import { load } from "cheerio";
/**
* Unescape JSON string escape sequences commonly found in JMAP body values.
* JMAP returns HTML body content as JSON strings, so literal \n, \", \t etc.
* must be converted to their real characters before HTML parsing.
*/
function unescapeJsonString(str: string): string {
return str
.replace(/\\n/g, "\n")
.replace(/\\r/g, "\r")
.replace(/\\t/g, "\t")
.replace(/\\"/g, '"')
.replace(/\\\\/g, "\\");
}
/**
* Sanitize email HTML using cheerio.
* Strips scripts, styles, tracking pixels, hidden elements,
* MSO conditional comments, and layout tables that produce noise.
*/
export function sanitizeEmailHtml(html: string): string {
// Unescape JSON string escapes (JMAP body values are JSON strings)
html = unescapeJsonString(html);
// Strip MSO conditional comments: <!--[if ...]>...<![endif]-->
// These contain <style> blocks and markup only relevant to Outlook
html = html.replace(/<!--\[if[^\]]*\]>[\s\S]*?<!\[endif\]-->/gi, "");
// Also handle the <![if !mso]> variant (non-comment form)
html = html.replace(/<!\[if[^\]]*\]>/gi, "");
html = html.replace(/<!--<!\[endif\]-->/gi, "");
const $ = load(html);
// Remove elements that should never appear in email text content
$("script, style, noscript, iframe, object, embed, applet").remove();
// Remove <head> content (meta tags, title) that leaks into output
$("head").remove();
// Remove hidden elements
$("[style*='display:none'], [style*='display: none']").remove();
$("[style*='visibility:hidden'], [style*='visibility: hidden']").remove();
$("[hidden]").remove();
// Remove tracking pixels (1x1 images or images with no meaningful src)
$("img").each(function () {
const width = $(this).attr("width");
const height = $(this).attr("height");
if ((width === "1" && height === "1") || (width === "0" && height === "0")) {
$(this).remove();
}
});
// Unwrap layout tables, keeping only data tables.
// In email HTML, tables are almost exclusively used for layout.
// A data table has <th> elements; everything else is layout.
// Must iterate innermost-first so nested layout tables unwrap correctly.
let changed = true;
while (changed) {
changed = false;
$("table").each(function () {
// Skip tables that contain nested tables — process inner ones first
if ($(this).find("table").length > 0) return;
const isDataTable =
$(this).find("th").length > 0 ||
$(this).attr("role") === "grid" ||
$(this).attr("role") === "table";
if (!isDataTable) {
// Replace the table with the contents of its cells
const cellContents: string[] = [];
$(this)
.find("td, th")
.each(function () {
const inner = $(this).html()?.trim();
if (inner) cellContents.push(inner);
});
$(this).replaceWith(cellContents.join("\n"));
changed = true;
}
});
}
// Remove all style attributes — they add noise and no value for text extraction
$("[style]").removeAttr("style");
// Remove presentational attributes that add no text value
$("[class]").removeAttr("class");
$("[bgcolor]").removeAttr("bgcolor");
$("[align]").removeAttr("align");
$("[valign]").removeAttr("valign");
$("[cellpadding]").removeAttr("cellpadding");
$("[cellspacing]").removeAttr("cellspacing");
$("[border]").removeAttr("border");
// Clean up leftover table wrapper elements
$("tbody, thead, tfoot").each(function () {
if ($(this).closest("table").length === 0) {
$(this).replaceWith($(this).html() || "");
}
});
$("tr").each(function () {
if ($(this).closest("table").length === 0) {
$(this).replaceWith($(this).html() || "");
}
});
$("td, th").each(function () {
if ($(this).closest("table").length === 0) {
$(this).replaceWith($(this).html() || "");
}
});
$("center").each(function () {
$(this).replaceWith($(this).html() || "");
});
// Strip HTML comments
let result = $.html();
result = result.replace(/<!--[\s\S]*?-->/g, "");
// Collapse runs of blank lines into a single blank line
result = result.replace(/\n{3,}/g, "\n\n");
return result.trim();
}
/**
* Get the body content from an email.
* Prefers htmlBody (sanitized) for consistent output.
* Falls back to textBody for plain-text emails.
*/
function getEmailBody(email: any): string {
if (!email.bodyValues) return "";
// Use htmlBody, sanitized for LLM consumption
if (email.htmlBody && email.htmlBody.length > 0) {
const htmlParts: string[] = [];
for (const part of email.htmlBody) {
const body = email.bodyValues[part.partId];
if (body?.value) {
htmlParts.push(body.value);
}
}
if (htmlParts.length > 0) {
return sanitizeEmailHtml(htmlParts.join("\n"));
}
}
// Fall back to textBody if no htmlBody
if (email.textBody && email.textBody.length > 0) {
const textParts: string[] = [];
for (const part of email.textBody) {
const body = email.bodyValues[part.partId];
if (body?.value) {
textParts.push(body.value);
}
}
if (textParts.length > 0) {
return textParts.join("\n").trim();
}
}
return "";
}
/**
* Escape XML attribute value
*/
function escapeXmlAttr(str: string): string {
return str
.replace(/&/g, "&")
.replace(/"/g, """)
.replace(/</g, "<")
.replace(/>/g, ">");
}
/**
* Escape XML text content
*/
function escapeXmlText(str: string): string {
return str.replace(/&/g, "&").replace(/</g, "<").replace(/>/g, ">");
}
/**
* Format address list as XML nodes
*/
function formatAddressNodes(
addresses: Array<{ name?: string; email: string }> | undefined,
tagName: string,
): string | null {
if (!addresses || addresses.length === 0) return null;
const addressTags = addresses.map((addr) => {
const nameAttr = addr.name ? ` name="${escapeXmlAttr(addr.name)}"` : "";
return ` <address${nameAttr} email="${escapeXmlAttr(addr.email)}" />`;
});
return ` <${tagName}>\n${addressTags.join("\n")}\n </${tagName}>`;
}
/**
* Format a single email as XML
*/
function formatEmailXml(email: any): string {
const lines: string[] = [];
// Email opening tag with core attributes
const attrs: string[] = [`id="${escapeXmlAttr(email.id)}"`];
if (email.receivedAt) {
attrs.push(`date="${new Date(email.receivedAt).toISOString()}"`);
} else if (email.sentAt) {
attrs.push(`date="${new Date(email.sentAt).toISOString()}"`);
}
const flags: string[] = [];
if (!email.keywords?.$seen) flags.push("unread");
if (email.keywords?.$flagged) flags.push("flagged");
if (email.keywords?.$answered) flags.push("replied");
if (email.keywords?.$draft) flags.push("draft");
if (flags.length > 0) attrs.push(`status="${flags.join(", ")}"`);
if (email.hasAttachment) attrs.push(`attachments="yes"`);
lines.push(`<email ${attrs.join(" ")}>`);
// Address fields per RFC 8621
const fromNodes = formatAddressNodes(email.from, "from");
if (fromNodes) lines.push(fromNodes);
const toNodes = formatAddressNodes(email.to, "to");
if (toNodes) lines.push(toNodes);
const ccNodes = formatAddressNodes(email.cc, "cc");
if (ccNodes) lines.push(ccNodes);
const bccNodes = formatAddressNodes(email.bcc, "bcc");
if (bccNodes) lines.push(bccNodes);
const replyToNodes = formatAddressNodes(email.replyTo, "reply_to");
if (replyToNodes) lines.push(replyToNodes);
const senderNodes = formatAddressNodes(email.sender, "sender");
if (senderNodes) lines.push(senderNodes);
// Subject
if (email.subject) {
lines.push(` <subject>${escapeXmlText(email.subject)}</subject>`);
}
// Body
const body = getEmailBody(email);
lines.push(` <body>\n${body}\n </body>`);
lines.push("</email>");
return lines.join("\n");
}
/**
* Format emails into XML structure grouped by thread.
* Sanitizes HTML bodies for cleaner LLM consumption.
*/
export function formatEmailsForLLM(emails: any[]): string {
// Group emails by threadId
const threads = new Map<string, any[]>();
for (const email of emails) {
const threadId = email.threadId || email.id;
if (!threads.has(threadId)) {
threads.set(threadId, []);
}
threads.get(threadId)!.push(email);
}
// Sort emails within each thread by date (oldest first)
for (const threadEmails of threads.values()) {
threadEmails.sort((a, b) => {
const dateA = new Date(a.receivedAt || a.sentAt || 0).getTime();
const dateB = new Date(b.receivedAt || b.sentAt || 0).getTime();
return dateA - dateB;
});
}
// Format each thread
const threadOutputs: string[] = [];
for (const [threadId, threadEmails] of threads) {
const emailTags = threadEmails.map(formatEmailXml);
threadOutputs.push(`<thread id="${threadId}">\n${emailTags.join("\n")}\n</thread>`);
}
return threadOutputs.join("\n\n");
}
