RecipeDeserializer.java

package com.loopperfect.buckaroo.serialization;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.gson.*;
import com.loopperfect.buckaroo.Identifier;
import com.loopperfect.buckaroo.Recipe;
import com.loopperfect.buckaroo.RecipeVersion;
import com.loopperfect.buckaroo.SemanticVersion;

import java.lang.reflect.Type;
import java.util.stream.Collectors;

public final class RecipeDeserializer implements JsonDeserializer<Recipe> {

    @Override
    public Recipe deserialize(final JsonElement jsonElement, final Type type, final JsonDeserializationContext context) throws JsonParseException {

        Preconditions.checkNotNull(jsonElement);
        Preconditions.checkNotNull(type);
        Preconditions.checkNotNull(context);

        final JsonObject jsonObject = jsonElement.getAsJsonObject();

        if (!jsonObject.has("name")) {
            throw new JsonParseException("Recipes must have a name element. ");
        }
        final String name = jsonObject.get("name").getAsString();

        if (!jsonObject.has("url")) {
            throw new JsonParseException("Recipes must have a url element. ");
        }
        final String url = jsonObject.get("url").getAsString();

        final JsonObject jsonObjectVersions = jsonObject.get("versions").getAsJsonObject();

        final ImmutableMap<SemanticVersion, RecipeVersion> versions = ImmutableMap.copyOf(
            jsonObjectVersions.entrySet().stream().collect(Collectors.toMap(
                x -> context.deserialize(new JsonPrimitive(x.getKey()), SemanticVersion.class),
                x -> context.deserialize(x.getValue(), RecipeVersion.class))));

        return Recipe.of(name, url, versions);
    }
}