feat: merge subnet facts

- add fact for environment
- define 198.18.18.0/24 subnet

modules/libs/lib/facter/subnet_facts.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require 'ipaddr'
+
+# a class that creates facts based on the subnet
+class SubnetAttributes
+  SUBNET_TO_ATTRIBUTES = {
+    '198.18.17.0/24' => { environment: 'prod', region: 'drw1', country: 'au' },
+    '198.18.18.0/24' => { environment: 'test', region: 'drw1', country: 'au' }
+  }.freeze
+
+  # Default attributes if no subnet matches, also defined as a constant
+  DEFAULT_ATTRIBUTES = { environment: 'unknown', region: 'unknown', country: 'unknown' }.freeze
+
+  # provide ip to return attributes
+  def self.attributes(ip)
+    SUBNET_TO_ATTRIBUTES.each do |subnet, attrs|
+      return attrs if IPAddr.new(subnet).include?(IPAddr.new(ip))
+    end
+
+    DEFAULT_ATTRIBUTES
+  end
+end
+
+# Use the primary IP address from facts
+ip = Facter.value(:networking)['ip']
+
+# Call the class method directly without creating an instance
+subnet_attributes = SubnetAttributes.attributes(ip)
+
+# Add separate facts for environment, region, and country
+Facter.add('environment') { setcode { subnet_attributes[:environment] } }
+Facter.add('region') { setcode { subnet_attributes[:region] } }
+Facter.add('country') { setcode { subnet_attributes[:country] } }