display nutrition data in recipe view

app/controllers/ingredients_controller.rb

@@ -118,7 +118,7 @@ class IngredientsController < ApplicationController
 
     # Never trust parameters from the scary internet, only allow the white list through.
     def ingredient_params
-      params.require(:ingredient).permit(:name, :notes, :ndbn, :density, :water, :protein, :lipids, :kcal, :fiber, :sugar)
+      params.require(:ingredient).permit(:name, :notes, :ndbn, :density, :water, :protein, :lipids, :carbohydrates, :kcal, :fiber, :sugar)
     end
 
     def conversion_params

app/models/ingredient.rb

@@ -40,6 +40,7 @@ class Ingredient < ActiveRecord::Base
     self.water = food.water
     self.protein = food.protein
     self.lipids = food.lipid
+    self.carbohydrates = food.carbohydrates
     self.ash = food.ash
     self.kcal = food.kcal
     self.fiber = food.fiber

app/models/nutrition_data.rb

@@ -0,0 +1,51 @@
+class NutritionData
+
+  attr_reader :protein, :lipids, :carbohydrates, :kcal, :fiber, :sugar, :errors
+
+  def initialize(recipe_ingredients)
+    @errors = []
+    @protein = 0.0
+    @lipids = 0.0
+    @kcal = 0.0
+    @fiber = 0.0
+    @sugar = 0.0
+    @carbohydrates = 0.0
+
+    valid_ingredients = []
+
+    recipe_ingredients.each do |i|
+      if i.ingredient_id.nil?
+        @errors << "#{i.name} has no nutrition data"
+      elsif !i.can_convert_to_grams?
+        @errors << "#{i.name} can't be converted to grams"
+      else
+        valid_ingredients << i
+      end
+    end
+
+    keys = [:protein, :lipids, :kcal, :fiber, :sugar, :carbohydrates]
+
+    valid_ingredients.each do |i|
+      grams = i.to_grams
+
+      keys.each do |k|
+        value = i.ingredient.send(k)
+        if value.present?
+          value = value.to_f
+          running_total = self.instance_variable_get("@#{k}".to_sym)
+          delta = (grams / 100.0) * value
+          self.instance_variable_set("@#{k}".to_sym, running_total + delta)
+        else
+          @errors << "#{i.name} missing #{k} data"
+        end
+      end
+    end
+
+    keys.each do |k|
+      v = self.instance_variable_get("@#{k}".to_sym)
+      self.instance_variable_set("@#{k}".to_sym, v.round(2))
+    end
+
+  end
+
+end

app/models/recipe.rb

@@ -30,5 +30,16 @@ class Recipe < ActiveRecord::Base
     end
   end
 
-
+  def nutrition_data(recalculate = false)
+    if recalculate || @nutrition_data.nil?
+      @nutrition_data = calculate_nutrition_data
+    end
+    @nutrition_data
+  end
+
+  private
+
+  def calculate_nutrition_data
+    NutritionData.new(recipe_ingredients)
+  end
 end

app/models/recipe_ingredient.rb

@@ -34,4 +34,19 @@ class RecipeIngredient < ActiveRecord::Base
     end
   end
 
+  def can_convert_to_grams?
+    if self.quantity.present? && self.units.present?
+      value_unit = UnitConversion.parse(self.quantity, self.units)
+      value_unit.mass? || (value_unit.volume? && self.ingredient && self.ingredient.density.present?)
+    else
+      false
+    end
+  end
+
+  def to_grams
+    value_unit = UnitConversion.parse(self.quantity, self.units)
+    gram_unit = value_unit.convert('g', self.ingredient ? self.ingredient.density : nil)
+    gram_unit.raw_value
+  end
+
 end

app/views/ingredients/_form.html.erb

@@ -57,6 +57,11 @@
           <%= f.text_field :lipids, class: 'form-control' %>
         </div>
 
+        <div class="form-group">
+          <%= f.label :carbohydrates, "Grams of Fat", class: 'control-label' %>
+          <%= f.text_field :carbohydrates, class: 'form-control' %>
+        </div>
+
         <div class="form-group">
           <%= f.label :kcal, "Calories", class: 'control-label' %>
           <%= f.text_field :kcal, class: 'form-control' %>

app/views/recipes/show.html.erb

@@ -91,6 +91,58 @@
     </div>
   </div>
 
+  <div class="row">
+    <div class="col-xs-12">
+      <div class="panel panel-default">
+        <div class="panel-heading">
+          <h3 class="panel-title">Nutrition Data</h3>
+        </div>
+        <div class="panel-body">
+          <table class="table">
+            <thread>
+              <tr>
+                <th>Item</th>
+                <th>Total</th>
+              </tr>
+            </thread>
+            <tr>
+              <td>Calories</td>
+              <td><%= @recipe.nutrition_data.kcal %></td>
+            </tr>
+            <tr>
+              <td>Grams Protein</td>
+              <td><%= @recipe.nutrition_data.protein %></td>
+            </tr>
+            <tr>
+              <td>Grams Fat</td>
+              <td><%= @recipe.nutrition_data.lipids %></td>
+            </tr>
+            <tr>
+              <td>Grams Carbohydrates</td>
+              <td><%= @recipe.nutrition_data.carbohydrates %></td>
+            </tr>
+            <tr>
+              <td>Grams Sugar</td>
+              <td><%= @recipe.nutrition_data.sugar %></td>
+            </tr>
+            <tr>
+              <td>Grams Fiber</td>
+              <td><%= @recipe.nutrition_data.fiber %></td>
+            </tr>
+          </table>
+
+          <h3>Nutrition Calculation Warnings</h3>
+
+          <ul>
+            <% @recipe.nutrition_data.errors.each do |err| %>
+              <li><%= err %></li>
+            <% end %>
+          </ul>
+        </div>
+      </div>
+    </div>
+  </div>
+
 </div>
 
 <div class="row">

spec/factories/ingredients.rb

@@ -5,4 +5,9 @@ FactoryGirl.define do
     notes 'note note note'
   end
 
+  factory :ingredient_with_density, parent: :ingredient do
+    name 'Butter'
+    density '8 oz/cup'
+  end
+
 end

spec/models/recipe_ingredient_spec.rb

@@ -2,4 +2,46 @@ require 'rails_helper'
 
 RSpec.describe RecipeIngredient, type: :model do
 
+  describe '#can_convert_to_grams' do
+    it 'returns false if no quantity or unit' do
+      ri = RecipeIngredient.new
+      expect(ri.can_convert_to_grams?).to be_falsey
+    end
+
+    it 'returns false if no quantity' do
+      ri = RecipeIngredient.new(units: 'lbs')
+      expect(ri.can_convert_to_grams?).to be_falsey
+    end
+
+    it 'returns false if no units' do
+      ri = RecipeIngredient.new(quantity: '5 1/2')
+      expect(ri.can_convert_to_grams?).to be_falsey
+    end
+
+    it 'returns false if weird units' do
+      ri = RecipeIngredient.new(quantity: '5 1/2', units: 'dogs')
+      expect(ri.can_convert_to_grams?).to be_falsey
+    end
+
+    it 'returns true if unit is mass' do
+      ri = RecipeIngredient.new(quantity: '5 1/2', units: 'lbs')
+      expect(ri.can_convert_to_grams?).to be_truthy
+    end
+
+    it 'returns false if unit is volume and there is no ingredient' do
+      ri = RecipeIngredient.new(quantity: '5 1/2', units: 'cups')
+      expect(ri.can_convert_to_grams?).to be_falsey
+    end
+
+    it 'returns false if unit is volume and ingredient has no density' do
+      ri = RecipeIngredient.new(quantity: '5 1/2', units: 'cups', ingredient: create(:ingredient))
+      expect(ri.can_convert_to_grams?).to be_falsey
+    end
+
+    it 'returns false if unit is volume and ingredient has density' do
+      ri = RecipeIngredient.new(quantity: '5 1/2', units: 'cups', ingredient: create(:ingredient_with_density))
+      expect(ri.can_convert_to_grams?).to be_truthy
+    end
+  end
+
 end