT_ID);
+		assertThat(id2, equalTo(id));
+		assertThat(id, equalTo(id2));
+	}
+
+	@Test
+	public void twoIdsHaveTheSameHashCodeIfTheyAreEqual() {
+		Id id2 = Id.from(SONE_ID, ELEMENT_ID);
+		assertThat(id2.hashCode(), equalTo(id.hashCode()));
+	}
+
+	@Test
+	public void nullIsNotEqualToId() {
+		assertThat(id, not(equalTo(null)));
+	}
+
+	@Test
+	public void objectOfDifferentClassIsNotEqualToId() {
+		assertThat(id, not(equalTo(new Object())));
+	}
+
+	@Test
+	public void stringRepresentationMatchesTheExternalId() {
+		assertThat(id.toString(), is(EXPECTED_ID));
+	}
+
+}
-- 
2.7.4