feat(commons/kcal): kcal eval infrastructure

commons/src/main/java/commons/FormalIngredient.java

@@ -76,4 +76,15 @@ public class FormalIngredient extends RecipeIngredient implements Scalable<Forma
     public int hashCode() {
         return Objects.hash(super.hashCode(), amount, unitSuffix);
     }
+
+    @Override
+    public double kcal() {
+        final double PER_GRAMS = 100;
+        return ingredient.kcalPer100g() * amountInBaseUnit() / PER_GRAMS;
+    }
+
+    @Override
+    public double amount() {
+        return amountInBaseUnit();
+    }
 }

commons/src/main/java/commons/Recipe.java

@@ -198,7 +198,12 @@ public class Recipe {
             default -> throw new IllegalStateException("Unexpected value: " + ri);
         }).toList();
         return new Recipe(recipe.getId(), recipe.getName(), recipe.getLocale(), i, recipe.getPreparationSteps());
-
+    }
+    public double kcal() {
+        final double PER = 100; // Gram
+        return
+                this.ingredients.stream().mapToDouble(RecipeIngredient::kcal).sum() /
+                this.ingredients.stream().mapToDouble(RecipeIngredient::amount).sum() * PER;
     }
 
 }

commons/src/main/java/commons/RecipeIngredient.java

@@ -92,4 +92,6 @@ public abstract class RecipeIngredient {
     public int hashCode() {
         return Objects.hash(id, ingredient);
     }
+    public abstract double kcal();
+    public abstract double amount();
 }

commons/src/main/java/commons/VagueIngredient.java

@@ -50,4 +50,13 @@ public class VagueIngredient extends RecipeIngredient {
     public int hashCode() {
         return Objects.hashCode(description);
     }
+
+    @Override
+    public double kcal() {
+        return 0;
+    }
+    @Override
+    public double amount() {
+        return 0;
+    }
 }