/*
 * Copyright (c) 2015 EMC Corporation
 * All Rights Reserved
 */
package util;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import play.mvc.results.RenderJson;

import com.google.gson.ExclusionStrategy;
import com.google.gson.FieldAttributes;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class Json {

    /**
     * Serializes the given object to JSON, ignoring any fields marked with {@link JsonIgnore}
     */
    public static String toSafeJson(Object object) {
        Gson gson = new GsonBuilder().addSerializationExclusionStrategy(new IgnoreExclusionStrategy())
                .create();

        return gson.toJson(object);
    }

    /**
     * Renders a Controller response as JSON, ignoring any fields marked with {@link JsonIgnore}
     */
    public static void renderSafeJson(Object object) {
        throw new RenderJson(toSafeJson(object));
    }

    public static String toPrettyJson(Object object) {
        Gson gson = new GsonBuilder().setPrettyPrinting().create();
        return gson.toJson(object);
    }

    /**
     * Renders a Controller response as JSON, ignoring any fields marked with {@link JsonIgnore}
     */
    public static void renderPrettyJson(Object object) {
        throw new RenderJson(toPrettyJson(object));
    }

    /**
     * Signifies that the specified field should NOT be included during Json Serialization
     */
    @Retention(RetentionPolicy.RUNTIME)
    @java.lang.annotation.Target(java.lang.annotation.ElementType.FIELD)
    public @interface JsonIgnore {
    }

    private static class IgnoreExclusionStrategy implements ExclusionStrategy {
        @Override
        public boolean shouldSkipClass(Class<?> classAttrs) {
            return false;
        }

        @Override
        public boolean shouldSkipField(FieldAttributes fieldAttrs) {
            return fieldAttrs.getAnnotation(JsonIgnore.class) != null;
        }
    }
}