/*
 * Copyright 2019 The FATE Authors. 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.
 */

package com.webank.ai.fate.register.loadbalance;

import com.webank.ai.fate.register.url.CollectionUtils;
import com.webank.ai.fate.register.url.URL;

import java.util.List;

import static com.webank.ai.fate.register.common.Constants.WEIGHT_KEY;

public abstract class AbstractLoadBalancer implements LoadBalancer {

    public static int DEFAULT_WEIGHT = 100;

    @Override
    public List<URL> select(List<URL> urls) {
        if (CollectionUtils.isEmpty(urls)) {
            return null;
        }
        if (urls.size() == 1) {
            return urls;
        }

        return doSelect(urls);
    }

    protected abstract List<URL> doSelect(List<URL> url);

    protected int getWeight(URL url) {
        int weight = url.getParameter(WEIGHT_KEY, DEFAULT_WEIGHT);
        return weight;
    }

}
