/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.servicecomb.core.transport;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.servicecomb.core.Endpoint;
import org.apache.servicecomb.core.SCBEngine;
import org.apache.servicecomb.core.Transport;
import org.apache.servicecomb.foundation.common.exceptions.ServiceCombException;
import org.apache.servicecomb.foundation.common.utils.SPIServiceUtils;
import org.apache.servicecomb.registry.RegistrationManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class TransportManager {
  private static final Logger LOGGER = LoggerFactory.getLogger(TransportManager.class);

  private final List<Transport> transports = new ArrayList<>(SPIServiceUtils.getOrLoadSortedService(Transport.class));

  private final Map<String, Transport> transportMap = new HashMap<>();

  public void clearTransportBeforeInit() {
    transports.clear();
  }

  public void addTransportBeforeInit(Transport transport) {
    this.transports.add(transport);
  }

  public void addTransportsBeforeInit(List<Transport> transports) {
    this.transports.addAll(transports);
  }

  public void init(SCBEngine scbEngine) throws Exception {
    buildTransportMap();

    for (Transport transport : transportMap.values()) {
      if (transport.init()) {
        Endpoint endpoint = transport.getPublishEndpoint();
        if (endpoint != null && endpoint.getEndpoint() != null) {
          LOGGER.info("endpoint to publish: {}", endpoint.getEndpoint());
          RegistrationManager.INSTANCE.addEndpoint(endpoint.getEndpoint());
        }
        continue;
      }
    }
  }

  protected void buildTransportMap() {
    Map<String, List<Transport>> groups = groupByName();

    for (Entry<String, List<Transport>> entry : groups.entrySet()) {
      List<Transport> group = entry.getValue();

      checkTransportGroup(group);
      Transport transport = chooseOneTransport(group);
      transportMap.put(transport.getName(), transport);
    }
  }

  protected Transport chooseOneTransport(List<Transport> group) {
    group.sort(Comparator.comparingInt(Transport::getOrder));

    for (Transport transport : group) {
      if (transport.canInit()) {
        LOGGER.info("choose {} for {}.", transport.getClass().getName(), transport.getName());
        return transport;
      }
    }

    throw new ServiceCombException(
        String.format("all transport named %s refused to init.", group.get(0).getName()));
  }

  protected void checkTransportGroup(List<Transport> group) {
    // order value must be different, otherwise, maybe will choose a random transport
    Map<Integer, Transport> orderMap = new HashMap<>();
    for (Transport transport : group) {
      Transport existTransport = orderMap.putIfAbsent(transport.getOrder(), transport);
      if (existTransport != null) {
        throw new ServiceCombException(String.format("%s and %s have the same order %d",
            existTransport.getClass().getName(),
            transport.getClass().getName(),
            transport.getOrder()));
      }
    }
  }

  protected Map<String, List<Transport>> groupByName() {
    Map<String, List<Transport>> groups = new HashMap<>();
    for (Transport transport : transports) {
      List<Transport> list = groups.computeIfAbsent(transport.getName(), name -> new ArrayList<>());
      list.add(transport);
    }
    return groups;
  }

  public Transport findTransport(String transportName) {
    return transportMap.get(transportName);
  }
}
