using MessengerBroker.Configuration.Model;
using MessengerBroker.Factories;
using Microsoft.EntityFrameworkCore;

namespace MessengerBroker.Handlers
{
    public class HousekeepingHandler
    {
        private readonly BrokerConfiguration brokerConfiguration;
        private readonly BrokerDbContextFactory brokerDbContextFactory;

        public HousekeepingHandler(BrokerConfiguration brokerConfiguration)
        {
            this.brokerConfiguration = brokerConfiguration;
        }

        public Task BeginHousekeeping(CancellationToken ct = default)
        {
            if(this.brokerConfiguration.HousekeepingEnabled == false)
            {
                return Task.CompletedTask;
            }

            return Task.Run(async () =>
            {
                while (!ct.IsCancellationRequested)
                {
                    await Task.Delay(TimeSpan.FromMinutes(1));

                    using var context = this.brokerDbContextFactory.CreateDbContext();

                    var oldestAllowedTimestamp = DateTime.UtcNow.AddMinutes(-this.brokerConfiguration.HousekeepingMessageAgeInMinutes);

                    await context.Messages
                        .Where(x => x.TimestampUtc < oldestAllowedTimestamp)
                        .ExecuteDeleteAsync();
                }
            });
        }
    }
}