[#19] Add another part of custom exceptions, add error handling in examples

Author: sgdevnet

Examples/Examples/Program.cs

@@ -4,6 +4,7 @@
 using Examples.Chat;
 using Examples.Mcp;
 using MaIN.Core;
+using MaIN.Domain.Exceptions;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -121,7 +122,20 @@ async Task RunSelectedExample(IServiceProvider serviceProvider)
         Console.ResetColor();
 
         var selectedExample = examples[selection - 1].Instance;
-        await selectedExample.Start();
+        try
+        {
+            await selectedExample.Start();
+        }
+        catch (Exception ex)
+        {
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.WriteLine("╔════════════════════════════════════════════════════════════════════╗");
+            Console.WriteLine("║                               Error                                ║");
+            Console.WriteLine("╚════════════════════════════════════════════════════════════════════╝");
+            Console.ResetColor();
+            
+                Console.WriteLine(ex.Message);
+        }
     }
     else
     {

src/MaIN.Core/Hub/AiHub.cs

@@ -2,6 +2,7 @@
 using MaIN.Core.Hub.Contexts;
 using MaIN.Core.Interfaces;
 using MaIN.Domain.Configuration;
+using MaIN.Domain.Exceptions;
 using MaIN.Services.Services.Abstract;
 
 namespace MaIN.Core.Hub;
@@ -23,8 +24,7 @@ internal static void Initialize(IAIHubServices services,
 
     private static IAIHubServices Services =>
         _services ??
-        throw new InvalidOperationException(
-            "AIHub has not been initialized. Make sure to call AddAIHub() in your service configuration.");
+        throw new AIHubNotInitializedException();
 
     public static ModelContext Model() => new ModelContext(_settings, _httpClientFactory);
     public static ChatContext Chat() => new(Services.ChatService);

src/MaIN.Core/Hub/Contexts/AgentContext.cs

@@ -8,6 +8,7 @@
 using MaIN.Core.Hub.Utils;
 using MaIN.Domain.Entities.Agents.Knowledge;
 using MaIN.Domain.Entities.Tools;
+using MaIN.Domain.Exceptions;
 using MaIN.Services.Constants;
 
 namespace MaIN.Core.Hub.Contexts;
@@ -341,7 +342,9 @@ public static async Task<AgentContext> FromExisting(IAgentService agentService,
     {
         var existingAgent = await agentService.GetAgentById(agentId);
         if (existingAgent == null)
-            throw new ArgumentException("Agent not found", nameof(agentId));
+        {
+            throw new AgentNotFoundException(agentId);
+        }
 
         var context = new AgentContext(agentService, existingAgent);
         context.LoadExistingKnowledgeIfExists();

src/MaIN.Core/Hub/Contexts/FlowContext.cs

@@ -4,6 +4,7 @@
 using MaIN.Domain.Entities;
 using MaIN.Domain.Entities.Agents;
 using MaIN.Domain.Entities.Agents.AgentSource;
+using MaIN.Domain.Exceptions;
 using MaIN.Services.Dtos;
 using MaIN.Services.Mappers;
 using MaIN.Services.Services.Abstract;
@@ -210,7 +211,7 @@ public async Task<AgentFlow> CreateAsync()
     public async Task Delete()
     {
         if (_flow.Id == null)
-            throw new InvalidOperationException("Flow has not been created yet.");
+            throw new FlowNotInitializedException();
 
         await _flowService.DeleteFlow(_flow.Id);
     }
@@ -219,7 +220,7 @@ public async Task Delete()
     public async Task<AgentFlow> GetCurrentFlow()
     {
         if (_flow.Id == null)
-            throw new InvalidOperationException("Flow has not been created yet.");
+            throw new FlowNotInitializedException();
 
         return await _flowService.GetFlowById(_flow.Id);
     }
@@ -233,9 +234,8 @@ public async Task<List<AgentFlow>> GetAllFlows()
     public async Task<FlowContext> FromExisting(string flowId)
     {
         var existingFlow = await _flowService.GetFlowById(flowId);
-        if (existingFlow == null)
-            throw new ArgumentException("Flow not found", nameof(flowId));
-
-        return this;
+        return existingFlow == null
+            ? throw new FlowFoundException(flowId)
+            : this;
     }
 }

src/MaIN.Core/Hub/Contexts/McpContext.cs

@@ -1,6 +1,7 @@
 
 using MaIN.Domain.Configuration;
 using MaIN.Domain.Entities;
+using MaIN.Domain.Exceptions;
 using MaIN.Services.Constants;
 using MaIN.Services.Services;
 using MaIN.Services.Services.Abstract;
@@ -35,7 +36,7 @@ public async Task<McpResult> PromptAsync(string prompt)
     {
         if (_mcpConfig == null)
         {
-            throw new InvalidOperationException("MCP config not found");
+            throw new MPCConfigNotFoundException();
         }
 
         return await _mcpService.Prompt(_mcpConfig!, [new Message()

src/MaIN.Domain/Exceptions/AIHubNotInitializedException.cs

@@ -0,0 +1,10 @@
+using System.Net;
+
+namespace MaIN.Domain.Exceptions;
+
+public class AIHubNotInitializedException()
+    : MaINCustomException("AIHub has not been initialized. Make sure to call 'AddAIHub' in your service configuration.")
+{
+    public override string PublicErrorMessage => LogMessage;
+    public override HttpStatusCode HttpStatusCode => HttpStatusCode.Conflict;
+}

src/MaIN.Domain/Exceptions/APIKeyNotConfiguredException.cs

@@ -0,0 +1,9 @@
+using System.Net;
+
+namespace MaIN.Domain.Exceptions;
+
+public class APIKeyNotConfiguredException(string apiName) : MaINCustomException($"The API key of '{apiName}' has not been configured.")
+{
+    public override string PublicErrorMessage => "Agent not found.";
+    public override HttpStatusCode HttpStatusCode => HttpStatusCode.InternalServerError;
+}

src/MaIN.Domain/Exceptions/AgentAlreadyExistsException.cs

@@ -0,0 +1,10 @@
+using System.Net;
+
+namespace MaIN.Domain.Exceptions;
+
+public class AgentAlreadyExistsException(string agentId) 
+    : MaINCustomException($"Agent with id: '{agentId}' already exists.")
+{
+    public override string PublicErrorMessage => "Agent already exists.";
+    public override HttpStatusCode HttpStatusCode => HttpStatusCode.Conflict;
+}

src/MaIN.Domain/Exceptions/ChatAlreadyExistsException.cs

@@ -0,0 +1,10 @@
+using System.Net;
+
+namespace MaIN.Domain.Exceptions;
+
+public class ChatAlreadyExistsException(string chatId) 
+    : MaINCustomException($"Chat with id: '{chatId}' already exists.")
+{
+    public override string PublicErrorMessage => "Chat already exists.";
+    public override HttpStatusCode HttpStatusCode => HttpStatusCode.Conflict;
+}

src/MaIN.Domain/Exceptions/FlowAlreadyExistsException.cs

@@ -0,0 +1,10 @@
+using System.Net;
+
+namespace MaIN.Domain.Exceptions;
+
+public class FlowAlreadyExistsException(string flowId) 
+    : MaINCustomException($"Flow with id: '{flowId}' already exists.")
+{
+    public override string PublicErrorMessage => "Flow already exists.";
+    public override HttpStatusCode HttpStatusCode => HttpStatusCode.Conflict;
+}