compute, secure and archive period total and cumulative total of each accounting period

app/models/accounting_period.rb

@@ -8,6 +8,7 @@ require 'version'
 class AccountingPeriod < ActiveRecord::Base
   before_destroy { false }
   before_update { false }
+  before_create :compute_totals
   after_create :archive_closed_data
 
   validates :start_at, :end_at, :closed_at, :closed_by, presence: true
@@ -19,6 +20,10 @@ class AccountingPeriod < ActiveRecord::Base
     false
   end
 
+  def invoices
+    Invoice.where('created_at >= :start_date AND created_at < :end_date', start_date: start_at, end_date: end_at)
+  end
+
   def archive_file
     dir = 'accounting'
 
@@ -37,6 +42,9 @@ class AccountingPeriod < ActiveRecord::Base
       partial: 'archive/accounting',
       locals: {
         invoices: invoices,
+        period_total: period_total,
+        perpetual_total: perpetual_total,
+        period_footprint: footprint,
         code_checksum: code_checksum,
         last_archive_checksum: last_archive_checksum,
         previous_file: previous_file,
@@ -52,8 +60,21 @@ class AccountingPeriod < ActiveRecord::Base
   end
 
   def archive_closed_data
-    data = Invoice.where('created_at >= :start_date AND created_at < :end_date', start_date: start_at, end_date: end_at)
-                  .includes(:invoice_items)
+    data = invoices.includes(:invoice_items)
     File.write(archive_file, to_json_archive(data))
   end
+
+  def compute_totals
+    self.period_total = invoices.all.map(&:total).reduce(:+)
+    self.perpetual_total = Invoice.where('created_at < :end_date', end_date: end_at).all.map(&:total).reduce(:+)
+    self.footprint = compute_footprint
+  end
+
+  def compute_footprint
+    columns  = Invoice.columns.map(&:name)
+                      .delete_if { |c| %w[footprint updated_at].include? c }
+
+    sha256 = Digest::SHA256.new
+    sha256.hexdigest "#{columns.map { |c| self[c] }.join}#{previous_period ? previous_period.footprint : ''}"
+  end
 end

app/views/archive/_accounting.json.jbuilder

@@ -50,6 +50,11 @@ json.invoices do
   end
 end
 
+json.totals do
+  json.period_total period_total / 100.0
+  json.perpetual_total perpetual_total / 100.0
+end
+
 json.software do
   json.name 'Fab-Manager'
   json.version software_version
@@ -60,3 +65,5 @@ json.previous_archive do
   json.filename previous_file
   json.checksum last_archive_checksum
 end
+
+json.period_footprint period_footprint

db/migrate/20190225101256_add_totals_to_accounting_period.rb

@@ -0,0 +1,6 @@
+class AddTotalsToAccountingPeriod < ActiveRecord::Migration
+  def change
+    add_column :accounting_periods, :period_total, :integer
+    add_column :accounting_periods, :perpetual_total, :integer
+  end
+end

db/migrate/20190225102847_add_footprint_to_accounting_period.rb

@@ -0,0 +1,5 @@
+class AddFootprintToAccountingPeriod < ActiveRecord::Migration
+  def change
+    add_column :accounting_periods, :footprint, :string
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20190211124726) do
+ActiveRecord::Schema.define(version: 20190225102847) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -36,8 +36,11 @@ ActiveRecord::Schema.define(version: 20190211124726) do
     t.date     "end_at"
     t.datetime "closed_at"
     t.integer  "closed_by"
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
+    t.datetime "created_at",      null: false
+    t.datetime "updated_at",      null: false
+    t.integer  "period_total"
+    t.integer  "perpetual_total"
+    t.string   "footprint"
   end
 
   create_table "addresses", force: :cascade do |t|