/*
 * 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 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 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.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.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.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.JsonParserStream;
import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.impl.schema.NormalizedNodeResult;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;
import org.opendaylight.yangtools.yang.model.api.SchemaNode;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.opendaylight.yangtools.yang.model.util.SchemaContextUtil;
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 final static Logger LOG = LoggerFactory.getLogger(JsonNormalizedNodeBodyReader.class);

    @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) {
                return new NormalizedNodeContext(path, null);
            }
            final NormalizedNodeResult resultHolder = new NormalizedNodeResult();
            final NormalizedNodeStreamWriter writer = ImmutableNormalizedNodeStreamWriter.from(resultHolder);

            final SchemaNode parentSchema;
            if(isPost()) {
                // FIXME: We need dispatch for RPC.
                parentSchema = path.getSchemaNode();
            } else if(path.getSchemaNode() instanceof SchemaContext) {
                parentSchema = path.getSchemaContext();
            } else {
                if (SchemaPath.ROOT.equals(path.getSchemaNode().getPath().getParent())) {
                    parentSchema = path.getSchemaContext();
                } else {
                    parentSchema = SchemaContextUtil.findDataSchemaNode(path.getSchemaContext(), path.getSchemaNode().getPath().getParent());
                }
            }

            final JsonParserStream jsonParser = JsonParserStream.create(writer, path.getSchemaContext(), parentSchema);
            final JsonReader reader = new JsonReader(new InputStreamReader(entityStream));
            jsonParser.parse(reader);

            NormalizedNode<?, ?> partialResult = resultHolder.getResult();
            final NormalizedNode<?, ?> result;

            // unwrap result from augmentation and choice nodes on PUT
            if (!isPost()) {
                while (partialResult instanceof AugmentationNode || partialResult instanceof ChoiceNode) {
                    final Object childNode = ((DataContainerNode) partialResult).getValue().iterator().next();
                    partialResult = (NormalizedNode<?, ?>) childNode;
                }
            }

            if (partialResult instanceof MapNode) {
                result = Iterables.getOnlyElement(((MapNode) partialResult).getValue());
            } else {
                result = partialResult;
            }
            return new NormalizedNodeContext(path,result);
        } catch (final Exception e) {
            LOG.debug("Error parsing json input", e);

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