Prevent user to open multiple strategy on the same ticker

src/Managing.Api/Controllers/BotController.cs

@@ -139,6 +139,11 @@ public class BotController : BaseController
             await NotifyBotSubscriberAsync();
             return Ok(result);
         }
+        catch (InvalidOperationException ex) when (ex.Message.Contains("already have a strategy"))
+        {
+            // Return 400 for validation errors about existing strategies on same ticker
+            return BadRequest(ex.Message);
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error starting bot");
@@ -168,6 +173,11 @@ public class BotController : BaseController
             await NotifyBotSubscriberAsync();
             return Ok(result);
         }
+        catch (InvalidOperationException ex) when (ex.Message.Contains("already have a strategy"))
+        {
+            // Return 400 for validation errors about existing strategies on same ticker
+            return BadRequest(ex.Message);
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error starting copy trading bot");
@@ -192,6 +202,11 @@ public class BotController : BaseController
 
             return Ok(result);
         }
+        catch (InvalidOperationException ex) when (ex.Message.Contains("already have a strategy"))
+        {
+            // Return 400 for validation errors about existing strategies on same ticker
+            return BadRequest(ex.Message);
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error saving bot");
@@ -319,6 +334,11 @@ public class BotController : BaseController
 
             return Ok(result);
         }
+        catch (InvalidOperationException ex) when (ex.Message.Contains("already have another strategy"))
+        {
+            // Return 400 for validation errors about existing strategies on same ticker
+            return BadRequest(ex.Message);
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Error restarting bot");

src/Managing.Application/Abstractions/IBotService.cs

@@ -64,4 +64,12 @@ public interface IBotService
     /// <param name="account">The account to check balances for</param>
     /// <returns>Balance check result</returns>
     Task<BalanceCheckResult> CheckAccountBalancesAsync(Account account);
+
+    /// <summary>
+    /// Checks if the user already has a bot (Running or Saved) on the specified ticker
+    /// </summary>
+    /// <param name="userId">The user ID</param>
+    /// <param name="ticker">The ticker to check</param>
+    /// <returns>True if the user has a bot on this ticker, false otherwise</returns>
+    Task<bool> HasUserBotOnTickerAsync(int userId, Ticker ticker);
 }

src/Managing.Application/ManageBot/BotService.cs

@@ -524,5 +524,13 @@ namespace Managing.Application.ManageBot
                 };
             }
         }
+
+        public async Task<bool> HasUserBotOnTickerAsync(int userId, Ticker ticker)
+        {
+            var userBots = await _botRepository.GetBotsByUserIdAsync(userId);
+            return userBots.Any(bot =>
+                bot.Ticker == ticker &&
+                (bot.Status == BotStatus.Running || bot.Status == BotStatus.Saved));
+        }
     }
 }

src/Managing.Application/ManageBot/RestartBotCommandHandler.cs

@@ -16,6 +16,27 @@ namespace Managing.Application.ManageBot
 
         public async Task<BotStatus> Handle(RestartBotCommand request, CancellationToken cancellationToken)
         {
+            // Get the bot being restarted to check its ticker
+            var bot = await _botService.GetBotByIdentifier(request.Identifier);
+            if (bot == null)
+            {
+                throw new ArgumentException($"Bot with identifier {request.Identifier} not found");
+            }
+
+            // Check if user already has another bot on this ticker (excluding the one being restarted)
+            var userBots = await _botService.GetBotsByUser(bot.User.Id);
+            var hasAnotherBotOnSameTicker = userBots.Any(b =>
+                b.Identifier != request.Identifier && // Exclude the bot being restarted
+                b.Ticker == bot.Ticker &&
+                (b.Status == BotStatus.Running || b.Status == BotStatus.Saved));
+
+            if (hasAnotherBotOnSameTicker)
+            {
+                throw new InvalidOperationException(
+                    $"You already have another strategy running or saved on ticker {bot.Ticker}. " +
+                    "You cannot restart this bot while you have multiple strategies on the same ticker.");
+            }
+
             return await _botService.RestartBot(request.Identifier);
         }
     }

src/Managing.Application/ManageBot/StartBotCommandHandler.cs

@@ -43,6 +43,15 @@ namespace Managing.Application.ManageBot
                     $"Bot trading balance must be greater than {Constants.GMX.Config.MinimumPositionAmount}");
             }
 
+            // Check if user already has a bot on this ticker
+            var hasExistingBotOnTicker = await _botService.HasUserBotOnTickerAsync(request.User.Id, request.Config.Ticker);
+            if (hasExistingBotOnTicker)
+            {
+                throw new InvalidOperationException(
+                    $"You already have a strategy running or saved on ticker {request.Config.Ticker}. " +
+                    "You cannot create multiple strategies on the same ticker.");
+            }
+
             Account account;
             if (string.IsNullOrEmpty(request.Config.AccountName))
             {

src/Managing.Application/ManageBot/StartCopyTradingCommandHandler.cs

@@ -72,6 +72,15 @@ namespace Managing.Application.ManageBot
                 throw new InvalidOperationException($"Could not retrieve configuration for master bot {request.MasterBotIdentifier}");
             }
 
+            // Check if user already has a bot on this ticker (same as master bot)
+            var hasExistingBotOnTicker = await _botService.HasUserBotOnTickerAsync(request.User.Id, masterConfig.Ticker);
+            if (hasExistingBotOnTicker)
+            {
+                throw new InvalidOperationException(
+                    $"You already have a strategy running or saved on ticker {masterConfig.Ticker}. " +
+                    "You cannot create multiple strategies on the same ticker.");
+            }
+
             // Get account information from the requesting user's accounts
             var userAccounts = await _accountService.GetAccountsByUserAsync(request.User, true, true);
             var firstAccount = userAccounts.FirstOrDefault();