Support messaging over WhatsApp (foundation only)

funnel/models/notification.py

@@ -1303,7 +1303,7 @@ def main_notification_preferences(self) -> NotificationPreferences:
                 by_sms=True,
                 by_webpush=False,
                 by_telegram=False,
-                by_whatsapp=False,
+                by_whatsapp=True,
             )
             db.session.add(main)
             return main

funnel/transports/base.py

@@ -24,5 +24,7 @@ def init():
         platform_transports['email'] = True
     if sms_init():
         platform_transports['sms'] = True
+    if app.config.get('WHATSAPP_TOKEN'):
+        platform_transports['whatsapp'] = True
 
     # Other transports are not supported yet

funnel/transports/whatsapp.py

@@ -1,3 +1,111 @@
-"""Support functions for sending a WhatsApp message. Forthcoming."""
+"""Support functions for sending an Whatsapp messages."""
 
 from __future__ import annotations
+
+from typing import Union
+
+from models import PhoneNumber, PhoneNumberBlockedError
+import phonenumbers
+import requests
+
+from baseframe import _
+
+from .. import app
+from .exc import (
+    TransportConnectionError,
+    TransportRecipientError,
+    TransportTransactionError,
+)
+
+__all__ = ['send_wa_via_meta', 'send_wa_via_on_premise']
+
+
+def get_phone_number(
+    phone: Union[str, phonenumbers.PhoneNumber, PhoneNumber]
+) -> PhoneNumber:
+    if isinstance(phone, PhoneNumber):
+        if not phone.number:
+            raise TransportRecipientError(_("This phone number is not available"))
+        return phone
+    try:
+        phone_number = PhoneNumber.add(phone)
+    except PhoneNumberBlockedError as exc:
+        raise TransportRecipientError(_("This phone number has been blocked")) from exc
+    if not phone_number.allow_whatsapp:
+        raise TransportRecipientError(_("Whatsapp is disabled for this phone number"))
+    if not phone_number.number:
+        # This should never happen as :meth:`PhoneNumber.add` will restore the number
+        raise TransportRecipientError(_("This phone number is not available"))
+    return phone_number
+
+
+def send_wa_via_meta(phone: str, message, callback: bool = True) -> str:
+    """
+    Send the Whatsapp message using Meta Cloud API.
+
+    :param phone: Phone number
+    :param message: Message to deliver to phone number
+    :param callback: Whether to request a status callback
+    :return: Transaction id
+    """
+    phone_number = get_phone_number(phone)
+    sid = app.config['WHATSAPP_PHONE_ID']
+    token = app.config['WHATSAPP_TOKEN']
+    payload = {
+        "messaging_product": "whatsapp",
+        "recipient_type": "individual",
+        'to': phone_number.number,
+        "type": "template",
+        'body': str(message),
+        'DltEntityId': message.registered_entityid,
+    }
+    try:
+        r = requests.post(
+            f'https://graph.facebook.com/v15.0/{sid}/messages',
+            timeout=30,
+            auth=(token),
+            data=payload,
+        )
+        if r.status_code == 200:
+            jsonresponse = r.json()
+            transactionid = jsonresponse['messages'].get('id')
+            return transactionid
+        raise TransportTransactionError(_("Whatsapp API error"), r.status_code, r.text)
+    except requests.ConnectionError as exc:
+        raise TransportConnectionError(_("Whatsapp not reachable")) from exc
+
+
+def send_wa_via_on_premise(phone: str, message, callback: bool = True) -> str:
+    """
+    Send the Whatsapp message using Meta Cloud API.
+
+    :param phone: Phone number
+    :param message: Message to deliver to phone number
+    :param callback: Whether to request a status callback
+    :return: Transaction id
+    """
+    phone_number = get_phone_number(phone)
+    sid = app.config['WHATSAPP_PHONE_ID']
+    token = app.config['WHATSAPP_TOKEN']
+    payload = {
+        "messaging_product": "whatsapp",
+        "recipient_type": "individual",
+        'to': phone_number.number,
+        "type": "template",
+        'body': str(message),
+        'DltEntityId': message.registered_entityid,
+    }
+    try:
+        r = requests.post(
+            f'https://graph.facebook.com/v15.0/{sid}/messages',
+            timeout=30,
+            auth=(token),
+            data=payload,
+        )
+        if r.status_code == 200:
+            jsonresponse = r.json()
+            transactionid = jsonresponse['messages'].get('id')
+            return transactionid
+        raise TransportTransactionError(_("Whatsapp API error"), r.status_code, r.text)
+    except requests.ConnectionError as exc:
+        raise TransportConnectionError(_("Whatsapp not reachable")) from exc

funnel/views/notification.py

@@ -546,8 +546,34 @@ def dispatch_transport_sms(user_notification, view):
     )
 
 
+@rqjob
+@transport_worker_wrapper
+def dispatch_transport_whatsapp(user_notification, view):
+    if not user_notification.user.main_notification_preferences.by_transport(
+        'whatsapp'
+    ):
+        # Cancel delivery if user's main switch is off. This was already checked, but
+        # the worker may be delayed and the user may have changed their preference.
+        user_notification.messageid_whatsapp = 'cancelled'
+        return
+    user_notification.messageid_whatsapp = sms.send(
+        str(view.transport_for('sms')), view.sms_with_unsubscribe()
+    )
+    statsd.incr(
+        'notification.transport',
+        tags={
+            'notification_type': user_notification.notification_type,
+            'transport': 'whatsapp',
+        },
+    )
+
+
 # Add transport workers here as their worker methods are written
-transport_workers = {'email': dispatch_transport_email, 'sms': dispatch_transport_sms}
+transport_workers = {
+    'email': dispatch_transport_email,
+    'sms': dispatch_transport_sms,
+    'whatsapp': dispatch_transport_whatsapp,
+}
 
 # --- Notification background workers --------------------------------------------------