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/*
 * DISCLAIMER
 *
 * Copyright 2017 ArangoDB GmbH, Cologne, Germany
 *
 * 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.
 *
 * Copyright holder is ArangoDB GmbH, Cologne, Germany
 */

package com.arangodb.internal.net;

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

/**
 * @author Mark Vollmary
 *
 */
public class RoundRobinHostHandler implements HostHandler {

	private final HostResolver resolver;
	private int current;
	private int fails;

	public RoundRobinHostHandler(final HostResolver resolver) {
		super();
		this.resolver = resolver;
		resolver.resolve(true, false);
		current = 0;
		fails = 0;
	}

	@Override
	public Host get(final HostHandle hostHandle, AccessType accessType) {
		final List hosts = resolver.resolve(false, false);
		final int size = hosts.size();
		if (fails > size) {
			return null;
		}
		final int index = (current++) % size;
		Host host = hosts.get(index);
		if (hostHandle != null) {
			final HostDescription hostDescription = hostHandle.getHost();
			if (hostDescription != null) {
				for (int i = index; i < index + size; i++) {
					host = hosts.get(i % size);
					if (hostDescription.equals(host.getDescription())) {
						break;
					}
				}
			} else {
				hostHandle.setHost(host.getDescription());
			}
		}
		return host;
	}

	@Override
	public void success() {
		fails = 0;
	}

	@Override
	public void fail() {
		fails++;
	}

	@Override
	public void reset() {
		fails = 0;
	}

	@Override
	public void confirm() {
	}

	@Override
	public void close() throws IOException {
		final List hosts = resolver.resolve(false, false);
		for (final Host host : hosts) {
			host.close();
		}
	}

	@Override
	public void closeCurrentOnError() {
		final List hosts = resolver.resolve(false, false);
		hosts.get(current).closeOnError();
	}

}