Support setting default UI in gerrit.config

The value of gerrit.ui chooses the default UI when the user doesn't
request a different preference via argument or cookie. Sanity check
during startup that the value of gerrit.ui is an enabled UI.

Change-Id: I5f18d3d0a252a886de4ae166a158e19c40eed82f

gerrit-httpd/src/main/java/com/google/gerrit/httpd/GerritOptions.java

@@ -14,23 +14,63 @@
 
 package com.google.gerrit.httpd;
 
+import static com.google.common.base.MoreObjects.firstNonNull;
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Enums;
+
 import org.eclipse.jgit.lib.Config;
 
 public class GerritOptions {
+  public enum UiPreference {
+    NONE,
+    GWT,
+    POLYGERRIT;
+  }
+
   private final boolean headless;
   private final boolean slave;
   private final boolean enablePolyGerrit;
   private final boolean enableGwtUi;
   private final boolean forcePolyGerritDev;
+  private final UiPreference defaultUi;
 
   public GerritOptions(Config cfg, boolean headless, boolean slave,
       boolean forcePolyGerritDev) {
-    this.headless = headless;
     this.slave = slave;
     this.enablePolyGerrit = forcePolyGerritDev
         || cfg.getBoolean("gerrit", null, "enablePolyGerrit", false);
     this.enableGwtUi = cfg.getBoolean("gerrit", null, "enableGwtUi", true);
     this.forcePolyGerritDev = forcePolyGerritDev;
+    this.headless = headless || (!enableGwtUi && !enablePolyGerrit);
+
+    UiPreference defaultUi = enablePolyGerrit && !enableGwtUi
+        ? UiPreference.POLYGERRIT
+        : UiPreference.GWT;
+    String uiStr = firstNonNull(
+        cfg.getString("gerrit", null, "ui"),
+        defaultUi.name().toUpperCase());
+    this.defaultUi =
+        Enums.getIfPresent(UiPreference.class, uiStr).or(UiPreference.NONE);
+    uiStr = defaultUi.name().toLowerCase();
+
+    switch (defaultUi) {
+      case GWT:
+        checkArgument(enableGwtUi,
+            "gerrit.ui = %s but GWT UI is disabled", uiStr);
+        break;
+      case POLYGERRIT:
+        checkArgument(enablePolyGerrit,
+            "gerrit.ui = %s but PolyGerrit is disabled", uiStr);
+        break;
+      case NONE:
+      default:
+        throw new IllegalArgumentException("invalid gerrit.ui: " + uiStr);
+    }
+  }
+
+  public boolean headless() {
+    return headless;
   }
 
   public boolean headless() {
@@ -52,4 +92,8 @@ public class GerritOptions {
   public boolean forcePolyGerritDev() {
     return !headless && forcePolyGerritDev;
   }
+
+  public UiPreference defaultUi() {
+    return defaultUi;
+  }
 }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/raw/StaticModule.java

@@ -23,6 +23,7 @@ import com.google.common.base.Enums;
 import com.google.common.cache.Cache;
 import com.google.common.collect.ImmutableList;
 import com.google.gerrit.httpd.GerritOptions;
+import com.google.gerrit.httpd.GerritOptions.UiPreference;
 import com.google.gerrit.httpd.XsrfCookieFilter;
 import com.google.gerrit.httpd.raw.ResourceServlet.Resource;
 import com.google.gerrit.launcher.GerritLauncher;
@@ -111,12 +112,6 @@ public class StaticModule extends ServletModule {
 
   private static final int GERRIT_UI_COOKIE_MAX_AGE = 60 * 60 * 24 * 365;
 
-  enum UiPreference {
-    NONE,
-    GWT,
-    POLYGERRIT;
-  }
-
   private final GerritOptions options;
   private Paths paths;
 
@@ -528,10 +523,7 @@ public class StaticModule extends ServletModule {
     }
 
     private boolean isPolyGerritCookie(HttpServletRequest req) {
-      UiPreference pref = UiPreference.GWT;
-      if (options.enablePolyGerrit() && !options.enableGwtUi()) {
-        pref = UiPreference.POLYGERRIT;
-      }
+      UiPreference pref = options.defaultUi();
       Cookie[] all = req.getCookies();
       if (all != null) {
         for (Cookie c : all) {