/*
 * Copyright (c) 2013 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.util.messages;

import com.google.common.base.Preconditions;
import io.netty.channel.Channel;
import org.opendaylight.controller.netconf.api.NetconfDocumentedException;
import org.opendaylight.controller.netconf.api.NetconfMessage;
import org.opendaylight.controller.netconf.api.NetconfSession;
import org.opendaylight.controller.netconf.util.xml.XMLNetconfUtil;
import org.opendaylight.controller.netconf.util.xml.XmlNetconfConstants;
import org.opendaylight.controller.netconf.util.xml.XmlUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.*;

import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import java.io.InputStream;
import java.util.Map.Entry;

public class SendErrorExceptionUtil {
    private static final Logger logger = LoggerFactory.getLogger(SendErrorExceptionUtil.class);

    public static void sendErrorMessage(final NetconfSession session,
            final NetconfDocumentedException sendErrorException) {
        logger.info("Sending error {}", sendErrorException.getMessage(), sendErrorException);
        final Document errorDocument = createDocument(sendErrorException);
        session.sendMessage(new NetconfMessage(errorDocument));
    }

    public static void sendErrorMessage(Channel channel, NetconfDocumentedException sendErrorException) {
        logger.info("Sending error {}", sendErrorException.getMessage(), sendErrorException);
        final Document errorDocument = createDocument(sendErrorException);
        channel.writeAndFlush(new NetconfMessage(errorDocument));
    }

    public static void sendErrorMessage(NetconfSession session, NetconfDocumentedException sendErrorException,
            NetconfMessage incommingMessage) {
        final Document errorDocument = createDocument(sendErrorException);
        logger.info("Sending error {}", XmlUtil.toString(errorDocument));
        tryToCopyAttributes(incommingMessage.getDocument(), errorDocument, sendErrorException);
        session.sendMessage(new NetconfMessage(errorDocument));
    }

    private static void tryToCopyAttributes(final Document incommingDocument, final Document errorDocument,
            final NetconfDocumentedException sendErrorException) {
        try {
            final Element incommingRpc = incommingDocument.getDocumentElement();
            Preconditions.checkState(incommingRpc.getTagName().equals(XmlNetconfConstants.RPC_KEY), "Missing "
                    + XmlNetconfConstants.RPC_KEY + " " + "element");

            final Element rpcReply = errorDocument.getDocumentElement();
            Preconditions.checkState(rpcReply.getTagName().equals(XmlNetconfConstants.RPC_REPLY_KEY), "Missing "
                    + XmlNetconfConstants.RPC_REPLY_KEY + " element");

            final NamedNodeMap incomingAttributes = incommingRpc.getAttributes();
            for (int i = 0; i < incomingAttributes.getLength(); i++) {
                final Attr attr = (Attr) incomingAttributes.item(i);
                // skip namespace
                if (attr.getNodeName().equals(XmlUtil.XMLNS_ATTRIBUTE_KEY))
                    continue;
                rpcReply.setAttributeNode((Attr) errorDocument.importNode(attr, true));
            }
        } catch (final Exception e) {
            logger.warn("Unable to copy incomming attributes to {}, returned rpc-error might be invalid for client",
                    sendErrorException, e);
        }
    }

    private static XPathExpression rpcErrorExpression = XMLNetconfUtil
            .compileXPath("/netconf:rpc-reply/netconf:rpc-error");
    private static XPathExpression errorTypeExpression = XMLNetconfUtil.compileXPath("netconf:error-type");
    private static XPathExpression errorTagExpression = XMLNetconfUtil.compileXPath("netconf:error-tag");
    private static XPathExpression errorSeverityExpression = XMLNetconfUtil.compileXPath("netconf:error-severity");

    private static Document createDocument(final NetconfDocumentedException sendErrorException) {

        final InputStream errIS = SendErrorExceptionUtil.class.getResourceAsStream("server_error.xml");
        Document originalErrorDocument;
        try {
            originalErrorDocument = XmlUtil.readXmlToDocument(errIS);
        } catch (final Exception e) {
            throw new IllegalStateException(e);
        }

        final Document errorDocument = XmlUtil.createDocumentCopy(originalErrorDocument);
        final Node rootNode = errorDocument.getFirstChild();

        final Node rpcErrorNode = (Node) XmlUtil.evaluateXPath(rpcErrorExpression, rootNode, XPathConstants.NODE);

        final Node errorTypeNode = (Node) XmlUtil.evaluateXPath(errorTypeExpression, rpcErrorNode, XPathConstants.NODE);
        errorTypeNode.setTextContent(sendErrorException.getErrorType().getTagValue());

        final Node errorTagNode = (Node) XmlUtil.evaluateXPath(errorTagExpression, rpcErrorNode, XPathConstants.NODE);
        errorTagNode.setTextContent(sendErrorException.getErrorTag().getTagValue());

        final Node errorSeverityNode = (Node) XmlUtil.evaluateXPath(errorSeverityExpression, rpcErrorNode,
                XPathConstants.NODE);
        errorSeverityNode.setTextContent(sendErrorException.getErrorSeverity().getTagValue());

        if (sendErrorException.getErrorInfo() != null && sendErrorException.getErrorInfo().isEmpty() == false) {
            /*
             * <error-info> <bad-attribute>message-id</bad-attribute>
             * <bad-element>rpc</bad-element> </error-info>
             */
            final Node errorInfoNode = errorDocument.createElementNS(
                    XmlNetconfConstants.URN_IETF_PARAMS_XML_NS_NETCONF_BASE_1_0, "error-info");

            errorInfoNode.setPrefix(rootNode.getPrefix());
            rpcErrorNode.appendChild(errorInfoNode);
            for (final Entry<String, String> errorInfoEntry : sendErrorException.getErrorInfo().entrySet()) {
                final Node node = errorDocument.createElementNS(
                        XmlNetconfConstants.URN_IETF_PARAMS_XML_NS_NETCONF_BASE_1_0, errorInfoEntry.getKey());
                node.setTextContent(errorInfoEntry.getValue());
                errorInfoNode.appendChild(node);
            }

        }
        return errorDocument;
    }

}