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.SendMessage(Chat, textMessage.ToString(), parseMode: ParseMode.Html);
    }
}