feat(api): add phone number registration endpoint and update related logic

pkg/whatsapp/businessapi/sending.go

@@ -226,27 +226,37 @@ func (c *Client) MarkAsRead(ctx context.Context, messageID string) error {
 	return nil
 }
 
-// ListPhoneNumbers returns all phone numbers for the business account.
+// ListPhoneNumbers returns all phone numbers for the WhatsApp Business Account.
+// The WABA ID is resolved from the phone number at connect time; it is distinct from
+// the Facebook Business Manager ID stored in business_account_id.
 func (c *Client) ListPhoneNumbers(ctx context.Context) (*PhoneNumberListResponse, error) {
-	if c.config.BusinessAccountID == "" {
-		return nil, errNoBusinessAccount
+	wabaID := c.wabaID
+	if wabaID == "" {
+		// Fallback: resolve on demand if Connect() was not called
+		id, err := c.fetchWABAID(ctx)
+		if err != nil {
+			return nil, fmt.Errorf("could not resolve WABA ID: %w", err)
+		}
+		c.wabaID = id
+		wabaID = id
 	}
 
 	params := url.Values{
-		"fields": {"id,display_phone_number,phone_number,verified_name,code_verification_status,quality_rating,throughput"},
+		"fields": {"id,display_phone_number,verified_name,code_verification_status,quality_rating,throughput"},
 	}
 
 	var resp PhoneNumberListResponse
-	if err := c.graphAPIGet(ctx, c.config.BusinessAccountID+"/phone_numbers", params, &resp); err != nil {
+	if err := c.graphAPIGet(ctx, wabaID+"/phone_numbers", params, &resp); err != nil {
 		return nil, err
 	}
 	return &resp, nil
 }
 
 // RequestVerificationCode sends a verification code (SMS or VOICE) to the given phone number.
-func (c *Client) RequestVerificationCode(ctx context.Context, phoneNumberID string, method string) error {
+func (c *Client) RequestVerificationCode(ctx context.Context, phoneNumberID string, method string, language string) error {
 	body := map[string]string{
-		"verification_method": method,
+		"code_method": method,
+		"language":    language,
 	}
 
 	var resp RequestCodeResponse
@@ -261,6 +271,17 @@ func (c *Client) VerifyCode(ctx context.Context, phoneNumberID string, code stri
 	return c.graphAPIPost(ctx, phoneNumberID+"/verify_code", body, &resp)
 }
 
+// RegisterPhoneNumber registers a phone number for use with the WhatsApp Cloud API.
+// POST /{phone-number-id}/register
+func (c *Client) RegisterPhoneNumber(ctx context.Context, phoneNumberID string, pin string) error {
+	body := RegisterPhoneNumberRequest{
+		MessagingProduct: "whatsapp",
+		Pin:              pin,
+	}
+	var resp RegisterPhoneNumberResponse
+	return c.graphAPIPost(ctx, phoneNumberID+"/register", body, &resp)
+}
+
 // DeleteMedia deletes a previously uploaded media file.
 func (c *Client) DeleteMedia(ctx context.Context, mediaID string) error {
 	return c.graphAPIDelete(ctx, mediaID, nil)