feat(Email Trigger (IMAP) Node): Migrate from imap-simple to @n8n/imap (#8899)

Co-authored-by: Jonathan Bennetts <jonathan.bennetts@gmail.com>

packages/@n8n/imap/src/helpers/getMessage.ts

@@ -0,0 +1,53 @@
+import {
+	parseHeader,
+	type ImapMessage,
+	type ImapMessageBodyInfo,
+	type ImapMessageAttributes,
+} from 'imap';
+import type { Message, MessageBodyPart } from '../types';
+
+/**
+ * Given an 'ImapMessage' from the node-imap library, retrieves the `Message`
+ */
+export async function getMessage(
+	/** an ImapMessage from the node-imap library */
+	message: ImapMessage,
+): Promise<Message> {
+	return await new Promise((resolve) => {
+		let attributes: ImapMessageAttributes;
+		const parts: MessageBodyPart[] = [];
+
+		const messageOnBody = (stream: NodeJS.ReadableStream, info: ImapMessageBodyInfo) => {
+			let body: string = '';
+
+			const streamOnData = (chunk: Buffer) => {
+				body += chunk.toString('utf8');
+			};
+
+			stream.on('data', streamOnData);
+			stream.once('end', () => {
+				stream.removeListener('data', streamOnData);
+
+				parts.push({
+					which: info.which,
+					size: info.size,
+					body: /^HEADER/g.test(info.which) ? parseHeader(body) : body,
+				});
+			});
+		};
+
+		const messageOnAttributes = (attrs: ImapMessageAttributes) => {
+			attributes = attrs;
+		};
+
+		const messageOnEnd = () => {
+			message.removeListener('body', messageOnBody);
+			message.removeListener('attributes', messageOnAttributes);
+			resolve({ attributes, parts });
+		};
+
+		message.on('body', messageOnBody);
+		message.once('attributes', messageOnAttributes);
+		message.once('end', messageOnEnd);
+	});
+}