feat: autogenerate vapid keys for push notifications (#3128)

* feat: Autogenerate push notification keys
* add vapid service class and remove pushkey model
* add spec for vapid service
* unset vapid env keys
* Unset VAPID_PRIVATE_KEY env variable

Co-authored-by: Sojan Jose <sojan@chatwoot.com>
Co-authored-by: Vishnu Narayanan <vishnu@chatwoot.com>

spec/lib/vapid_service_spec.rb

@@ -0,0 +1,53 @@
+require 'rails_helper'
+
+describe VapidService do
+  subject(:trigger) { described_class }
+
+  describe 'execute' do
+    context 'when called with default options' do
+      before do
+        GlobalConfig.clear_cache
+      end
+
+      it 'hit DB for the first call' do
+        expect(InstallationConfig).to receive(:find_by)
+        GlobalConfig.get('VAPID_KEYS')
+      end
+
+      it 'get public key from env' do
+        # this gets public key
+        ENV['VAPID_PUBLIC_KEY'] = 'test'
+        described_class.public_key
+
+        # subsequent calls should not hit DB
+        expect(InstallationConfig).not_to receive(:find_by)
+        described_class.public_key
+        ENV['VAPID_PUBLIC_KEY'] = nil
+      end
+
+      it 'get private key from env' do
+        # this gets private key
+        ENV['VAPID_PRIVATE_KEY'] = 'test'
+        described_class.private_key
+
+        # subsequent calls should not hit DB
+        expect(InstallationConfig).not_to receive(:find_by)
+        described_class.private_key
+        ENV['VAPID_PRIVATE_KEY'] = nil
+        ENV['VAPID_PRIVATE_KEY'] = nil
+      end
+
+      it 'clears cache and fetch from DB next time, when clear_cache is called' do
+        # this loads from DB and is cached
+        GlobalConfig.get('VAPID_KEYS')
+
+        # clears the cache
+        GlobalConfig.clear_cache
+
+        # should be loaded from DB
+        expect(InstallationConfig).to receive(:find_by).with({ name: 'VAPID_KEYS' }).and_return(nil)
+        GlobalConfig.get('VAPID_KEYS')
+      end
+    end
+  end
+end