/*
 * Copyright (c) 2015 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.netconf.mdsal.connector.ops;

import com.google.common.base.Optional;
import com.google.common.base.Throwables;
import com.google.common.util.concurrent.CheckedFuture;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import javax.annotation.Nullable;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.transform.dom.DOMResult;
import org.opendaylight.controller.md.sal.dom.api.DOMRpcException;
import org.opendaylight.controller.md.sal.dom.api.DOMRpcResult;
import org.opendaylight.controller.md.sal.dom.api.DOMRpcService;
import org.opendaylight.controller.netconf.api.NetconfDocumentedException;
import org.opendaylight.controller.netconf.api.NetconfDocumentedException.ErrorSeverity;
import org.opendaylight.controller.netconf.api.NetconfDocumentedException.ErrorTag;
import org.opendaylight.controller.netconf.api.NetconfDocumentedException.ErrorType;
import org.opendaylight.controller.netconf.api.xml.XmlNetconfConstants;
import org.opendaylight.controller.netconf.mapping.api.HandlingPriority;
import org.opendaylight.controller.netconf.mapping.api.NetconfOperationChainedExecution;
import org.opendaylight.controller.netconf.mdsal.connector.CurrentSchemaContext;
import org.opendaylight.controller.netconf.util.OrderedNormalizedNodeWriter;
import org.opendaylight.controller.netconf.util.exception.MissingNameSpaceException;
import org.opendaylight.controller.netconf.util.mapping.AbstractSingletonNetconfOperation;
import org.opendaylight.controller.netconf.util.xml.XmlElement;
import org.opendaylight.controller.netconf.util.xml.XmlUtil;
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.stream.NormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.impl.codec.xml.XMLStreamNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.impl.schema.transform.dom.DomUtils;
import org.opendaylight.yangtools.yang.data.impl.schema.transform.dom.parser.DomToNormalizedNodeParserFactory;
import org.opendaylight.yangtools.yang.model.api.ContainerSchemaNode;
import org.opendaylight.yangtools.yang.model.api.Module;
import org.opendaylight.yangtools.yang.model.api.RpcDefinition;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class RuntimeRpc extends AbstractSingletonNetconfOperation {

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

    private final CurrentSchemaContext schemaContext;
    private static final XMLOutputFactory XML_OUTPUT_FACTORY;

    static {
        XML_OUTPUT_FACTORY = XMLOutputFactory.newFactory();
        XML_OUTPUT_FACTORY.setProperty(XMLOutputFactory.IS_REPAIRING_NAMESPACES, true);
    }

    private final DOMRpcService rpcService;

    public RuntimeRpc(final String netconfSessionIdForReporting, CurrentSchemaContext schemaContext, DOMRpcService rpcService) {
        super(netconfSessionIdForReporting);
        this.schemaContext = schemaContext;
        this.rpcService = rpcService;
    }

    @Override
    protected HandlingPriority canHandle(final String netconfOperationName, final String namespace) {
        final URI namespaceURI = createNsUri(namespace);
        final Optional<Module> module = getModule(namespaceURI);

        if (!module.isPresent()) {
            LOG.debug("Cannot handle rpc: {}, {}", netconfOperationName, namespace);
            return HandlingPriority.CANNOT_HANDLE;
        }

        getRpcDefinitionFromModule(module.get(), namespaceURI, netconfOperationName);
        return HandlingPriority.HANDLE_WITH_DEFAULT_PRIORITY;

    }

    @Override
    protected String getOperationName() {
        throw new UnsupportedOperationException("Runtime rpc does not have a stable name");
    }

    private URI createNsUri(final String namespace) {
        final URI namespaceURI;
        try {
            namespaceURI = new URI(namespace);
        } catch (URISyntaxException e) {
            // Cannot occur, namespace in parsed XML cannot be invalid URI
            throw new IllegalStateException("Unable to parse URI " + namespace, e);
        }
        return namespaceURI;
    }

    //this returns module with the newest revision if more then 1 module with same namespace is found
    private Optional<Module> getModule(final URI namespaceURI) {
        return Optional.fromNullable(schemaContext.getCurrentContext().findModuleByNamespaceAndRevision(namespaceURI, null));
    }

    private Optional<RpcDefinition> getRpcDefinitionFromModule(Module module, URI namespaceURI, String name) {
        for (RpcDefinition rpcDef : module.getRpcs()) {
            if (rpcDef.getQName().getNamespace().equals(namespaceURI)
                    && rpcDef.getQName().getLocalName().equals(name)) {
                return Optional.of(rpcDef);
            }
        }
        return Optional.absent();
    }

    @Override
    protected Element handleWithNoSubsequentOperations(final Document document, final XmlElement operationElement) throws NetconfDocumentedException {

        final String netconfOperationName = operationElement.getName();
        final String netconfOperationNamespace;
        try {
            netconfOperationNamespace = operationElement.getNamespace();
        } catch (MissingNameSpaceException e) {
            LOG.debug("Cannot retrieve netconf operation namespace from message due to ", e);
            throw new NetconfDocumentedException("Cannot retrieve netconf operation namespace from message",
                    ErrorType.protocol, ErrorTag.unknown_namespace, ErrorSeverity.error);
        }

        final URI namespaceURI = createNsUri(netconfOperationNamespace);
        final Optional<Module> moduleOptional = getModule(namespaceURI);

        if (!moduleOptional.isPresent()) {
            throw new NetconfDocumentedException("Unable to find module in Schema Context with namespace and name : " +
                    namespaceURI + " " + netconfOperationName + schemaContext.getCurrentContext(),
                    ErrorType.application, ErrorTag.bad_element, ErrorSeverity.error);
        }

        final Optional<RpcDefinition> rpcDefinitionOptional = getRpcDefinitionFromModule(moduleOptional.get(), namespaceURI, netconfOperationName);

        if (!rpcDefinitionOptional.isPresent()) {
            throw new NetconfDocumentedException("Unable to find RpcDefinition with namespace and name : " + namespaceURI + " " + netconfOperationName,
                    ErrorType.application, ErrorTag.bad_element, ErrorSeverity.error);
        }

        final RpcDefinition rpcDefinition = rpcDefinitionOptional.get();
        final SchemaPath schemaPath = SchemaPath.create(Collections.singletonList(rpcDefinition.getQName()), true);
        final NormalizedNode<?, ?> inputNode = rpcToNNode(operationElement, rpcDefinition.getInput());

        final CheckedFuture<DOMRpcResult, DOMRpcException> rpcFuture = rpcService.invokeRpc(schemaPath, inputNode);
        try {
            final DOMRpcResult result = rpcFuture.checkedGet();
            if (result.getResult() == null) {
                return XmlUtil.createElement(document, XmlNetconfConstants.OK, Optional.of(XmlNetconfConstants.URN_IETF_PARAMS_XML_NS_NETCONF_BASE_1_0));
            }
            return (Element) transformNormalizedNode(document, result.getResult(), rpcDefinition.getOutput().getPath());
        } catch (DOMRpcException e) {
            throw NetconfDocumentedException.wrap(e);
        }
    }

    @Override
    public Document handle(final Document requestMessage,
                           final NetconfOperationChainedExecution subsequentOperation) throws NetconfDocumentedException {

        final XmlElement requestElement = getRequestElementWithCheck(requestMessage);

        final Document document = XmlUtil.newDocument();

        final XmlElement operationElement = requestElement.getOnlyChildElement();
        final Map<String, Attr> attributes = requestElement.getAttributes();

        final Element response = handle(document, operationElement, subsequentOperation);
        final Element rpcReply = XmlUtil.createElement(document, XmlNetconfConstants.RPC_REPLY_KEY, Optional.of(XmlNetconfConstants.URN_IETF_PARAMS_XML_NS_NETCONF_BASE_1_0));

        if(XmlElement.fromDomElement(response).hasNamespace()) {
            rpcReply.appendChild(response);
        } else {
            final NodeList list = response.getChildNodes();
            if (list.getLength() == 0) {
                rpcReply.appendChild(response);
            } else {
                while (list.getLength() != 0) {
                    rpcReply.appendChild(list.item(0));
                }
            }
        }

        for (Attr attribute : attributes.values()) {
            rpcReply.setAttributeNode((Attr) document.importNode(attribute, true));
        }
        document.appendChild(rpcReply);
        return document;
    }

    //TODO move all occurences of this method in mdsal netconf(and xml factories) to a utility class
    private Node transformNormalizedNode(final Document document, final NormalizedNode<?, ?> data, final SchemaPath rpcOutputPath) {
        final DOMResult result = new DOMResult(document.createElement(XmlNetconfConstants.RPC_REPLY_KEY));

        final XMLStreamWriter xmlWriter = getXmlStreamWriter(result);

        final NormalizedNodeStreamWriter nnStreamWriter = XMLStreamNormalizedNodeStreamWriter.create(xmlWriter,
                schemaContext.getCurrentContext(), rpcOutputPath);

        final OrderedNormalizedNodeWriter nnWriter = new OrderedNormalizedNodeWriter(nnStreamWriter, schemaContext.getCurrentContext(), rpcOutputPath);

        writeRootElement(xmlWriter, nnWriter, (ContainerNode) data);
        try {
            nnStreamWriter.close();
            xmlWriter.close();
        } catch (IOException | XMLStreamException e) {
            LOG.warn("Error while closing streams", e);
        }

        return result.getNode();
    }

    private XMLStreamWriter getXmlStreamWriter(final DOMResult result) {
        try {
            return XML_OUTPUT_FACTORY.createXMLStreamWriter(result);
        } catch (final XMLStreamException e) {
            throw new RuntimeException(e);
        }
    }

    private void writeRootElement(final XMLStreamWriter xmlWriter, final OrderedNormalizedNodeWriter nnWriter, final ContainerNode data) {
        try {
            Collection<DataContainerChild<?, ?>> value = (Collection) data.getValue();
            nnWriter.write(value);
            nnWriter.flush();
            xmlWriter.flush();
        } catch (XMLStreamException | IOException e) {
            Throwables.propagate(e);
        }
    }

    /**
     * Parses xml element rpc input into normalized node or null if rpc does not take any input
     * @param oElement rpc xml element
     * @param input input container schema node, or null if rpc does not take any input
     * @return parsed rpc into normalized node, or null if input schema is null
     */
    @Nullable
    private NormalizedNode<?, ?> rpcToNNode(final XmlElement oElement, @Nullable final ContainerSchemaNode input) {
        return input == null ? null : DomToNormalizedNodeParserFactory
                .getInstance(DomUtils.defaultValueCodecProvider(), schemaContext.getCurrentContext())
                .getContainerNodeParser()
                .parse(Collections.singletonList(oElement.getDomElement()), input);
    }

}