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/*
 * Copyright © 2021-present Arcade Data Ltd ([email protected])
 *
 * 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.
 *
 * SPDX-FileCopyrightText: 2021-present Arcade Data Ltd ([email protected])
 * SPDX-License-Identifier: Apache-2.0
 */
package com.arcadedb.graph;

import com.arcadedb.database.DatabaseInternal;
import com.arcadedb.utility.ResettableIterator;

import java.util.concurrent.atomic.*;

public abstract class ResettableIteratorBase implements ResettableIterator {
  protected final DatabaseInternal database;
  private final   EdgeSegment      initialContainer;
  protected       EdgeSegment      currentContainer;
  protected final AtomicInteger    currentPosition = new AtomicInteger(MutableEdgeSegment.CONTENT_START_POSITION);
  protected       int              browsed         = 0;

  protected ResettableIteratorBase(final DatabaseInternal database, final EdgeSegment current) {
    if (current == null)
      throw new IllegalArgumentException("Edge chunk is null");
    this.database = database;
    this.initialContainer = current;
    this.currentContainer = current;
  }

  @Override
  public void reset() {
    this.currentContainer = initialContainer;
    currentPosition.set(MutableEdgeSegment.CONTENT_START_POSITION);
    browsed = 0;
  }

  @Override
  public long countEntries() {
    long total = browsed;

    final EdgeSegment savedContainer = currentContainer;
    final int savedCurrentPosition = currentPosition.get();
    final int savedBrowsed = browsed;

    try {
      while (hasNext()) {
        next();
        ++total;
      }
    } finally {
      // RESTORE SAVED POSITION
      currentContainer = savedContainer;
      currentPosition.set(savedCurrentPosition);
      browsed = savedBrowsed;
    }

    return total;
  }

  @Override
  public long getBrowsed() {
    return browsed;
  }
}