Move SendEmailUtils to the /ui/server directory

SendEmailUtils is a general utility of the web console, and not specifically "only"
to the Registrar console.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=226187094

java/google/registry/ui/server/SendEmailUtils.java

@@ -0,0 +1,111 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.ui.server;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.Iterables.toArray;
+
+import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
+import com.google.common.flogger.FluentLogger;
+import google.registry.config.RegistryConfig.Config;
+import google.registry.util.SendEmailService;
+import java.util.List;
+import java.util.Objects;
+import javax.inject.Inject;
+import javax.mail.Message;
+import javax.mail.internet.AddressException;
+import javax.mail.internet.InternetAddress;
+
+/**
+ * Utility class for sending emails from the app.
+ */
+public class SendEmailUtils {
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  private final String gSuiteOutgoingEmailAddress;
+  private final String gSuiteOutgoingEmailDisplayName;
+  private final SendEmailService emailService;
+  private final ImmutableList<String> registrarChangesNotificationEmailAddresses;
+
+  @Inject
+  public SendEmailUtils(
+      @Config("gSuiteOutgoingEmailAddress") String gSuiteOutgoingEmailAddress,
+      @Config("gSuiteOutgoingEmailDisplayName") String gSuiteOutgoingEmailDisplayName,
+      @Config("registrarChangesNotificationEmailAddresses")
+          ImmutableList<String> registrarChangesNotificationEmailAddresses,
+      SendEmailService emailService) {
+    this.gSuiteOutgoingEmailAddress = gSuiteOutgoingEmailAddress;
+    this.gSuiteOutgoingEmailDisplayName = gSuiteOutgoingEmailDisplayName;
+    this.emailService = emailService;
+    this.registrarChangesNotificationEmailAddresses = registrarChangesNotificationEmailAddresses;
+  }
+
+  /**
+   * Sends an email from Nomulus to the registrarChangesNotificationEmailAddresses. Returns true iff
+   * sending to at least 1 address was successful.
+   *
+   * <p>This means that if there are no recepients ({@link #hasRecepients} returns false), this will
+   * return false even thought no error happened.
+   *
+   * <p>This also means that if there are multiple recepients, it will return true even if some (but
+   * not all) of the recepients had an error.
+   */
+  public boolean sendEmail(final String subject, String body) {
+    try {
+      Message msg = emailService.createMessage();
+      msg.setFrom(
+          new InternetAddress(gSuiteOutgoingEmailAddress, gSuiteOutgoingEmailDisplayName));
+      List<InternetAddress> emails =
+          registrarChangesNotificationEmailAddresses.stream()
+              .map(
+                  emailAddress -> {
+                    try {
+                      return new InternetAddress(emailAddress, true);
+                    } catch (AddressException e) {
+                      logger.atSevere().withCause(e).log(
+                          "Could not send email to %s with subject '%s'.", emailAddress, subject);
+                      // Returning null excludes this address from the list of recipients on the
+                      // email.
+                      return null;
+                    }
+                  })
+              .filter(Objects::nonNull)
+              .collect(toImmutableList());
+      if (emails.isEmpty()) {
+        return false;
+      }
+      msg.addRecipients(Message.RecipientType.TO, toArray(emails, InternetAddress.class));
+      msg.setSubject(subject);
+      msg.setText(body);
+      emailService.sendMessage(msg);
+    } catch (Throwable t) {
+      logger.atSevere().withCause(t).log(
+          "Could not email to addresses %s with subject '%s'.",
+          Joiner.on(", ").join(registrarChangesNotificationEmailAddresses), subject);
+      return false;
+    }
+    return true;
+  }
+
+  /**
+   * Returns whether there are any recepients set up. {@link #sendEmail} will always return false if
+   * there are no recepients.
+   */
+  public boolean hasRecepients() {
+    return !registrarChangesNotificationEmailAddresses.isEmpty();
+  }
+}