/*
 * Copyright 2017-present Open Networking Foundation
 *
 * 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.drivers.p4runtime;

import org.onosproject.net.DeviceId;
import org.onosproject.net.MastershipRole;
import org.onosproject.net.device.DeviceHandshaker;
import org.onosproject.p4runtime.api.P4RuntimeController;

import java.util.concurrent.CompletableFuture;

/**
 * Implementation of DeviceHandshaker for P4Runtime.
 */
public class P4RuntimeHandshaker extends AbstractP4RuntimeHandlerBehaviour implements DeviceHandshaker {

    // TODO: consider abstract class with empty connect method and  implementation into a protected one for reusability.

    @Override
    public CompletableFuture<Boolean> connect() {
        return CompletableFuture.supplyAsync(this::doConnect);
    }

    private boolean doConnect() {
        return super.createClient();
    }

    @Override
    public CompletableFuture<Boolean> disconnect() {
        return CompletableFuture.supplyAsync(() -> {
            P4RuntimeController controller = handler().get(P4RuntimeController.class);
            DeviceId deviceId = handler().data().deviceId();
            controller.removeClient(deviceId);
            return true;
        });
    }

    @Override
    public CompletableFuture<Boolean> isReachable() {
        return CompletableFuture.supplyAsync(() -> {
            P4RuntimeController controller = handler().get(P4RuntimeController.class);
            DeviceId deviceId = handler().data().deviceId();
            return controller.isReacheable(deviceId);
        });
    }

    @Override
    public CompletableFuture<MastershipRole> roleChanged(MastershipRole newRole) {
        deviceId = handler().data().deviceId();
        controller = handler().get(P4RuntimeController.class);
        CompletableFuture<MastershipRole> result = new CompletableFuture<>();

        client = controller.getClient(deviceId);
        if (client == null || !controller.isReacheable(deviceId)) {
            result.complete(MastershipRole.NONE);
            return result;
        }
        if (newRole.equals(MastershipRole.MASTER)) {
            client.sendMasterArbitrationUpdate().thenAcceptAsync(success -> {
                if (!success) {
                    log.warn("Device {} arbitration failed", deviceId);
                    result.complete(MastershipRole.STANDBY);
                } else {
                    result.complete(MastershipRole.MASTER);
                }
            });
        } else {
            // Since we don't need to do anything, we can complete it directly
            // Spec: The client with the highest election id is referred to as the
            // "master", while all other clients are referred to as "slaves".
            result.complete(newRole);
        }
        return result;
    }
}