/*
 * 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.netconf.mdsal.connector.ops;

import java.io.IOException;
import java.net.URISyntaxException;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ExecutionException;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.mdsal.dom.api.DOMRpcResult;
import org.opendaylight.mdsal.dom.api.DOMRpcService;
import org.opendaylight.netconf.api.DocumentedException;
import org.opendaylight.netconf.api.NetconfDocumentedException;
import org.opendaylight.netconf.api.xml.XmlElement;
import org.opendaylight.netconf.api.xml.XmlNetconfConstants;
import org.opendaylight.netconf.api.xml.XmlUtil;
import org.opendaylight.netconf.mapping.api.HandlingPriority;
import org.opendaylight.netconf.mapping.api.NetconfOperationChainedExecution;
import org.opendaylight.netconf.mdsal.connector.CurrentSchemaContext;
import org.opendaylight.netconf.util.mapping.AbstractSingletonNetconfOperation;
import org.opendaylight.yangtools.yang.common.ErrorSeverity;
import org.opendaylight.yangtools.yang.common.ErrorTag;
import org.opendaylight.yangtools.yang.common.ErrorType;
import org.opendaylight.yangtools.yang.common.XMLNamespace;
import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
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.codec.xml.XMLStreamNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.codec.xml.XmlParserStream;
import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.impl.schema.NormalizedNodeResult;
import org.opendaylight.yangtools.yang.data.impl.schema.SchemaOrderedNormalizedNodeWriter;
import org.opendaylight.yangtools.yang.model.api.Module;
import org.opendaylight.yangtools.yang.model.api.RpcDefinition;
import org.opendaylight.yangtools.yang.model.api.stmt.SchemaNodeIdentifier.Absolute;
import org.opendaylight.yangtools.yang.model.util.SchemaInferenceStack;
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.NodeList;
import org.xml.sax.SAXException;

public class RuntimeRpc extends AbstractSingletonNetconfOperation {

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

    private static final XMLOutputFactory XML_OUTPUT_FACTORY;

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

    private final CurrentSchemaContext schemaContext;
    private final DOMRpcService rpcService;

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

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

        if (module.isEmpty()) {
            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 static XMLNamespace createNsUri(final String namespace) {
        // May throw IllegalArgumentException, but that should never happen, as the namespace comes from parsed XML
        return XMLNamespace.of(namespace);
    }

    //this returns module with the newest revision if more then 1 module with same namespace is found
    private Optional<? extends Module> getModule(final XMLNamespace namespace) {
        return schemaContext.getCurrentContext().findModules(namespace).stream().findFirst();
    }

    private static Optional<RpcDefinition> getRpcDefinitionFromModule(final Module module, final XMLNamespace namespace,
            final String name) {
        for (final RpcDefinition rpcDef : module.getRpcs()) {
            if (rpcDef.getQName().getNamespace().equals(namespace) && rpcDef.getQName().getLocalName().equals(name)) {
                return Optional.of(rpcDef);
            }
        }
        return Optional.empty();
    }

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

        final String netconfOperationName = operationElement.getName();
        final String netconfOperationNamespace;
        try {
            netconfOperationNamespace = operationElement.getNamespace();
        } catch (final DocumentedException e) {
            LOG.debug("Cannot retrieve netconf operation namespace from message due to ", e);
            throw new DocumentedException("Cannot retrieve netconf operation namespace from message", e,
                    ErrorType.PROTOCOL, ErrorTag.UNKNOWN_NAMESPACE, ErrorSeverity.ERROR);
        }

        final XMLNamespace namespaceURI = createNsUri(netconfOperationNamespace);
        final Optional<? extends Module> moduleOptional = getModule(namespaceURI);

        if (moduleOptional.isEmpty()) {
            throw new DocumentedException("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.isEmpty()) {
            throw new DocumentedException(
                    "Unable to find RpcDefinition with namespace and name : "
                        + namespaceURI + " " + netconfOperationName,
                    ErrorType.APPLICATION, ErrorTag.BAD_ELEMENT, ErrorSeverity.ERROR);
        }

        final RpcDefinition rpcDefinition = rpcDefinitionOptional.get();
        final ContainerNode inputNode = rpcToNNode(operationElement, rpcDefinition);

        final DOMRpcResult result;
        try {
            result = rpcService.invokeRpc(rpcDefinition.getQName(), inputNode).get();
        } catch (final InterruptedException | ExecutionException e) {
            throw DocumentedException.wrap(e);
        }
        if (result.getResult() == null) {
            return XmlUtil.createElement(document, XmlNetconfConstants.OK,
                Optional.of(XmlNetconfConstants.URN_IETF_PARAMS_XML_NS_NETCONF_BASE_1_0));
        }
        return transformNormalizedNode(document, result.getResult(),
                Absolute.of(rpcDefinition.getQName(), rpcDefinition.getOutput().getQName()));
    }

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

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

    private Element transformNormalizedNode(final Document document, final NormalizedNode data,
                                            final Absolute 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 SchemaOrderedNormalizedNodeWriter nnWriter = new SchemaOrderedNormalizedNodeWriter(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 (Element) result.getNode();
    }

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

    private static void writeRootElement(final XMLStreamWriter xmlWriter,
            final SchemaOrderedNormalizedNodeWriter nnWriter, final ContainerNode data) {
        try {
            nnWriter.write(data.body());
            nnWriter.flush();
            xmlWriter.flush();
        } catch (XMLStreamException | IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Parses xml element rpc input into normalized node or null if rpc does not take any input.
     *
     * @param element rpc xml element
     * @param rpcDefinition   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
     */
    private @Nullable ContainerNode rpcToNNode(final XmlElement element,
            final RpcDefinition rpcDefinition) throws DocumentedException {
        final NormalizedNodeResult resultHolder = new NormalizedNodeResult();
        final NormalizedNodeStreamWriter writer = ImmutableNormalizedNodeStreamWriter.from(resultHolder);
        final XmlParserStream xmlParser = XmlParserStream.create(writer, SchemaInferenceStack.of(
            schemaContext.getCurrentContext(),
            Absolute.of(rpcDefinition.getQName(), rpcDefinition.getInput().getQName())).toInference());

        try {
            xmlParser.traverse(new DOMSource(element.getDomElement()));
        } catch (final XMLStreamException | URISyntaxException | IOException | SAXException ex) {
            throw new NetconfDocumentedException("Error parsing input: " + ex.getMessage(), ex,
                ErrorType.PROTOCOL, ErrorTag.MALFORMED_MESSAGE, ErrorSeverity.ERROR);
        }

        return (ContainerNode) resultHolder.getResult();
    }
}