From b4c32fd82aa6c88397bdf37b3b9a3b2a6fab0c1d Mon Sep 17 00:00:00 2001
From: =?utf8?q?David=20=E2=80=98Bombe=E2=80=99=20Roden?=
 <bombe@pterodactylus.net>
Date: Thu, 30 Jul 2015 06:50:00 +0200
Subject: [PATCH] Add list accessor that can return random elements

---
 .../pterodactylus/sone/template/ListAccessor.java  | 30 +++++++++++++
 .../net/pterodactylus/sone/web/WebInterface.java   |  2 +
 .../sone/template/ListAccessorTest.java            | 50 ++++++++++++++++++++++
 3 files changed, 82 insertions(+)
 create mode 100644 src/main/java/net/pterodactylus/sone/template/ListAccessor.java
 create mode 100644 src/test/java/net/pterodactylus/sone/template/ListAccessorTest.java

diff --git a/src/main/java/net/pterodactylus/sone/template/ListAccessor.java b/src/main/java/net/pterodactylus/sone/template/ListAccessor.java
new file mode 100644
index 0000000..159a1ff
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sone/template/ListAccessor.java
@@ -0,0 +1,30 @@
+package net.pterodactylus.sone.template;
+
+import java.util.List;
+import java.util.Random;
+
+import net.pterodactylus.util.template.Accessor;
+import net.pterodactylus.util.template.TemplateContext;
+
+/**
+ * {@link Accessor} implementation for {@link List}s that can return a random value from the list.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class ListAccessor extends net.pterodactylus.util.template.ListAccessor {
+
+	private Random random = new Random();
+
+	@Override
+	public Object get(TemplateContext templateContext, Object object, String member) {
+		if ("random".equals(member)) {
+			List<?> list = (List<?>) object;
+			if (!list.isEmpty()) {
+				return list.get(random.nextInt(list.size()));
+			}
+			return null;
+		}
+		return super.get(templateContext, object, member);
+	}
+
+}
diff --git a/src/main/java/net/pterodactylus/sone/web/WebInterface.java b/src/main/java/net/pterodactylus/sone/web/WebInterface.java
index 06ebf8d..ef75b2c 100644
--- a/src/main/java/net/pterodactylus/sone/web/WebInterface.java
+++ b/src/main/java/net/pterodactylus/sone/web/WebInterface.java
@@ -81,6 +81,7 @@ import net.pterodactylus.sone.template.IdentityAccessor;
 import net.pterodactylus.sone.template.ImageAccessor;
 import net.pterodactylus.sone.template.ImageLinkFilter;
 import net.pterodactylus.sone.template.JavascriptFilter;
+import net.pterodactylus.sone.template.ListAccessor;
 import net.pterodactylus.sone.template.ParserFilter;
 import net.pterodactylus.sone.template.PostAccessor;
 import net.pterodactylus.sone.template.ProfileAccessor;
@@ -264,6 +265,7 @@ public class WebInterface {
 		templateContextFactory.addAccessor(Trust.class, new TrustAccessor());
 		templateContextFactory.addAccessor(HTTPRequest.class, new HttpRequestAccessor());
 		templateContextFactory.addAccessor(Profile.class, new ProfileAccessor(getCore()));
+		templateContextFactory.addAccessor(List.class, new ListAccessor());
 		templateContextFactory.addFilter("date", new DateFilter());
 		templateContextFactory.addFilter("html", new HtmlFilter());
 		templateContextFactory.addFilter("replace", new ReplaceFilter());
diff --git a/src/test/java/net/pterodactylus/sone/template/ListAccessorTest.java b/src/test/java/net/pterodactylus/sone/template/ListAccessorTest.java
new file mode 100644
index 0000000..0c63aca
--- /dev/null
+++ b/src/test/java/net/pterodactylus/sone/template/ListAccessorTest.java
@@ -0,0 +1,50 @@
+package net.pterodactylus.sone.template;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.greaterThanOrEqualTo;
+import static org.hamcrest.Matchers.nullValue;
+import static org.hamcrest.Matchers.sameInstance;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import net.pterodactylus.util.template.Accessor;
+
+import org.junit.Test;
+
+/**
+ * Unit test for {@link ListAccessorTest}.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class ListAccessorTest {
+
+	private final Accessor accessor = new ListAccessor();
+
+	@Test
+	public void gettingARandomElementFromAnEmptyListReturnsNull() {
+		assertThat(accessor.get(null, Collections.emptyList(), "random"), nullValue());
+	}
+
+	@Test
+	public void gettingARandomElementFromAListOfOneWillReturnTheOneElement() {
+		Object object = new Object();
+		assertThat(accessor.get(null, Arrays.asList(object), "random"), sameInstance(object));
+	}
+
+	@Test
+	public void gettingRandomElementsFromAListTwoElementsWillReturnBothWithSomeProportion() {
+		Object first = new Object();
+		Object second = new Object();
+		List<?> objects = Arrays.asList(first, second);
+		int gotFirst = 0;
+		for (int i = 0; i < 10000; i++) {
+			if (accessor.get(null, objects, "random") == first) {
+				gotFirst++;
+			}
+		}
+		assertThat(gotFirst, greaterThanOrEqualTo(4000));
+	}
+
+}
-- 
2.7.4