/*
 * Copyright (c) 2017 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.vpp.classifier.write;

import java.util.Optional;
import io.fd.hc2vpp.common.translate.util.ByteDataTranslator;
import io.fd.hc2vpp.common.translate.util.JvppReplyConsumer;
import io.fd.hc2vpp.common.translate.util.NamingContext;
import io.fd.hc2vpp.vpp.classifier.context.VppClassifierContextManager;
import io.fd.honeycomb.translate.MappingContext;
import io.fd.honeycomb.translate.spi.write.ListWriterCustomizer;
import io.fd.honeycomb.translate.write.WriteContext;
import io.fd.honeycomb.translate.write.WriteFailedException;
import io.fd.jvpp.VppBaseCallException;
import io.fd.jvpp.core.dto.ClassifyAddDelSession;
import io.fd.jvpp.core.dto.ClassifyAddDelSessionReply;
import io.fd.jvpp.core.future.FutureJVppCore;
import java.util.concurrent.CompletionStage;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.OpaqueIndex;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.classify.session.attributes.NextNode;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.classify.session.attributes.next_node.Policer;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.classify.session.attributes.next_node.Standard;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.classify.table.base.attributes.ClassifySession;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.classify.table.base.attributes.ClassifySessionKey;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.vpp.classifier.ClassifyTable;
import org.opendaylight.yang.gen.v1.http.fd.io.hc2vpp.yang.vpp.classifier.rev170327.vpp.classifier.ClassifyTableKey;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Writer customizer responsible for classify session create/delete.<br> Sends {@code classify_add_del_session} message
 * to VPP.<br> Equivalent to invoking {@code vppctl classify table} command.
 */
public class ClassifySessionWriter extends VppNodeWriter
    implements ListWriterCustomizer<ClassifySession, ClassifySessionKey>, ByteDataTranslator, ClassifyWriter,
    JvppReplyConsumer {

    private static final Logger LOG = LoggerFactory.getLogger(ClassifySessionWriter.class);
    private final VppClassifierContextManager classifyTableContext;
    private final NamingContext policerContext;

    public ClassifySessionWriter(@Nonnull final FutureJVppCore futureJVppCore,
                                 @Nonnull final VppClassifierContextManager classifyTableContext,
                                 @Nonnull final NamingContext policerContext) {
        super(futureJVppCore);
        this.classifyTableContext = classifyTableContext;
        this.policerContext = policerContext;
    }

    @Override
    public void writeCurrentAttributes(@Nonnull final InstanceIdentifier<ClassifySession> id,
                                       @Nonnull final ClassifySession dataAfter,
                                       @Nonnull final WriteContext writeContext) throws WriteFailedException {
        LOG.debug("Creating classify session: iid={} dataAfter={}", id, dataAfter);
        try {
            classifyAddDelSession(true, id, dataAfter, writeContext);
            LOG.debug("Successfully created classify session: iid={} dataAfter={}", id, dataAfter);
        } catch (VppBaseCallException e) {
            throw new WriteFailedException.CreateFailedException(id, dataAfter, e);
        }
    }

    @Override
    public void updateCurrentAttributes(@Nonnull final InstanceIdentifier<ClassifySession> id,
                                        @Nonnull final ClassifySession dataBefore,
                                        @Nonnull final ClassifySession dataAfter,
                                        @Nonnull final WriteContext writeContext) throws WriteFailedException {
        throw new UnsupportedOperationException("Classify session update is not supported");
    }

    @Override
    public void deleteCurrentAttributes(@Nonnull final InstanceIdentifier<ClassifySession> id,
                                        @Nonnull final ClassifySession dataBefore,
                                        @Nonnull final WriteContext writeContext) throws WriteFailedException {
        LOG.debug("Removing classify session: iid={} dataBefore={}", id, dataBefore);
        try {
            classifyAddDelSession(false, id, dataBefore, writeContext);
            LOG.debug("Successfully removed classify session: iid={} dataBefore={}", id, dataBefore);
        } catch (VppBaseCallException e) {
            throw new WriteFailedException.DeleteFailedException(id, e);
        }
    }

    private void classifyAddDelSession(final boolean isAdd, @Nonnull final InstanceIdentifier<ClassifySession> id,
                                       @Nonnull final ClassifySession classifySession,
                                       @Nonnull final WriteContext writeContext)
            throws VppBaseCallException, WriteFailedException {
        final ClassifyTableKey tableKey = id.firstKeyOf(ClassifyTable.class);
        final String tableName = tableKey.getName();
        final int tableIndex = classifyTableContext.getTableIndex(tableName, writeContext.getMappingContext());

        final ClassifyTable classifyTable = getClassifyTable(writeContext, id, isAdd);
        final ClassifyAddDelSession request =
            getClassifyAddDelSessionRequest(isAdd, classifySession, classifyTable, tableIndex);

        // TODO(HC2VPP-9): registry of next_node translators would allow to weaken dependency between policer
        // and vpp-classifier models
        final NextNode nextNode = classifySession.getNextNode();
        if (nextNode instanceof Standard) {
            translateNode(request, id, (Standard)nextNode, classifyTable, writeContext.getMappingContext());
        } else if (nextNode instanceof Policer) {
            translateNode(request, (Policer)nextNode, writeContext.getMappingContext());
        }
        final CompletionStage<ClassifyAddDelSessionReply> createClassifyTableReplyCompletionStage = getFutureJVpp()
                .classifyAddDelSession(request);
        getReplyForWrite(createClassifyTableReplyCompletionStage.toCompletableFuture(), id);
    }

    private void translateNode(final ClassifyAddDelSession request, final InstanceIdentifier<ClassifySession> id,
                               final Standard nextNode, final ClassifyTable classifyTable, final MappingContext ctx)
        throws VppBaseCallException, WriteFailedException {
        request.hitNextIndex = getNodeIndex(nextNode.getHitNext(), classifyTable, classifyTableContext, ctx, id);
        request.opaqueIndex = getOpaqueIndex(nextNode.getOpaqueIndex(), classifyTable, ctx, id);
    }

    private void translateNode(final ClassifyAddDelSession request, final Policer policer, final MappingContext ctx) {
        request.hitNextIndex = policerContext.getIndex(policer.getPolicerHitNext(), ctx);
        request.opaqueIndex = policer.getColorClassfier().getIntValue();
    }

    private ClassifyTable getClassifyTable(@Nonnull final WriteContext writeContext,
                                           @Nonnull final InstanceIdentifier<ClassifySession> id,
                                           final boolean isAdd) {
        final InstanceIdentifier<ClassifyTable>  tableId = id.firstIdentifierOf(ClassifyTable.class);
        final Optional<ClassifyTable> classifyTable;
        if (isAdd) {
            classifyTable = writeContext.readAfter(tableId);
        } else {
            classifyTable = writeContext.readBefore(tableId);
        }
        if (!classifyTable.isPresent()) {
            throw new IllegalStateException("Missing classify table for session " + id);
        }
        return classifyTable.get();
    }

    private ClassifyAddDelSession getClassifyAddDelSessionRequest(final boolean isAdd,
                                                                  @Nonnull final ClassifySession classifySession,
                                                                  final ClassifyTable classifyTable,
                                                                  final int tableIndex) {
        ClassifyAddDelSession request = new ClassifyAddDelSession();
        request.isAdd = booleanToByte(isAdd);
        request.tableIndex = tableIndex;

        // default 0:
        request.advance = classifySession.getAdvance();

        // VPP requires match vector of size mask + skip_n_vectors*16 bytes,
        // so align it with zeros:
        final int matchLength =
            (int) (16 * classifyTable.getSkipNVectors() + getBinaryVector(classifyTable.getMask()).length);
        request.match = new byte[matchLength];
        final byte[] actualMatch = getBinaryVector(classifySession.getMatch());
        System.arraycopy(actualMatch, 0, request.match, 0, actualMatch.length);
        request.matchLen = matchLength;
        return request;
    }

    private int getOpaqueIndex(@Nullable final OpaqueIndex opaqueIndex, final ClassifyTable classifyTable,
                               final MappingContext ctx, final InstanceIdentifier<ClassifySession> id)
            throws VppBaseCallException, WriteFailedException {
        if (opaqueIndex == null) {
            return ~0; // value not specified
        }
        if (opaqueIndex.getUint32() != null) {
            return opaqueIndex.getUint32().intValue();
        } else {
            return getNodeIndex(opaqueIndex.getVppNode(), classifyTable, classifyTableContext, ctx, id);
        }
    }
}