import { createMimeMessage } from "mimetext";
import type { ImapClient } from "./client.js";
import { buildCompositeId, parseCompositeId } from "./resolve.js";
export interface DraftOptions {
to: string;
subject: string;
body: string;
cc?: string;
bcc?: string;
/** Composite ID or raw Message-ID of the email being replied to */
inReplyTo?: string;
}
export interface DraftResult {
id: string;
subject: string;
to: string;
date: string;
}
/**
* Find the Drafts folder by looking for the \Drafts special-use attribute.
* Falls back to a folder named "Drafts" if no special-use attribute is found.
*/
export async function findDraftsFolder(imapClient: ImapClient): Promise<string> {
const client = await imapClient.connect();
const mailboxes = await client.list();
// Look for \Drafts special-use attribute
for (const mb of mailboxes) {
if (mb.specialUse === "\\Drafts") {
return mb.path;
}
}
// Fallback: look for a folder named "Drafts" (case-insensitive)
for (const mb of mailboxes) {
if (mb.name.toLowerCase() === "drafts") {
return mb.path;
}
}
throw new Error(
"Could not find Drafts folder. Available folders can be listed with list_folders."
);
}
/**
* Build a raw RFC 2822 message from draft options.
*/
function buildMessage(
sender: string,
options: DraftOptions,
messageId?: string | null
): string {
const msg = createMimeMessage();
msg.setSender(sender);
msg.setTo(options.to);
msg.setSubject(options.subject);
if (options.cc) {
msg.setCc(options.cc);
}
if (options.bcc) {
msg.setBcc(options.bcc);
}
if (messageId) {
msg.setHeader("In-Reply-To", messageId);
msg.setHeader("References", messageId);
}
msg.addMessage({
contentType: "text/plain",
data: options.body,
});
return msg.asRaw();
}
/**
* Create a new email draft in the Drafts folder.
* If `inReplyTo` is provided, parses the composite ID to extract the Message-ID
* and sets In-Reply-To + References headers for proper threading.
*/
export async function createDraft(
imapClient: ImapClient,
sender: string,
options: DraftOptions
): Promise<DraftResult> {
let replyMessageId: string | null = null;
if (options.inReplyTo) {
const { messageId } = parseCompositeId(options.inReplyTo);
replyMessageId = messageId || null;
}
const raw = buildMessage(sender, options, replyMessageId);
// Extract the generated Message-ID from the raw message
const msgIdMatch = raw.match(/^Message-ID:\s*(.+)$/mi);
const generatedMessageId = msgIdMatch ? msgIdMatch[1].trim() : "";
const draftsFolder = await findDraftsFolder(imapClient);
const client = await imapClient.connect();
await client.append(
draftsFolder,
Buffer.from(raw, "utf-8"),
["\\Draft"]
);
const now = new Date();
return {
id: buildCompositeId(now, generatedMessageId),
subject: options.subject,
to: options.to,
date: now.toISOString(),
};
}
/**
* Replace an existing draft. Verifies the UID is in the Drafts folder,
* appends the new version, then deletes the old one.
* Accepts internal IMAP UID (tool handler resolves composite ID first).
*/
export async function updateDraft(
imapClient: ImapClient,
sender: string,
uid: number,
options: DraftOptions
): Promise<DraftResult> {
const draftsFolder = await findDraftsFolder(imapClient);
// Verify the UID exists in the Drafts folder
const lock = await imapClient.openMailbox(draftsFolder);
try {
const client = imapClient.getClient();
const msg = await client.fetchOne(String(uid), { uid: true }, { uid: true });
if (!msg) {
throw new Error(
"You can only update drafts. The email you provided is not in the drafts folder."
);
}
} finally {
lock.release();
}
// Create the replacement draft
const newDraft = await createDraft(imapClient, sender, options);
// Delete the old draft
const deleteLock = await imapClient.openMailbox(draftsFolder);
try {
const client = imapClient.getClient();
await client.messageDelete(String(uid), { uid: true });
} finally {
deleteLock.release();
}
return newDraft;
}
