/*
 * Copyright 2016-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.incubator.net.virtual.impl;


import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.apache.felix.scr.annotations.Service;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.incubator.net.tunnel.TunnelId;
import org.onosproject.incubator.net.virtual.DefaultVirtualLink;
import org.onosproject.incubator.net.virtual.NetworkId;
import org.onosproject.incubator.net.virtual.VirtualNetworkProvider;
import org.onosproject.incubator.net.virtual.VirtualNetworkProviderRegistry;
import org.onosproject.incubator.net.virtual.VirtualNetworkProviderService;
import org.onosproject.net.ConnectPoint;
import org.onosproject.net.EncapsulationType;
import org.onosproject.net.intent.Constraint;
import org.onosproject.net.intent.Intent;
import org.onosproject.net.intent.IntentService;
import org.onosproject.net.intent.IntentState;
import org.onosproject.net.intent.Key;
import org.onosproject.net.intent.PointToPointIntent;
import org.onosproject.net.intent.constraint.EncapsulationConstraint;
import org.onosproject.net.provider.AbstractProvider;
import org.slf4j.Logger;

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

import static com.google.common.base.Preconditions.checkNotNull;
import static java.lang.Thread.sleep;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Point to point intent VirtualNetworkProvider implementation.
 */
@Component(immediate = true)
@Service
public class PtToPtIntentVirtualNetworkProvider extends AbstractProvider implements VirtualNetworkProvider {

    private final Logger log = getLogger(PtToPtIntentVirtualNetworkProvider.class);
    private static final String NETWORK_ID_NULL = "Network ID cannot be null";
    private static final String CONNECT_POINT_NULL = "Connect Point cannot be null";
    private static final String INTENT_NULL = "Intent cannot be null";
    protected static final String KEY_FORMAT = "networkId=%s src=%s dst=%s";
    private static final int MAX_WAIT_COUNT = 30;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected VirtualNetworkProviderRegistry providerRegistry;

    private VirtualNetworkProviderService providerService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected IntentService intentService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected CoreService coreService;

    protected static final String PTPT_INTENT_APPID = "org.onosproject.vnet.intent";
    private ApplicationId appId;

    /**
     * Default constructor.
     */
    public PtToPtIntentVirtualNetworkProvider() {
        super(DefaultVirtualLink.PID);
    }

    @Activate
    public void activate() {
        providerService = providerRegistry.register(this);
        appId = coreService.registerApplication(PTPT_INTENT_APPID);

        log.info("Started");
    }

    @Deactivate
    public void deactivate() {
        providerRegistry.unregister(this);
        providerService = null;
        log.info("Stopped");
    }

    @Override
    public TunnelId createTunnel(NetworkId networkId, ConnectPoint src, ConnectPoint dst) {
        checkNotNull(NETWORK_ID_NULL, networkId);
        checkNotNull(CONNECT_POINT_NULL, src);
        checkNotNull(CONNECT_POINT_NULL, dst);
        String key = String.format(KEY_FORMAT, networkId.toString(), src.toString(), dst.toString());
        Key intentKey = Key.of(key, appId);

        List<Constraint> constraints = new ArrayList<>();
        constraints.add(new EncapsulationConstraint(EncapsulationType.VLAN));

        // TODO Currently there can only be one tunnel/intent between the src and dst across
        // all virtual networks. We may want to support multiple intents between the same src/dst pairs.
        PointToPointIntent intent = PointToPointIntent.builder()
                .key(intentKey)
                .appId(appId)
                .ingressPoint(src)
                .egressPoint(dst)
                .constraints(constraints)
                .build();
        intentService.submit(intent);

        // construct tunnelId from the key
        return TunnelId.valueOf(key);
    }

    @Override
    public void destroyTunnel(NetworkId networkId, TunnelId tunnelId) {
        String key = tunnelId.id();
        Key intentKey = Key.of(key, appId);
        Intent intent = intentService.getIntent(intentKey);
        checkNotNull(intent, INTENT_NULL);
        intentService.withdraw(intent);
        try {
            int count = 0;
            // Loop waiting for the intent to go into a withdrawn or failed state
            // before attempting to purge it.
            while (++count <= MAX_WAIT_COUNT) {
                IntentState state = intentService.getIntentState(intentKey);
                if ((state == IntentState.FAILED) || (state == IntentState.WITHDRAWN)) {
                    intentService.purge(intent);
                    break;
                }
                sleep(1000);
            }
        } catch (Exception e) {
            log.error("Exception: " + e);
        }
    }
}