[MM-29845] Add CWS Webhook endpoint and payment failed email (#16351)

* Add a new handler to allow authentication via CWS API Key

* Make error better

* Add tests and cases for new handler functions

* Move some code around

* Add test for GetCloudSession function

* unset the env after test completion

* Remove white space

* Add CWS Webhook endpoint and email code

* handle returned errors from email sending function

* Change FailureCode to FailureMessage

* Remove unnecessary translations

* Fix translations

* Forgot to add template

* Update api4/cloud.go

Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>

* Update api4/cloud.go

Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>

* Update api4/cloud.go

Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>

* PR changes

* Update app/email.go

Co-authored-by: Mario de Frutos Dieguez <mario@defrutos.org>

* Close body in proper spot

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>
Co-authored-by: Mario de Frutos Dieguez <mario@defrutos.org>

api4/cloud.go

@@ -35,6 +35,9 @@ func (api *API) InitCloud() {
 	api.BaseRoutes.Cloud.Handle("/subscription", api.ApiSessionRequired(getSubscription)).Methods("GET")
 	api.BaseRoutes.Cloud.Handle("/subscription/invoices", api.ApiSessionRequired(getInvoicesForSubscription)).Methods("GET")
 	api.BaseRoutes.Cloud.Handle("/subscription/invoices/{invoice_id:in_[A-Za-z0-9]+}/pdf", api.ApiSessionRequired(getSubscriptionInvoicePDF)).Methods("GET")
+
+	// POST /api/v4/cloud/webhook
+	api.BaseRoutes.Cloud.Handle("/webhook", api.CloudApiKeyRequired(handleCWSWebhook)).Methods("POST")
 }
 
 func getSubscription(c *Context, w http.ResponseWriter, r *http.Request) {
@@ -324,3 +327,34 @@ func getSubscriptionInvoicePDF(c *Context, w http.ResponseWriter, r *http.Reques
 		return
 	}
 }
+
+func handleCWSWebhook(c *Context, w http.ResponseWriter, r *http.Request) {
+	if c.App.Srv().License() == nil || !*c.App.Srv().License().Features.Cloud {
+		c.Err = model.NewAppError("Api4.handleCWSWebhook", "api.cloud.license_error", nil, "", http.StatusNotImplemented)
+		return
+	}
+
+	bodyBytes, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		c.Err = model.NewAppError("Api4.handleCWSWebhook", "api.cloud.app_error", nil, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	defer r.Body.Close()
+
+	var event *model.CWSWebhookPayload
+	if err = json.Unmarshal(bodyBytes, &event); err != nil {
+		c.Err = model.NewAppError("Api4.handleCWSWebhook", "api.cloud.app_error", nil, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	switch event.Event {
+	case model.EventTypeFailedPayment:
+		if nErr := c.App.SendPaymentFailedEmail(event.FailedPayment); nErr != nil {
+			c.Err = nErr
+			return
+		}
+
+	}
+
+	ReturnStatusOK(w)
+}