/*
 * Copyright (C) 2017 Julien Viet
 *
 * 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 io.vertx.pgclient.pubsub;

import io.vertx.pgclient.PgConnectOptions;
import io.vertx.pgclient.PgConnection;
import io.vertx.pgclient.impl.pubsub.PgSubscriberImpl;
import io.vertx.codegen.annotations.Fluent;
import io.vertx.codegen.annotations.VertxGen;
import io.vertx.core.AsyncResult;
import io.vertx.core.Handler;
import io.vertx.core.Vertx;

import java.util.function.Function;

A class for managing subscriptions using LISTEN/UNLISTEN to Postgres channels. 

The subscriber manages a single connection to Postgres.
/**
 * A class for managing subscriptions using {@code LISTEN/UNLISTEN} to Postgres channels.
 * <p/>
 * The subscriber manages a single connection to Postgres.
 */
@VertxGen
public interface PgSubscriber {

  
Create a subscriber.
Params:
vertx – the vertx instance
options – the connect options
Returns:
the subscriber/**
   * Create a subscriber.
   *
   * @param vertx the vertx instance
   * @param options the connect options
   * @return the subscriber
   */
  static PgSubscriber subscriber(Vertx vertx, PgConnectOptions options) {
    return new PgSubscriberImpl(vertx, options);
  }

  
Return a channel for the given name. 
Params:
name – the channel name
 This will be the name of the channel exactly as held by Postgres for sending notifications. Internally this name will be truncated to the Postgres identifier maxiumum length of (NAMEDATALEN = 64) - 1 == 63 characters, and prepared as a quoted identifier without unicode escape sequence support for use in LISTEN/UNLISTEN commands. Examples of channel names and corresponding NOTIFY commands: 

  
when name == "the_channel": NOTIFY the_channel, 'msg', NOTIFY The_Channel, 'msg', or NOTIFY "the_channel", 'msg' succeed in delivering a message to the created channel 
  
when name == "The_Channel": NOTIFY "The_Channel", 'msg', succeeds in delivering a message to the created channel 
  

Returns:
the channel/**
   * Return a channel for the given {@code name}.
   *
   * @param name the channel name
   * <p/>
   * This will be the name of the channel exactly as held by Postgres for sending
   * notifications.  Internally this name will be truncated to the Postgres identifier
   * maxiumum length of {@code (NAMEDATALEN = 64) - 1 == 63} characters, and prepared
   * as a quoted identifier without unicode escape sequence support for use in
   * {@code LISTEN/UNLISTEN} commands.  Examples of channel names and corresponding
   * {@code NOTIFY} commands:
   * <ul>
   *   <li>when {@code name == "the_channel"}: {@code NOTIFY the_channel, 'msg'},
   *   {@code NOTIFY The_Channel, 'msg'}, or {@code NOTIFY "the_channel", 'msg'}
   *   succeed in delivering a message to the created channel
   *   </li>
   *   <li>when {@code name == "The_Channel"}: {@code NOTIFY "The_Channel", 'msg'},
   *   succeeds in delivering a message to the created channel
   *   </li>
   *   <li></li>
   * </ul>
   * @return the channel
   */
  PgChannel channel(String name);

  
Connect the subscriber to Postgres.
Params:
handler – the handler notified of the connection success or failure
Returns:
a reference to this, so the API can be used fluently/**
   * Connect the subscriber to Postgres.
   *
   * @param handler the handler notified of the connection success or failure
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  PgSubscriber connect(Handler<AsyncResult<Void>> handler);

  
Set the reconnect policy that is executed when the subscriber is disconnected.
 When the subscriber is disconnected, the policy function is called with the actual number of retries and returns an amountOfTime value: 

  
when amountOfTime < 0: the subscriber is closed and there is no retry
  
when amountOfTime == 0: the subscriber retries to connect immediately
  
when amountOfTime > 0: the subscriber retries after amountOfTime milliseconds


The default policy does not perform any retries.
Params:
policy – the policy to set
Returns:
a reference to this, so the API can be used fluently/**
   * Set the reconnect policy that is executed when the subscriber is disconnected.
   * <p/>
   * When the subscriber is disconnected, the {@code policy} function is called with the actual
   * number of retries and returns an {@code amountOfTime} value:
   * <ul>
   *   <li>when {@code amountOfTime < 0}: the subscriber is closed and there is no retry</li>
   *   <li>when {@code amountOfTime == 0}: the subscriber retries to connect immediately</li>
   *   <li>when {@code amountOfTime > 0}: the subscriber retries after {@code amountOfTime} milliseconds</li>
   * </ul>
   * <p/>
   * The default policy does not perform any retries.
   *
   * @param policy the policy to set
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  PgSubscriber reconnectPolicy(Function<Integer, Long> policy);

  
Set an handler called when the subscriber is closed.
Params:
handler – the handler
Returns:
a reference to this, so the API can be used fluently/**
   * Set an handler called when the subscriber is closed.
   *
   * @param handler the handler
   * @return a reference to this, so the API can be used fluently
   */
  @Fluent
  PgSubscriber closeHandler(Handler<Void> handler);

  
Returns:
the actual connection to Postgres, it might be null/**
   * @return the actual connection to Postgres, it might be {@code null}
   */
  PgConnection actualConnection();

  
Returns:
whether the subscriber is closed/**
   * @return whether the subscriber is closed
   */
  boolean closed();

  
Close the subscriber, the retry policy will not be invoked.
/**
   * Close the subscriber, the retry policy will not be invoked.
   */
  void close();

}