implement dynamic price service

app/services/billable_metrics/aggregations/base_service.rb

@@ -26,6 +26,10 @@ def aggregate(options: {})
         else
           compute_aggregation(options:)
         end
+        if charge.dynamic?
+          compute_precise_total_amount_cents(options:)
+        end
+        result
       end
 
       def compute_aggregation(options: {})
@@ -36,6 +40,10 @@ def compute_grouped_by_aggregation(options: {})
         raise NotImplementedError
       end
 
+      def compute_precise_total_amount_cents(options: {})
+        raise NotImplementedError
+      end
+
       def per_event_aggregation(exclude_event: false)
         Result.new.tap do |result|
           result.event_aggregation = compute_per_event_aggregation(exclude_event:)

app/services/billable_metrics/aggregations/sum_service.rb

@@ -4,7 +4,7 @@ module BillableMetrics
   module Aggregations
     class SumService < BillableMetrics::Aggregations::BaseService
       def initialize(...)
-        super(...)
+        super
 
         event_store.numeric_property = true
         event_store.aggregation_property = billable_metric.field_name
@@ -64,6 +64,10 @@ def compute_grouped_by_aggregation(options: {})
         result.service_failure!(code: 'aggregation_failure', message: e.message)
       end
 
+      def compute_precise_total_amount_cents(options: {})
+        result.precise_total_amount_cents = event_store.sum_precise_total_amount_cents
+      end
+
       # NOTE: Return cumulative sum of field_name based on the number of free units
       #       (per_events or per_total_aggregation).
       def running_total(options)

app/services/charges/charge_models/dynamic_service.rb

@@ -6,7 +6,7 @@ class DynamicService < Charges::ChargeModels::BaseService
       protected
 
       def compute_amount
-        (units * BigDecimal(properties['amount']))
+        aggregation_result.precise_total_amount_cents
       end
 
       def unit_amount

app/services/events/stores/postgres_store.rb

@@ -189,6 +189,10 @@ def grouped_last
         prepare_grouped_result(Event.connection.select_all(sql).rows)
       end
 
+      def sum_precise_total_amount_cents
+        events.sum(:precise_total_amount_cents)
+      end
+
       def sum
         events.sum("(#{sanitized_property_name})::numeric")
       end