/*
 * 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.parquet.filter;

/**
 * Filter which will only materialize a page worth of results.
 */
public final class PagedRecordFilter implements RecordFilter {

  private final long startPos;
  private final long endPos;
  private long currentPos = 0;

  /**
   * Returns builder for creating a paged query.
   *
   * @param startPos The record to start from, numbering starts at 1.
   * @param pageSize The size of the page.
   * @return a paged record filter
   */
  public static UnboundRecordFilter page(final long startPos, final long pageSize) {
    return readers -> new PagedRecordFilter(startPos, pageSize);
  }

  /**
   * Private constructor, use column() instead.
   */
  private PagedRecordFilter(long startPos, long pageSize) {
    this.startPos = startPos;
    this.endPos = startPos + pageSize;
  }

  /**
   * Keeps track of how many times it is called. Only returns matches when the
   * record number is in the range.
   */
  @Override
  public boolean isMatch() {
    currentPos++;
    return ((currentPos >= startPos) && (currentPos < endPos));
  }
}
