From 132e58735a563fd0f13e2d598e95369c08df4d66 Mon Sep 17 00:00:00 2001
From: Mark Veidemanis <m@zm.is>
Date: Wed, 20 Apr 2022 19:08:10 +0100
Subject: [PATCH] Implement webhook callback handling

---
 handler/ux/verify.py | 57 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/handler/ux/verify.py b/handler/ux/verify.py
index 9ce6405..4f0fcdb 100644
--- a/handler/ux/verify.py
+++ b/handler/ux/verify.py
@@ -15,6 +15,63 @@ class Verify(util.Base):
     Class to handle user verification.
     """
 
+    def verification_successful(self, external_user_id):
+        """
+        Called when verification has been successfully passed.
+        """
+        self.tx.user_verification_successful(external_user_id)
+
+    def update_verification_status(self, external_user_id, review_status, review_answer=None):
+        """
+        Update the authentication status of a external user ID.
+        """
+        print("Updating verification status", external_user_id, review_status)
+        if review_status == "completed" and review_answer == "GREEN":
+            self.verification_successful(external_user_id)
+
+    def verify_webhook_signature(self, content, payload_digest):
+        if type(content) == str:
+            content = content.encode("utf-8")
+        # hmac needs bytes
+        signature = hmac.new(settings.Verify.WebHookSecret.encode("utf-8"), content, digestmod=hashlib.sha1).hexdigest()
+
+        return signature == payload_digest
+
+    def process_callback(self, content_json):
+        print("CONTENT JSON", content_json)
+        if "externalUserId" in content_json:
+            external_user_id = content_json["externalUserId"]
+        else:
+            self.log.warning("Useless callback received. No external user ID.")
+            return False
+        if "reviewStatus" in content_json:
+            review_status = content_json["reviewStatus"]
+        else:
+            self.log.warning("Useless callback received. No review status.")
+            return False
+
+        review_answer = None
+        if review_status == "completed":
+            if "reviewResult" in content_json:
+                if "reviewAnswer" in content_json["reviewResult"]:
+                    review_answer = content_json["reviewResult"]["reviewAnswer"]
+
+        self.update_verification_status(external_user_id, review_status, review_answer=review_answer)
+        return True
+
+    def handle_callback(self, request):
+        """
+        Handle a webhook callback.
+        """
+        content = request.content.read()
+        payload_digest = request.getHeader("x-payload-digest")
+        if not self.verify_webhook_signature(content, payload_digest):
+            self.log.error("Webhook is not signed. Aborting.")
+            return False
+        content_json = json.loads(content)
+        rtrn = self.process_callback(content_json)
+        return rtrn
+
     def create_applicant_and_get_link(self, external_user_id):
         """
         Create the applicant and return the authentication link.