telegram-bot/modules/RichSiteSummary/Handler/StatsHandler.cs

using System.Linq;
using System.Text;
using System.Threading.Tasks;
using BotFramework.Attributes;
using Kruzya.TelegramBot.RichSiteSummary.Data;
using Microsoft.EntityFrameworkCore;
using Telegram.Bot;
using Telegram.Bot.Types.Enums;

namespace Kruzya.TelegramBot.RichSiteSummary.Handler
{
    public class StatsHandler : AbstractHandler
    {
        public StatsHandler(RichSiteSummaryContext dbContext) : base(dbContext)
        {
        }
        
        [Command("rss_stats")]
        public async Task Execute()
        {
            var feedCount = await _dbContext.Feeds.CountAsync();
            var postsCount = await _dbContext.Posts.CountAsync();
            var subscriptionsCount = await _dbContext.Subscriptions.CountAsync();
            var uniqueSubscribers =
                await _dbContext.Subscriptions.Select(sub => sub.SubscriberId).Distinct().CountAsync();
            
            var textMessage = new StringBuilder();
            textMessage.Append("ℹ️ In database on this moment:\n");
            textMessage.Append($"- registered <b>{feedCount} feeds</b>\n");
            textMessage.Append($"- saved <b>{postsCount} posts</b> for prevent re-sending\n");
            textMessage.Append(
                $"- exists <b>{subscriptionsCount} subscriptions on feeds</b> (<b>unique subscribers: {uniqueSubscribers}</b>)");

            await Bot.SendTextMessageAsync(Chat, textMessage.ToString(), parseMode: ParseMode.Html);
        }
    }
}