feat(#2056): Make email templates configurable in UI (#2057)

* feat(#2056): Make email templates configurable in UI

* Suppress checkstyle warning for HTML templates

* Remove obsolete code

* Fix content type in rest interface

* Move email default template to resources, use syntax highlighting in UI

* Fix misleading comment

streampipes-mail/src/main/java/org/apache/streampipes/mail/MailSender.java

@@ -18,6 +18,7 @@
 package org.apache.streampipes.mail;
 
 import org.apache.streampipes.mail.template.AccountActiviationMailTemplate;
+import org.apache.streampipes.mail.template.CustomMailTemplate;
 import org.apache.streampipes.mail.template.InitialPasswordMailTemplate;
 import org.apache.streampipes.mail.template.PasswordRecoveryMailTemplate;
 import org.apache.streampipes.mail.utils.MailUtils;
@@ -29,11 +30,14 @@
 
 public class MailSender extends AbstractMailer {
 
-  public void sendEmail(SpEmail mail) {
+  public void sendEmail(SpEmail mail) throws IOException {
     Email email = baseEmail()
         .withRecipients(toSimpleRecipientList(mail.getRecipients()))
         .withSubject(mail.getSubject())
-        .appendText(mail.getMessage())
+        .appendTextHTML(new CustomMailTemplate(
+            mail.getSubject(),
+            mail.getPreheader(),
+            mail.getMessage()).generateTemplate())
         .buildEmail();
 
     deliverMail(email);

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/AbstractMailTemplate.java

@@ -21,7 +21,7 @@
 import org.apache.streampipes.mail.template.generation.MailTemplateBuilder;
 import org.apache.streampipes.mail.template.part.BaseUrlPart;
 import org.apache.streampipes.mail.template.part.LogoPart;
-import org.apache.streampipes.mail.template.part.MailTemplatePart;
+import org.apache.streampipes.storage.management.StorageDispatcher;
 
 import java.io.IOException;
 import java.util.HashMap;
@@ -35,22 +35,27 @@ public abstract class AbstractMailTemplate {
 
   protected abstract void addPlaceholders(Map<String, String> placeholders);
 
-  protected abstract void addTemplateParts(Map<String, MailTemplatePart> templateParts);
+  protected abstract void configureTemplate(MailTemplateBuilder builder);
 
   public String generateTemplate() throws IOException {
-    Map<String, MailTemplatePart> templateParts = new HashMap<>();
     Map<String, String> placeholders = new HashMap<>();
-    addTemplateParts(templateParts);
     addPlaceholders(placeholders);
 
-    return MailTemplateBuilder.create(MailTemplatePart.MAIL_TEMPLATE_OUTER)
-        .addSubpart(DefaultPlaceholders.FOOTER, MailTemplatePart.MAIL_TEMPLATE_FOOTER)
-        .addSubparts(templateParts)
+    var template = StorageDispatcher.INSTANCE
+        .getNoSqlStore()
+        .getSpCoreConfigurationStorage()
+        .get()
+        .getEmailTemplateConfig()
+        .getTemplate();
+
+    var builder = MailTemplateBuilder.create(template)
         .withPlaceholder(DefaultPlaceholders.TITLE, getTitle())
         .withPlaceholder(DefaultPlaceholders.PREHEADER, getPreHeader())
         .withPlaceholder(DefaultPlaceholders.LOGO, new LogoPart().generate())
         .withPlaceholder(DefaultPlaceholders.BASE_URL, new BaseUrlPart().generate())
-        .withPlaceholders(placeholders)
-        .generateHtmlTemplate();
+        .withPlaceholders(placeholders);
+
+    configureTemplate(builder);
+    return builder.generateHtmlTemplate();
   }
 }

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/AccountActiviationMailTemplate.java

@@ -18,6 +18,7 @@
 package org.apache.streampipes.mail.template;
 
 import org.apache.streampipes.mail.template.generation.DefaultPlaceholders;
+import org.apache.streampipes.mail.template.generation.MailTemplateBuilder;
 import org.apache.streampipes.mail.template.part.LinkPart;
 import org.apache.streampipes.mail.template.part.MailTemplatePart;
 import org.apache.streampipes.mail.utils.MailUtils;
@@ -54,8 +55,8 @@ protected void addPlaceholders(Map<String, String> placeholders) {
   }
 
   @Override
-  protected void addTemplateParts(Map<String, MailTemplatePart> templateParts) {
-    templateParts.put(DefaultPlaceholders.INNER.key(), MailTemplatePart.MAIL_TEMPLATE_INNER_BUTTON);
+  protected void configureTemplate(MailTemplateBuilder builder) {
+    builder.withInnerPart(MailTemplatePart.MAIL_TEMPLATE_INNER_BUTTON);
   }
 
   private String makeLink() {

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/CustomMailTemplate.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.streampipes.mail.template;
+
+import org.apache.streampipes.mail.template.generation.MailTemplateBuilder;
+
+import java.util.Map;
+
+public class CustomMailTemplate extends AbstractMailTemplate {
+
+  private final String title;
+  private final String preheader;
+  private final String content;
+
+  public CustomMailTemplate(String title,
+                            String preheader,
+                            String content) {
+    this.title = title;
+    this.preheader = preheader;
+    this.content = content;
+  }
+
+  @Override
+  protected String getTitle() {
+    return title;
+  }
+
+  @Override
+  protected String getPreHeader() {
+    return preheader;
+  }
+
+  @Override
+  protected void addPlaceholders(Map<String, String> placeholders) {
+  }
+
+  @Override
+  protected void configureTemplate(MailTemplateBuilder builder) {
+    builder.withInnerPart(content);
+  }
+}

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/InitialPasswordMailTemplate.java

@@ -18,6 +18,7 @@
 package org.apache.streampipes.mail.template;
 
 import org.apache.streampipes.mail.template.generation.DefaultPlaceholders;
+import org.apache.streampipes.mail.template.generation.MailTemplateBuilder;
 import org.apache.streampipes.mail.template.part.LinkPart;
 import org.apache.streampipes.mail.template.part.MailTemplatePart;
 import org.apache.streampipes.mail.utils.MailUtils;
@@ -54,8 +55,8 @@ protected void addPlaceholders(Map<String, String> placeholders) {
   }
 
   @Override
-  protected void addTemplateParts(Map<String, MailTemplatePart> templateParts) {
-    templateParts.put(DefaultPlaceholders.INNER.key(), MailTemplatePart.MAIL_TEMPLATE_INNER_BUTTON);
+  protected void configureTemplate(MailTemplateBuilder builder) {
+    builder.withInnerPart(MailTemplatePart.MAIL_TEMPLATE_INNER_BUTTON);
   }
 
   private String makeLink() {

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/PasswordRecoveryMailTemplate.java

@@ -18,6 +18,7 @@
 package org.apache.streampipes.mail.template;
 
 import org.apache.streampipes.mail.template.generation.DefaultPlaceholders;
+import org.apache.streampipes.mail.template.generation.MailTemplateBuilder;
 import org.apache.streampipes.mail.template.part.LinkPart;
 import org.apache.streampipes.mail.template.part.MailTemplatePart;
 import org.apache.streampipes.mail.utils.MailUtils;
@@ -54,9 +55,8 @@ protected void addPlaceholders(Map<String, String> placeholders) {
   }
 
   @Override
-  protected void addTemplateParts(Map<String, MailTemplatePart> templateParts) {
-    templateParts.put(DefaultPlaceholders.INNER.key(), MailTemplatePart.MAIL_TEMPLATE_INNER_BUTTON);
-    templateParts.put(DefaultPlaceholders.FOOTER.key(), MailTemplatePart.MAIL_TEMPLATE_FOOTER);
+  protected void configureTemplate(MailTemplateBuilder builder) {
+    builder.withInnerPart(MailTemplatePart.MAIL_TEMPLATE_INNER_BUTTON);
   }
 
   private String makeLink() {

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/TestMailTemplate.java

@@ -18,6 +18,7 @@
 package org.apache.streampipes.mail.template;
 
 import org.apache.streampipes.mail.template.generation.DefaultPlaceholders;
+import org.apache.streampipes.mail.template.generation.MailTemplateBuilder;
 import org.apache.streampipes.mail.template.part.MailTemplatePart;
 import org.apache.streampipes.mail.utils.MailUtils;
 
@@ -41,8 +42,8 @@ protected void addPlaceholders(Map<String, String> placeholders) {
   }
 
   @Override
-  protected void addTemplateParts(Map<String, MailTemplatePart> templateParts) {
-    templateParts.put(DefaultPlaceholders.INNER.key(), MailTemplatePart.MAIL_TEMPLATE_INNER_PLAIN);
+  protected void configureTemplate(MailTemplateBuilder builder) {
+    builder.withInnerPart(MailTemplatePart.MAIL_TEMPLATE_INNER_PLAIN);
   }
 
   private String makeText() {

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/generation/DefaultPlaceholders.java

@@ -21,8 +21,6 @@ public enum DefaultPlaceholders {
 
   TITLE("TITLE"),
   PREHEADER("PREHEADER"),
-  FOOTER("FOOTER"),
-  FOOTER_TEXT("FOOTER_TEXT"),
   INNER("INNER"),
 
   BUTTON_TEXT("BUTTON_TEXT"),

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/generation/MailTemplateBuilder.java

@@ -18,41 +18,37 @@
 package org.apache.streampipes.mail.template.generation;
 
 import org.apache.streampipes.mail.template.part.MailTemplatePart;
-import org.apache.streampipes.mail.utils.MailUtils;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 
 public class MailTemplateBuilder {
 
-  private final MailTemplatePart outerPart;
-  private final Map<String, MailTemplatePart> innerParts;
+  private final String outerTemplate;
+  private String innerPart;
   private final Map<String, String> placeholders;
 
-  private MailTemplateBuilder(MailTemplatePart outerPart) {
-    this.outerPart = outerPart;
-    this.innerParts = new HashMap<>();
+  private MailTemplateBuilder(String outerTemplate) {
+    this.outerTemplate = outerTemplate;
     this.placeholders = new HashMap<>();
   }
 
-  public static MailTemplateBuilder create(MailTemplatePart outerPart) {
-    return new MailTemplateBuilder(outerPart);
+  public static MailTemplateBuilder create(String outerTemplate) {
+    return new MailTemplateBuilder(outerTemplate);
   }
 
-  public MailTemplateBuilder addSubpart(String placeholder, MailTemplatePart templatePart) {
-    this.innerParts.put(placeholder, templatePart);
-
+  public MailTemplateBuilder withInnerPart(MailTemplatePart innerPart) {
+    try {
+      this.innerPart = innerPart.getContent();
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
     return this;
   }
 
-  public MailTemplateBuilder addSubpart(DefaultPlaceholders placeholder, MailTemplatePart templatePart) {
-    return addSubpart(placeholder.key(), templatePart);
-
-  }
-
-  public MailTemplateBuilder addSubparts(Map<String, MailTemplatePart> templateParts) {
-    this.innerParts.putAll(templateParts);
+  public MailTemplateBuilder withInnerPart(String content) {
+    this.innerPart = content;
     return this;
   }
 
@@ -72,8 +68,8 @@ public MailTemplateBuilder withPlaceholder(DefaultPlaceholders placeholder, Stri
     return withPlaceholder(placeholder.key(), content);
   }
 
-  public String generateHtmlTemplate() throws IOException {
-    String fullTemplate = getAndApplyPlaceholders(outerPart);
+  public String generateHtmlTemplate() {
+    String fullTemplate = getAndApplyPlaceholders(outerTemplate);
 
     for (String key : placeholders.keySet()) {
       String placeholder = makeKey(key);
@@ -83,30 +79,15 @@ public String generateHtmlTemplate() throws IOException {
     return fullTemplate;
   }
 
-  private String readFileContentsToString(MailTemplatePart part) throws IOException {
-    return MailUtils.readResourceFileToString(part.getTemplateFilename());
+  private String getAndApplyPlaceholders(String outerTemplate) {
+    return applyInnerTemplate(outerTemplate);
   }
 
-  private String getAndApplyPlaceholders(MailTemplatePart partContent) throws IOException {
-    String partContentAsString = readFileContentsToString(partContent);
-    for (String innerPartKey : innerParts.keySet()) {
-      String templateKey = makeKey(innerPartKey);
-      if (hasPlaceholder(partContentAsString, templateKey)) {
-        partContentAsString =
-            partContentAsString.replaceAll(templateKey, getAndApplyPlaceholders(innerParts.get(innerPartKey)));
-      }
-    }
-
-    return partContentAsString;
-  }
-
-  private boolean hasPlaceholder(String content, String placeholder) {
-    return content.contains(placeholder);
+  private String applyInnerTemplate(String content) {
+    return content.replaceAll(makeKey(DefaultPlaceholders.INNER.key()), innerPart);
   }
 
   private String makeKey(String key) {
     return "###" + key + "###";
   }
-
-
 }

streampipes-mail/src/main/java/org/apache/streampipes/mail/template/part/MailTemplatePart.java

@@ -17,20 +17,22 @@
  */
 package org.apache.streampipes.mail.template.part;
 
+import org.apache.streampipes.mail.utils.MailUtils;
+
+import java.io.IOException;
+
 public enum MailTemplatePart {
 
-  MAIL_TEMPLATE_OUTER("mail-template-outer.html"),
   MAIL_TEMPLATE_INNER_BUTTON("mail-template-inner-button.html"),
-  MAIL_TEMPLATE_INNER_PLAIN("mail-template-inner-plain.html"),
-  MAIL_TEMPLATE_FOOTER("mail-template-footer.html");
+  MAIL_TEMPLATE_INNER_PLAIN("mail-template-inner-plain.html");
 
-  private String templateFilename;
+  private final String templateFilename;
 
   MailTemplatePart(String templateFilename) {
     this.templateFilename = templateFilename;
   }
 
-  public String getTemplateFilename() {
-    return this.templateFilename;
+  public String getContent() throws IOException {
+    return MailUtils.readResourceFileToString(templateFilename);
   }
 }