/*
 * Copyright 2015-present Open Networking Laboratory
 *
 * 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 org.onosproject.openflow.controller.driver;

import com.google.common.base.MoreObjects;
import com.google.common.collect.Lists;

import org.onosproject.net.Device;
import org.onosproject.net.driver.AbstractHandlerBehaviour;
import org.onosproject.openflow.controller.Dpid;
import org.onosproject.openflow.controller.OpenFlowSession;
import org.onosproject.openflow.controller.RoleState;
import org.projectfloodlight.openflow.protocol.OFDescStatsReply;
import org.projectfloodlight.openflow.protocol.OFErrorMsg;
import org.projectfloodlight.openflow.protocol.OFExperimenter;
import org.projectfloodlight.openflow.protocol.OFFactories;
import org.projectfloodlight.openflow.protocol.OFFactory;
import org.projectfloodlight.openflow.protocol.OFFeaturesReply;
import org.projectfloodlight.openflow.protocol.OFMessage;
import org.projectfloodlight.openflow.protocol.OFMeterFeatures;
import org.projectfloodlight.openflow.protocol.OFMeterFeaturesStatsReply;
import org.projectfloodlight.openflow.protocol.OFNiciraControllerRoleRequest;
import org.projectfloodlight.openflow.protocol.OFPortDesc;
import org.projectfloodlight.openflow.protocol.OFPortDescStatsReply;
import org.projectfloodlight.openflow.protocol.OFPortStatus;
import org.projectfloodlight.openflow.protocol.OFRoleReply;
import org.projectfloodlight.openflow.protocol.OFRoleRequest;
import org.projectfloodlight.openflow.protocol.OFVersion;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.Collectors;

/**
 * An abstract representation of an OpenFlow switch. Can be extended by others
 * to serve as a base for their vendor specific representation of a switch.
 */
public abstract class AbstractOpenFlowSwitch extends AbstractHandlerBehaviour
        implements OpenFlowSwitchDriver {

    protected final Logger log = LoggerFactory.getLogger(getClass());

    private OpenFlowSession channel;
    protected String channelId;

    private boolean connected;
    protected boolean startDriverHandshakeCalled = false;
    private Dpid dpid;
    private OpenFlowAgent agent;
    private final AtomicInteger xidCounter = new AtomicInteger(0);

    private OFVersion ofVersion;
    private OFFactory ofFactory;

    protected List<OFPortDescStatsReply> ports = new ArrayList<>();

    protected boolean tableFull;

    private RoleHandler roleMan;

    // TODO this is accessed from multiple threads, but volatile may have performance implications
    protected volatile RoleState role;

    protected OFFeaturesReply features;
    protected OFDescStatsReply desc;

    protected OFMeterFeaturesStatsReply meterfeatures;

    // messagesPendingMastership is used as synchronization variable for
    // all mastership related changes. In this block, mastership (including
    // role update) will have either occurred or not.
    private final AtomicReference<List<OFMessage>> messagesPendingMastership
            = new AtomicReference<>();

    @Override
    public void init(Dpid dpid, OFDescStatsReply desc, OFVersion ofv) {
        this.dpid = dpid;
        this.desc = desc;
        this.ofVersion = ofv;
    }

    //************************
    // Channel related
    //************************

    @Override
    public final void disconnectSwitch() {
        setConnected(false);
        this.channel.closeSession();
    }

    @Override
    public void sendMsg(OFMessage msg) {
        this.sendMsg(Collections.singletonList(msg));
    }

    @Override
    public final void sendMsg(List<OFMessage> msgs) {
        /*
           It is possible that in this block, we transition to SLAVE/EQUAL.
           If this is the case, the supplied messages will race with the
           RoleRequest message, and they could be rejected by the switch.
           In the interest of performance, we will not protect this block with
           a synchronization primitive, because the message would have just been
           dropped anyway.
        */

        if (role == RoleState.MASTER) {
            // fast path send when we are master
            sendMsgsOnChannel(msgs);
            return;
        }
        // check to see if mastership transition is in progress
        synchronized (messagesPendingMastership) {
            /*
               messagesPendingMastership is used as synchronization variable for
               all mastership related changes. In this block, mastership (including
               role update) will have either occurred or not.
            */
            if (role == RoleState.MASTER) {
                // transition to MASTER complete, send messages
                sendMsgsOnChannel(msgs);
                return;
            }

            List<OFMessage> messages = messagesPendingMastership.get();
            if (messages != null) {
                // we are transitioning to MASTER, so add messages to queue
                messages.addAll(msgs);
                log.debug("Enqueue message for switch {}. queue size after is {}",
                          dpid, messages.size());
            } else {
                // not transitioning to MASTER
                log.warn("Dropping message for switch {} (role: {}, active: {}): {}",
                         dpid, role, channel.isActive(), msgs);
            }
        }
    }

    private void sendMsgsOnChannel(List<OFMessage> msgs) {
        if (channel.sendMsg(msgs)) {
            agent.processDownstreamMessage(dpid, msgs);
        } else {
            log.warn("Dropping messages for switch {} because channel is not connected: {}",
                     dpid, msgs);
        }
    }

    @Override
    public final void sendRoleRequest(OFMessage msg) {
        if (msg instanceof OFRoleRequest ||
                msg instanceof OFNiciraControllerRoleRequest) {
            sendMsgsOnChannel(Collections.singletonList(msg));
            return;
        }
        throw new IllegalArgumentException("Someone is trying to send " +
                                                   "a non role request message");
    }

    @Override
    public final void
    sendHandshakeMessage(OFMessage message) {
        if (!this.isDriverHandshakeComplete()) {
            sendMsgsOnChannel(Collections.singletonList(message));
        }
    }

    @Override
    public final boolean isConnected() {
        return this.connected;
    }

    @Override
    public final void setConnected(boolean connected) {
        this.connected = connected;
    }

    @Override
    public final void setChannel(OpenFlowSession channel) {
        this.channel = channel;
        channelId = channel.sessionInfo().toString();
    }

    @Override
    public String channelId() {
        return channelId;
    }

    //************************
    // Switch features related
    //************************

    @Override
    public final long getId() {
        return this.dpid.value();
    }

    @Override
    public Dpid getDpid() {
        return this.dpid;
    }

    @Override
    public final String getStringId() {
        return this.dpid.toString();
    }

    @Override
    public final void setOFVersion(OFVersion ofV) {
        this.ofVersion = ofV;
        this.ofFactory = OFFactories.getFactory(ofV);
    }

    @Override
    public void setTableFull(boolean full) {
        this.tableFull = full;
    }

    @Override
    public void setFeaturesReply(OFFeaturesReply featuresReply) {
        this.features = featuresReply;
    }

    @Override
    public void setMeterFeaturesReply(OFMeterFeaturesStatsReply meterFeaturesReply) {
        meterfeatures = meterFeaturesReply;
    }

    @Override
    public abstract Boolean supportNxRole();

    //************************
    //  Message handling
    //************************
    /**
     * Handle the message coming from the dataplane.
     *
     * @param m the actual message
     */
    @Override
    public final void handleMessage(OFMessage m) {
        if (this.role == RoleState.MASTER || m instanceof OFPortStatus) {
            try {
                this.agent.processMessage(dpid, m);
            } catch (Exception e) {
                log.warn("Unhandled exception processing {}@{}", m, dpid, e);
            }
        } else {
            log.trace("Dropping received message {}, was not MASTER", m);
        }
    }

    @Override
    public RoleState getRole() {
        return role;
    }

    @Override
    public final boolean connectSwitch() {
        return this.agent.addConnectedSwitch(dpid, this);
    }

    @Override
    public final boolean activateMasterSwitch() {
        return this.agent.addActivatedMasterSwitch(dpid, this);
    }

    @Override
    public final boolean activateEqualSwitch() {
        return this.agent.addActivatedEqualSwitch(dpid, this);
    }

    @Override
    public final void transitionToEqualSwitch() {
        this.agent.transitionToEqualSwitch(dpid);
    }

    @Override
    public final void transitionToMasterSwitch() {
        this.agent.transitionToMasterSwitch(dpid);
        synchronized (messagesPendingMastership) {
            List<OFMessage> messages = messagesPendingMastership.get();
            if (messages != null) {
                // Cannot use sendMsg here. It will only append to pending list.
                sendMsgsOnChannel(messages);
                log.debug("Sending {} pending messages to switch {}",
                          messages.size(), dpid);
                messagesPendingMastership.set(null);
            }
            // perform role transition after clearing messages queue
            this.role = RoleState.MASTER;
        }
    }

    @Override
    public final void removeConnectedSwitch() {
        this.agent.removeConnectedSwitch(dpid);
    }

    @Override
    public OFFactory factory() {
        return ofFactory;
    }

    @Override
    public void setPortDescReply(OFPortDescStatsReply portDescReply) {
        this.ports.add(portDescReply);
    }

    @Override
    public void setPortDescReplies(List<OFPortDescStatsReply> portDescReplies) {
        this.ports.addAll(portDescReplies);
    }

    @Override
    public void returnRoleReply(RoleState requested, RoleState response) {
        this.agent.returnRoleReply(dpid, requested, response);
    }

    @Override
    public abstract void startDriverHandshake();

    @Override
    public abstract boolean isDriverHandshakeComplete();

    @Override
    public abstract void processDriverHandshakeMessage(OFMessage m);


    // Role Handling

    @Override
    public void setRole(RoleState role) {
        try {
            if (role == RoleState.SLAVE || role == RoleState.EQUAL) {
                // perform role transition to SLAVE/EQUAL before sending role request
                this.role = role;
            }
            if (this.roleMan.sendRoleRequest(role, RoleRecvStatus.MATCHED_SET_ROLE)) {
                log.debug("Sending role {} to switch {}", role, getStringId());
                if (role == RoleState.MASTER) {
                    synchronized (messagesPendingMastership) {
                        if (messagesPendingMastership.get() == null) {
                            log.debug("Initializing new message queue for switch {}", dpid);
                            /*
                               The presence of messagesPendingMastership indicates that
                               a switch is currently transitioning to MASTER, but
                               is still awaiting role reply from switch.
                            */
                            messagesPendingMastership.set(Lists.newArrayList());
                        }
                    }
                }
            } else if (role == RoleState.MASTER) {
                // role request not support; transition switch to MASTER
                this.role = role;
            }
        } catch (IOException e) {
            log.error("Unable to write to switch {}.", this.dpid);
        }
    }

    @Override
    public void reassertRole() {
        // TODO should messages be sent directly or queue during reassertion?
        if (this.getRole() == RoleState.MASTER) {
            log.warn("Received permission error from switch {} while " +
                    "being master. Reasserting master role.",
                    this.getStringId());
            this.setRole(RoleState.MASTER);
        }
    }

    @Override
    public void handleRole(OFMessage m) throws SwitchStateException {
        RoleReplyInfo rri = roleMan.extractOFRoleReply((OFRoleReply) m);
        RoleRecvStatus rrs = roleMan.deliverRoleReply(rri);
        if (rrs == RoleRecvStatus.MATCHED_SET_ROLE) {
            if (rri.getRole() == RoleState.MASTER) {
                this.transitionToMasterSwitch();
            } else if (rri.getRole() == RoleState.EQUAL ||
                       rri.getRole() == RoleState.SLAVE) {
                this.transitionToEqualSwitch();
            }
        }  else {
            log.warn("Failed to set role for {}", this.getStringId());
        }
    }

    @Override
    public void handleNiciraRole(OFMessage m) throws SwitchStateException {
        RoleState r = this.roleMan.extractNiciraRoleReply((OFExperimenter) m);
        if (r == null) {
            // The message wasn't really a Nicira role reply. We just
            // dispatch it to the OFMessage listeners in this case.
            this.handleMessage(m);
            return;
        }

        RoleRecvStatus rrs = this.roleMan.deliverRoleReply(
                new RoleReplyInfo(r, null, m.getXid()));
        if (rrs == RoleRecvStatus.MATCHED_SET_ROLE) {
            if (r == RoleState.MASTER) {
                this.transitionToMasterSwitch();
            } else if (r == RoleState.EQUAL ||
                       r == RoleState.SLAVE) {
                this.transitionToEqualSwitch();
            }
        } else {
            this.disconnectSwitch();
        }
    }

    @Override
    public boolean handleRoleError(OFErrorMsg error) {
        try {
            return RoleRecvStatus.OTHER_EXPECTATION != this.roleMan.deliverError(error);
        } catch (SwitchStateException e) {
            this.disconnectSwitch();
        }
        return true;
    }

    @Override
    public final void setAgent(OpenFlowAgent ag) {
        if (this.agent == null) {
            this.agent = ag;
        }
    }

    @Override
    public final void setRoleHandler(RoleHandler roleHandler) {
        if (this.roleMan == null) {
            this.roleMan = roleHandler;
        }
    }

    @Override
    public void setSwitchDescription(OFDescStatsReply d) {
        this.desc = d;
    }

    @Override
    public int getNextTransactionId() {
        return this.xidCounter.getAndIncrement();
    }

    @Override
    public List<OFPortDesc> getPorts() {
        return this.ports.stream()
                  .flatMap(portReply -> portReply.getEntries().stream())
                  .collect(Collectors.toList());
    }

    @Override
    public OFMeterFeatures getMeterFeatures() {
        if (this.meterfeatures != null) {
            return this.meterfeatures.getFeatures();
        } else {
            return null;
        }
    }

    @Override
    public String manufacturerDescription() {
        return this.desc.getMfrDesc();
    }

    @Override
    public String datapathDescription() {
        return this.desc.getDpDesc();
    }

    @Override
    public String hardwareDescription() {
        return this.desc.getHwDesc();
    }

    @Override
    public String softwareDescription() {
        return this.desc.getSwDesc();
    }

    @Override
    public String serialNumber() {
        return this.desc.getSerialNum();
    }

    @Override
    public Device.Type deviceType() {
        return Device.Type.SWITCH;
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(getClass())
                .add("session", channel.sessionInfo())
                .add("dpid", dpid)
                .toString();
    }
}