/*
 *
 *  Copyright 2015 Netflix, Inc.
 *
 *     Licensed under the Apache License, Version 2.0 (the "License");
 *     you may not use this file except in compliance with the License.
 *     You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 *
 */
package com.netflix.genie.common.util;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.netflix.genie.common.exceptions.GenieException;
import com.netflix.genie.common.exceptions.GenieServerException;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;
import java.util.Collection;

/**
 * Utility methods for interacting with JSON.
 *
 * @author tgianos
 * @since 3.0.0
 */
public final class JsonUtils {
    /**
     * Protected constructor for a utility class.
     */
    protected JsonUtils() {
    }

    /**
     * Convert a Java object to a JSON string.
     *
     * @param value The Java object to marshall
     * @return The JSON string
     * @throws GenieException For any marshalling exception
     */
    public static String marshall(final Object value) throws GenieException {
        try {
            final ObjectMapper mapper = new ObjectMapper();
            return mapper.writeValueAsString(value);
        } catch (final JsonProcessingException jpe) {
            throw new GenieServerException(jpe);
        }
    }

    /**
     * Convert a JSON string of a collection back to a Java object.
     *
     * @param source        The JSON string
     * @param typeReference The type reference of the collection to unmarshall to
     * @param <T>           The type of the collection ie Set of String
     * @return The Java object
     * @throws GenieException For any exception during unmarshalling
     */
    public static <T extends Collection> T unmarshall(
            final String source,
            final TypeReference<T> typeReference
    ) throws GenieException {
        try {
            final ObjectMapper mapper = new ObjectMapper();
            if (StringUtils.isNotBlank(source)) {
                return mapper.readValue(source, typeReference);
            } else {
                return mapper.readValue("[]", typeReference);
            }
        } catch (final IOException ioe) {
            throw new GenieServerException(ioe);
        }
    }
}