Add TradeTariffBackend::NumberFormatter

Helps format duty expression amounts. Cases:

* If we have 0.3435 we want this exact number => 0.3435
* If we have 0.34528 we want it rounded to 4 precision points => 0.3453
* If we have 0.23 we want to leave it as it is => 0.23
* If we have 0.2 we want add single leading zero => 0.20
* If we have 1 we want to add two leading zeros => 1.00

app/formatters/duty_expression_formatter.rb

@@ -1,68 +1,74 @@
 class DutyExpressionFormatter
+  class << self
+    def prettify(float)
+      TradeTariffBackend.number_formatter.number_with_precision(
+        float,
+        minimum_decimal_points: 2,
+        precision: 4,
+        strip_insignificant_zeros: true
+      )
+    end
 
-  def self.prettify(float)
-    sprintf("%.2f", float)
-  end
-
-  def self.format(opts={})
-    duty_expression_id = opts[:duty_expression_id]
-    duty_expression_description = opts[:duty_expression_description]
-    duty_expression_abbreviation = opts[:duty_expression_abbreviation]
-    duty_amount = opts[:duty_amount]
-    monetary_unit = opts[:monetary_unit_abbreviation].presence || opts[:monetary_unit]
-    measurement_unit = opts[:measurement_unit]
-    measurement_unit_qualifier = opts[:formatted_measurement_unit_qualifier]
+    def format(opts={})
+      duty_expression_id = opts[:duty_expression_id]
+      duty_expression_description = opts[:duty_expression_description]
+      duty_expression_abbreviation = opts[:duty_expression_abbreviation]
+      duty_amount = opts[:duty_amount]
+      monetary_unit = opts[:monetary_unit_abbreviation].presence || opts[:monetary_unit]
+      measurement_unit = opts[:measurement_unit]
+      measurement_unit_qualifier = opts[:formatted_measurement_unit_qualifier]
 
-    output = []
+      output = []
 
-    case duty_expression_id
-    when "99"
-      output << measurement_unit
-    when "12", "14", "37", "40", "41", "42", "43", "44", "21", "25", "27", "29"
-      if duty_expression_abbreviation.present?
-        output << duty_expression_abbreviation
-      elsif duty_expression_description.present?
-        output << duty_expression_description
-      end
-    when "02", "04", "15", "17", "19", "20", "36"
-      if duty_expression_abbreviation.present?
-        output << duty_expression_abbreviation
-      elsif duty_expression_description.present?
-        output << duty_expression_description
-      end
-      if duty_amount.present?
-        output << prettify(duty_amount).to_s
-      end
-      if monetary_unit.present?
-        output << monetary_unit
+      case duty_expression_id
+      when "99"
+        output << measurement_unit
+      when "12", "14", "37", "40", "41", "42", "43", "44", "21", "25", "27", "29"
+        if duty_expression_abbreviation.present?
+          output << duty_expression_abbreviation
+        elsif duty_expression_description.present?
+          output << duty_expression_description
+        end
+      when "02", "04", "15", "17", "19", "20", "36"
+        if duty_expression_abbreviation.present?
+          output << duty_expression_abbreviation
+        elsif duty_expression_description.present?
+          output << duty_expression_description
+        end
+        if duty_amount.present?
+          output << prettify(duty_amount).to_s
+        end
+        if monetary_unit.present?
+          output << monetary_unit
+        else
+          output << "%"
+        end
+        if measurement_unit.present? && measurement_unit_qualifier.present?
+          output << "/ (#{measurement_unit}/#{measurement_unit_qualifier})"
+        elsif measurement_unit.present?
+          output << "/ #{measurement_unit}"
+        end
       else
-        output << "%"
-      end
-      if measurement_unit.present? && measurement_unit_qualifier.present?
-        output << "/ (#{measurement_unit}/#{measurement_unit_qualifier})"
-      elsif measurement_unit.present?
-        output << "/ #{measurement_unit}"
-      end
-    else
-      if duty_amount.present?
-        output << prettify(duty_amount).to_s
-      end
-      if duty_expression_abbreviation.present? && !monetary_unit.present?
-        output << duty_expression_abbreviation
-      elsif duty_expression_description.present? && !monetary_unit.present?
-        output << duty_expression_description
-      elsif duty_expression_description.blank?
-        output << "%"
-      end
-      if monetary_unit.present?
-        output << monetary_unit
-      end
-      if measurement_unit.present? && measurement_unit_qualifier.present?
-        output << "/ (#{measurement_unit}/#{measurement_unit_qualifier})"
-      elsif measurement_unit.present?
-        output << "/ #{measurement_unit}"
+        if duty_amount.present?
+          output << prettify(duty_amount).to_s
+        end
+        if duty_expression_abbreviation.present? && !monetary_unit.present?
+          output << duty_expression_abbreviation
+        elsif duty_expression_description.present? && !monetary_unit.present?
+          output << duty_expression_description
+        elsif duty_expression_description.blank?
+          output << "%"
+        end
+        if monetary_unit.present?
+          output << monetary_unit
+        end
+        if measurement_unit.present? && measurement_unit_qualifier.present?
+          output << "/ (#{measurement_unit}/#{measurement_unit_qualifier})"
+        elsif measurement_unit.present?
+          output << "/ #{measurement_unit}"
+        end
       end
+      output.join(" ").html_safe
     end
-    output.join(" ").html_safe
   end
 end

app/formatters/requirement_duty_expression_formatter.rb

@@ -1,27 +1,34 @@
 class RequirementDutyExpressionFormatter
-  def self.prettify(float)
-    sprintf("%.2f", float)
-  end
+  class << self
+    def prettify(float)
+      TradeTariffBackend.number_formatter.number_with_precision(
+        float,
+        precision: 4,
+        minimum_decimal_points: 2,
+        strip_insignificant_zeros: true
+      )
+    end
 
-  def self.format(opts={})
-    duty_amount = opts[:duty_amount]
-    monetary_unit = opts[:monetary_unit_abbreviation].presence || opts[:monetary_unit]
-    measurement_unit = opts[:measurement_unit]
-    measurement_unit_qualifier = opts[:formatted_measurement_unit_qualifier]
+    def format(opts={})
+      duty_amount = opts[:duty_amount]
+      monetary_unit = opts[:monetary_unit_abbreviation].presence || opts[:monetary_unit]
+      measurement_unit = opts[:measurement_unit]
+      measurement_unit_qualifier = opts[:formatted_measurement_unit_qualifier]
 
-    output = []
+      output = []
 
-    if duty_amount.present?
-      output << prettify(duty_amount).to_s
-    end
+      if duty_amount.present?
+        output << prettify(duty_amount).to_s
+      end
 
-    if monetary_unit.present? && measurement_unit.present? && measurement_unit_qualifier.present?
-      output << "#{monetary_unit}/(#{measurement_unit}/#{measurement_unit_qualifier})"
-    elsif monetary_unit.present? && measurement_unit.present?
-      output << "#{monetary_unit}/#{measurement_unit}"
-    elsif measurement_unit.present?
-      output << measurement_unit
+      if monetary_unit.present? && measurement_unit.present? && measurement_unit_qualifier.present?
+        output << "#{monetary_unit}/(#{measurement_unit}/#{measurement_unit_qualifier})"
+      elsif monetary_unit.present? && measurement_unit.present?
+        output << "#{monetary_unit}/#{measurement_unit}"
+      elsif measurement_unit.present?
+        output << measurement_unit
+      end
+      output.join(" ").html_safe
     end
-    output.join(" ").html_safe
   end
 end

lib/trade_tariff_backend.rb

@@ -6,8 +6,9 @@ module TradeTariffBackend
   autoload :DataMigrator,    'trade_tariff_backend/data_migrator'
   autoload :Indexer,         'trade_tariff_backend/indexer'
   autoload :Mailer,          'trade_tariff_backend/mailer'
+  autoload :NumberFormatter, 'trade_tariff_backend/number_formatter'
   autoload :SearchIndex,     'trade_tariff_backend/search_index'
-  autoload :Validator,        'trade_tariff_backend/validator'
+  autoload :Validator,       'trade_tariff_backend/validator'
 
   class << self
 
@@ -76,6 +77,10 @@ def search_index
       SearchIndex
     end
 
+    def number_formatter
+      @number_formatter ||= TradeTariffBackend::NumberFormatter.new
+    end
+
     private
 
     def load_secrets

lib/trade_tariff_backend/number_formatter.rb

@@ -0,0 +1,33 @@
+module TradeTariffBackend
+  class NumberFormatter
+    # NOTE: Port to ActiveSupport::NumberHelper when on Rails 4
+    include ActionView::Helpers::NumberHelper
+
+    # Extension to #number_with_precision that allows
+    # to have certain number of decimal zeros even
+    # when stripping of insignificant zeros is enabled
+    #
+    # E.g.:
+    #
+    # number_with_precision(1.2, minimum_decimal_points: 2) => '1.20'
+    # number_with_precision(1.2456, minimum_decimal_points: 2, precision: 4, strip_insignificant_zeros: true) => '1.2456'
+    # number_with_precision(1.3, minimum_decimal_points: 2, precision: 4, strip_insignificant_zeros: true) => '1.30'
+
+    def number_with_precision(number, opts = {})
+      minimum_decimal_points = opts.delete(:minimum_decimal_points)
+      formatted_number = super(number, opts)
+
+      if minimum_decimal_points && precision_for(formatted_number) < minimum_decimal_points
+        "%.#{minimum_decimal_points}f" % formatted_number.to_f
+      else
+        formatted_number
+      end
+    end
+
+    private
+
+    def precision_for(number)
+      number.to_f.to_s.split('.').last.size
+    end
+  end
+end

spec/formatters/duty_expression_formatter_spec.rb

@@ -133,4 +133,18 @@
       end
     end
   end
+
+  describe '.prettify' do
+    context 'has less than 4 decimal places' do
+      it 'returns number with insignificant zeros stripped up to 2 decimal points' do
+        expect(DutyExpressionFormatter.prettify(1.2)).to eq '1.20'
+      end
+    end
+
+    context 'has 4 or more decimal places' do
+      it 'returns formatted number with 4 decimal places' do
+        expect(DutyExpressionFormatter.prettify(1.23456)).to eq '1.2346'
+      end
+    end
+  end
 end

spec/formatters/requirement_duty_expression_formatter_spec.rb

@@ -42,4 +42,18 @@
       end
     end
   end
+
+  describe '.prettify' do
+    context 'has less than 4 decimal places' do
+      it 'returns number with insignificant zeros stripped up to 2 decimal points' do
+        expect(RequirementDutyExpressionFormatter.prettify(1.2)).to eq '1.20'
+      end
+    end
+
+    context 'has 4 or more decimal places' do
+      it 'returns formatted number with 4 decimal places' do
+        expect(RequirementDutyExpressionFormatter.prettify(1.23456)).to eq '1.2346'
+      end
+    end
+  end
 end

spec/unit/trade_tariff_backend/number_formatter_spec.rb

@@ -0,0 +1,49 @@
+require 'spec_helper'
+
+describe TradeTariffBackend::NumberFormatter do
+  let(:number_formatter) { described_class.new }
+
+  describe '#number_with_precision' do
+    context 'with minimum_decimal_points option' do
+      it 'adds leading zero decimal numbers up to specified count' do
+        expect(number_formatter.number_with_precision(1.2, minimum_decimal_points: 4)).to eq '1.2000'
+        expect(number_formatter.number_with_precision(1, minimum_decimal_points: 4)).to eq '1.0000'
+        expect(number_formatter.number_with_precision(1.23, minimum_decimal_points: 4)).to eq '1.2300'
+      end
+
+      context 'with precision specified' do
+        it 'rounds to specified precision and adds leading decimal numbers if needed' do
+          expect(
+            number_formatter.number_with_precision(
+              1.256,
+              minimum_decimal_points: 2,
+              precision: 1
+            )
+          ).to eq '1.30'
+        end
+      end
+
+      context 'with stripping of insignificant zeros enabled' do
+        it 'strips insignificant zeroes up to minimum decimal points size' do
+          expect(
+            number_formatter.number_with_precision(
+              1.256,
+              minimum_decimal_points: 2,
+              precision: 1,
+              strip_insignificant_zeroes: true
+            )
+          ).to eq '1.30'
+
+          expect(
+            number_formatter.number_with_precision(
+              1.25656,
+              minimum_decimal_points: 4,
+              precision: 3,
+              strip_insignificant_zeroes: true
+            )
+          ).to eq '1.2570'
+        end
+      end
+    end
+  end
+end