/*-
 * ============LICENSE_START=======================================================
 * ONAP
 * ================================================================================
 * Copyright (C) 2020-2021 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.common.gson;

import com.google.gson.TypeAdapter;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.time.Instant;

/**
 * GSON Type Adapter for "Instant" fields, that encodes them as milliseconds.
 */
public class InstantAsMillisTypeAdapter extends TypeAdapter<Instant> {

    @Override
    public void write(JsonWriter out, Instant value) throws IOException {
        if (value == null) {
            out.nullValue();
        } else {
            out.value(value.toEpochMilli());
        }
    }

    @Override
    public Instant read(JsonReader in) throws IOException {
        if (in.peek() == JsonToken.NULL) {
            in.nextNull();
            return null;
        } else {
            var millis = in.nextLong();
            return Instant.ofEpochMilli(millis);
        }
    }
}