/*
 * Copyright 2015-present Open Networking Foundation
 *
 * 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.
 */

package org.onosproject.net.topology;

import org.onlab.graph.ScalarWeight;
import org.onlab.graph.Weight;
import org.onosproject.net.AnnotationKeys;

/**
 * Link weight for measuring link cost using the link metric annotation.
 */
public class MetricLinkWeight implements LinkWeigher {

    @Override
    public Weight getInitialWeight() {
        return ScalarWeight.toWeight(0.0);
    }

    @Override
    public Weight getNonViableWeight() {
        return ScalarWeight.NON_VIABLE_WEIGHT;
    }

    @Override
    public Weight weight(TopologyEdge edge) {
        String v = edge.link().annotations().value(AnnotationKeys.METRIC);
        try {
            return ScalarWeight.toWeight(v != null ? Double.parseDouble(v) : 1);
        } catch (NumberFormatException e) {
            return ScalarWeight.toWeight(1.0);
        }
    }
}