feat: Add APIs for limit check in accounts (#7242)

enterprise/app/controllers/enterprise/api/v1/accounts_controller.rb

@@ -1,6 +1,8 @@
 class Enterprise::Api::V1::AccountsController < Api::BaseController
+  include BillingHelper
   before_action :fetch_account
   before_action :check_authorization
+  before_action :check_cloud_env, only: [:limits]
 
   def subscription
     if stripe_customer_id.blank? && @account.custom_attributes['is_creating_customer'].blank?
@@ -10,12 +12,40 @@ class Enterprise::Api::V1::AccountsController < Api::BaseController
     head :no_content
   end
 
+  def limits
+    limits = {
+      'conversation' => {},
+      'non_web_inboxes' => {}
+    }
+
+    if default_plan?(@account)
+      limits = {
+        'conversation' => {
+          'allowed' => 500,
+          'consumed' => conversations_this_month(@account)
+        },
+        'non_web_inboxes' => {
+          'allowed' => 0,
+          'consumed' => non_web_inboxes(@account)
+        }
+      }
+    end
+
+    # include id in response to ensure that the store can be updated on the frontend
+    render json: { id: @account.id, limits: limits }, status: :ok
+  end
+
   def checkout
     return create_stripe_billing_session(stripe_customer_id) if stripe_customer_id.present?
 
     render_invalid_billing_details
   end
 
+  def check_cloud_env
+    installation_config = InstallationConfig.find_by(name: 'DEPLOYMENT_ENV')
+    render json: { error: 'Not found' }, status: :not_found unless installation_config&.value == 'cloud'
+  end
+
   private
 
   def fetch_account