refactor: centralize WhatsApp target normalization

src/whatsapp/normalize.ts

@@ -0,0 +1,33 @@
+import { normalizeE164 } from "../utils.js";
+
+function stripWhatsAppTargetPrefixes(value: string): string {
+  let candidate = value.trim();
+  for (;;) {
+    const before = candidate;
+    candidate = candidate
+      .replace(/^whatsapp:/i, "")
+      .replace(/^group:/i, "")
+      .trim();
+    if (candidate === before) return candidate;
+  }
+}
+
+export function isWhatsAppGroupJid(value: string): boolean {
+  const candidate = stripWhatsAppTargetPrefixes(value);
+  const lower = candidate.toLowerCase();
+  if (!lower.endsWith("@g.us")) return false;
+  const localPart = candidate.slice(0, candidate.length - "@g.us".length);
+  if (!localPart || localPart.includes("@")) return false;
+  return /^[0-9]+(-[0-9]+)*$/.test(localPart);
+}
+
+export function normalizeWhatsAppTarget(value: string): string | null {
+  const candidate = stripWhatsAppTargetPrefixes(value);
+  if (!candidate) return null;
+  if (isWhatsAppGroupJid(candidate)) {
+    const localPart = candidate.slice(0, candidate.length - "@g.us".length);
+    return `${localPart}@g.us`;
+  }
+  const normalized = normalizeE164(candidate);
+  return normalized.length > 1 ? normalized : null;
+}