/*
 * Copyright (c) 2016 Cisco and/or its affiliates.
 *
 * 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 io.fd.hc2vpp.nat.read;

import io.fd.honeycomb.translate.read.ReadContext;
import io.fd.honeycomb.translate.read.ReadFailedException;
import io.fd.honeycomb.translate.spi.read.Initialized;
import io.fd.honeycomb.translate.spi.read.InitializingListReaderCustomizer;
import io.fd.honeycomb.translate.util.read.cache.DumpCacheManager;
import io.fd.jvpp.nat.dto.Nat44StaticMappingDetailsReplyDump;
import io.fd.jvpp.nat.dto.Nat64BibDetailsReplyDump;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import javax.annotation.Nonnull;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.nat.rev180628.nat.InstancesBuilder;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.nat.rev180628.nat.instances.Instance;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.nat.rev180628.nat.instances.InstanceBuilder;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.nat.rev180628.nat.instances.InstanceKey;
import org.opendaylight.yangtools.concepts.Builder;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Nat instance ID is mapped to VRF-ID in VPP.
 */
final class NatInstanceCustomizer
        implements InitializingListReaderCustomizer<Instance, InstanceKey, InstanceBuilder> {

    private static final Logger LOG = LoggerFactory.getLogger(NatInstanceCustomizer.class);
    static final InstanceKey DEFAULT_VRF_ID = new InstanceKey(0L);

    private final DumpCacheManager<Nat44StaticMappingDetailsReplyDump, Void> nat44DumpManager;
    private final DumpCacheManager<Nat64BibDetailsReplyDump, Void> nat64DumpManager;

    NatInstanceCustomizer(
            final DumpCacheManager<Nat44StaticMappingDetailsReplyDump, Void> nat44DumpManager,
            final DumpCacheManager<Nat64BibDetailsReplyDump, Void> nat64DumpManager) {
        this.nat44DumpManager = nat44DumpManager;
        this.nat64DumpManager = nat64DumpManager;
    }

    @Nonnull
    @Override
    public InstanceBuilder getBuilder(@Nonnull final InstanceIdentifier<Instance> id) {
        return new InstanceBuilder();
    }

    @Override
    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<Instance> id,
                                      @Nonnull final InstanceBuilder builder, @Nonnull final ReadContext ctx)
            throws ReadFailedException {
        LOG.trace("Reading current attributes for nat-instance: {}", id);
        builder.setId(id.firstKeyOf(Instance.class).getId());
    }

    @Nonnull
    @Override
    public List<InstanceKey> getAllIds(@Nonnull final InstanceIdentifier<Instance> id,
                                          @Nonnull final ReadContext context) throws ReadFailedException {
        LOG.trace("Listing IDs for all nat-instances");

        // Find the nat instance IDs (vrf-ids) by listing all static mappings and their VRF assignment
        final List<InstanceKey> vrfIds = Stream.concat(
                nat44DumpManager.getDump(id, context.getModificationCache())
                        .orElse(new Nat44StaticMappingDetailsReplyDump()).nat44StaticMappingDetails.stream()
                        .map(detail -> detail.vrfId),
                nat64DumpManager.getDump(id, context.getModificationCache())
                        .orElse(new Nat64BibDetailsReplyDump()).nat64BibDetails.stream()
                        .map(detail -> detail.vrfId))
                // V4 (nat44) and V6 (nat64) VRFs in VPP can have the same id. We store them under single nat instance,
                // because the ietf-nat model does not require separate instances for nat44 and nat64 features.
                .distinct()
                .map(vrfId -> new InstanceKey((long) vrfId))
                .collect(Collectors.toList());

        // Add default vrf id if not present
        if (!vrfIds.contains(DEFAULT_VRF_ID)) {
            vrfIds.add(0, DEFAULT_VRF_ID);
        }

        LOG.debug("List of nat-instance keys (vrf-ids): {}", vrfIds);
        return vrfIds;
    }

    @Override
    public void merge(@Nonnull final Builder<? extends DataObject> builder, @Nonnull final List<Instance> readData) {
        ((InstancesBuilder) builder).setInstance(readData);
    }

    @Override
    public Initialized<Instance> init(
            @Nonnull final InstanceIdentifier<Instance> id,
            @Nonnull final Instance readValue,
            @Nonnull final ReadContext ctx) {
        return Initialized.create(id, readValue);
    }
}