/*
 * 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.solr.client.solrj.io.eval;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

public class LeftShiftEvaluator extends RecursiveObjectEvaluator implements TwoValueWorker {
  protected static final long serialVersionUID = 1L;

  public LeftShiftEvaluator(StreamExpression expression, StreamFactory factory) throws IOException{
    super(expression, factory);

    if(2 != containedEvaluators.size()){
      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting exactly 2 value but found %d",expression,containedEvaluators.size()));
    }
  }

  @Override
  public Object doWork(Object value1, Object value2) throws IOException {
    if (value1 instanceof List && value2 instanceof Number) {
      List<?> actual = (List<?>) value1;
      int val = ((Number) value2).intValue();

      List<Object> shifted = new ArrayList<>();
      for (int i = val; i < actual.size(); i++) {
        shifted.add(actual.get(i));
      }
      return shifted;
    } else {
      throw new IOException("The ltrim function takes two parameters: an array and number to trim it by");
    }
  }
}