feat(#13): add calendar subscription link to Telegram export

src/GmRelay.Bot/Features/Sessions/ExportCalendar/ExportCalendarHandler.cs

@@ -1,9 +1,11 @@
 using System.Text;
 using Dapper;
 using GmRelay.Shared.Domain;
+using Microsoft.Extensions.Configuration;
 using Npgsql;
 using Telegram.Bot;
 using Telegram.Bot.Types;
+using Telegram.Bot.Types.ReplyMarkups;
 
 namespace GmRelay.Bot.Features.Sessions.ExportCalendar;
 
@@ -11,7 +13,8 @@ internal sealed record CalendarSessionDto(Guid Id, string Title, DateTime Schedu
 
 public sealed class ExportCalendarHandler(
     NpgsqlDataSource dataSource,
-    ITelegramBotClient botClient)
+    ITelegramBotClient botClient,
+    IConfiguration configuration)
 {
     public async Task HandleAsync(Message message, CancellationToken cancellationToken)
     {
@@ -64,11 +67,45 @@ public sealed class ExportCalendarHandler(
 
         var inputFile = InputFile.FromStream(stream, "schedule.ics");
 
+        // Create calendar subscription
+        string? subscriptionUrl = null;
+        var baseUrl = configuration["Web:BaseUrl"];
+        var senderId = message.From?.Id;
+        if (!string.IsNullOrWhiteSpace(baseUrl) && senderId.HasValue)
+        {
+            try
+            {
+                var token = Guid.NewGuid().ToString("N");
+                var groupId = await connection.QueryFirstOrDefaultAsync<Guid?>(
+                    @"SELECT id FROM game_groups WHERE telegram_chat_id = @ChatId",
+                    new { ChatId = message.Chat.Id });
+
+                await connection.ExecuteAsync(
+                    @"INSERT INTO calendar_subscriptions (id, token, user_telegram_id, group_id, filter_type, created_at, expires_at)
+                      VALUES (gen_random_uuid(), @token, @userTelegramId, @groupId, @filterType, now(), NULL)",
+                    new { token, userTelegramId = senderId.Value, groupId, filterType = (int)CalendarSubscriptionFilter.SpecificGroup });
+
+                subscriptionUrl = $"{baseUrl.TrimEnd('/')}/calendar/{token}.ics";
+            }
+            catch
+            {
+                // Non-critical: if subscription creation fails, still send the file
+            }
+        }
+
+        var replyMarkup = subscriptionUrl is not null
+            ? new InlineKeyboardMarkup(new[]
+            {
+                new[] { InlineKeyboardButton.WithUrl("🔗 Подписаться на календарь", subscriptionUrl) }
+            })
+            : null;
+
         await botClient.SendDocument(
              chatId: message.Chat.Id,
              document: inputFile,
              caption: "📅 <b>Ваш календарь игр!</b>\nОткройте файл на устройстве, чтобы добавить события в свой календарь.",
              parseMode: Telegram.Bot.Types.Enums.ParseMode.Html,
+             replyMarkup: replyMarkup,
              messageThreadId: message.MessageThreadId,
              cancellationToken: cancellationToken);
     }