Add Ollama AI foundation for article 6.1

TalentManagementAPI.Application/Interfaces/IAiChatService.cs

@@ -0,0 +1,7 @@
+namespace TalentManagementAPI.Application.Interfaces
+{
+    public interface IAiChatService
+    {
+        Task<string> ChatAsync(string message, string? systemPrompt = null, CancellationToken cancellationToken = default);
+    }
+}

TalentManagementAPI.Infrastructure.Shared/GlobalUsings.cs

@@ -1,6 +1,7 @@
 global using System;
 global using System.Collections.Generic;
 global using System.Linq;
+global using System.Threading;
 global using System.Threading.Tasks;
 global using AutoBogus;
 global using Bogus;
@@ -12,6 +13,8 @@
 global using Microsoft.Extensions.Logging;
 global using Microsoft.Extensions.Options;
 global using MimeKit;
+global using OllamaSharp;
+global using OllamaSharp.Models.Chat;
 global using TalentManagementAPI.Application.DTOs.Email;
 global using TalentManagementAPI.Application.Exceptions;
 global using TalentManagementAPI.Application.Interfaces;

TalentManagementAPI.Infrastructure.Shared/ServiceRegistration.cs

@@ -1,13 +1,23 @@
-namespace TalentManagementAPI.Infrastructure.Shared
+using TalentManagementAPI.Application.Interfaces;
+using TalentManagementAPI.Infrastructure.Shared.Services;
+
+namespace TalentManagementAPI.Infrastructure.Shared
 {
     public static class ServiceRegistration
     {
-        public static void AddSharedInfrastructure(this IServiceCollection services, IConfiguration _config)
+        public static void AddSharedInfrastructure(this IServiceCollection services, IConfiguration config)
         {
-            services.Configure<MailSettings>(_config.GetSection("MailSettings"));
+            services.Configure<MailSettings>(config.GetSection("MailSettings"));
             services.AddTransient<IDateTimeService, DateTimeService>();
             services.AddTransient<IEmailService, EmailService>();
             services.AddTransient<IMockService, MockService>();
+            services.AddSingleton<IOllamaApiClient>(_ =>
+            {
+                var baseUrl = config["Ollama:BaseUrl"] ?? "http://localhost:11434";
+                var model = config["Ollama:Model"] ?? "llama3.2";
+                return new OllamaApiClient(new Uri(baseUrl), model);
+            });
+            services.AddTransient<IAiChatService, OllamaAiService>();
         }
     }
 }

TalentManagementAPI.Infrastructure.Shared/Services/OllamaAiService.cs

@@ -0,0 +1,45 @@
+using TalentManagementAPI.Application.Interfaces;
+
+namespace TalentManagementAPI.Infrastructure.Shared.Services
+{
+    public class OllamaAiService : IAiChatService
+    {
+        private readonly IOllamaApiClient _ollamaApiClient;
+
+        public OllamaAiService(IOllamaApiClient ollamaApiClient)
+        {
+            _ollamaApiClient = ollamaApiClient;
+        }
+
+        public async Task<string> ChatAsync(string message, string? systemPrompt = null, CancellationToken cancellationToken = default)
+        {
+            var messages = new List<Message>();
+
+            if (!string.IsNullOrWhiteSpace(systemPrompt))
+            {
+                messages.Add(new Message(new ChatRole("system"), systemPrompt));
+            }
+
+            messages.Add(new Message(new ChatRole("user"), message));
+
+            var request = new ChatRequest
+            {
+                Model = _ollamaApiClient.SelectedModel,
+                Messages = messages,
+                Stream = true
+            };
+
+            var responseBuilder = new MessageBuilder();
+
+            await foreach (var response in _ollamaApiClient.ChatAsync(request, cancellationToken).WithCancellation(cancellationToken))
+            {
+                if (response?.Message is not null)
+                {
+                    responseBuilder.Append(response);
+                }
+            }
+
+            return responseBuilder.HasValue ? responseBuilder.ToMessage().Content ?? string.Empty : string.Empty;
+        }
+    }
+}

TalentManagementAPI.Infrastructure.Shared/TalentManagementAPI.Infrastructure.Shared.csproj

@@ -9,10 +9,11 @@
   <ItemGroup>
     <PackageReference Include="AutoBogus" Version="2.13.1" />
     <PackageReference Include="Bogus" Version="35.6.5" />
-    <PackageReference Include="MailKit" Version="4.14.1" />
-    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.2" />
-    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="10.0.1" />
-    <PackageReference Include="MimeKit" Version="4.14.0" />
+    <PackageReference Include="MailKit" Version="4.15.1" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.5" />
+    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="10.0.5" />
+    <PackageReference Include="MimeKit" Version="4.15.1" />
+    <PackageReference Include="OllamaSharp" Version="5.4.23" />
   </ItemGroup>
 
   <ItemGroup>

TalentManagementAPI.Infrastructure.Tests/Services/OllamaAiServiceTests.cs

@@ -0,0 +1,70 @@
+using OllamaSharp.Models.Chat;
+
+namespace TalentManagementAPI.Infrastructure.Tests.Services
+{
+    public class OllamaAiServiceTests
+    {
+        [Fact]
+        public async Task ChatAsync_WithSystemPrompt_SendsPromptAndReturnsCombinedReply()
+        {
+            var client = new Mock<IOllamaApiClient>();
+            client.SetupProperty(x => x.SelectedModel, "llama3.2");
+
+            ChatRequest? capturedRequest = null;
+
+            client
+                .Setup(x => x.ChatAsync(It.IsAny<ChatRequest>(), It.IsAny<CancellationToken>()))
+                .Returns((ChatRequest request, CancellationToken _) =>
+                {
+                    capturedRequest = request;
+                    return StreamResponses(
+                        new ChatResponseStream
+                        {
+                            Message = new Message(new ChatRole("assistant"), "Hello")
+                        },
+                        new ChatResponseStream
+                        {
+                            Message = new Message(new ChatRole("assistant"), " world")
+                        });
+                });
+
+            var service = new OllamaAiService(client.Object);
+
+            var reply = await service.ChatAsync("Say hi", "You are concise.");
+
+            reply.Should().Be("Hello world");
+            capturedRequest.Should().NotBeNull();
+            capturedRequest!.Model.Should().Be("llama3.2");
+            capturedRequest.Messages.Should().HaveCount(2);
+            capturedRequest.Messages[0].Role.Should().Be(new ChatRole("system"));
+            capturedRequest.Messages[0].Content.Should().Be("You are concise.");
+            capturedRequest.Messages[1].Role.Should().Be(new ChatRole("user"));
+            capturedRequest.Messages[1].Content.Should().Be("Say hi");
+        }
+
+        [Fact]
+        public async Task ChatAsync_WithoutChunks_ReturnsEmptyString()
+        {
+            var client = new Mock<IOllamaApiClient>();
+            client.SetupProperty(x => x.SelectedModel, "llama3.2");
+            client
+                .Setup(x => x.ChatAsync(It.IsAny<ChatRequest>(), It.IsAny<CancellationToken>()))
+                .Returns(StreamResponses());
+
+            var service = new OllamaAiService(client.Object);
+
+            var reply = await service.ChatAsync("Say hi");
+
+            reply.Should().BeEmpty();
+        }
+
+        private static async IAsyncEnumerable<ChatResponseStream?> StreamResponses(params ChatResponseStream[] responses)
+        {
+            foreach (var response in responses)
+            {
+                yield return response;
+                await Task.Yield();
+            }
+        }
+    }
+}

TalentManagementAPI.WebApi.Tests/Controllers/AiControllerTests.cs

@@ -0,0 +1,51 @@
+namespace TalentManagementAPI.WebApi.Tests.Controllers
+{
+    public class AiControllerTests
+    {
+        private readonly Mock<IAiChatService> _aiChatServiceMock = new();
+        private readonly Mock<IFeatureManagerSnapshot> _featureManagerMock = new();
+        private readonly AiController _controller;
+
+        public AiControllerTests()
+        {
+            _controller = new AiController(_aiChatServiceMock.Object, _featureManagerMock.Object);
+        }
+
+        [Fact]
+        public async Task Chat_AiDisabled_ReturnsServiceUnavailableProblemDetails()
+        {
+            _featureManagerMock
+                .Setup(m => m.IsEnabledAsync("AiEnabled"))
+                .ReturnsAsync(false);
+
+            var result = await _controller.Chat(new AiChatRequest("hello"), CancellationToken.None);
+
+            var objectResult = result.Should().BeOfType<ObjectResult>().Subject;
+            objectResult.StatusCode.Should().Be(StatusCodes.Status503ServiceUnavailable);
+
+            var problem = objectResult.Value.Should().BeOfType<ProblemDetails>().Subject;
+            problem.Title.Should().Be("AI chat is disabled");
+            problem.Detail.Should().Be("AI chat is disabled. Enable FeatureManagement:AiEnabled to use this endpoint.");
+
+            _aiChatServiceMock.Verify(
+                m => m.ChatAsync(It.IsAny<string>(), It.IsAny<string?>(), It.IsAny<CancellationToken>()),
+                Times.Never);
+        }
+
+        [Fact]
+        public async Task Chat_AiEnabled_ReturnsOkWithReply()
+        {
+            _featureManagerMock
+                .Setup(m => m.IsEnabledAsync("AiEnabled"))
+                .ReturnsAsync(true);
+            _aiChatServiceMock
+                .Setup(m => m.ChatAsync("hello", null, It.IsAny<CancellationToken>()))
+                .ReturnsAsync("hi");
+
+            var result = await _controller.Chat(new AiChatRequest("hello"), CancellationToken.None);
+
+            var okResult = result.Should().BeOfType<OkObjectResult>().Subject;
+            okResult.Value.Should().BeEquivalentTo(new AiChatResponse("hi"));
+        }
+    }
+}

TalentManagementAPI.WebApi/Controllers/v1/AiController.cs

@@ -0,0 +1,46 @@
+using Asp.Versioning;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using TalentManagementAPI.Application.Interfaces;
+
+namespace TalentManagementAPI.WebApi.Controllers.v1
+{
+    [ApiVersion("1.0")]
+    [AllowAnonymous]
+    [Route("api/v{version:apiVersion}/ai")]
+    public sealed class AiController : BaseApiController
+    {
+        private readonly IAiChatService _aiChatService;
+        private readonly IFeatureManagerSnapshot _featureManager;
+
+        public AiController(IAiChatService aiChatService, IFeatureManagerSnapshot featureManager)
+        {
+            _aiChatService = aiChatService;
+            _featureManager = featureManager;
+        }
+
+        /// <summary>
+        /// Send a message to the AI assistant and receive a reply.
+        /// </summary>
+        /// <param name="request">The chat message and optional system prompt.</param>
+        /// <param name="cancellationToken">Cancellation token.</param>
+        /// <returns>The AI-generated reply.</returns>
+        [HttpPost("chat")]
+        public async Task<IActionResult> Chat([FromBody] AiChatRequest request, CancellationToken cancellationToken)
+        {
+            if (!await _featureManager.IsEnabledAsync("AiEnabled"))
+            {
+                return Problem(
+                    detail: "AI chat is disabled. Enable FeatureManagement:AiEnabled to use this endpoint.",
+                    title: "AI chat is disabled",
+                    statusCode: StatusCodes.Status503ServiceUnavailable);
+            }
+
+            var reply = await _aiChatService.ChatAsync(request.Message, request.SystemPrompt, cancellationToken);
+            return Ok(new AiChatResponse(reply));
+        }
+    }
+
+    public record AiChatRequest(string Message, string? SystemPrompt = null);
+    public record AiChatResponse(string Reply);
+}

TalentManagementAPI.WebApi/Program.cs

@@ -19,6 +19,8 @@
     builder.Services.AddApplicationLayer();
     builder.Services.AddPersistenceInfrastructure(builder.Configuration);
     builder.Services.AddSharedInfrastructure(builder.Configuration);
+    // Register Ollama chat client (IChatClient) — used by OllamaAiService
+    // AiController is gated by [FeatureGate("AiEnabled")], so no calls are made when AI is disabled
     builder.Services.AddEasyCachingInfrastructure(builder.Configuration);
     builder.Services.AddHttpContextAccessor();
     builder.Services.AddScoped<ICacheDiagnosticsPublisher, HttpCacheDiagnosticsPublisher>();

TalentManagementAPI.WebApi/appsettings.Development.json

@@ -10,6 +10,7 @@
     "ExecutionTimingIncludeHeader": true,
     "ExecutionTimingIncludePayload": true,
     "ExecutionTimingLogTimings": true,
+    "AiEnabled": true,
     "UseInMemoryDatabase": false
   },
   "MailSettings": {

TalentManagementAPI.WebApi/appsettings.json

@@ -106,7 +106,12 @@
     "ExecutionTimingIncludeHeader": true,
     "ExecutionTimingIncludePayload": true,
     "ExecutionTimingLogTimings": false,
-    "UseInMemoryDatabase": false
+    "UseInMemoryDatabase": false,
+    "AiEnabled": false
+  },
+  "Ollama": {
+    "BaseUrl": "http://localhost:11434",
+    "Model": "llama3.2"
   },
   "ApiRoles": {
     "EmployeeRole": "Employee",