fix: resolve TG message character limit overflow

mail-worker/src/template/email-msg.js

@@ -1,39 +1,62 @@
 import emailUtils from '../utils/email-utils';
 
+const TELEGRAM_MESSAGE_LIMIT = 3500;
+const TRUNCATED_SUFFIX = '...';
+
+function escapeHtml(text = '') {
+	return text
+		.replace(/</g, '&lt;')
+		.replace(/>/g, '&gt;');
+}
+
+function truncateText(text, maxLength) {
+	if (!text || text.length <= maxLength) {
+		return text || '';
+	}
+
+	if (maxLength <= TRUNCATED_SUFFIX.length) {
+		return TRUNCATED_SUFFIX.slice(0, maxLength);
+	}
+
+	return text.slice(0, maxLength - TRUNCATED_SUFFIX.length) + TRUNCATED_SUFFIX;
+}
+
 export default function emailMsgTemplate(email, tgMsgTo, tgMsgFrom, tgMsgText) {
 
-	let template = `<b>${email.subject}</b>`
+	let template = `<b>${escapeHtml(email.subject || '')}</b>`
 
 		if (tgMsgFrom === 'only-name') {
 			template += `
 
-From\u200B：${email.name}`
+From\u200B：${escapeHtml(email.name || '')}`
 		}
 
 		if (tgMsgFrom === 'show') {
 			template += `
 
-From\u200B：${email.name}  &lt;${email.sendEmail}&gt;`
+From\u200B：${escapeHtml(email.name || '')}  &lt;${escapeHtml(email.sendEmail || '')}&gt;`
 		}
 
 		if(tgMsgTo === 'show' && tgMsgFrom === 'hide') {
 			template += `
 
-To：\u200B${email.toEmail}`
+To：\u200B${escapeHtml(email.toEmail || '')}`
 
 		} else if(tgMsgTo === 'show') {
 		template += `
-To：\u200B${email.toEmail}`
+To：\u200B${escapeHtml(email.toEmail || '')}`
 	}
 
-	const text = (emailUtils.formatText(email.text) || emailUtils.htmlToText(email.content))
+	const text = escapeHtml(emailUtils.formatText(email.text) || emailUtils.htmlToText(email.content));
-		.replace(/</g, '&lt;')
-		.replace(/>/g, '&gt;');
 
 	if(tgMsgText === 'show') {
+		const prefix = `${template}
+
+`;
+		const maxTextLength = Math.max(0, TELEGRAM_MESSAGE_LIMIT - prefix.length);
 		template += `
 
-${text}`
+${truncateText(text, maxTextLength)}`
 	}
 
 	return template;