[CPDLP-3937] Add mentor funding statement and output calculators

app/components/finance/statements/ecf_details_table.rb

@@ -9,7 +9,7 @@ class ECFDetailsTable < BaseComponent
 
       def initialize(statement:)
         @statement = statement
-        @calculator = Finance::ECF::StatementCalculator.new(statement: @statement)
+        @calculator = Finance::ECF::ECT::StatementCalculator.new(statement: @statement)
       end
     end
   end

app/controllers/finance/ecf/statements_controller.rb

@@ -6,8 +6,12 @@ class StatementsController < BaseController
       def show
         @ecf_lead_provider = lead_provider_scope.find(params[:payment_breakdown_id])
         @statement = @ecf_lead_provider.statements.find(params[:id])
-        @calculator = StatementCalculator.new(statement: @statement)
+        @calculator = ECT::StatementCalculator.new(statement: @statement)
         set_important_message(title: t("finance.statements.payment_authorisations.banner.title"), content: t("finance.statements.payment_authorisations.banner.content", statement_marked_as_paid_at: @statement.marked_as_paid_at.strftime("%-I:%M%P on %-e %b %Y"))) if authorising_for_payment_banner_visible?(@statement)
+
+        if @statement.cohort.mentor_funding?
+          @mentor_calculator = Mentor::StatementCalculator.new(statement: @statement)
+        end
       end
 
     private

app/models/finance/statement/ecf.rb

@@ -30,7 +30,7 @@ def paid!
   end
 
   def calculator
-    @calculator ||= Finance::ECF::StatementCalculator.new(statement: self)
+    @calculator ||= Finance::ECF::ECT::StatementCalculator.new(statement: self)
   end
 
   def previous_statements

app/services/finance/ecf/ect/output_calculator.rb

@@ -0,0 +1,250 @@
+# frozen_string_literal: true
+
+module Finance
+  module ECF
+    module ECT
+      class OutputCalculator < Finance::ECF::OutputCalculator
+        COHORT_WITH_MENTOR_FUNDING_DECLARATION_CLASS_TYPES = ["ParticipantDeclaration::ECT"].freeze
+
+        def banding_breakdown
+          @banding_breakdown ||= begin
+            bandings = declaration_types.map do |declaration_type|
+              current_banding_for_declaration_type(declaration_type)
+            end
+
+            result = bandings[0]
+
+            band_letters.each do |letter|
+              bandings[1..].each do |banding|
+                new_chunk = banding.find { |e| e[:band] == letter }
+                result.find { |e| e[:band] == letter }.merge!(new_chunk)
+              end
+            end
+
+            result
+          end
+        end
+
+        def uplift_breakdown
+          @uplift_breakdown ||= {
+            previous_count: previous_fill_level_for_uplift,
+            count: current_billable_count_for_uplift - current_refundable_count_for_uplift,
+            additions: current_billable_count_for_uplift,
+            subtractions: current_refundable_count_for_uplift,
+          }
+        end
+
+        def fee_for_declaration(band_letter:, type:)
+          percentage = case type
+                       when :started
+                         started_event_percentage
+                       when :completed
+                         completed_event_percentage
+                       when :retained_1, :retained_2, :retained_3, :retained_4
+                         retained_event_percentage
+                       when :extended_1, :extended_2, :extended_3
+                         extended_event_percentage
+                       end
+
+          percentage * band_for_letter(band_letter).output_payment_per_participant
+        end
+
+      private
+
+        def band_for_letter(letter)
+          bands.zip(:a..:z).find { |e| e[1] == letter }[0]
+        end
+
+        def started_event_percentage
+          0.2
+        end
+
+        def completed_event_percentage
+          0.2
+        end
+
+        def retained_event_percentage
+          0.15
+        end
+
+        def extended_event_percentage
+          0.15
+        end
+
+        def declaration_types
+          %w[
+            started
+            retained-1
+            retained-2
+            retained-3
+            retained-4
+            completed
+            extended-1
+            extended-2
+            extended-3
+          ]
+        end
+
+        # this is a 3 pass algorithm
+        # first pass adds billable declarations
+        # second pass subtracts refunds
+        # third pass further subtracts refunds if statement is net negative
+        def current_banding_for_declaration_type(declaration_type)
+          pot_size = current_billable_count_for_declaration_type(declaration_type)
+
+          banding = previous_banding_for_declaration_type(declaration_type).map do |hash|
+            band_capacity = hash[:max] - (hash[:min] - 1) - hash[:"previous_#{declaration_type.underscore}_count"]
+
+            fill_level = [pot_size, band_capacity].min
+
+            pot_size -= fill_level
+
+            hash[:"#{declaration_type.underscore}_count"] = fill_level
+            hash[:"#{declaration_type.underscore}_additions"] = fill_level
+
+            hash
+          end
+
+          pot_size = current_refundable_count_declaration_type(declaration_type)
+
+          banding = banding.reverse.map do |hash|
+            fill_level = hash[:"#{declaration_type.underscore}_count"]
+
+            available = [fill_level, pot_size].min
+
+            hash[:"#{declaration_type.underscore}_count"] = fill_level - available
+            hash[:"#{declaration_type.underscore}_subtractions"] = available
+
+            pot_size -= available
+
+            hash
+          end
+
+          if pot_size.positive?
+            banding = banding.map do |hash|
+              available = hash[:"previous_#{declaration_type.underscore}_count"]
+
+              unless available.zero?
+                reduction = [pot_size, available].min
+
+                hash[:"#{declaration_type.underscore}_count"] = -reduction
+                hash[:"#{declaration_type.underscore}_subtractions"] += reduction
+
+                pot_size -= reduction
+              end
+
+              hash
+            end
+          end
+
+          banding.reverse
+        end
+
+        def previous_banding_for_declaration_type(declaration_type)
+          pot_size = previous_fill_level_for_declaration_type(declaration_type)
+
+          bands.zip(:a..:z).map do |band, letter|
+            # minimum band should always be 1 or more, otherwise band a will go over
+            # its max limit
+            band_min = band.min.to_i.zero? ? 1 : band.min
+
+            band_capacity = band.max - band_min + 1
+
+            fill_level = [pot_size, band_capacity].min
+
+            pot_size -= fill_level
+
+            key_name = "previous_#{declaration_type.underscore}_count".to_sym
+
+            {
+              band: letter,
+              min: band_min,
+              max: band.max,
+              key_name => fill_level,
+            }
+          end
+        end
+
+        def bands
+          statement.contract.bands.order(max: :asc)
+        end
+
+        def band_letters
+          bands.zip(:a..:z).map { |e| e[1] }
+        end
+
+        def previous_fill_level_for_declaration_type(declaration_type)
+          billable = Finance::StatementLineItem
+            .where(statement: statement.previous_statements)
+            .billable
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type:, type: participant_declaration_class_types })
+            .count
+
+          refundable = Finance::StatementLineItem
+            .where(statement: statement.previous_statements)
+            .refundable
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type:, type: participant_declaration_class_types })
+            .count
+
+          billable - refundable
+        end
+
+        def previous_fill_level_for_uplift
+          billable = Finance::StatementLineItem
+            .where(statement: statement.previous_statements)
+            .billable
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type: "started", type: participant_declaration_class_types })
+            .where("participant_declarations.sparsity_uplift = true OR participant_declarations.pupil_premium_uplift = true")
+            .count
+
+          refundable = Finance::StatementLineItem
+            .where(statement: statement.previous_statements)
+            .refundable
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type: "started", type: participant_declaration_class_types })
+            .where("participant_declarations.sparsity_uplift = true OR participant_declarations.pupil_premium_uplift = true")
+            .count
+
+          billable - refundable
+        end
+
+        def current_billable_count_for_declaration_type(declaration_type)
+          statement
+            .billable_statement_line_items
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type:, type: participant_declaration_class_types })
+            .count
+        end
+
+        def current_refundable_count_declaration_type(declaration_type)
+          statement
+            .refundable_statement_line_items
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type:, type: participant_declaration_class_types })
+            .count
+        end
+
+        def current_billable_count_for_uplift
+          statement
+            .billable_statement_line_items
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type: "started", type: participant_declaration_class_types })
+            .where("participant_declarations.sparsity_uplift = true OR participant_declarations.pupil_premium_uplift = true")
+            .count
+        end
+
+        def current_refundable_count_for_uplift
+          statement
+            .refundable_statement_line_items
+            .joins(:participant_declaration)
+            .where(participant_declarations: { declaration_type: "started", type: participant_declaration_class_types })
+            .where("participant_declarations.sparsity_uplift = true OR participant_declarations.pupil_premium_uplift = true")
+            .count
+        end
+      end
+    end
+  end
+end