/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.phoenix.monitoring;

import java.util.List;
import org.apache.phoenix.util.InstanceResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;

/**
 * This class helps resolve the metricpublisher supplier class at the run time. Based on the
 * classString name passed, it will return the appropriate class Instance.
 */
public class MetricServiceResolver {

  private static final Logger LOGGER = LoggerFactory.getLogger(MetricServiceResolver.class);

  private MetricPublisherSupplierFactory metricSupplier = null;

  public MetricPublisherSupplierFactory instantiate(String classString) {
    Preconditions.checkNotNull(classString);
    if (metricSupplier == null) {
      try {
        Class clazz = Class.forName(classString);
        List<MetricPublisherSupplierFactory> factoryList =
          InstanceResolver.get(MetricPublisherSupplierFactory.class, null);
        for (MetricPublisherSupplierFactory factory : factoryList) {
          if (clazz.isInstance(factory)) {
            metricSupplier = factory;
            LOGGER.info(String.format(
              "Sucessfully loaded class for MetricPublishFactory of type: %s", classString));
            break;
          }
        }
        if (metricSupplier == null) {
          String msg = String.format("Could not load/instantiate class %s", classString);
          LOGGER.error(msg);
        }
      } catch (ClassNotFoundException e) {
        LOGGER.error(String.format("Could not load/instantiate class %s", classString), e);
      }
    }
    return metricSupplier;
  }
}
