/*
 * Copyright (c) 2017 AT&T Intellectual Property. 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.l3vpn.unicast;

import com.google.common.base.Preconditions;
import io.netty.buffer.ByteBuf;
import java.util.ArrayList;
import java.util.List;
import org.opendaylight.bgp.concepts.RouteDistinguisherUtil;
import org.opendaylight.protocol.bgp.labeled.unicast.LUNlriParser;
import org.opendaylight.protocol.bgp.parser.BgpTableTypeImpl;
import org.opendaylight.protocol.bgp.parser.spi.MultiPathSupportUtil;
import org.opendaylight.protocol.bgp.parser.spi.PathIdUtil;
import org.opendaylight.protocol.bgp.parser.spi.PeerSpecificParserConstraint;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.labeled.unicast.rev180329.labeled.unicast.LabelStack;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev200120.AddressFamily;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev200120.SubsequentAddressFamily;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.vpn.rev180329.l3vpn.ip.destination.type.VpnDestination;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.vpn.rev180329.l3vpn.ip.destination.type.VpnDestinationBuilder;

final class VpnDestinationUtil {
    private VpnDestinationUtil() {
        // Hidden on purpose
    }

    static List<VpnDestination> parseNlri(
            final ByteBuf nlri,
            final PeerSpecificParserConstraint constraints,
            final AddressFamily afi,
            final SubsequentAddressFamily safi) {
        if (!nlri.isReadable()) {
            return null;
        }
        final List<VpnDestination> dests = new ArrayList<>();

        while (nlri.isReadable()) {
            final VpnDestinationBuilder builder = new VpnDestinationBuilder();
            if (MultiPathSupportUtil.isTableTypeSupported(constraints, new BgpTableTypeImpl(afi, safi))) {
                builder.setPathId(PathIdUtil.readPathId(nlri));
            }
            final short length = nlri.readUnsignedByte();
            final List<LabelStack> labels = LUNlriParser.parseLabel(nlri);
            builder.setLabelStack(labels);
            final int labelNum = labels != null ? labels.size() : 1;
            final int prefixLen = length - LUNlriParser.LABEL_LENGTH * Byte.SIZE * labelNum
                    - RouteDistinguisherUtil.RD_LENGTH * Byte.SIZE;
            builder.setRouteDistinguisher(RouteDistinguisherUtil.parseRouteDistinguisher(nlri));
            Preconditions.checkState(prefixLen > 0, "A valid VPN IP prefix is required.");
            builder.setPrefix(LUNlriParser.parseIpPrefix(nlri, prefixLen, afi));
            dests.add(builder.build());
        }
        return dests;
    }
}