package org.opendaylight.controller.sal.connect.netconf;

import static org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil.NETCONF_DATA_QNAME;
import static org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil.NETCONF_GET_QNAME;
import static org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil.toId;
import static org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil.toPath;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.base.Strings;
import com.google.common.collect.Collections2;
import com.google.common.collect.Sets;
import java.net.URI;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import org.opendaylight.controller.md.sal.dom.api.DOMRpcResult;
import org.opendaylight.controller.sal.connect.netconf.listener.NetconfSessionPreferences;
import org.opendaylight.controller.sal.connect.netconf.sal.NetconfDeviceRpc;
import org.opendaylight.controller.sal.connect.netconf.util.NetconfMessageTransformUtil;
import org.opendaylight.controller.sal.connect.util.RemoteDeviceId;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.monitoring.rev101004.NetconfState;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.monitoring.rev101004.Yang;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.monitoring.rev101004.netconf.state.Schemas;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.netconf.monitoring.rev101004.netconf.state.schemas.Schema;
import org.opendaylight.yangtools.yang.common.QName;
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.DataContainerNode;
import org.opendaylight.yangtools.yang.data.api.schema.LeafSetEntryNode;
import org.opendaylight.yangtools.yang.data.api.schema.LeafSetNode;
import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.impl.schema.Builders;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Holds QNames for all yang modules reported by ietf-netconf-monitoring/state/schemas
 */
public final class NetconfStateSchemas {

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

    /**
     * Factory for NetconfStateSchemas
     */
    public interface NetconfStateSchemasResolver {
        NetconfStateSchemas resolve(final NetconfDeviceRpc deviceRpc, final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceId id);
    }

    /**
     * Default implementation resolving schemas QNames from netconf-state
     */
    public static final class NetconfStateSchemasResolverImpl implements NetconfStateSchemasResolver {

        @Override
        public NetconfStateSchemas resolve(final NetconfDeviceRpc deviceRpc, final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceId id) {
            return NetconfStateSchemas.create(deviceRpc, remoteSessionCapabilities, id);
        }
    }

    public static final NetconfStateSchemas EMPTY = new NetconfStateSchemas(Collections.<RemoteYangSchema>emptySet());

    private static final YangInstanceIdentifier STATE_SCHEMAS_IDENTIFIER =
            YangInstanceIdentifier.builder().node(NetconfState.QNAME).node(Schemas.QNAME).build();

    private static final ContainerNode GET_SCHEMAS_RPC;
    static {
        final DataContainerChild<?, ?> filter = NetconfMessageTransformUtil.toFilterStructure(STATE_SCHEMAS_IDENTIFIER, NetconfDevice.INIT_SCHEMA_CTX);
        GET_SCHEMAS_RPC
                = Builders.containerBuilder().withNodeIdentifier(toId(NETCONF_GET_QNAME)).withChild(filter).build();
    }

    private final Set<RemoteYangSchema> availableYangSchemas;

    public NetconfStateSchemas(final Set<RemoteYangSchema> availableYangSchemas) {
        this.availableYangSchemas = availableYangSchemas;
    }

    public Set<RemoteYangSchema> getAvailableYangSchemas() {
        return availableYangSchemas;
    }

    public Set<QName> getAvailableYangSchemasQNames() {
        return Sets.newHashSet(Collections2.transform(getAvailableYangSchemas(), new Function<RemoteYangSchema, QName>() {
            @Override
            public QName apply(final RemoteYangSchema input) {
                return input.getQName();
            }
        }));
    }

    /**
     * Issue get request to remote device and parse response to find all schemas under netconf-state/schemas
     */
    private static NetconfStateSchemas create(final NetconfDeviceRpc deviceRpc, final NetconfSessionPreferences remoteSessionCapabilities, final RemoteDeviceId id) {
        if(remoteSessionCapabilities.isMonitoringSupported() == false) {
            LOG.warn("{}: Netconf monitoring not supported on device, cannot detect provided schemas");
            return EMPTY;
        }

        final DOMRpcResult schemasNodeResult;
        try {
            schemasNodeResult = deviceRpc.invokeRpc(toPath(NETCONF_GET_QNAME), GET_SCHEMAS_RPC).get();
        } catch (final InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new RuntimeException(id + ": Interrupted while waiting for response to " + STATE_SCHEMAS_IDENTIFIER, e);
        } catch (final ExecutionException e) {
            LOG.warn("{}: Unable to detect available schemas, get to {} failed", id, STATE_SCHEMAS_IDENTIFIER, e);
            return EMPTY;
        }

        if(schemasNodeResult.getErrors().isEmpty() == false) {
            LOG.warn("{}: Unable to detect available schemas, get to {} failed, {}", id, STATE_SCHEMAS_IDENTIFIER, schemasNodeResult.getErrors());
            return EMPTY;
        }

        final Optional<? extends NormalizedNode<?, ?>> schemasNode = findSchemasNode(schemasNodeResult.getResult());

        if(schemasNode.isPresent()) {
            Preconditions.checkState(schemasNode.get() instanceof ContainerNode,
                    "Expecting container containing schemas, but was %s", schemasNode.get());
            return create(id, ((ContainerNode) schemasNode.get()));
        } else {
            LOG.warn("{}: Unable to detect available schemas, get to {} was empty", id, STATE_SCHEMAS_IDENTIFIER);
            return EMPTY;
        }
    }

    private static Optional<? extends NormalizedNode<?, ?>> findSchemasNode(final NormalizedNode<?, ?> result) {
        if(result == null) {
            return Optional.absent();
        }
        final Optional<DataContainerChild<?, ?>> dataNode = ((DataContainerNode<?>) result).getChild(toId(NETCONF_DATA_QNAME));
        if(dataNode.isPresent() == false) {
            return Optional.absent();
        }

        final Optional<DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?>> nStateNode =
                ((DataContainerNode<?>) dataNode.get()).getChild(toId(NetconfState.QNAME));
        if(nStateNode.isPresent() == false) {
            return Optional.absent();
        }

        return ((DataContainerNode<?>) nStateNode.get()).getChild(toId(Schemas.QNAME));
    }

    /**
     * Parse response of get(netconf-state/schemas) to find all schemas under netconf-state/schemas
     */
    @VisibleForTesting
    protected static NetconfStateSchemas create(final RemoteDeviceId id, final ContainerNode schemasNode) {
        final Set<RemoteYangSchema> availableYangSchemas = Sets.newHashSet();

        final Optional<DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?>> child = schemasNode.getChild(toId(Schema.QNAME));
        Preconditions.checkState(child.isPresent(), "Unable to find list: %s in response: %s", Schema.QNAME.withoutRevision(), schemasNode);
        Preconditions.checkState(child.get() instanceof MapNode, "Unexpected structure for container: %s in response: %s. Expecting a list", Schema.QNAME.withoutRevision(), schemasNode);

        for (final MapEntryNode schemaNode : ((MapNode) child.get()).getValue()) {
            final Optional<RemoteYangSchema> fromCompositeNode = RemoteYangSchema.createFromNormalizedNode(id, schemaNode);
            if(fromCompositeNode.isPresent()) {
                availableYangSchemas.add(fromCompositeNode.get());
            }
        }

        return new NetconfStateSchemas(availableYangSchemas);
    }

    public final static class RemoteYangSchema {
        private final QName qname;

        RemoteYangSchema(final QName qname) {
            this.qname = qname;
        }

        public QName getQName() {
            return qname;
        }

        static Optional<RemoteYangSchema> createFromNormalizedNode(final RemoteDeviceId id, final MapEntryNode schemaNode) {
            Preconditions.checkArgument(schemaNode.getNodeType().equals(Schema.QNAME), "Wrong QName %s", schemaNode.getNodeType());

            QName childNode = NetconfMessageTransformUtil.IETF_NETCONF_MONITORING_SCHEMA_FORMAT;

            String formatAsString = getSingleChildNodeValue(schemaNode, childNode).get();

            if(formatAsString.equals(Yang.QNAME.toString()) == false) {
                LOG.debug("{}: Ignoring schema due to unsupported format: {}", id, formatAsString);
                return Optional.absent();
            }

            childNode = NetconfMessageTransformUtil.IETF_NETCONF_MONITORING_SCHEMA_LOCATION;
            final Set<String> locationsAsString = getAllChildNodeValues(schemaNode, childNode);
            if(locationsAsString.contains(Schema.Location.Enumeration.NETCONF.toString()) == false) {
                LOG.debug("{}: Ignoring schema due to unsupported location: {}", id, locationsAsString);
                return Optional.absent();
            }

            childNode = NetconfMessageTransformUtil.IETF_NETCONF_MONITORING_SCHEMA_NAMESPACE;
            final String namespaceAsString = getSingleChildNodeValue(schemaNode, childNode).get();

            childNode = NetconfMessageTransformUtil.IETF_NETCONF_MONITORING_SCHEMA_VERSION;
            // Revision does not have to be filled
            final Optional<String> revisionAsString = getSingleChildNodeValue(schemaNode, childNode);

            childNode = NetconfMessageTransformUtil.IETF_NETCONF_MONITORING_SCHEMA_IDENTIFIER;
            final String moduleNameAsString = getSingleChildNodeValue(schemaNode, childNode).get();

            final QName moduleQName = revisionAsString.isPresent()
                    ? QName.create(namespaceAsString, revisionAsString.get(), moduleNameAsString)
                    : QName.create(URI.create(namespaceAsString), null, moduleNameAsString);

            return Optional.of(new RemoteYangSchema(moduleQName));
        }

        /**
         * Extracts all values of a leaf-list node as a set of strings
         */
        private static Set<String> getAllChildNodeValues(final DataContainerNode<?> schemaNode, final QName childNodeQName) {
            final Set<String> extractedValues = Sets.newHashSet();
            final Optional<DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?>> child = schemaNode.getChild(toId(childNodeQName));
            Preconditions.checkArgument(child.isPresent(), "Child nodes %s not present", childNodeQName);
            Preconditions.checkArgument(child.get() instanceof LeafSetNode<?>, "Child nodes %s not present", childNodeQName);
            for (final LeafSetEntryNode<?> childNode : ((LeafSetNode<?>) child.get()).getValue()) {
                extractedValues.add(getValueOfSimpleNode(childNode).get());
            }
            return extractedValues;
        }

        private static Optional<String> getSingleChildNodeValue(final DataContainerNode<?> schemaNode, final QName childNode) {
            final Optional<DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?>> node = schemaNode.getChild(toId(childNode));
            Preconditions.checkArgument(node.isPresent(), "Child node %s not present", childNode);
            return getValueOfSimpleNode(node.get());
        }

        private static Optional<String> getValueOfSimpleNode(final NormalizedNode<? extends YangInstanceIdentifier.PathArgument, ?> node) {
            final Object value = node.getValue();
            return value == null || Strings.isNullOrEmpty(value.toString()) ? Optional.<String>absent() : Optional.of(value.toString().trim());
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            final RemoteYangSchema that = (RemoteYangSchema) o;

            if (!qname.equals(that.qname)) {
                return false;
            }

            return true;
        }

        @Override
        public int hashCode() {
            return qname.hashCode();
        }
    }
}