/*
    * 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.shardingsphere.proxy.backend.mysql.handler.admin.executor;
  
  import com.google.common.eventbus.Subscribe;
  import lombok.Getter;
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.QueryResult;
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.QueryResultMetaData;
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.impl.raw.metadata.RawQueryResultColumnMetaData;
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.impl.raw.metadata.RawQueryResultMetaData;
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.impl.raw.type.RawMemoryQueryResult;
  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.type.memory.row.MemoryQueryResultDataRow;
  import org.apache.shardingsphere.infra.executor.sql.process.Process;
  import org.apache.shardingsphere.infra.merge.result.MergedResult;
  import org.apache.shardingsphere.infra.merge.result.impl.transparent.TransparentMergedResult;
  import org.apache.shardingsphere.infra.util.eventbus.EventSubscriber;
  import org.apache.shardingsphere.mode.process.event.ShowProcessListRequestEvent;
  import org.apache.shardingsphere.mode.process.event.ShowProcessListResponseEvent;
  import org.apache.shardingsphere.proxy.backend.context.ProxyContext;
  import org.apache.shardingsphere.proxy.backend.handler.admin.executor.DatabaseAdminQueryExecutor;
  import org.apache.shardingsphere.proxy.backend.session.ConnectionSession;
  
  import java.sql.Types;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  import java.util.stream.Collectors;
  
  /**
   * Show process list executor.
   */
  public final class ShowProcessListExecutor implements DatabaseAdminQueryExecutor, EventSubscriber {
      
      private final boolean showFullProcesslist;
      
      private Collection<Process> processes;
      
      @Getter
      private QueryResultMetaData queryResultMetaData;
      
      @Getter
      private MergedResult mergedResult;
      
      public ShowProcessListExecutor(final boolean showFullProcesslist) {
          this.showFullProcesslist = showFullProcesslist;
          ProxyContext.getInstance().getContextManager().getInstanceContext().getEventBusContext().register(this);
      }
      
      /**
       * Receive and handle response event.
       *
       * @param event show process list response event
       */
      @SuppressWarnings("unused")
      @Subscribe
      public void receiveProcessListData(final ShowProcessListResponseEvent event) {
          processes = event.getProcesses();
      }
      
      @Override
      public void execute(final ConnectionSession connectionSession) {
          queryResultMetaData = createQueryResultMetaData();
          mergedResult = new TransparentMergedResult(getQueryResult());
      }
      
      private QueryResult getQueryResult() {
          ProxyContext.getInstance().getContextManager().getInstanceContext().getEventBusContext().post(new ShowProcessListRequestEvent());
          if (null == processes || processes.isEmpty()) {
              return new RawMemoryQueryResult(queryResultMetaData, Collections.emptyList());
          }
          List<MemoryQueryResultDataRow> rows = processes.stream().map(this::getMemoryQueryResultDataRow).collect(Collectors.toList());
          return new RawMemoryQueryResult(queryResultMetaData, rows);
      }
      
      private MemoryQueryResultDataRow getMemoryQueryResultDataRow(final Process process) {
          List<Object> rowValues = new ArrayList<>(8);
          rowValues.add(process.getId());
          rowValues.add(process.getUsername());
          rowValues.add(process.getHostname());
          rowValues.add(process.getDatabaseName());
          rowValues.add(process.isIdle() ? "Sleep" : "Execute");
          rowValues.add(TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis() - process.getStartMillis()));
         String sql = null;
         if (process.isIdle()) {
             rowValues.add("");
         } else {
             int processDoneCount = process.getCompletedUnitCount().get();
             String statePrefix = "Executing ";
             rowValues.add(statePrefix + processDoneCount + "/" + process.getTotalUnitCount().get());
             sql = process.getSql();
         }
         if (null != sql && sql.length() > 100 && !showFullProcesslist) {
             sql = sql.substring(0, 100);
         }
         rowValues.add(null != sql ? sql : "");
         return new MemoryQueryResultDataRow(rowValues);
     }
     
     private QueryResultMetaData createQueryResultMetaData() {
         List<RawQueryResultColumnMetaData> columns = new ArrayList<>(8);
         columns.add(new RawQueryResultColumnMetaData("", "Id", "Id", Types.VARCHAR, "VARCHAR", 20, 0));
         columns.add(new RawQueryResultColumnMetaData("", "User", "User", Types.VARCHAR, "VARCHAR", 20, 0));
         columns.add(new RawQueryResultColumnMetaData("", "Host", "Host", Types.VARCHAR, "VARCHAR", 64, 0));
         columns.add(new RawQueryResultColumnMetaData("", "db", "db", Types.VARCHAR, "VARCHAR", 64, 0));
         columns.add(new RawQueryResultColumnMetaData("", "Command", "Command", Types.VARCHAR, "VARCHAR", 64, 0));
         columns.add(new RawQueryResultColumnMetaData("", "Time", "Time", Types.VARCHAR, "VARCHAR", 10, 0));
         columns.add(new RawQueryResultColumnMetaData("", "State", "State", Types.VARCHAR, "VARCHAR", 64, 0));
         columns.add(new RawQueryResultColumnMetaData("", "Info", "Info", Types.VARCHAR, "VARCHAR", 120, 0));
         return new RawQueryResultMetaData(columns);
     }
 }