java-recipe-manager/src/main/lombok/org/leumasjaffe/recipe/model/Ingredient.java

package org.leumasjaffe.recipe.model;

import org.leumasjaffe.container.Either;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.Getter;

@Data @AllArgsConstructor
public class Ingredient {
	@AllArgsConstructor @Getter
	public static enum Volume {
		ml("ml", 1),
		tsp("tsp", 5),
		Tbsp("Tbsp", 15),
		cup("cup", 240);

		final String displayName;
		final double atomicUnits;
	}
	
	@AllArgsConstructor @Getter
	public static enum Weight {
		g("g", 1),
		oz("oz", 28.3495),
		lb("lb", 453.592),
		kg("kg", 1000),
		pinch("pinch", 0.36),
		dash("dash", 0.72);
		
		final String displayName;
		final double atomicUnits;
	}
	
	String name;
	double value = 0;
	@JsonIgnore Either<Volume, Weight> measure;
	
	Ingredient plus(final Ingredient rhs) {
		if (!name.equals(rhs.name)) {
			throw new IllegalArgumentException("Combining ingredients of differing types");
		} else if (measure.getState() != rhs.measure.getState()) {
			throw new IllegalArgumentException("Cannot merge mass and volume together");
		}
		return new Ingredient(name, value + (rhs.value * conversionRatio(rhs.measure)), measure);
	}

	private double conversionRatio(Either<Volume, Weight> rhs) {
		return units(rhs) / units(measure);
	}

	private static double units(Either<Volume, Weight> measure) {
		return measure.unify(Volume::getAtomicUnits, Weight::getAtomicUnits);
	}
	
	@JsonProperty("unit")
	private String[] measureToString() {
		String[] rval = {null, null};
		return rval;
	}
	
	@JsonProperty("unit")
	private void measureFromString(String[] s) {
		if (s[0] != null) {
			measure = Either.ofLeft(Volume.valueOf(s[0]));
		} else if (s[1] != null) {
			measure = Either.ofRight(Weight.valueOf(s[1]));
		}
	}
}