Only enable Delete on identities tab when we have selections

Don't turn on the Delete button unless at least one identity
was picked from the table using its checkbox.

If there are no identities available for deletion, don't show
the Delete button at all.

Change-Id: I1f57ee71a31a8b21d12f8f231fe55b74107baaec
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-gwtui/src/main/java/com/google/gerrit/client/account/ExternalIdPanel.java

@@ -24,6 +24,8 @@ import com.google.gerrit.common.auth.openid.OpenIdUrls;
 import com.google.gerrit.reviewdb.AccountExternalId;
 import com.google.gwt.event.dom.client.ClickEvent;
 import com.google.gwt.event.dom.client.ClickHandler;
+import com.google.gwt.event.logical.shared.ValueChangeEvent;
+import com.google.gwt.event.logical.shared.ValueChangeHandler;
 import com.google.gwt.user.client.History;
 import com.google.gwt.user.client.ui.Button;
 import com.google.gwt.user.client.ui.CheckBox;
@@ -48,6 +50,7 @@ class ExternalIdPanel extends Composite {
     body.add(identites);
 
     deleteIdentity = new Button(Util.C.buttonDeleteIdentity());
+    deleteIdentity.setEnabled(false);
     deleteIdentity.addClickHandler(new ClickHandler() {
       @Override
       public void onClick(final ClickEvent event) {
@@ -90,6 +93,8 @@ class ExternalIdPanel extends Composite {
   }
 
   private class IdTable extends FancyFlexTable<AccountExternalId> {
+    private ValueChangeHandler<Boolean> updateDeleteHandler;
+
     IdTable() {
       table.setWidth("");
       table.setText(0, 2, Util.C.webIdStatus());
@@ -101,6 +106,13 @@ class ExternalIdPanel extends Composite {
       fmt.addStyleName(0, 2, Gerrit.RESOURCES.css().dataHeader());
       fmt.addStyleName(0, 3, Gerrit.RESOURCES.css().dataHeader());
       fmt.addStyleName(0, 4, Gerrit.RESOURCES.css().dataHeader());
+
+      updateDeleteHandler = new ValueChangeHandler<Boolean>() {
+        @Override
+        public void onValueChange(ValueChangeEvent<Boolean> event) {
+          updateDeleteButton();
+        }
+      };
     }
 
     void deleteChecked() {
@@ -119,12 +131,13 @@ class ExternalIdPanel extends Composite {
           keys.add(k.getKey());
         }
       }
-      if (!keys.isEmpty()) {
+      if (keys.isEmpty()) {
+        updateDeleteButton();
+      } else {
         deleteIdentity.setEnabled(false);
         Util.ACCOUNT_SEC.deleteExternalIds(keys,
             new GerritCallback<Set<AccountExternalId.Key>>() {
               public void onSuccess(final Set<AccountExternalId.Key> removed) {
-                deleteIdentity.setEnabled(true);
                 for (int row = 1; row < table.getRowCount();) {
                   final AccountExternalId k = getRowItem(row);
                   if (k != null && removed.contains(k.getKey())) {
@@ -133,17 +146,36 @@ class ExternalIdPanel extends Composite {
                     row++;
                   }
                 }
+                updateDeleteButton();
               }
 
               @Override
               public void onFailure(Throwable caught) {
-                deleteIdentity.setEnabled(true);
+                updateDeleteButton();
                 super.onFailure(caught);
               }
             });
       }
     }
 
+    void updateDeleteButton() {
+      int off = 0;
+      boolean on = false;
+      for (int row = 1; row < table.getRowCount(); row++) {
+        if (table.getWidget(row, 1) == null) {
+          off++;
+        } else {
+          CheckBox sel = (CheckBox) table.getWidget(row, 1);
+          if (sel.getValue()) {
+            on = true;
+            break;
+          }
+        }
+      }
+      deleteIdentity.setVisible(off < table.getRowCount() - 1);
+      deleteIdentity.setEnabled(on);
+    }
+
     void display(final List<AccountExternalId> result) {
       Collections.sort(result, new Comparator<AccountExternalId>() {
         @Override
@@ -162,6 +194,7 @@ class ExternalIdPanel extends Composite {
       for (final AccountExternalId k : result) {
         addOneId(k);
       }
+      updateDeleteButton();
     }
 
     void addOneId(final AccountExternalId k) {
@@ -176,7 +209,9 @@ class ExternalIdPanel extends Composite {
       applyDataRowStyle(row);
 
       if (k.canDelete()) {
-        table.setWidget(row, 1, new CheckBox());
+        final CheckBox sel = new CheckBox();
+        sel.addValueChangeHandler(updateDeleteHandler);
+        table.setWidget(row, 1, sel);
       } else {
         table.setText(row, 1, "");
       }