using System;
using Confluent.Kafka;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using xEventService.Configuration;
using xEventService.Constants;

namespace xEventService.Providers
{
    /// <summary>
    /// an Abstract Kafka Consumer Service ...
    /// </summary>
    public abstract class XKafkaConsumerServiceBase : BackgroundService
    {
        /// <summary>
        /// Consumed Topic Messages ...
        /// </summary>
        private readonly string topic;

        /// <summary>
        /// Kafka Consumer Class ...
        /// </summary>
        public readonly IConsumer<Ignore, string> consumer;

        private readonly XEventServiceConfiguration configuration;

        private readonly ILogger<XKafkaConsumerServiceBase> logger;

        protected XKafkaConsumerServiceBase(
            XEventServiceConfiguration configuration,
            ILogger<XKafkaConsumerServiceBase> logger,
            string topic = XEventServiceConstants.XDefaultTopic
        )
        {
            //
            this.topic = topic;
            this.logger = logger;
            this.configuration = configuration;

            //
            // Prepare Kafka Consumer Configuration ...
            var config = new ConsumerConfig
            {
                EnableAutoCommit = false,
                BootstrapServers = configuration.Url,
                AutoOffsetReset = AutoOffsetReset.Earliest,
                GroupId = XEventServiceConstants.XDefaultConsumerGroup,
            };
            consumer = new ConsumerBuilder<Ignore, string>(config).Build();
        }

        /// <summary>
        /// Dispose Implementation ...
        /// </summary>
        public override void Dispose()
        {
            //
            consumer.Close();
            consumer.Dispose();
            GC.SuppressFinalize(this);
            base.Dispose();
        }
    }
}