/*
 * Copyright (c) 2014 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.controller.sal.connect.netconf.sal.tx;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.util.concurrent.CheckedFuture;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.concurrent.ExecutionException;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
import org.opendaylight.controller.md.sal.dom.api.DOMDataReadOnlyTransaction;
import org.opendaylight.controller.md.sal.dom.api.DOMRpcResult;
import org.opendaylight.controller.sal.connect.netconf.util.NetconfBaseOps;
import org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil;
import org.opendaylight.controller.sal.connect.util.RemoteDeviceId;
import org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNodes;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


public final class ReadOnlyTx implements DOMDataReadOnlyTransaction {

    private static final Logger LOG  = LoggerFactory.getLogger(ReadOnlyTx.class);

    private final NetconfBaseOps netconfOps;
    private final RemoteDeviceId id;
    private final FutureCallback<DOMRpcResult> loggingCallback;

    public ReadOnlyTx(final NetconfBaseOps netconfOps, final RemoteDeviceId id) {
        this.netconfOps = netconfOps;
        this.id = id;

        // Simple logging callback to log result of read operation
        loggingCallback = new FutureCallback<DOMRpcResult>() {
            @Override
            public void onSuccess(final DOMRpcResult result) {
                if(AbstractWriteTx.isSuccess(result)) {
                    LOG.trace("{}: Reading data successful", id);
                } else {
                    LOG.warn("{}: Reading data unsuccessful: {}", id, result.getErrors());
                }

            }

            @Override
            public void onFailure(final Throwable t) {
                LOG.warn("{}: Reading data failed", id, t);
            }
        };
    }

    private CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readConfigurationData(
            final YangInstanceIdentifier path) {
        final ListenableFuture<DOMRpcResult> configRunning = netconfOps.getConfigRunning(loggingCallback, Optional.fromNullable(path));

        final ListenableFuture<Optional<NormalizedNode<?, ?>>> transformedFuture = Futures.transform(configRunning, new Function<DOMRpcResult, Optional<NormalizedNode<?, ?>>>() {
            @Override
            public Optional<NormalizedNode<?, ?>> apply(final DOMRpcResult result) {
                checkReadSuccess(result, path);

                final DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?> dataNode = findDataNode(result);
                return NormalizedNodes.findNode(dataNode, path.getPathArguments());
            }
        });

        return MappingCheckedFuture.create(transformedFuture, ReadFailedException.MAPPER);
    }

    private DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?> findDataNode(final DOMRpcResult result) {
        return ((ContainerNode) result.getResult()).getChild(NetconfMessageTransformUtil.toId(NetconfMessageTransformUtil.NETCONF_DATA_QNAME)).get();
    }

    private void checkReadSuccess(final DOMRpcResult result, final YangInstanceIdentifier path) {
        try {
            Preconditions.checkArgument(AbstractWriteTx.isSuccess(result), "%s: Unable to read data: %s, errors: %s", id, path, result.getErrors());
        } catch (final IllegalArgumentException e) {
            LOG.warn("{}: Unable to read data: {}, errors: {}", id, path, result.getErrors());
            throw e;
        }
    }

    private CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> readOperationalData(
            final YangInstanceIdentifier path) {
        final ListenableFuture<DOMRpcResult> configCandidate = netconfOps.get(loggingCallback, Optional.fromNullable(path));

        // Find data node and normalize its content
        final ListenableFuture<Optional<NormalizedNode<?, ?>>> transformedFuture = Futures.transform(configCandidate, new Function<DOMRpcResult, Optional<NormalizedNode<?, ?>>>() {
            @Override
            public Optional<NormalizedNode<?, ?>> apply(final DOMRpcResult result) {
                checkReadSuccess(result, path);

                final DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?> dataNode = findDataNode(result);
                return NormalizedNodes.findNode(dataNode, path.getPathArguments());
            }
        });

        return MappingCheckedFuture.create(transformedFuture, ReadFailedException.MAPPER);
    }

    @Override
    public void close() {
        // NOOP
    }

    @Override
    public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(
            final LogicalDatastoreType store, final YangInstanceIdentifier path) {
        switch (store) {
            case CONFIGURATION : {
                return readConfigurationData(path);
            }
            case OPERATIONAL : {
                return readOperationalData(path);
            }
        }

        throw new IllegalArgumentException(String.format("%s, Cannot read data %s for %s datastore, unknown datastore type", id, path, store));
    }

    @Override
    public CheckedFuture<Boolean, ReadFailedException> exists(final LogicalDatastoreType store, final YangInstanceIdentifier path) {
        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> data = read(store, path);

        try {
            return Futures.immediateCheckedFuture(data.get().isPresent());
        } catch (InterruptedException | ExecutionException e) {
            return Futures.immediateFailedCheckedFuture(new ReadFailedException("Exists failed",e));
        }
    }

    @Override
    public Object getIdentifier() {
        return this;
    }
}