feat: add WhatsApp ID normalization utility

src/utils/whatsapp.ts

@@ -0,0 +1,61 @@
+/**
+ * Normalizes a WhatsApp ID by removing the domain part (@s.whatsapp.net, @g.us)
+ * and any participant identifier (:12).
+ * Handles potential variations like participant IDs in group messages.
+ * 
+ * Examples:
+ * - '1234567890@s.whatsapp.net' -> '1234567890'
+ * - '1234567890-1234567890@g.us' -> '1234567890-1234567890'
+ * - '1234567890:12@s.whatsapp.net' -> '1234567890' (handles participant format)
+ * - 'status_me@broadcast' -> 'status_me' (handles status broadcast)
+ * 
+ * @param id The raw WhatsApp ID string. Can be null or undefined.
+ * @returns The normalized ID string, or null if the input is null/undefined or invalid after normalization.
+ */
+export function normalizeWhatsAppId(id: string | null | undefined): string | null {
+  if (!id) {
+    return null;
+  }
+  
+  // Remove domain part (@s.whatsapp.net, @g.us, @broadcast etc.)
+  let normalized = id.split('@')[0];
+  
+  // Handle potential participant format like '1234567890:12' by taking the part before ':'
+  normalized = normalized.split(':')[0];
+  
+  // Basic validation: should contain alphanumeric characters, possibly hyphens for group IDs
+  // Allows simple numbers, group IDs with hyphens, and potentially status_me
+  if (!/^[a-zA-Z0-9_-]+$/.test(normalized)) {
+    console.warn(`[normalizeWhatsAppId] Invalid characters found in WhatsApp ID after normalization: ${id} -> ${normalized}`);
+    // Return null for clearly invalid IDs after normalization
+    return null; 
+  }
+
+  // Prevent empty strings after normalization
+  if (normalized.length === 0) {
+    console.warn(`[normalizeWhatsAppId] Empty string resulted from normalization: ${id}`);
+    return null;
+  }
+  
+  return normalized;
+}
+
+/**
+ * Checks if a given raw JID represents a group chat.
+ * 
+ * @param jid The raw JID string (e.g., '123-456@g.us').
+ * @returns True if the JID ends with '@g.us', false otherwise.
+ */
+export function isGroupId(jid: string | null | undefined): boolean {
+  return !!jid && jid.endsWith('@g.us');
+}
+
+/**
+ * Checks if a given raw JID represents a standard user chat.
+ * 
+ * @param jid The raw JID string (e.g., '123456@s.whatsapp.net').
+ * @returns True if the JID ends with '@s.whatsapp.net', false otherwise.
+ */
+export function isUserJid(jid: string | null | undefined): boolean {
+  return !!jid && jid.endsWith('@s.whatsapp.net');
+}