/*
 * 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.rest.impl;

import com.google.common.collect.Iterables;
import java.io.IOException;
import java.io.InputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.List;
import javax.ws.rs.Consumes;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.Provider;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.opendaylight.controller.sal.rest.api.Draft02;
import org.opendaylight.controller.sal.rest.api.RestconfService;
import org.opendaylight.controller.sal.restconf.impl.InstanceIdentifierContext;
import org.opendaylight.controller.sal.restconf.impl.NormalizedNodeContext;
import org.opendaylight.controller.sal.restconf.impl.RestconfDocumentedException;
import org.opendaylight.controller.sal.restconf.impl.RestconfError.ErrorTag;
import org.opendaylight.controller.sal.restconf.impl.RestconfError.ErrorType;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlUtils;
import org.opendaylight.yangtools.yang.data.impl.schema.SchemaUtils;
import org.opendaylight.yangtools.yang.data.impl.schema.transform.dom.parser.DomToNormalizedNodeParserFactory;
import org.opendaylight.yangtools.yang.model.api.AugmentationSchema;
import org.opendaylight.yangtools.yang.model.api.AugmentationTarget;
import org.opendaylight.yangtools.yang.model.api.ChoiceCaseNode;
import org.opendaylight.yangtools.yang.model.api.ChoiceSchemaNode;
import org.opendaylight.yangtools.yang.model.api.ContainerSchemaNode;
import org.opendaylight.yangtools.yang.model.api.DataNodeContainer;
import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;
import org.opendaylight.yangtools.yang.model.api.ListSchemaNode;
import org.opendaylight.yangtools.yang.model.api.RpcDefinition;
import org.opendaylight.yangtools.yang.model.api.SchemaNode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

@Provider
@Consumes({ Draft02.MediaTypes.DATA + RestconfService.XML, Draft02.MediaTypes.OPERATION + RestconfService.XML,
    MediaType.APPLICATION_XML, MediaType.TEXT_XML })
public class XmlNormalizedNodeBodyReader extends AbstractIdentifierAwareJaxRsProvider implements MessageBodyReader<NormalizedNodeContext> {

    private final static Logger LOG = LoggerFactory.getLogger(XmlNormalizedNodeBodyReader.class);
    private static final DocumentBuilderFactory BUILDERFACTORY;

    static {
        final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        try {
            factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
            factory.setFeature("http://xml.org/sax/features/external-general-entities", false);
            factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
            factory.setXIncludeAware(false);
            factory.setExpandEntityReferences(false);
        } catch (final ParserConfigurationException e) {
            throw new ExceptionInInitializerError(e);
        }
        factory.setNamespaceAware(true);
        factory.setCoalescing(true);
        factory.setIgnoringElementContentWhitespace(true);
        factory.setIgnoringComments(true);
        BUILDERFACTORY = factory;
    }

    @Override
    public boolean isReadable(final Class<?> type, final Type genericType, final Annotation[] annotations,
            final MediaType mediaType) {
        return true;
    }

    @Override
    public NormalizedNodeContext readFrom(final Class<NormalizedNodeContext> type, final Type genericType,
            final Annotation[] annotations, final MediaType mediaType,
            final MultivaluedMap<String, String> httpHeaders, final InputStream entityStream) throws IOException,
            WebApplicationException {
        try {
            final InstanceIdentifierContext<?> path = getInstanceIdentifierContext();

            if (entityStream.available() < 1) {
                // represent empty nopayload input
                return new NormalizedNodeContext(path, null);
            }

            final DocumentBuilder dBuilder;
            try {
                dBuilder = BUILDERFACTORY.newDocumentBuilder();
            } catch (final ParserConfigurationException e) {
                throw new RuntimeException("Failed to parse XML document", e);
            }
            final Document doc = dBuilder.parse(entityStream);

            return parse(path,doc);
        } catch (final RestconfDocumentedException e){
            throw e;
        } catch (final Exception e) {
            LOG.debug("Error parsing xml input", e);

            throw new RestconfDocumentedException("Error parsing input: " + e.getMessage(), ErrorType.PROTOCOL,
                    ErrorTag.MALFORMED_MESSAGE);
        }
    }

    private NormalizedNodeContext parse(final InstanceIdentifierContext<?> pathContext,final Document doc) {

        final List<Element> elements = Collections.singletonList(doc.getDocumentElement());
        final SchemaNode schemaNodeContext = pathContext.getSchemaNode();
        DataSchemaNode schemaNode;
        boolean isRpc = false;
        if (schemaNodeContext instanceof RpcDefinition) {
            schemaNode = ((RpcDefinition) schemaNodeContext).getInput();
            isRpc = true;
        } else if (schemaNodeContext instanceof DataSchemaNode) {
            schemaNode = (DataSchemaNode) schemaNodeContext;
        } else {
            throw new IllegalStateException("Unknow SchemaNode");
        }

        final String docRootElm = doc.getDocumentElement().getLocalName();
        final List<YangInstanceIdentifier.PathArgument> iiToDataList = new ArrayList<>();
        InstanceIdentifierContext<? extends SchemaNode> outIIContext;


        // FIXME the factory instance should be cached if the schema context is the same
        final DomToNormalizedNodeParserFactory parserFactory =
                DomToNormalizedNodeParserFactory.getInstance(XmlUtils.DEFAULT_XML_CODEC_PROVIDER, pathContext.getSchemaContext());

        if (isPost() && !isRpc) {
            final Deque<Object> foundSchemaNodes = findPathToSchemaNodeByName(schemaNode, docRootElm);
            if (foundSchemaNodes.isEmpty()) {
                throw new IllegalStateException(String.format("Child \"%s\" was not found in parent schema node \"%s\"",
                        docRootElm, schemaNode.getQName()));
            }
            while (!foundSchemaNodes.isEmpty()) {
                final Object child = foundSchemaNodes.pop();
                if (child instanceof AugmentationSchema) {
                    final AugmentationSchema augmentSchemaNode = (AugmentationSchema) child;
                    iiToDataList.add(SchemaUtils.getNodeIdentifierForAugmentation(augmentSchemaNode));
                } else if (child instanceof DataSchemaNode) {
                    schemaNode = (DataSchemaNode) child;
                    iiToDataList.add(new YangInstanceIdentifier.NodeIdentifier(schemaNode.getQName()));
                }
            }
        }

        NormalizedNode<?, ?> parsed = null;

        if(schemaNode instanceof ContainerSchemaNode) {
            parsed = parserFactory.getContainerNodeParser().parse(Collections.singletonList(doc.getDocumentElement()), (ContainerSchemaNode) schemaNode);
        } else if(schemaNode instanceof ListSchemaNode) {
            final ListSchemaNode casted = (ListSchemaNode) schemaNode;
            parsed = parserFactory.getMapEntryNodeParser().parse(elements, casted);
            if (isPost()) {
                iiToDataList.add(parsed.getIdentifier());
            }
        }
        // FIXME : add another DataSchemaNode extensions e.g. LeafSchemaNode

        final YangInstanceIdentifier fullIIToData = YangInstanceIdentifier.create(Iterables.concat(
                pathContext.getInstanceIdentifier().getPathArguments(), iiToDataList));

        outIIContext = new InstanceIdentifierContext<>(fullIIToData, pathContext.getSchemaNode(), pathContext.getMountPoint(),
                pathContext.getSchemaContext());

        return new NormalizedNodeContext(outIIContext, parsed);
    }

    private static Deque<Object> findPathToSchemaNodeByName(final DataSchemaNode schemaNode, final String elementName) {
        final Deque<Object> result = new ArrayDeque<>();
        final ArrayList<ChoiceSchemaNode> choiceSchemaNodes = new ArrayList<>();
        final Collection<DataSchemaNode> children = ((DataNodeContainer) schemaNode).getChildNodes();
        for (final DataSchemaNode child : children) {
            if (child instanceof ChoiceSchemaNode) {
                choiceSchemaNodes.add((ChoiceSchemaNode) child);
            } else if (child.getQName().getLocalName().equalsIgnoreCase(elementName)) {
                result.push(child);
                if (child.isAugmenting()) {
                    final AugmentationSchema augment = findCorrespondingAugment(schemaNode, child);
                    if (augment != null) {
                        result.push(augment);
                    }
                }
                return result;
            }
        }

        for (final ChoiceSchemaNode choiceNode : choiceSchemaNodes) {
            for (final ChoiceCaseNode caseNode : choiceNode.getCases()) {
                final Deque<Object> resultFromRecursion = findPathToSchemaNodeByName(caseNode, elementName);
                if (!resultFromRecursion.isEmpty()) {
                    resultFromRecursion.push(choiceNode);
                    if (choiceNode.isAugmenting()) {
                        final AugmentationSchema augment = findCorrespondingAugment(schemaNode, choiceNode);
                        if (augment != null) {
                            resultFromRecursion.push(augment);
                        }
                    }
                    return resultFromRecursion;
                }
            }
        }
        return result;
    }

    private static AugmentationSchema findCorrespondingAugment(final DataSchemaNode parent, final DataSchemaNode child) {
        if (parent instanceof AugmentationTarget && !(parent instanceof ChoiceSchemaNode)) {
            for (final AugmentationSchema augmentation : ((AugmentationTarget) parent).getAvailableAugmentations()) {
                final DataSchemaNode childInAugmentation = augmentation.getDataChildByName(child.getQName());
                if (childInAugmentation != null) {
                    return augmentation;
                }
            }
        }
        return null;
    }
}