/**
*    Copyright 2011,2012, Big Switch Networks, Inc. 
*    Originally created by David Erickson, Stanford University
* 
*    Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
*    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 net.floodlightcontroller.devicemanager.internal;

import java.util.Date;

import net.floodlightcontroller.core.web.serializers.IPv4Serializer;
import net.floodlightcontroller.core.web.serializers.MACSerializer;
import net.floodlightcontroller.core.web.serializers.DPIDSerializer;
import net.floodlightcontroller.packet.IPv4;

import org.codehaus.jackson.map.annotate.JsonSerialize;
import org.openflow.util.HexString;

/**
 * An entity on the network is a visible trace of a device that corresponds
 * to a packet received from a particular interface on the edge of a network,
 * with a particular VLAN tag, and a particular MAC address, along with any
 * other packet characteristics we might want to consider as helpful for
 * disambiguating devices.
 * 
 * Entities are the most basic element of devices; devices consist of one or
 * more entities.  Entities are immutable once created, except for the last
 * seen timestamp.
 *  
 * @author readams
 *
 */
public class Entity implements Comparable<Entity> {
    /**
     * Timeout for computing {@link Entity#activeSince}.
     * @see {@link Entity#activeSince}
     */
    protected static int ACTIVITY_TIMEOUT = 30000;
    
    /**
     * The MAC address associated with this entity
     */
    protected long macAddress;
    
    /**
     * The IP address associated with this entity, or null if no IP learned
     * from the network observation associated with this entity
     */
    protected Integer ipv4Address;
    
    /**
     * The VLAN tag on this entity, or null if untagged
     */
    protected Short vlan;
    
    /**
     * The DPID of the switch for the ingress point for this entity,
     * or null if not present
     */
    protected Long switchDPID;
    
    /**
     * The port number of the switch for the ingress point for this entity,
     * or null if not present
     */
    protected Integer switchPort;
    
    /**
     * The last time we observed this entity on the network
     */
    protected Date lastSeenTimestamp;

    /**
     * The time between {@link Entity#activeSince} and 
     * {@link Entity#lastSeenTimestamp} is a period of activity for this
     * entity where it was observed repeatedly.  If, when the entity is
     * observed, the  is longer ago than the activity timeout, 
     * {@link Entity#lastSeenTimestamp} and {@link Entity#activeSince} will 
     * be set to the current time.
     */
    protected Date activeSince;
    
    private int hashCode = 0;

    // ************
    // Constructors
    // ************
    
    /**
     * Create a new entity
     * 
     * @param macAddress
     * @param vlan
     * @param ipv4Address
     * @param switchDPID
     * @param switchPort
     * @param lastSeenTimestamp
     */
    public Entity(long macAddress, Short vlan, 
                  Integer ipv4Address, Long switchDPID, Integer switchPort, 
                  Date lastSeenTimestamp) {
        this.macAddress = macAddress;
        this.ipv4Address = ipv4Address;
        this.vlan = vlan;
        this.switchDPID = switchDPID;
        this.switchPort = switchPort;
        this.lastSeenTimestamp = lastSeenTimestamp;
        this.activeSince = lastSeenTimestamp;
    }

    // ***************
    // Getters/Setters
    // ***************

    @JsonSerialize(using=MACSerializer.class)
    public long getMacAddress() {
        return macAddress;
    }

    @JsonSerialize(using=IPv4Serializer.class)
    public Integer getIpv4Address() {
        return ipv4Address;
    }

    public Short getVlan() {
        return vlan;
    }

    @JsonSerialize(using=DPIDSerializer.class)
    public Long getSwitchDPID() {
        return switchDPID;
    }

    public Integer getSwitchPort() {
        return switchPort;
    }

    public Date getLastSeenTimestamp() {
        return lastSeenTimestamp;
    }

    /**
     * Set the last seen timestamp and also update {@link Entity#activeSince}
     * if appropriate
     * @param lastSeenTimestamp the new last seen timestamp
     * @see {@link Entity#activeSince}
     */
    public void setLastSeenTimestamp(Date lastSeenTimestamp) {
        if (activeSince == null ||
            (activeSince.getTime() +  ACTIVITY_TIMEOUT) <
                lastSeenTimestamp.getTime())
            this.activeSince = lastSeenTimestamp;
        this.lastSeenTimestamp = lastSeenTimestamp;
    }

    public Date getActiveSince() {
        return activeSince;
    }

    public void setActiveSince(Date activeSince) {
        this.activeSince = activeSince;
    }
    
    @Override
    public int hashCode() {
        if (hashCode != 0) return hashCode;
        final int prime = 31;
        hashCode = 1;
        hashCode = prime * hashCode
                 + ((ipv4Address == null) ? 0 : ipv4Address.hashCode());
        hashCode = prime * hashCode + (int) (macAddress ^ (macAddress >>> 32));
        hashCode = prime * hashCode
                 + ((switchDPID == null) ? 0 : switchDPID.hashCode());
        hashCode = prime * hashCode
                 + ((switchPort == null) ? 0 : switchPort.hashCode());
        hashCode = prime * hashCode + ((vlan == null) ? 0 : vlan.hashCode());
        return hashCode;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        Entity other = (Entity) obj;
        if (hashCode() != other.hashCode()) return false;
        if (ipv4Address == null) {
            if (other.ipv4Address != null) return false;
        } else if (!ipv4Address.equals(other.ipv4Address)) return false;
        if (macAddress != other.macAddress) return false;
        if (switchDPID == null) {
            if (other.switchDPID != null) return false;
        } else if (!switchDPID.equals(other.switchDPID)) return false;
        if (switchPort == null) {
            if (other.switchPort != null) return false;
        } else if (!switchPort.equals(other.switchPort)) return false;
        if (vlan == null) {
            if (other.vlan != null) return false;
        } else if (!vlan.equals(other.vlan)) return false;
        return true;
    }

    
    
    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("Entity [macAddress=");
        builder.append(HexString.toHexString(macAddress, 6));
        builder.append(", ipv4Address=");
        builder.append(IPv4.fromIPv4Address(ipv4Address==null ?
                       0 : ipv4Address.intValue()));
        builder.append(", vlan=");
        builder.append(vlan);
        builder.append(", switchDPID=");
        builder.append(switchDPID);
        builder.append(", switchPort=");
        builder.append(switchPort);
        builder.append(", lastSeenTimestamp=");
        builder.append(lastSeenTimestamp == null? "null" : lastSeenTimestamp.getTime());
        builder.append(", activeSince=");
        builder.append(activeSince == null? "null" : activeSince.getTime());
        builder.append("]");
        return builder.toString();
    }

    @Override
    public int compareTo(Entity o) {
        if (macAddress < o.macAddress) return -1;
        if (macAddress > o.macAddress) return 1;

        int r;
        if (switchDPID == null)
            r = o.switchDPID == null ? 0 : -1;
        else if (o.switchDPID == null)
            r = 1;
        else
            r = switchDPID.compareTo(o.switchDPID);
        if (r != 0) return r;

        if (switchPort == null)
            r = o.switchPort == null ? 0 : -1;
        else if (o.switchPort == null)
            r = 1;
        else
            r = switchPort.compareTo(o.switchPort);
        if (r != 0) return r;

        if (ipv4Address == null)
            r = o.ipv4Address == null ? 0 : -1;
        else if (o.ipv4Address == null)
            r = 1;
        else
            r = ipv4Address.compareTo(o.ipv4Address);
        if (r != 0) return r;

        if (vlan == null)
            r = o.vlan == null ? 0 : -1;
        else if (o.vlan == null)
            r = 1;
        else
            r = vlan.compareTo(o.vlan);
        if (r != 0) return r;

        return 0;
    }
    
}