Fixes #66

app/helpers/articles_helper.rb

@@ -15,13 +15,6 @@ def row_classes(article)
     classes.join(' ')
   end
 
-  def format_unit(unit_property, article)
-    unit_code = article.send(unit_property)
-    return article.unit if unit_code.nil?
-
-    ArticleUnitsLib.human_readable_unit(unit_code)
-  end
-
   def format_supplier_order_unit(article)
     format_unit(:supplier_order_unit, article)
   end
@@ -34,23 +27,6 @@ def format_billing_unit(article)
     format_unit(:billing_unit, article)
   end
 
-  def format_unit_with_ratios(unit_property, article)
-    base = format_unit(unit_property, article)
-    unit_code = article.send(unit_property)
-    return base if ArticleUnitsLib.unit_is_si_convertible(unit_code)
-
-    relevant_units = [article.article_unit_ratios.map(&:unit)]
-    relevant_units << article.supplier_order_unit unless unit_property == :supplier_order_unit
-    first_si_convertible_unit = relevant_units
-                                .flatten
-                                .find { |unit| ArticleUnitsLib.unit_is_si_convertible(unit) }
-
-    return base if first_si_convertible_unit.nil?
-
-    quantity = article.convert_quantity(1, unit_code, first_si_convertible_unit)
-    "#{base} (#{number_with_precision(quantity, precision: 2, strip_insignificant_zeros: true)}\u00a0#{ArticleUnitsLib.units.to_h[first_si_convertible_unit][:symbol]})"
-  end
-
   def format_supplier_order_unit_with_ratios(article)
     format_unit_with_ratios(:supplier_order_unit, article)
   end
@@ -77,4 +53,83 @@ def field_with_preset_value_and_errors(options)
       safe_join(output)
     end
   end
+
+  private
+
+  def format_unit_with_ratios(unit_property, article_version, reference_unit = :group_order_unit)
+    base = format_unit(unit_property, article_version)
+
+    factorized_unit_str = get_factorized_unit_str(article_version, unit_property, reference_unit) unless reference_unit.nil?
+    return base if factorized_unit_str.nil?
+
+    "#{base} (#{factorized_unit_str})"
+  end
+
+  def format_unit(unit_property, article)
+    unit_code = article.send(unit_property)
+    return article.unit if unit_code.nil?
+
+    ArticleUnitsLib.human_readable_unit(unit_code)
+  end
+
+  def get_factorized_unit_str(article_version, unit_property, reference_unit)
+    unit_code = article_version.send(unit_property)
+    reference_unit_code = article_version.send(reference_unit) || article_version.supplier_order_unit
+    return nil if ArticleUnitsLib.unit_is_si_convertible(unit_code)
+
+    factors = [{
+      quantity: article_version.convert_quantity(1, unit_code, reference_unit_code),
+      code: reference_unit_code
+    }]
+
+    first_si_conversible_unit_after_reference_unit = get_first_si_conversible_unit(article_version, reference_unit_code) unless ArticleUnitsLib.unit_is_si_convertible(reference_unit_code)
+    unless first_si_conversible_unit_after_reference_unit.nil?
+      factors << {
+        quantity: article_version.convert_quantity(1, reference_unit_code, first_si_conversible_unit_after_reference_unit),
+        code: first_si_conversible_unit_after_reference_unit
+      }
+    end
+
+    return nil if factors.length == 1 && factors.first[:quantity] == 1 && factors.first[:code] == unit_code
+
+    format_unit_factors(factors)
+  end
+
+  def get_first_si_conversible_unit(article_version, after_unit)
+    relevant_units = [article_version.supplier_order_unit] + article_version.article_unit_ratios.map(&:unit)
+
+    unit_index = relevant_units.find_index { |unit| unit == after_unit }
+    return nil if unit_index.nil?
+
+    relevant_units[unit_index + 1..].find { |unit| ArticleUnitsLib.unit_is_si_convertible(unit) }
+  end
+
+  def format_unit_factors(factors)
+    factor_str_arr = factors.each_with_index.map do |factor, index|
+      is_last = index + 1 == factors.length
+      format_unit_factor(factor, is_last)
+    end
+
+    factor_str_arr
+      .compact
+      .join("#{Prawn::Text::NBSP}×#{Prawn::Text::NBSP}")
+  end
+
+  def format_unit_factor(factor, with_unit)
+    return nil if !with_unit && factor[:quantity] == 1
+
+    quantity_str = number_with_precision(factor[:quantity], precision: 2, strip_insignificant_zeros: true)
+    return quantity_str unless with_unit
+
+    unit_data = ArticleUnitsLib.units.to_h[factor[:code]]
+    is_si_conversible = ArticleUnitsLib.unit_is_si_convertible(factor[:code])
+    unit_label = is_si_conversible ? unit_data[:symbol] : unit_data[:name]
+    return unit_label if factor[:quantity] == 1
+
+    multiplier_str = '×' unless is_si_conversible
+
+    [quantity_str, multiplier_str, unit_label]
+      .compact
+      .join(Prawn::Text::NBSP)
+  end
 end

spec/helpers/articles_helper_spec.rb

@@ -0,0 +1,125 @@
+require_relative '../spec_helper'
+
+describe ArticlesHelper do
+  include described_class
+
+  let(:article) { create(:article) }
+  let(:article_version) { article.latest_article_version }
+
+  describe 'formatting supplier order unit' do
+    def test_with_article_data(supplier_order_unit: nil, group_order_unit: nil, ratios: nil)
+      setup_article_version(supplier_order_unit: supplier_order_unit, group_order_unit: group_order_unit, ratios: ratios)
+      format_supplier_order_unit_with_ratios(article_version).gsub(Prawn::Text::NBSP, ' ')
+    end
+
+    describe 'without ratios' do
+      it 'formats SI conversible unit without ratios' do
+        result = test_with_article_data(supplier_order_unit: 'KGM')
+        expect(result).to eq('kg')
+      end
+
+      it 'formats non SI conversible unit' do
+        result = test_with_article_data(supplier_order_unit: 'XPK')
+        expect(result).to eq('Package')
+      end
+    end
+
+    describe 'with ratios' do
+      it 'formats ratio to group order unit' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XPK',
+          ratios: [[250, 'GRM']],
+          group_order_unit: 'GRM'
+        )
+        expect(result).to eq('Package (250 g)')
+      end
+
+      it 'formats ratio to first SI ratio if group order unit equals or defaults to supplier order unit' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XPK',
+          ratios: [[250, 'GRM']],
+          group_order_unit: nil
+        )
+        expect(result).to eq('Package (250 g)')
+      end
+
+      it 'formats ratio to group order unit with multiple ratios' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XCR',
+          ratios: [[20.148, 'KGM'], [20, 'XBO'], [10, 'LTR']],
+          group_order_unit: 'XBO'
+        )
+        expect(result).to eq('Crate (20 × 0.5 l)')
+      end
+
+      it 'formats ratio from group order unit to first SI ratio if group order unit equals or defaults to supplier order unit' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XPX',
+          ratios: [[100, 'XPC'], [400, 'XPK'], [4000, 'X6H'], [200_000, 'GRM']],
+          group_order_unit: 'XPK'
+        )
+        expect(result).to eq('Pallet (400 × 500 g)')
+      end
+
+      it 'formats ratio from group order unit to first SI ratio' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XPX',
+          ratios: [[100, 'XPC'], [400, 'XPK'], [4000, 'X6H'], [200_000, 'GRM']],
+          group_order_unit: 'KGM'
+        )
+        expect(result).to eq('Pallet (200 kg)')
+      end
+    end
+  end
+
+  describe 'formatting group order unit' do
+    def test_with_article_data(supplier_order_unit: nil, group_order_unit: nil, ratios: nil)
+      setup_article_version(supplier_order_unit: supplier_order_unit, group_order_unit: group_order_unit, ratios: ratios)
+      format_group_order_unit_with_ratios(article_version).gsub(Prawn::Text::NBSP, ' ')
+    end
+
+    describe 'without ratios' do
+      it 'formats SI conversible unit without ratios' do
+        result = test_with_article_data(supplier_order_unit: 'KGM', group_order_unit: 'KGM')
+        expect(result).to eq('kg')
+      end
+
+      it 'formats non SI conversible unit' do
+        result = test_with_article_data(supplier_order_unit: 'XPK', group_order_unit: 'XPK')
+        expect(result).to eq('Package')
+      end
+    end
+
+    describe 'with ratios' do
+      it 'formats group order unit without ratios if group order unit is SI conversible' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XPK',
+          ratios: [[250, 'GRM']],
+          group_order_unit: 'GRM'
+        )
+        expect(result).to eq('g')
+      end
+
+      it 'formats group order unit with ratio to first SI unit if group order unit is not SI conversible' do
+        result = test_with_article_data(
+          supplier_order_unit: 'XCR',
+          ratios: [[20.148, 'KGM'], [20, 'XBO'], [10, 'LTR']],
+          group_order_unit: 'XBO'
+        )
+        expect(result).to eq('Bottle (0.5 l)')
+      end
+    end
+  end
+end
+
+private
+
+def setup_article_version(supplier_order_unit:, ratios:, group_order_unit:)
+  article_version.supplier_order_unit = supplier_order_unit unless supplier_order_unit.nil?
+  unless ratios.nil?
+    article_version.article_unit_ratios = ratios.each_with_index.map do |ratio_data, index|
+      ArticleUnitRatio.create(sort: index, quantity: ratio_data[0], unit: ratio_data[1])
+    end
+  end
+  article_version.group_order_unit = group_order_unit unless group_order_unit.nil?
+end

spec/integration/articles_spec.rb

@@ -157,7 +157,7 @@
     end
 
     describe 'can update existing article' do
-      let!(:article) { create(:article, supplier: supplier, name: 'Foobar', order_number: 1, unit: '250 g') }
+      let!(:article) { create(:article, supplier: supplier, name: 'Foobar', order_number: 1, unit: '250 g', group_order_unit: nil) }
 
       it do
         find('input[type="submit"]').click
@@ -198,7 +198,7 @@
     end
 
     describe 'can convert units when updating' do
-      let!(:article) { create(:article, supplier: supplier, order_number: 1, unit: '250 g') }
+      let!(:article) { create(:article, supplier: supplier, order_number: 1, unit: '250 g', group_order_unit: nil) }
 
       it do
         check('articles_convert_units')