/*
 * 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.base.Charsets;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.net.URI;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
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.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
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.api.schema.stream.NormalizedNodeWriter;
import org.opendaylight.yangtools.yang.data.codec.gson.JSONCodecFactory;
import org.opendaylight.yangtools.yang.data.codec.gson.JSONNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.codec.gson.JsonWriterFactory;
import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;
import org.opendaylight.yangtools.yang.model.api.RpcDefinition;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;
import org.opendaylight.yangtools.yang.model.api.SchemaNode;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;

@Provider
@Produces({ Draft02.MediaTypes.API + RestconfService.JSON, Draft02.MediaTypes.DATA + RestconfService.JSON,
    Draft02.MediaTypes.OPERATION + RestconfService.JSON, MediaType.APPLICATION_JSON })
public class NormalizedNodeJsonBodyWriter implements MessageBodyWriter<NormalizedNodeContext> {

    @Override
    public boolean isWriteable(final Class<?> type, final Type genericType, final Annotation[] annotations, final MediaType mediaType) {
        return type.equals(NormalizedNodeContext.class);
    }

    @Override
    public long getSize(final NormalizedNodeContext t, final Class<?> type, final Type genericType, final Annotation[] annotations, final MediaType mediaType) {
        return -1;
    }

    @Override
    public void writeTo(final NormalizedNodeContext t, final Class<?> type, final Type genericType, final Annotation[] annotations,
            final MediaType mediaType, final MultivaluedMap<String, Object> httpHeaders, final OutputStream entityStream)
                    throws IOException, WebApplicationException {
        NormalizedNode<?, ?> data = t.getData();
        if (data == null) {
            return;
        }

        final InstanceIdentifierContext<SchemaNode> context = (InstanceIdentifierContext<SchemaNode>) t.getInstanceIdentifierContext();

        SchemaPath path = context.getSchemaNode().getPath();
        boolean isDataRoot = false;
        if (SchemaPath.ROOT.equals(path)) {
            isDataRoot = true;
        } else if (context.getSchemaNode() instanceof RpcDefinition) {
            isDataRoot = true;
            path = ((RpcDefinition) context.getSchemaNode()).getOutput().getPath();
        } else {
            path = path.getParent();
            // FIXME: Add proper handling of reading root.
        }

        final JsonWriter jsonWriter = createJsonWriter(entityStream);
        final NormalizedNodeWriter nnWriter = createNormalizedNodeWriter(context,path,jsonWriter);

        jsonWriter.beginObject();
        if(isDataRoot) {
            writeDataRoot(nnWriter,(ContainerNode) data);
        } else {
            if(data instanceof MapEntryNode) {
                data = ImmutableNodes.mapNodeBuilder(data.getNodeType()).withChild(((MapEntryNode) data)).build();
            }
            nnWriter.write(data);
        }

        nnWriter.flush();
        jsonWriter.endObject();
        jsonWriter.flush();
    }

    private NormalizedNodeWriter createNormalizedNodeWriter(final InstanceIdentifierContext<SchemaNode> context,
            final SchemaPath path, final JsonWriter jsonWriter) {

        final SchemaNode schema = context.getSchemaNode();
        final JSONCodecFactory codecs = getCodecFactory(context);

        URI initialNs = null;
        if ( ! (schema instanceof RpcDefinition) && (!((DataSchemaNode)schema).isAugmenting() && !(schema instanceof SchemaContext))) {
            initialNs = schema.getQName().getNamespace();
        }
        final NormalizedNodeStreamWriter streamWriter = JSONNormalizedNodeStreamWriter.createNestedWriter(codecs,path,initialNs,jsonWriter);
        return NormalizedNodeWriter.forStreamWriter(streamWriter);
    }

    private JsonWriter createJsonWriter(final OutputStream entityStream) {
        // FIXME BUG-2153: Add pretty print support
        return JsonWriterFactory.createJsonWriter(new OutputStreamWriter(entityStream, Charsets.UTF_8));

    }

    private JSONCodecFactory getCodecFactory(final InstanceIdentifierContext context) {
        // TODO: Performance: Cache JSON Codec factory and schema context
        return JSONCodecFactory.create(context.getSchemaContext());
    }

    private void writeDataRoot(final NormalizedNodeWriter nnWriter, final ContainerNode data) throws IOException {
        for(final DataContainerChild<? extends PathArgument, ?> child : data.getValue()) {
            nnWriter.write(child);
        }
    }

}