/*
 * 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.flink.table.runtime.util;

import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.core.memory.MemorySegmentFactory;

import java.util.Collections;
import java.util.List;

/**
 */
public class BytesHashMapSpillMemorySegmentPool implements MemorySegmentPool {

	private final List<MemorySegment> segments;
	private final int pageSize;
	private int allocated;

	public BytesHashMapSpillMemorySegmentPool(int pageSize) {
		this.segments = Collections.EMPTY_LIST;
		this.pageSize = pageSize;
		this.allocated = 0;
	}

	public BytesHashMapSpillMemorySegmentPool(List<MemorySegment> memorySegments) {
		this.segments = memorySegments;
		this.pageSize = memorySegments.get(0).size();
		this.allocated = 0;
	}

	@Override
	public MemorySegment nextSegment() {
		allocated++;
		if (allocated <= segments.size()) {
			return segments.get(allocated - 1);
		} else {
			return MemorySegmentFactory.wrap(new byte[pageSize()]);
		}
	}

	@Override
	public void returnAll(List<MemorySegment> memory) {
		throw new UnsupportedOperationException("not support!");
	}

	@Override
	public int pageSize() {
		return pageSize;
	}

	@Override
	public void clear() {
		allocated = 0;
	}
}