/*
 * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.protocol.bgp.mode.impl.base;

import static java.util.Objects.requireNonNull;

import com.google.common.primitives.UnsignedInteger;
import org.opendaylight.protocol.bgp.mode.api.BestPathState;
import org.opendaylight.protocol.bgp.mode.impl.BestPathStateImpl;
import org.opendaylight.protocol.bgp.mode.spi.AbstractBestPathSelector;
import org.opendaylight.protocol.bgp.rib.spi.RouterIds;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev180329.path.attributes.Attributes;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

final class BasePathSelector extends AbstractBestPathSelector {
    private static final Logger LOG = LoggerFactory.getLogger(BasePathSelector.class);

    private UnsignedInteger bestRouterId = null;

    BasePathSelector(final Long ourAs) {
        super(ourAs);
    }

    void processPath(final UnsignedInteger routerId, final Attributes attrs) {
        requireNonNull(routerId, "Router ID may not be null");

        // Consider only non-null attributes
        if (attrs != null) {
            final UnsignedInteger originatorId = replaceOriginator(routerId, attrs.getOriginatorId());
            /*
             * Store the new details if we have nothing stored or when the selection algorithm indicates new details
             * are better.
             */
            final BestPathState state = new BestPathStateImpl(attrs);
            if (this.bestOriginatorId == null || !isExistingPathBetter(state)) {
                LOG.trace("Selecting path from router {}", RouterIds.createPeerId(routerId).getValue());
                this.bestOriginatorId = originatorId;
                this.bestRouterId = routerId;
                this.bestState = state;
            }
        }
    }


    BaseBestPath result() {
        return this.bestRouterId == null ? null : new BaseBestPath(this.bestRouterId, this.bestState);
    }
}