Add enabledExperiments to soy template

This will add ENABLED_EXPERIMENTS to window,
it should contain a list of enabled experiments for the given user.

Provides the ability to pass in experiments from url with
`?experiment=a&experiment=b`.

Change-Id: Ia79157e6968946e6bd91cfe8e1ab23cba140d11d

java/com/google/gerrit/httpd/raw/IndexHtmlUtil.java

@@ -38,6 +38,7 @@ import com.google.template.soy.data.SanitizedContent;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.Function;
@@ -48,6 +49,9 @@ import java.util.regex.Pattern;
 @UsedAt(Project.GOOGLE)
 public class IndexHtmlUtil {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  private static final Gson gson = OutputFormat.JSON_COMPACT.newGson();
+
   public static final String changeCanonicalUrl = ".*/c/(?<project>.+)/\\+/(?<changeNum>\\d+)";
   public static final String basePatchNumUrlPart = "(/(-?\\d+|edit)(\\.\\.(\\d+|edit))?)";
   public static final Pattern changeUrlPattern =
@@ -107,8 +111,8 @@ public class IndexHtmlUtil {
       Function<String, SanitizedContent> urlInScriptTagOrdainer,
       String requestedURL)
       throws URISyntaxException, RestApiException {
-    return ImmutableMap.<String, Object>builder()
-        .putAll(
+    ImmutableMap.Builder<String, Object> data = ImmutableMap.builder();
+    data.putAll(
             staticTemplateData(
                 canonicalURL,
                 cdnPath,
@@ -116,15 +120,19 @@ public class IndexHtmlUtil {
                 urlParameterMap,
                 urlInScriptTagOrdainer,
                 requestedURL))
-        .putAll(dynamicTemplateData(gerritApi))
-        .build();
+        .putAll(dynamicTemplateData(gerritApi));
+
+    Set<String> enabledExperiments = experimentData(urlParameterMap);
+    if (!enabledExperiments.isEmpty()) {
+      data.put("enabledExperiments", serializeObject(gson, enabledExperiments));
+    }
+    return data.build();
   }
 
   /** Returns dynamic parameters of {@code index.html}. */
   public static ImmutableMap<String, Object> dynamicTemplateData(GerritApi gerritApi)
       throws RestApiException {
     ImmutableMap.Builder<String, Object> data = ImmutableMap.builder();
-    Gson gson = OutputFormat.JSON_COMPACT.newGson();
     Map<String, SanitizedContent> initialData = new HashMap<>();
     Server serverApi = gerritApi.config().server();
     initialData.put("\"/config/server/info\"", serializeObject(gson, serverApi.getInfo()));
@@ -210,6 +218,24 @@ public class IndexHtmlUtil {
     return data.build();
   }
 
+  /** Returns experimentData to be used in {@code index.html}. */
+  static Set<String> experimentData(Map<String, String[]> urlParameterMap)
+      throws URISyntaxException {
+    Set<String> enabledExperiments = new HashSet<>();
+
+    // Allow enable experiments with url
+    // ?experiment=a&experiment=b should result in:
+    // "experiment" => [a,b]
+    if (urlParameterMap.containsKey("experiment")) {
+      String[] experiments = urlParameterMap.get("experiment");
+      for (String exp : experiments) {
+        enabledExperiments.add(exp);
+      }
+    }
+
+    return enabledExperiments;
+  }
+
   private static String computeCanonicalPath(@Nullable String canonicalURL)
       throws URISyntaxException {
     if (Strings.isNullOrEmpty(canonicalURL)) {

javatests/com/google/gerrit/httpd/BUILD

@@ -6,6 +6,7 @@ junit_tests(
     deps = [
         "//java/com/google/gerrit/extensions:api",
         "//java/com/google/gerrit/httpd",
+        "//java/com/google/gerrit/json",
         "//java/com/google/gerrit/server",
         "//java/com/google/gerrit/testing:gerrit-test-util",
         "//javatests/com/google/gerrit/util/http/testutil",

javatests/com/google/gerrit/httpd/raw/IndexHtmlUtilTest.java

@@ -18,12 +18,15 @@ import static com.google.common.truth.Truth.assertThat;
 import static com.google.gerrit.httpd.raw.IndexHtmlUtil.changeUrlPattern;
 import static com.google.gerrit.httpd.raw.IndexHtmlUtil.computeChangeRequestsPath;
 import static com.google.gerrit.httpd.raw.IndexHtmlUtil.diffUrlPattern;
+import static com.google.gerrit.httpd.raw.IndexHtmlUtil.experimentData;
 import static com.google.gerrit.httpd.raw.IndexHtmlUtil.staticTemplateData;
 
 import com.google.template.soy.data.SanitizedContent;
 import com.google.template.soy.data.UnsafeSanitizedContentOrdainer;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 import org.junit.Test;
 
 public class IndexHtmlUtilTest {
@@ -137,4 +140,17 @@ public class IndexHtmlUtilTest {
     return UnsafeSanitizedContentOrdainer.ordainAsSafe(
         s, SanitizedContent.ContentKind.TRUSTED_RESOURCE_URI);
   }
+
+  @Test
+  public void useExperiments() throws Exception {
+    Map<String, String[]> urlParms = new HashMap<>();
+    String[] experiments = new String[] {"foo", "bar", "foo"};
+    Set<String> expected = new HashSet<>();
+    for (String exp : experiments) {
+      expected.add(exp);
+    }
+    urlParms.put("experiment", experiments);
+    Set<String> data = experimentData(urlParms);
+    assertThat(data).isEqualTo(expected);
+  }
 }

resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy

@@ -20,6 +20,7 @@
   {@param canonicalPath: ?}
   {@param staticResourcePath: ?}
   {@param gerritInitialData: /** {string} map of REST endpoint to response for startup. */ ?}
+  {@param? enabledExperiments: /** A list of enabled experiments for current user. */ ?}
   {@param? assetsPath: ?}  /** {string} URL to static assets root, if served from CDN. */
   {@param? assetsBundle: ?}  /** {string} Assets bundle .html file, served from $assetsPath. */
   {@param? faviconPath: ?}
@@ -71,6 +72,11 @@
       // '/accounts/self/detail' => { 'username' : 'gerrit-user' }
       window.INITIAL_DATA = JSON.parse({$gerritInitialData});
     {/if}
+    {if $enabledExperiments}
+      // ENABLED_EXPERIMENTS is a list of string that contains all enabled experiments
+      // for the given user.
+      window.ENABLED_EXPERIMENTS = JSON.parse($enabledExperiments);
+    {/if}
   </script>{\n}
 
   {if $faviconPath}