using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Threading.Tasks;
using BotFramework.Abstractions;
using Kruzya.TelegramBot.Core.Service;
using Kruzya.TelegramBot.RichSiteSummary.Data;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Telegram.Bot.Types;

namespace Kruzya.TelegramBot.RichSiteSummary.Service;

public class Unsubscriber : AbstractTimedHostedService
{
    protected readonly ConcurrentQueue<UserUnsubscribe> Queue;
    protected readonly IServiceScopeFactory ScopeFactory;

    protected override TimeSpan TimerPeriod => TimeSpan.FromSeconds(1);

    public Unsubscriber(ILogger<Unsubscriber> logger, IBotInstance bot, ConcurrentQueue<UserUnsubscribe> queue, IServiceScopeFactory scopeFactory) : base(logger, bot)
    {
        ScopeFactory = scopeFactory;
        Queue = queue;
    }

    protected override async Task OnRun()
    {
        if (Queue.IsEmpty || !Queue.TryDequeue(out var user))
        {
            return;
        }

        await UnsubscribeUser(user.ChatId);
    }

    private async Task UnsubscribeUser(ChatId chatId)
    {
        using var scope = ScopeFactory.CreateScope();
        var dbContext = scope.ServiceProvider.GetRequiredService<RichSiteSummaryContext>();

        var subscriptions = dbContext.Subscriptions;
        subscriptions.RemoveRange(
            subscriptions.Where(s => s.SubscriberId == chatId.Identifier)
        );
        await dbContext.SaveChangesAsync();
    }
}