/**
 * Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com)
 *
 * 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.linkedin.pinot.controller.helix.core.sharding;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.apache.helix.HelixAdmin;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.linkedin.pinot.common.segment.SegmentMetadata;
import com.linkedin.pinot.common.utils.ControllerTenantNameBuilder;
import com.linkedin.pinot.common.utils.helix.HelixHelper;


/**
 * Assigns a segment to the instance that has same sharding key.
 *
 *
 */
public class BucketizedSegmentStrategy implements SegmentAssignmentStrategy {
  private static final Logger LOGGER = LoggerFactory.getLogger(BucketizedSegmentStrategy.class);

  @Override
  public List<String> getAssignedInstances(HelixAdmin helixAdmin, String helixClusterName,
      SegmentMetadata segmentMetadata, int numReplicas, String tenantName) {
    String serverTenantName = null;
    if ("realtime".equalsIgnoreCase(segmentMetadata.getIndexType())) {
      serverTenantName = ControllerTenantNameBuilder.getRealtimeTenantNameForTenant(tenantName);
    } else {
      serverTenantName = ControllerTenantNameBuilder.getOfflineTenantNameForTenant(tenantName);
    }

    List<String> allInstances = HelixHelper.getEnabledInstancesWithTag(helixAdmin, helixClusterName, serverTenantName);
    List<String> selectedInstanceList = new ArrayList<String>();
    if (segmentMetadata.getShardingKey() != null) {
      for (String instance : allInstances) {
        if (HelixHelper.getInstanceConfigsMapFor(instance, helixClusterName, helixAdmin).get("shardingKey")
            .equalsIgnoreCase(segmentMetadata.getShardingKey())) {
          selectedInstanceList.add(instance);
        }
      }
      LOGGER.info("Segment assignment result for : " + segmentMetadata.getName() + ", in resource : "
          + segmentMetadata.getTableName() + ", selected instances: "
          + Arrays.toString(selectedInstanceList.toArray()));
      return selectedInstanceList;
    } else {
      throw new RuntimeException("Segment missing sharding key!");
    }
  }
}