CAMEL-23258: Add google-mail:draft DataType transformer

catalog/camel-catalog/src/generated/resources/org/apache/camel/catalog/transformers.properties

@@ -21,6 +21,7 @@ azure-storage-blob-application-cloudevents
 azure-storage-datalake-application-cloudevents
 azure-storage-queue-application-cloudevents
 google-calendar-stream-application-cloudevents
+google-mail-draft
 google-mail-stream-application-cloudevents
 google-mail-update-message-labels
 google-pubsub-application-cloudevents

catalog/camel-catalog/src/generated/resources/org/apache/camel/catalog/transformers/google-mail-draft.json

@@ -0,0 +1,14 @@
+{
+  "transformer": {
+    "kind": "transformer",
+    "name": "google-mail:draft",
+    "title": "Google Mail (Draft)",
+    "description": "Creates a Gmail Draft from String body and threading metadata from headers",
+    "deprecated": false,
+    "javaType": "org.apache.camel.component.google.mail.transform.GoogleMailDraftDataTypeTransformer",
+    "groupId": "org.apache.camel",
+    "artifactId": "camel-google-mail",
+    "version": "4.19.0-SNAPSHOT"
+  }
+}
+

components/camel-google/camel-google-mail/pom.xml

@@ -155,6 +155,11 @@
             <artifactId>commons-codec</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
 
     </dependencies>
 

components/camel-google/camel-google-mail/src/generated/resources/META-INF/services/org/apache/camel/transformer.properties

@@ -1,5 +1,5 @@
 # Generated by camel build tools - do NOT edit this file!
-transformers=google-mail-stream:application-cloudevents google-mail:update-message-labels
+transformers=google-mail-stream:application-cloudevents google-mail:draft google-mail:update-message-labels
 groupId=org.apache.camel
 artifactId=camel-google-mail
 version=4.19.0-SNAPSHOT

components/camel-google/camel-google-mail/src/generated/resources/META-INF/services/org/apache/camel/transformer/google-mail-draft

@@ -0,0 +1,2 @@
+# Generated by camel build tools - do NOT edit this file!
+class=org.apache.camel.component.google.mail.transform.GoogleMailDraftDataTypeTransformer

components/camel-google/camel-google-mail/src/generated/resources/META-INF/services/org/apache/camel/transformer/google-mail-draft.json

@@ -0,0 +1,14 @@
+{
+  "transformer": {
+    "kind": "transformer",
+    "name": "google-mail:draft",
+    "title": "Google Mail (Draft)",
+    "description": "Creates a Gmail Draft from String body and threading metadata from headers",
+    "deprecated": false,
+    "javaType": "org.apache.camel.component.google.mail.transform.GoogleMailDraftDataTypeTransformer",
+    "groupId": "org.apache.camel",
+    "artifactId": "camel-google-mail",
+    "version": "4.19.0-SNAPSHOT"
+  }
+}
+

components/camel-google/camel-google-mail/src/main/docs/google-mail-component.adoc

@@ -140,6 +140,165 @@ XML::
 </route>
 ----
 ====
+== Data Type Transformer: draft
+
+The `google-mail:draft` transformer converts a String body into a Gmail `Draft` using mail headers from the exchange.
+
+It works with `google-mail-stream`, which sets headers like `threadId`, `messageId`, `from`, `to`, `cc`, `bcc`, and `subject` automatically when consuming messages.
+You can also set these headers manually to create drafts from scratch.
+
+=== Headers
+
+The transformer reads the following headers:
+
+[cols="1,1,3"]
+|===
+| Header | Type | Description
+
+| `CamelGoogleMailStreamThreadId`
+| `String`
+| Thread ID for the conversation (optional, used for replies)
+
+| `CamelGoogleMailStreamMessageId`
+| `String`
+| Message ID to reply to (optional, sets In-Reply-To and References headers)
+
+| `CamelGoogleMailStreamFrom`
+| `String`
+| From address (optional)
+
+| `CamelGoogleMailStreamTo`
+| `String`
+| To address (optional)
+
+| `CamelGoogleMailStreamCc`
+| `String`
+| CC address (optional)
+
+| `CamelGoogleMailStreamBcc`
+| `String`
+| BCC address (optional)
+
+| `CamelGoogleMailStreamSubject`
+| `String`
+| Email subject (optional)
+|===
+
+All headers are optional.
+
+=== Message Body
+
+The message body is a `String` with the email content (plain text or HTML).
+
+Content type defaults to `text/plain; charset=UTF-8`. For HTML, set `Exchange.CONTENT_TYPE` to `text/html; charset=UTF-8`.
+
+The transformer:
+
+* Builds an RFC 2822 MIME message and encodes it as Base64 URL-safe (required by Gmail API)
+* Sets `In-Reply-To` and `References` headers when `messageId` is present
+* Associates the draft with the correct thread when `threadId` is present
+
+=== Examples
+
+[tabs]
+====
+Java::
++
+[source,java]
+----
+// Create a draft reply from a received message
+from("google-mail-stream:0")
+    .setBody(constant("Thank you for your message. I will respond soon."))
+    .transformDataType(new DataType("google-mail:draft"))
+    .to("google-mail:drafts/create?inBody=content");
+
+// Create a new draft (no threading)
+from("direct:newDraft")
+    .setBody(constant("This is a new draft message"))
+    .setHeader("CamelGoogleMailStreamFrom", constant("sender@example.com"))
+    .setHeader("CamelGoogleMailStreamTo", constant("recipient@example.com"))
+    .setHeader("CamelGoogleMailStreamSubject", constant("New Draft"))
+    .transformDataType(new DataType("google-mail:draft"))
+    .to("google-mail:drafts/create?inBody=content");
+----
+
+YAML::
++
+[source,yaml]
+----
+# Create a draft reply from a received message
+- route:
+    from:
+      uri: "google-mail-stream:0"
+    steps:
+      - setBody:
+          constant: "Thank you for your message. I will respond soon."
+      - transformDataType:
+          toType: "google-mail:draft"
+      - to:
+          uri: "google-mail:drafts/create"
+          parameters:
+            inBody: content
+
+# Create a new draft (no threading)
+- route:
+    from:
+      uri: "direct:newDraft"
+    steps:
+      - setBody:
+          constant: "This is a new draft message"
+      - setHeader:
+          name: CamelGoogleMailStreamFrom
+          constant: "sender@example.com"
+      - setHeader:
+          name: CamelGoogleMailStreamTo
+          constant: "recipient@example.com"
+      - setHeader:
+          name: CamelGoogleMailStreamSubject
+          constant: "New Draft"
+      - transformDataType:
+          toType: "google-mail:draft"
+      - to:
+          uri: "google-mail:drafts/create"
+          parameters:
+            inBody: content
+----
+
+XML::
++
+[source,xml]
+----
+<!-- Create a draft reply from a received message -->
+<route>
+    <from uri="google-mail-stream:0"/>
+    <setBody>
+        <constant>Thank you for your message. I will respond soon.</constant>
+    </setBody>
+    <transformDataType toType="google-mail:draft"/>
+    <to uri="google-mail:drafts/create?inBody=content"/>
+</route>
+
+<!-- Create a new draft (no threading) -->
+<route>
+    <from uri="direct:newDraft"/>
+    <setBody>
+        <constant>This is a new draft message</constant>
+    </setBody>
+    <setHeader name="CamelGoogleMailStreamFrom">
+        <constant>sender@example.com</constant>
+    </setHeader>
+    <setHeader name="CamelGoogleMailStreamTo">
+        <constant>recipient@example.com</constant>
+    </setHeader>
+    <setHeader name="CamelGoogleMailStreamSubject">
+        <constant>New Draft</constant>
+    </setHeader>
+    <transformDataType toType="google-mail:draft"/>
+    <to uri="google-mail:drafts/create?inBody=content"/>
+</route>
+----
+====
+
 
 == More Information
 

components/camel-google/camel-google-mail/src/main/java/org/apache/camel/component/google/mail/transform/GoogleMailDraftDataTypeTransformer.java

@@ -0,0 +1,111 @@
+/*
+ * 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.camel.component.google.mail.transform;
+
+import java.io.ByteArrayOutputStream;
+import java.util.Properties;
+
+import jakarta.mail.Session;
+import jakarta.mail.internet.InternetAddress;
+import jakarta.mail.internet.MimeMessage;
+
+import com.google.api.client.util.Base64;
+import com.google.api.services.gmail.model.Draft;
+import com.google.api.services.gmail.model.Message;
+import org.apache.camel.Exchange;
+import org.apache.camel.component.google.mail.stream.GoogleMailStreamConstants;
+import org.apache.camel.spi.DataType;
+import org.apache.camel.spi.DataTypeTransformer;
+import org.apache.camel.spi.Transformer;
+import org.apache.camel.util.ObjectHelper;
+
+import static jakarta.mail.Message.RecipientType.BCC;
+import static jakarta.mail.Message.RecipientType.CC;
+import static jakarta.mail.Message.RecipientType.TO;
+
+/**
+ * Data type transformer that builds a {@link Draft} from a String body and mail headers populated by
+ * google-mail-stream.
+ */
+@DataTypeTransformer(name = "google-mail:draft",
+                     description = "Creates a Gmail Draft from String body and threading metadata from headers")
+public class GoogleMailDraftDataTypeTransformer extends Transformer {
+
+    @Override
+    public void transform(org.apache.camel.Message message, DataType fromType, DataType toType) throws Exception {
+        String body = message.getBody(String.class);
+        if (ObjectHelper.isEmpty(body)) {
+            throw new IllegalArgumentException("Draft body must not be null or empty");
+        }
+
+        String threadId = message.getHeader(GoogleMailStreamConstants.MAIL_THREAD_ID, String.class);
+        String messageId = message.getHeader(GoogleMailStreamConstants.MAIL_MESSAGE_ID, String.class);
+        String from = message.getHeader(GoogleMailStreamConstants.MAIL_FROM, String.class);
+        String subject = message.getHeader(GoogleMailStreamConstants.MAIL_SUBJECT, String.class);
+        String to = message.getHeader(GoogleMailStreamConstants.MAIL_TO, String.class);
+        String cc = message.getHeader(GoogleMailStreamConstants.MAIL_CC, String.class);
+        String bcc = message.getHeader(GoogleMailStreamConstants.MAIL_BCC, String.class);
+
+        Session session = Session.getDefaultInstance(new Properties());
+        MimeMessage mimeMessage = new MimeMessage(session);
+
+        if (ObjectHelper.isNotEmpty(from)) {
+            mimeMessage.setFrom(new InternetAddress(from, true));
+        }
+        if (ObjectHelper.isNotEmpty(to)) {
+            mimeMessage.addRecipients(TO, InternetAddress.parse(to, true));
+        }
+        if (ObjectHelper.isNotEmpty(cc)) {
+            mimeMessage.addRecipients(CC, InternetAddress.parse(cc, true));
+        }
+        if (ObjectHelper.isNotEmpty(bcc)) {
+            mimeMessage.addRecipients(BCC, InternetAddress.parse(bcc, true));
+        }
+        if (ObjectHelper.isNotEmpty(subject)) {
+            mimeMessage.setSubject(subject, "UTF-8");
+        }
+
+        if (ObjectHelper.isNotEmpty(messageId)) {
+            mimeMessage.setHeader("In-Reply-To", messageId);
+            mimeMessage.setHeader("References", messageId);
+        }
+
+        String contentType = message.getHeader(Exchange.CONTENT_TYPE, String.class);
+        if (contentType == null) {
+            contentType = "text/plain; charset=UTF-8";
+        }
+        mimeMessage.setContent(body, contentType);
+
+        String encodedEmail;
+        try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+            mimeMessage.writeTo(baos);
+            encodedEmail = Base64.encodeBase64URLSafeString(baos.toByteArray());
+        }
+
+        Message gmailMessage = new Message();
+        gmailMessage.setRaw(encodedEmail);
+
+        if (ObjectHelper.isNotEmpty(threadId)) {
+            gmailMessage.setThreadId(threadId);
+        }
+
+        Draft draft = new Draft();
+        draft.setMessage(gmailMessage);
+
+        message.setBody(draft);
+    }
+}