content: /*
   * 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.calcite.adapter.os;
  
  import org.apache.calcite.linq4j.Enumerator;
  import org.apache.calcite.linq4j.Linq4j;
  import org.apache.calcite.util.trace.CalciteTrace;
  
  import org.slf4j.Logger;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Locale;
  
  /**
   * Enumerator that reads from OS's System.
   */
  public class OsQuery implements Enumerator<Object[]> {
    private static final Logger LOGGER = CalciteTrace.getParserTracer();
  
    private final Enumerator<Object[]> enumerator;
  
    public OsQuery(String type) {
      this.enumerator = Linq4j.enumerator(eval(type));
    }
  
    public Enumerator<Object[]> getEnumerator() {
      return enumerator;
    }
  
    @Override public Object[] current() {
      return enumerator.current();
    }
  
    @Override public boolean moveNext() {
      return enumerator.moveNext();
    }
  
    @Override public void reset() {
      enumerator.reset();
    }
  
    @Override public void close() {
      enumerator.close();
    }
  
    public List<Object[]> eval(String type) {
      OsQueryType queryType = OsQueryType.valueOf(type.toUpperCase(Locale.ROOT));
      try {
        return queryType.getInfo();
      } catch (Exception e) {
        LOGGER.error("Failed to get result's info", e);
        return new ArrayList<>();
      }
    }
  }
  