/*
 * Copyright (c) 2013 Pantheon Technologies s.r.o. 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.openflowjava.protocol.impl.util;

import io.netty.buffer.ByteBuf;

import java.util.ArrayList;
import java.util.List;

import org.opendaylight.openflowjava.protocol.api.extensibility.DeserializerRegistry;
import org.opendaylight.openflowjava.protocol.api.extensibility.HeaderDeserializer;
import org.opendaylight.openflowjava.protocol.api.extensibility.OFDeserializer;
import org.opendaylight.openflowjava.protocol.api.keys.MessageCodeKey;
import org.opendaylight.openflowjava.protocol.api.util.EncodeConstants;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author michal.polkorab
 *
 */
public final class ListDeserializer {
    private static final Logger LOG = LoggerFactory.getLogger(ListDeserializer.class);

    private ListDeserializer() {
        throw new UnsupportedOperationException("Utility class shouldn't be instantiated");
    }

    /**
     * Deserializes items into list
     * @param version openflow wire version
     * @param length length of list in ByteBuf (bytes)
     * @param input input buffer
     * @param keyMaker creates keys for deserializer lookup
     * @param registry stores deserializers
     * @return list of items
     */
    public static <E extends DataObject> List<E> deserializeList(short version, int length,
            ByteBuf input, CodeKeyMaker keyMaker, DeserializerRegistry registry) {
        List<E> items = null;
        if (input.readableBytes() > 0) {
            items = new ArrayList<>();
            int startIndex = input.readerIndex();
            while ((input.readerIndex() - startIndex) < length){
                OFDeserializer<E> deserializer = registry.getDeserializer(keyMaker.make(input));
                E item = deserializer.deserialize(input);
                items.add(item);
            }
        }
        return items;
    }

    /**
     * Deserializes headers of items into list (used in MultipartReplyMessage - Table features)
     * @param version openflow wire version
     * @param length length of list in ByteBuf (bytes)
     * @param input input buffer
     * @param keyMaker creates keys for deserializer lookup
     * @param registry stores deserializers
     * @return list of items
     */
    public static <E extends DataObject> List<E> deserializeHeaders(short version, int length,
            ByteBuf input, CodeKeyMaker keyMaker, DeserializerRegistry registry) {
        List<E> items = null;
        if (input.readableBytes() > 0) {
            items = new ArrayList<>();
            int startIndex = input.readerIndex();
            boolean exceptionLogged = false;
            while ((input.readerIndex() - startIndex) < length){
                HeaderDeserializer<E> deserializer;
                MessageCodeKey key = keyMaker.make(input);
                try {
                    deserializer = registry.getDeserializer(key);
                } catch (ClassCastException | IllegalStateException e) {
                    // Following "if" is only hotfix to prevent log flooding. Log flooding is originally
                    // caused by using OVS 2.4 which directly uses / reports Nicira extensions. These extensions
                    // are not yet (2nd February 2016) fully supported by existing OF Plugin.
                    // TODO - simplify to correctly report exception during deserialization
                    if (!exceptionLogged) {
                        LOG.warn("Problem during reading table feature property. Skipping unknown feature property: {}." +
                                "If more information is needed, set org.opendaylight.openflowjava do DEBUG log level.",
                                key, e.getMessage());
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Detailed exception: {}", e);
                            LOG.debug("This exception is logged only once for each multipart reply (table features) to "
                                    + "prevent log flooding. There might be more of table features related exceptions.");
                        }
                        exceptionLogged = true;
                    }
                    input.skipBytes(2 * EncodeConstants.SIZE_OF_SHORT_IN_BYTES);
                    continue;
                }
                E item = deserializer.deserializeHeader(input);
                items.add(item);
            }
        }
        return items;
    }
}