/*
 * Copyright (c) 2013 Big Switch Networks, Inc.
 *
 * Licensed under the Eclipse Public License, Version 1.0 (the
 * "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 *
 *      http://www.eclipse.org/legal/epl-v10.html
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package org.opendaylight.controller.hosttracker.internal;

import java.util.EnumSet;

import org.opendaylight.controller.hosttracker.Entity;
import org.opendaylight.controller.hosttracker.IDeviceService;
import org.opendaylight.controller.hosttracker.IDeviceService.DeviceField;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This is a thin wrapper around {@link Entity} that allows overriding the
 * behavior of {@link Object#hashCode()} and {@link Object#equals(Object)} so
 * that the keying behavior in a hash map can be changed dynamically
 *
 * @author readams
 */
public class IndexedEntity {
    protected EnumSet<DeviceField> keyFields;
    protected Entity entity;
    private int hashCode = 0;
    protected static Logger logger = LoggerFactory
            .getLogger(IndexedEntity.class);

    /**
     * Create a new {@link IndexedEntity} for the given {@link Entity} using the
     * provided key fields.
     *
     * @param keyFields
     *            The key fields that will be used for computing
     *            {@link IndexedEntity#hashCode()} and
     *            {@link IndexedEntity#equals(Object)}
     * @param entity
     *            the entity to wrap
     */
    public IndexedEntity(EnumSet<DeviceField> keyFields, Entity entity) {
        super();
        this.keyFields = keyFields;
        this.entity = entity;
    }

    /**
     * Check whether this entity has non-null values in any of its key fields
     *
     * @return true if any key fields have a non-null value
     */
    public boolean hasNonNullKeys() {
        for (DeviceField f : keyFields) {
            switch (f) {
            case MAC:
                return true;
            case IPV4:
                if (entity.getIpv4Address() != null)
                    return true;
                break;
            case SWITCHPORT:
                if (entity.getPort() != null)
                    return true;
                break;
            case VLAN:
                if (entity.getVlan() != null)
                    return true;
                break;
            }
        }
        return false;
    }

    @Override
    public int hashCode() {

        if (hashCode != 0) {
            return hashCode;
        }

        final int prime = 31;
        hashCode = 1;
        for (DeviceField f : keyFields) {
            switch (f) {
            case MAC:
                hashCode = prime
                        * hashCode
                        + (int) (entity.getMacAddress() ^ (entity
                                .getMacAddress() >>> 32));
                break;
            case IPV4:
                hashCode = prime
                        * hashCode
                        + ((entity.getIpv4Address() == null) ? 0 : entity
                                .getIpv4Address().hashCode());
                break;
            case SWITCHPORT:
                hashCode = prime
                        * hashCode
                        + ((entity.getPort() == null) ? 0 : entity.getPort()
                                .hashCode());
                break;
            case VLAN:
                hashCode = prime
                        * hashCode
                        + ((entity.getVlan() == null) ? 0 : entity.getVlan()
                                .hashCode());
                break;
            }
        }
        return hashCode;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        IndexedEntity other = (IndexedEntity) obj;

        if (!keyFields.equals(other.keyFields))
            return false;

        for (IDeviceService.DeviceField f : keyFields) {
            switch (f) {
            case MAC:
                if (entity.getMacAddress() != other.entity.getMacAddress())
                    return false;
                break;
            case IPV4:
                if (entity.getIpv4Address() == null) {
                    if (other.entity.getIpv4Address() != null)
                        return false;
                } else if (!entity.getIpv4Address().equals(
                        other.entity.getIpv4Address()))
                    return false;
                break;
            case SWITCHPORT:
                if (entity.getPort() == null) {
                    if (other.entity.getPort() != null)
                        return false;
                } else if (!entity.getPort().equals(other.entity.getPort()))
                    return false;
                break;
            case VLAN:
                if (entity.getVlan() == null) {
                    if (other.entity.getVlan() != null)
                        return false;
                } else if (!entity.getVlan().equals(other.entity.getVlan()))
                    return false;
                break;
            }
        }

        return true;
    }

}