feat: allow players to leave sessions

src/GmRelay.Bot/Features/Sessions/CreateSession/LeaveSessionHandler.cs

@@ -0,0 +1,217 @@
+using Dapper;
+using GmRelay.Shared.Domain;
+using GmRelay.Shared.Rendering;
+using Npgsql;
+using Telegram.Bot;
+
+namespace GmRelay.Bot.Features.Sessions.CreateSession;
+
+public sealed record LeaveSessionCommand(
+    Guid SessionId,
+    long TelegramUserId,
+    string CallbackQueryId,
+    long ChatId,
+    int MessageId);
+
+internal sealed record LeaveSessionInfoDto(string Title, Guid BatchId, string Status, int? MaxPlayers);
+internal sealed record LeaveSessionParticipantDto(Guid ParticipantRowId, string DisplayName, string RegistrationStatus);
+internal sealed record LeaveSessionPromotionDto(Guid ParticipantRowId, string DisplayName);
+
+public sealed class LeaveSessionHandler(
+    NpgsqlDataSource dataSource,
+    ITelegramBotClient bot,
+    ILogger<LeaveSessionHandler> logger)
+{
+    public async Task HandleAsync(LeaveSessionCommand command, CancellationToken ct)
+    {
+        await using var connection = await dataSource.OpenConnectionAsync(ct);
+        await using var transaction = await connection.BeginTransactionAsync(ct);
+        var transactionCommitted = false;
+
+        try
+        {
+            var session = await connection.QuerySingleOrDefaultAsync<LeaveSessionInfoDto>(
+                """
+                SELECT title AS Title,
+                       batch_id AS BatchId,
+                       status AS Status,
+                       max_players AS MaxPlayers
+                FROM sessions
+                WHERE id = @SessionId
+                FOR UPDATE
+                """,
+                new { command.SessionId },
+                transaction);
+
+            if (session is null)
+            {
+                await transaction.RollbackAsync(ct);
+                await bot.AnswerCallbackQuery(command.CallbackQueryId, "Сессия не найдена.", cancellationToken: ct);
+                return;
+            }
+
+            if (SessionStatus.IsCancelled(session.Status))
+            {
+                await transaction.RollbackAsync(ct);
+                await bot.AnswerCallbackQuery(command.CallbackQueryId, "Сессия уже отменена.", cancellationToken: ct);
+                return;
+            }
+
+            var participant = await connection.QuerySingleOrDefaultAsync<LeaveSessionParticipantDto>(
+                """
+                SELECT sp.id AS ParticipantRowId,
+                       p.display_name AS DisplayName,
+                       sp.registration_status AS RegistrationStatus
+                FROM session_participants sp
+                JOIN players p ON p.id = sp.player_id
+                WHERE sp.session_id = @SessionId
+                  AND p.telegram_id = @TelegramUserId
+                  AND sp.is_gm = false
+                FOR UPDATE OF sp
+                """,
+                new { command.SessionId, command.TelegramUserId },
+                transaction);
+
+            if (participant is null)
+            {
+                await transaction.RollbackAsync(ct);
+                await bot.AnswerCallbackQuery(command.CallbackQueryId, "Вы не записаны на эту сессию.", cancellationToken: ct);
+                return;
+            }
+
+            await connection.ExecuteAsync(
+                """
+                DELETE FROM session_participants
+                WHERE id = @ParticipantRowId
+                """,
+                new { participant.ParticipantRowId },
+                transaction);
+
+            var activeParticipantsAfterLeave = await connection.ExecuteScalarAsync<int>(
+                """
+                SELECT COUNT(*)
+                FROM session_participants
+                WHERE session_id = @SessionId
+                  AND is_gm = false
+                  AND registration_status = @Active
+                """,
+                new { command.SessionId, Active = ParticipantRegistrationStatus.Active },
+                transaction);
+
+            var waitlistedParticipants = await connection.ExecuteScalarAsync<int>(
+                """
+                SELECT COUNT(*)
+                FROM session_participants
+                WHERE session_id = @SessionId
+                  AND is_gm = false
+                  AND registration_status = @Waitlisted
+                """,
+                new { command.SessionId, Waitlisted = ParticipantRegistrationStatus.Waitlisted },
+                transaction);
+
+            string? promotedDisplayName = null;
+            if (SessionCapacityRules.ShouldPromoteAfterParticipantLeaves(
+                participant.RegistrationStatus,
+                session.MaxPlayers,
+                activeParticipantsAfterLeave,
+                waitlistedParticipants))
+            {
+                var promoted = await connection.QuerySingleAsync<LeaveSessionPromotionDto>(
+                    """
+                    SELECT sp.id AS ParticipantRowId,
+                           p.display_name AS DisplayName
+                    FROM session_participants sp
+                    JOIN players p ON p.id = sp.player_id
+                    WHERE sp.session_id = @SessionId
+                      AND sp.is_gm = false
+                      AND sp.registration_status = @Waitlisted
+                    ORDER BY sp.created_at ASC, sp.id ASC
+                    LIMIT 1
+                    FOR UPDATE OF sp
+                    """,
+                    new { command.SessionId, Waitlisted = ParticipantRegistrationStatus.Waitlisted },
+                    transaction);
+
+                await connection.ExecuteAsync(
+                    """
+                    UPDATE session_participants
+                    SET registration_status = @Active,
+                        rsvp_status = @Pending,
+                        responded_at = NULL
+                    WHERE id = @ParticipantRowId
+                    """,
+                    new
+                    {
+                        promoted.ParticipantRowId,
+                        Active = ParticipantRegistrationStatus.Active,
+                        Pending = RsvpStatus.Pending
+                    },
+                    transaction);
+
+                promotedDisplayName = promoted.DisplayName;
+            }
+
+            var batchSessions = (await connection.QueryAsync<SessionBatchDto>(
+                """
+                SELECT id AS SessionId,
+                       scheduled_at AS ScheduledAt,
+                       status AS Status,
+                       max_players AS MaxPlayers
+                FROM sessions
+                WHERE batch_id = @BatchId
+                ORDER BY scheduled_at
+                """,
+                new { session.BatchId },
+                transaction)).ToList();
+
+            var batchParticipants = (await connection.QueryAsync<ParticipantBatchDto>(
+                """
+                SELECT sp.session_id AS SessionId,
+                       p.display_name AS DisplayName,
+                       p.telegram_username AS TelegramUsername,
+                       sp.registration_status AS RegistrationStatus
+                FROM session_participants sp
+                JOIN players p ON sp.player_id = p.id
+                JOIN sessions s ON sp.session_id = s.id
+                WHERE s.batch_id = @BatchId AND sp.is_gm = false
+                ORDER BY sp.registration_status ASC, sp.created_at ASC, sp.responded_at ASC, p.created_at ASC
+                """,
+                new { session.BatchId },
+                transaction)).ToList();
+
+            await transaction.CommitAsync(ct);
+            transactionCommitted = true;
+
+            var renderResult = SessionBatchRenderer.Render(session.Title, batchSessions, batchParticipants);
+
+            await bot.EditMessageText(
+                chatId: command.ChatId,
+                messageId: command.MessageId,
+                text: renderResult.Text,
+                parseMode: Telegram.Bot.Types.Enums.ParseMode.Html,
+                replyMarkup: renderResult.Markup,
+                cancellationToken: ct);
+
+            var callbackText = participant.RegistrationStatus == ParticipantRegistrationStatus.Waitlisted
+                ? "Вы удалены из листа ожидания."
+                : promotedDisplayName is null
+                    ? "Вы отписались от сессии."
+                    : $"Вы отписались от сессии. Место получил(а) {promotedDisplayName}.";
+
+            await bot.AnswerCallbackQuery(command.CallbackQueryId, callbackText, cancellationToken: ct);
+        }
+        catch (Exception ex)
+        {
+            logger.LogError(ex, "Ошибка при самостоятельной отмене записи на сессию {SessionId}", command.SessionId);
+            if (!transactionCommitted)
+            {
+                await transaction.RollbackAsync(ct);
+            }
+
+            var errorText = transactionCommitted
+                ? "Запись снята, но не удалось обновить сообщение расписания."
+                : "Произошла ошибка при отмене записи.";
+            await bot.AnswerCallbackQuery(command.CallbackQueryId, errorText, cancellationToken: ct);
+        }
+    }
+}

src/GmRelay.Bot/Infrastructure/Telegram/UpdateRouter.cs

@@ -20,6 +20,7 @@ public sealed class UpdateRouter(
     HandleRsvpHandler rsvpHandler,
     CreateSessionHandler createSessionHandler,
     JoinSessionHandler joinSessionHandler,
+    LeaveSessionHandler leaveSessionHandler,
     PromoteWaitlistedPlayerHandler promoteWaitlistedPlayerHandler,
     CancelSessionHandler cancelSessionHandler,
     DeleteSessionHandler deleteSessionHandler,
@@ -73,6 +74,19 @@ public sealed class UpdateRouter(
             return;
         }
 
+        if (action == "leave_session" && parts.Length >= 2 && Guid.TryParse(parts[1], out var leaveSessionId))
+        {
+            var command = new LeaveSessionCommand(
+                SessionId: leaveSessionId,
+                TelegramUserId: query.From.Id,
+                CallbackQueryId: query.Id,
+                ChatId: message.Chat.Id,
+                MessageId: message.MessageId);
+
+            await leaveSessionHandler.HandleAsync(command, ct);
+            return;
+        }
+
         if (action == "cancel_session" && parts.Length >= 2 && Guid.TryParse(parts[1], out var cancelSessionId))
         {
             var command = new CancelSessionCommand(
@@ -210,6 +224,7 @@ public sealed class UpdateRouter(
                         Ссылка: https://link
 
                         /listsessions — список предстоящих сессий
+                        Игроки могут записаться кнопкой «На дату» и сняться кнопкой «Выйти».
                         /help — эта справка
                         """,
                     cancellationToken: ct);

src/GmRelay.Bot/Program.cs

@@ -54,6 +54,7 @@ builder.Services.AddSingleton<HandleRsvpHandler>();
 builder.Services.AddSingleton<SendJoinLinkHandler>();
 builder.Services.AddSingleton<CreateSessionHandler>();
 builder.Services.AddSingleton<JoinSessionHandler>();
+builder.Services.AddSingleton<LeaveSessionHandler>();
 builder.Services.AddSingleton<PromoteWaitlistedPlayerHandler>();
 builder.Services.AddSingleton<CancelSessionHandler>();
 builder.Services.AddSingleton<GmRelay.Bot.Features.Sessions.ListSessions.DeleteSessionHandler>();