Refactor amounts calculation

app/controllers/classes_controller.rb

@@ -54,7 +54,7 @@ def bulk_pfmp_completion
   def update_bulk_pfmp
     @pfmps = bulk_pfmp_completion_params[:pfmps].map do |pfmp_params|
       @classe.pfmps.find(pfmp_params[:id]).tap do |pfmp|
-        pfmp.day_count = pfmp_params[:day_count]
+        PfmpManager.new(pfmp).update(day_count: pfmp_params[:day_count])
       end
     end
 

app/controllers/pfmps_controller.rb

@@ -22,7 +22,7 @@ def edit; end
   def create
     @pfmp = Pfmp.new(pfmp_params.merge(schooling: @schooling))
 
-    if @pfmp.save
+    if PfmpManager.new(@pfmp).update(pfmp_params)
       redirect_to student_path(@schooling.student),
                   notice: t("pfmps.new.success")
     else
@@ -31,7 +31,7 @@ def create
   end
 
   def update
-    if @pfmp.update(pfmp_params)
+    if PfmpManager.new(@pfmp).update(pfmp_params)
       redirect_to school_year_class_schooling_pfmp_path(selected_school_year, @classe, @schooling, @pfmp),
                   notice: t("pfmps.edit.success")
     else

app/models/pfmp.rb

@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
 class Pfmp < ApplicationRecord # rubocop:disable Metrics/ClassLength
-  include PfmpAmountCalculator
-
   TRANSITION_CLASS = PfmpTransition
   STATE_MACHINE_CLASS = PfmpStateMachine
   TRANSITION_RELATION_NAME = :transitions
@@ -50,6 +48,8 @@ class Pfmp < ApplicationRecord # rubocop:disable Metrics/ClassLength
             comparison: { greater_than_or_equal_to: :start_date },
             if: -> { start_date && end_date }
 
+  validates :amount, numericality: { only_integer: true, allow_nil: true, greater_than_or_equal_to: 0 }
+
   validates :day_count,
             numericality: {
               only_integer: true,
@@ -66,25 +66,6 @@ class Pfmp < ApplicationRecord # rubocop:disable Metrics/ClassLength
 
   before_destroy :ensure_destroyable?, prepend: true
 
-  after_save do
-    if day_count.present?
-      transition_to!(:completed) if in_state?(:pending)
-    elsif in_state?(:completed, :validated)
-      transition_to!(:pending)
-    end
-  end
-
-  after_save :recalculate_amounts_if_needed
-
-  # Recalculate amounts for the current PFMP and all follow up PFMPs that are still modifiable
-  def recalculate_amounts_if_needed
-    changed_day_count = day_count_before_last_save != day_count
-
-    return if !changed_day_count
-
-    PfmpManager.new(self).recalculate_amounts!
-  end
-
   def validate!
     transition_to!(:validated)
   end
@@ -156,15 +137,24 @@ def can_retrigger_payment?
     latest_payment_request.failed?
   end
 
+  def all_pfmps_for_mef
+    student.pfmps
+           .joins(schooling: :classe)
+           .where("classes.mef_id": mef.id, "classes.school_year_id": school_year.id)
+  end
+
   private
 
   def amounts_yearly_cap
     return unless mef
 
+    pfmps = all_pfmps_for_mef
     cap = mef.wage.yearly_cap
-    total = all_pfmps_for_mef.sum(:amount)
+    total = pfmps.sum(:amount)
     return unless total > cap
 
-    errors.add(:amount, "Yearly cap of #{cap} not respected for Mef code: #{mef.code}")
+    errors.add(:amount,
+               "Yearly cap of #{cap} not respected for Mef code: #{mef.code} \\
+               -> #{total}/#{cap} with #{pfmps.count} PFMPs")
   end
 end

app/services/pfmp_manager.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 # Simple Ruby service to Handle complex actions on PFMPs
-# TODO: refactor PfmpAmountCalculator to be part of this class (requires a lot of spec changes)
 
 class PfmpManager
   class PfmpManagerError < StandardError; end
@@ -15,12 +14,29 @@ def initialize(pfmp)
     @pfmp = pfmp
   end
 
+  def update(params)
+    update!(params)
+    true
+  rescue ActiveRecord::RecordInvalid
+    false
+  end
+
+  def update!(params)
+    old_day_count = pfmp.day_count
+    pfmp.update!(params)
+
+    recalculate_amounts! if params[:day_count].present? && old_day_count != params[:day_count]
+
+    transition!
+  end
+
   def recalculate_amounts!
     raise PfmpNotModifiableError unless pfmp.can_be_modified?
 
-    ApplicationRecord.transaction do
-      pfmp.update!(amount: pfmp.calculate_amount)
-      rebalance_following_pfmps!
+    Pfmp.transaction do
+      pfmp.all_pfmps_for_mef.lock!
+      pfmp.update!(amount: calculate_amount)
+      rebalance_other_pfmps!
     end
   end
 
@@ -41,13 +57,29 @@ def retry_incomplete_payment_request!
   end
 
   def rectify_and_update_attributes!(confirmed_pfmp_params, confirmed_address_params)
-    ApplicationRecord.transaction do
+    Pfmp.transaction do
       @pfmp.update!(confirmed_pfmp_params)
       @pfmp.student.update!(confirmed_address_params)
       @pfmp.rectify!
     end
   end
 
+  def calculate_amount
+    return 0 if pfmp.day_count.nil?
+
+    [
+      pfmp.day_count * pfmp.wage.daily_rate,
+      pfmp.wage.yearly_cap - previously_locked_amount
+    ].min
+  end
+
+  def previously_locked_amount
+    other_priced_pfmps
+      .map(&:amount)
+      .compact
+      .sum
+  end
+
   def retry_payment_request!(reasons)
     return unless @pfmp.latest_payment_request&.eligible_for_rejected_or_unpaid_auto_retry?(reasons)
 
@@ -57,9 +89,31 @@ def retry_payment_request!(reasons)
 
   private
 
-  def rebalance_following_pfmps!
-    pfmp.rebalancable_pfmps.each do |pfmp|
-      pfmp.update!(amount: pfmp.calculate_amount)
+  def other_pfmps_for_mef
+    pfmp.all_pfmps_for_mef.excluding(pfmp)
+  end
+
+  def other_priced_pfmps
+    other_pfmps_for_mef
+      .where.not(amount: nil)
+  end
+
+  def rebalancable_pfmps
+    @rebalancable_pfmps ||= other_pfmps_for_mef
+                            .select(&:can_be_rebalanced?)
+  end
+
+  def rebalance_other_pfmps!
+    rebalancable_pfmps.each do |rebalancable_pfmp|
+      rebalancable_pfmp.update!(amount: PfmpManager.new(rebalancable_pfmp).calculate_amount)
+    end
+  end
+
+  def transition!
+    if pfmp.day_count.present?
+      pfmp.transition_to!(:completed) if pfmp.in_state?(:pending)
+    elsif pfmp.in_state?(:completed, :validated)
+      pfmp.transition_to!(:pending)
     end
   end
 end

app/views/pfmps/_payment_panel.html.haml

@@ -13,5 +13,5 @@
     = number_to_currency pfmp.wage.yearly_cap
     de plafond maximum par an
   %div.fr-mb-1w
-    = number_to_currency pfmp.previously_locked_amount
+    = number_to_currency PfmpManager.new(pfmp).previously_locked_amount
     déjà engagés par d'autres PFMPs sur cette scolarité.

spec/factories/pfmps.rb

@@ -11,7 +11,12 @@
     end
 
     trait :completed do
-      day_count { rand(1..6) } # lovely roll dice
+      transient do
+        day_count { 3 }
+      end
+      after(:create) do |pfmp, eval|
+        PfmpManager.new(pfmp).update!(day_count: eval.day_count)
+      end
     end
 
     trait :can_be_validated do
@@ -44,5 +49,9 @@
         pfmp.reload.rectify!
       end
     end
+
+    after(:build) do |pfmp, _|
+      PfmpManager.new(pfmp).update!(day_count: pfmp.day_count)
+    end
   end
 end