Fix email signature rendering

lib/signature-utils.ts

@@ -0,0 +1,158 @@
+import { parseHtmlSafely, sanitizeSignatureHtml } from '@/lib/email-sanitization';
+
+type SignatureSource = {
+  textSignature?: string;
+  htmlSignature?: string;
+};
+
+const BLOCK_TAGS = new Set([
+  'address',
+  'article',
+  'aside',
+  'blockquote',
+  'div',
+  'footer',
+  'header',
+  'li',
+  'nav',
+  'p',
+  'section',
+  'tr',
+]);
+
+function normalizeSignatureLineBreaks(value: string): string {
+  return value
+    .replace(/\r\n?/g, '\n')
+    .replace(/\u00a0/g, ' ')
+    .replace(/[ \t]+\n/g, '\n')
+    .replace(/\n{3,}/g, '\n\n')
+    .trim();
+}
+
+function htmlToPlainText(html: string): string {
+  const document = parseHtmlSafely(html);
+  const chunks: string[] = [];
+
+  const appendText = (value: string) => {
+    if (!value) return;
+    const normalized = value.replace(/\s+/g, ' ');
+    if (!normalized.trim()) return;
+    const previous = chunks[chunks.length - 1];
+    if (previous && !previous.endsWith('\n') && !previous.endsWith(' ')) {
+      chunks.push(' ');
+    }
+    chunks.push(normalized);
+  };
+
+  const appendNewline = () => {
+    const previous = chunks[chunks.length - 1];
+    if (previous === '\n') return;
+    if (previous?.endsWith('\n')) return;
+    chunks.push('\n');
+  };
+
+  const walk = (node: Node) => {
+    if (node.nodeType === Node.TEXT_NODE) {
+      appendText(node.textContent || '');
+      return;
+    }
+
+    if (node.nodeType !== Node.ELEMENT_NODE) {
+      return;
+    }
+
+    const element = node as HTMLElement;
+    const tagName = element.tagName.toLowerCase();
+
+    if (tagName === 'br') {
+      appendNewline();
+      return;
+    }
+
+    if (tagName === 'a') {
+      const text = element.textContent?.replace(/\s+/g, ' ').trim() || '';
+      const href = element.getAttribute('href')?.trim() || '';
+      const normalizedHref = href.replace(/^mailto:/i, '');
+      if (text && normalizedHref && text === normalizedHref) {
+        appendText(text);
+        return;
+      }
+      if (text && href && text !== href) {
+        appendText(`${text} <${href}>`);
+        return;
+      }
+    }
+
+    if (BLOCK_TAGS.has(tagName) && chunks.length > 0) {
+      appendNewline();
+    }
+
+    Array.from(element.childNodes).forEach(walk);
+
+    if (BLOCK_TAGS.has(tagName)) {
+      appendNewline();
+    }
+  };
+
+  Array.from(document.body.childNodes).forEach(walk);
+  return normalizeSignatureLineBreaks(chunks.join(''));
+}
+
+export function getPlainTextSignature(signature?: SignatureSource | null): string {
+  if (signature?.textSignature?.trim()) {
+    return normalizeSignatureLineBreaks(signature.textSignature);
+  }
+
+  if (signature?.htmlSignature?.trim()) {
+    return htmlToPlainText(sanitizeSignatureHtml(signature.htmlSignature));
+  }
+
+  return '';
+}
+
+export function appendPlainTextSignature(body: string, signature?: SignatureSource | null): string {
+  const plainTextSignature = getPlainTextSignature(signature);
+  if (!plainTextSignature) {
+    return body;
+  }
+
+  return `${body}\n\n-- \n${plainTextSignature}`;
+}
+
+export function hasMeaningfulHtmlBody(html: string): boolean {
+  if (!html.trim()) return false;
+
+  const document = parseHtmlSafely(html);
+  const richSelector = [
+    'table',
+    'img',
+    'style',
+    'b',
+    'strong',
+    'i',
+    'em',
+    'u',
+    'font',
+    'a[href]',
+    'div[style]',
+    'span[style]',
+    'p[style]',
+    'h1',
+    'h2',
+    'h3',
+    'h4',
+    'h5',
+    'h6',
+    'ul',
+    'ol',
+    'blockquote',
+    'br',
+  ].join(', ');
+
+  if (document.querySelector(richSelector)) {
+    return true;
+  }
+
+  const blockElements = document.body.querySelectorAll('p, div, blockquote, li');
+  return blockElements.length > 1;
+}