feat: support co-gm group delegation

src/GmRelay.Web/Services/AuthorizedSessionService.cs

@@ -7,6 +7,24 @@ public sealed class AuthorizedSessionService(ISessionStore sessionStore)
     public Task<List<WebGameGroup>> GetGroupsForGmAsync(long gmId) =>
         sessionStore.GetGroupsForGmAsync(gmId);
 
+    public async Task<WebGroupManagement?> GetGroupManagementForGmAsync(Guid groupId, long gmId)
+    {
+        if (!await GroupBelongsToGmAsync(groupId, gmId))
+        {
+            return null;
+        }
+
+        var group = await sessionStore.GetGroupAsync(groupId);
+        if (group is null)
+        {
+            return null;
+        }
+
+        var managers = await sessionStore.GetGroupManagersAsync(groupId);
+        var isOwner = await sessionStore.IsGroupOwnerAsync(groupId, gmId);
+        return new WebGroupManagement(group, managers, isOwner);
+    }
+
     public async Task<List<WebSession>?> GetUpcomingSessionsForGmAsync(Guid groupId, long gmId)
     {
         if (!await GroupBelongsToGmAsync(groupId, gmId))
@@ -110,9 +128,45 @@ public sealed class AuthorizedSessionService(ISessionStore sessionStore)
         return await sessionStore.CloneBatchAsync(batchId, batch.GroupId, interval);
     }
 
+    public async Task AddCoGmForOwnerAsync(Guid groupId, long ownerTelegramId, long coGmTelegramId, string displayName, string? telegramUsername)
+    {
+        if (coGmTelegramId <= 0)
+        {
+            throw new ArgumentOutOfRangeException(nameof(coGmTelegramId), coGmTelegramId, "Telegram id must be greater than zero.");
+        }
+
+        if (ownerTelegramId == coGmTelegramId)
+        {
+            throw new InvalidOperationException("Owner is already a group manager.");
+        }
+
+        if (!await sessionStore.IsGroupOwnerAsync(groupId, ownerTelegramId))
+        {
+            throw new SessionAccessDeniedException(groupId, ownerTelegramId);
+        }
+
+        var normalizedName = string.IsNullOrWhiteSpace(displayName)
+            ? $"Telegram {coGmTelegramId.ToString(System.Globalization.CultureInfo.InvariantCulture)}"
+            : displayName.Trim();
+        var normalizedUsername = string.IsNullOrWhiteSpace(telegramUsername)
+            ? null
+            : telegramUsername.Trim().TrimStart('@');
+
+        await sessionStore.AddGroupCoGmAsync(groupId, ownerTelegramId, coGmTelegramId, normalizedName, normalizedUsername);
+    }
+
+    public async Task RemoveCoGmForOwnerAsync(Guid groupId, long ownerTelegramId, long coGmTelegramId)
+    {
+        if (!await sessionStore.IsGroupOwnerAsync(groupId, ownerTelegramId))
+        {
+            throw new SessionAccessDeniedException(groupId, ownerTelegramId);
+        }
+
+        await sessionStore.RemoveGroupCoGmAsync(groupId, coGmTelegramId);
+    }
+
     private async Task<bool> GroupBelongsToGmAsync(Guid groupId, long gmId)
     {
-        var group = await sessionStore.GetGroupAsync(groupId);
-        return group?.GmTelegramId == gmId;
+        return await sessionStore.IsGroupManagerAsync(groupId, gmId);
     }
 }