Implement lookup by list id

app/controllers/webhooks/mailchimp_unsubscribes_controller.rb

@@ -1,7 +1,16 @@
 class Webhooks::MailchimpUnsubscribesController < ApplicationController
+  class InvalidListID < StandardError; end
+
+  LIST_MAPPINGS = {
+    mailchimp_newsletter_id: :email_newsletter,
+    mailchimp_sustaining_members_id: :email_membership_newsletter,
+    mailchimp_tag_moderators_id: :email_tag_mod_newsletter,
+    mailchimp_community_moderators_id: :email_community_mod_newsletter
+  }.freeze
+
   def create
     not_authorized unless valid_secret?
-    user = User.find_by(email: params.dig(:data, :email))
+    user = User.find_by!(email: params.dig(:data, :email))
     user.update(email_type => false)
   end
 
@@ -12,7 +21,10 @@ def valid_secret?
   end
 
   def email_type
-    # TODO: map list id to email type
-    :email_digest_periodic
+    list_id = params.dig(:data, :list_id)
+    key = LIST_MAPPINGS.keys.detect { |k| SiteConfig.public_send(k) == list_id }
+    raise InvalidListID unless key
+
+    LIST_MAPPINGS[key]
   end
 end

spec/requests/webhooks/mailchimp/unsubscribe_spec.rb

@@ -5,7 +5,8 @@
 
   describe "POST /webhooks/mailchimp/:secret/unsubscribe" do
     let(:secret) { "secret" }
-    let(:params) { { data: { email: user.email } } }
+    let(:list_id) { "1234" }
+    let(:params) { { data: { email: user.email, list_id: list_id } } }
 
     before do
       allow(SiteConfig).to receive(:mailchimp_webhook_secret).and_return(secret)
@@ -18,9 +19,11 @@
     end
 
     it "unsubscribes the user if the secret is correct" do
+      SiteConfig.mailchimp_newsletter_id = list_id
+
       expect do
         post "/webhooks/mailchimp/#{secret}/unsubscribe", params: params
-      end.to change { user.reload.email_digest_periodic }.from(true).to(false)
+      end.to change { user.reload.email_newsletter }.from(true).to(false)
     end
   end
 end