/*
 * 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.netconf.sal.rest.impl;

import com.google.common.base.Throwables;
import com.google.common.collect.Iterables;
import com.google.gson.stream.JsonReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
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 org.opendaylight.netconf.sal.rest.api.Draft02;
import org.opendaylight.netconf.sal.rest.api.RestconfService;
import org.opendaylight.netconf.sal.restconf.impl.ControllerContext;
import org.opendaylight.restconf.common.context.InstanceIdentifierContext;
import org.opendaylight.restconf.common.errors.RestconfDocumentedException;
import org.opendaylight.restconf.common.util.RestUtil;
import org.opendaylight.yangtools.yang.common.ErrorTag;
import org.opendaylight.yangtools.yang.common.ErrorType;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.AugmentationNode;
import org.opendaylight.yangtools.yang.data.api.schema.ChoiceNode;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerNode;
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.api.schema.stream.NormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.codec.gson.JSONCodecFactorySupplier;
import org.opendaylight.yangtools.yang.data.codec.gson.JsonParserStream;
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.ResultAlreadySetException;
import org.opendaylight.yangtools.yang.model.api.SchemaNode;
import org.opendaylight.yangtools.yang.model.api.stmt.RpcEffectiveStatement;
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;

@Provider
@Consumes({
    Draft02.MediaTypes.DATA + RestconfService.JSON,
    Draft02.MediaTypes.OPERATION + RestconfService.JSON,
    MediaType.APPLICATION_JSON
})
public class JsonNormalizedNodeBodyReader
        extends AbstractIdentifierAwareJaxRsProvider implements MessageBodyReader<NormalizedNodeContext> {

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

    public JsonNormalizedNodeBodyReader(final ControllerContext controllerContext) {
        super(controllerContext);
    }

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

    @SuppressWarnings("checkstyle:IllegalCatch")
    @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
        WebApplicationException {
        try {
            return readFrom(getInstanceIdentifierContext(), entityStream, isPost());
        } catch (final Exception e) {
            propagateExceptionAs(e);
            return null; // no-op
        }
    }

    @SuppressWarnings("checkstyle:IllegalCatch")
    public static NormalizedNodeContext readFrom(final String uriPath, final InputStream entityStream,
            final boolean isPost, final ControllerContext controllerContext) throws RestconfDocumentedException {

        try {
            return readFrom(controllerContext.toInstanceIdentifier(uriPath), entityStream, isPost);
        } catch (final Exception e) {
            propagateExceptionAs(e);
            return null; // no-op
        }
    }

    private static NormalizedNodeContext readFrom(final InstanceIdentifierContext<?> path,
                                                  final InputStream entityStream, final boolean isPost)
            throws IOException {
        final Optional<InputStream> nonEmptyInputStreamOptional = RestUtil.isInputStreamEmpty(entityStream);
        if (nonEmptyInputStreamOptional.isEmpty()) {
            return new NormalizedNodeContext(path, null);
        }
        final NormalizedNodeResult resultHolder = new NormalizedNodeResult();
        final NormalizedNodeStreamWriter writer = ImmutableNormalizedNodeStreamWriter.from(resultHolder);

        final SchemaInferenceStack stack;
        if (path.getSchemaNode() instanceof RpcEffectiveStatement) {
            stack = SchemaInferenceStack.of(path.getSchemaContext(), Absolute.of(path.getSchemaNode().getQName()));
        } else {
            stack = SchemaInferenceStack.of(path.getSchemaContext());
            path.getInstanceIdentifier().getPathArguments().stream()
                    .filter(arg -> !(arg instanceof YangInstanceIdentifier.NodeIdentifierWithPredicates))
                    .filter(arg -> !(arg instanceof YangInstanceIdentifier.AugmentationIdentifier))
                    .forEach(p -> stack.enterSchemaTree(p.getNodeType()));
        }

        if (!isPost) {
            stack.exit();
        }

        final JsonParserStream jsonParser = JsonParserStream.create(writer,
            JSONCodecFactorySupplier.DRAFT_LHOTKA_NETMOD_YANG_JSON_02.getShared(path.getSchemaContext()),
            stack.toInference());
        final JsonReader reader = new JsonReader(new InputStreamReader(nonEmptyInputStreamOptional.get(),
                StandardCharsets.UTF_8));
        jsonParser.parse(reader);

        NormalizedNode result = resultHolder.getResult();
        final List<YangInstanceIdentifier.PathArgument> iiToDataList = new ArrayList<>();
        InstanceIdentifierContext<? extends SchemaNode> newIIContext;

        while (result instanceof AugmentationNode || result instanceof ChoiceNode) {
            final Object childNode = ((DataContainerNode) result).body().iterator().next();
            if (isPost) {
                iiToDataList.add(result.getIdentifier());
            }
            result = (NormalizedNode) childNode;
        }

        if (isPost) {
            if (result instanceof MapEntryNode) {
                iiToDataList.add(new YangInstanceIdentifier.NodeIdentifier(result.getIdentifier().getNodeType()));
                iiToDataList.add(result.getIdentifier());
            } else {
                iiToDataList.add(result.getIdentifier());
            }
        } else {
            if (result instanceof MapNode) {
                result = Iterables.getOnlyElement(((MapNode) result).body());
            }
        }

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

        newIIContext = new InstanceIdentifierContext<>(fullIIToData, path.getSchemaNode(), path.getMountPoint(),
                path.getSchemaContext());

        return new NormalizedNodeContext(newIIContext, result);
    }

    private static void propagateExceptionAs(final Exception exception) throws RestconfDocumentedException {
        Throwables.throwIfInstanceOf(exception, RestconfDocumentedException.class);
        LOG.debug("Error parsing json input", exception);

        if (exception instanceof ResultAlreadySetException) {
            throw new RestconfDocumentedException("Error parsing json input: Failed to create new parse result data. "
                    + "Are you creating multiple resources/subresources in POST request?", exception);
        }

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