Add Regex capabilities to templating service

docs/release-notes/breaking-changes.md

@@ -3,6 +3,18 @@
 > [!NOTE]
 > This section is for changes that are not yet released but will affect future releases.
 
+## Starting with 0.9.1
+
+Prompt prefixes and suffixes support FoundationaLLM variables for dynamic replacement at runtime. The variable format is `{{foundationallm:variable_name[:format]}}` where
+- `variable_name` is the name of the well-known variable.
+- `format` is the optional formatting applied to the value of the variable.
+
+The following variables are supported:
+
+| Name | Value | Example
+| --- | --- | --- |
+| `current_datetime_utc` | The current UTC date and time. | `The current date is {{foundationallm:current_datetime_utc:dddd, MMMM dd, yyyy}}. This looks great.` -> `The current date is Sunday, December 15, 2024. This looks great.`
+
 ## Starting with 0.9.0
 
 ### Configuration changes

src/dotnet/Common/Constants/Templates/TemplateVariables.cs

@@ -0,0 +1,13 @@
+namespace FoundationaLLM.Common.Constants.Templates
+{
+    /// <summary>
+    /// Provides template variables that can be used in templates.
+    /// </summary>
+    public static class TemplateVariables
+    {
+        /// <summary>
+        /// Token for current date in UTC format.
+        /// </summary>
+        public const string CurrentDateTimeUTC = "current_datetime_utc";
+    }
+}

src/dotnet/Common/Interfaces/ITemplatingService.cs

@@ -0,0 +1,15 @@
+namespace FoundationaLLM.Common.Interfaces
+{
+    /// <summary>
+    /// Defines the interface for a templating engine.
+    /// </summary>
+    public interface ITemplatingService
+    {
+        /// <summary>
+        /// Transforms the input string by replacing tokens with the corresponding values.
+        /// </summary>
+        /// <param name="s">The input string to be transformed.</param>
+        /// <returns>The transformed string where all the valid tokens have been replaced.</returns>
+        string Transform(string s);
+    }
+}

src/dotnet/Common/Services/DependencyInjection.cs

@@ -10,6 +10,7 @@
 using FoundationaLLM.Common.Services.API;
 using FoundationaLLM.Common.Services.Azure;
 using FoundationaLLM.Common.Services.Security;
+using FoundationaLLM.Common.Services.Templates;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.Azure.Cosmos;
 using Microsoft.Azure.Cosmos.Fluent;
@@ -297,5 +298,19 @@ public static void AddAzureCosmosDBService(this IServiceCollection services, ICo
 
             services.AddSingleton<IAzureCosmosDBService, AzureCosmosDBService>();
         }
+
+        /// <summary>
+        /// Registers the <see cref="ITemplatingService"/> implementation with the dependency injection container.
+        /// </summary>
+        /// <param name="builder">The <see cref="IHostApplicationBuilder"/> application builder managing the dependency injection container.</param>
+        public static void AddRegexTemplatingEngine(this IHostApplicationBuilder builder) =>
+            builder.Services.AddSingleton<ITemplatingService, RegexTemplatingService>();
+
+        /// <summary>
+        /// Registers the <see cref="ITemplatingService"/> implementation with the dependency injection container.
+        /// </summary>
+        /// <param name="services">The <see cref="IServiceCollection"/> dependency injection container service collection.</param>
+        public static void AddRegexTemplatingEngine(this IServiceCollection services) =>
+            services.AddSingleton<ITemplatingService, RegexTemplatingService>();
     }
 }

src/dotnet/Common/Services/Templates/RegexTemplatingService.cs

@@ -0,0 +1,78 @@
+using FoundationaLLM.Common.Constants.Templates;
+using FoundationaLLM.Common.Interfaces;
+using Microsoft.Extensions.Logging;
+using System.Text.RegularExpressions;
+
+namespace FoundationaLLM.Common.Services.Templates
+{
+    /// <summary>
+    /// Templating engine that uses regular expressions to replace tokens in strings.
+    /// </summary>
+    /// <param name="logger">The logger used for logging.</param>
+    public partial class RegexTemplatingService(
+        ILogger<RegexTemplatingService> logger) : ITemplatingService
+    {
+        /// <summary>
+        /// Regular expression pattern for template variables.
+        /// </summary>
+        private const string REGEX_VARIABLE_PATTERN = "\\{\\{foundationallm:(.*?)\\}\\}";
+
+        private readonly ILogger<RegexTemplatingService> _logger = logger;
+
+        [GeneratedRegex(REGEX_VARIABLE_PATTERN, RegexOptions.Compiled)]
+        private static partial Regex VariableRegex();
+
+        /// <inheritdoc/>
+        public string Transform(string s)
+        {
+            if (string.IsNullOrWhiteSpace(s))
+            {
+                return string.Empty;
+            }
+
+            try
+            {
+                // Expects the format {{foundationallm:variable_name[:format]}}
+
+                var matches = VariableRegex().Matches(s);
+                Dictionary<string, string> replacements = [];
+
+                foreach (Match match in matches)
+                {
+                    var matchedVariable = match.Value;
+
+                    var variableTokens = match.Groups[1].Value.Split(":", 2);
+                    var variableName = variableTokens[0];
+                    var variableFormat = variableTokens.Length > 1 ? variableTokens[1] : null;
+
+                    switch (variableName)
+                    {
+                        case TemplateVariables.CurrentDateTimeUTC:
+                            replacements.Add(
+                                matchedVariable,
+                                string.IsNullOrWhiteSpace(variableFormat)
+                                    ? DateTime.UtcNow.ToString()
+                                    : DateTime.UtcNow.ToString(variableFormat));
+                            break;
+                        default:
+                            break;
+                    }
+                }
+
+                var transformedString = s;
+                foreach (var replacement in replacements)
+                {
+                    transformedString = transformedString.Replace(replacement.Key, replacement.Value);
+                }
+
+                return transformedString;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error occurred while transforming the string.");
+            }
+
+            return s;
+        }
+    }
+}

src/dotnet/Orchestration/Orchestration/OrchestrationBuilder.cs

@@ -15,7 +15,6 @@
 using FoundationaLLM.Common.Models.ResourceProviders.DataSource;
 using FoundationaLLM.Common.Models.ResourceProviders.Prompt;
 using FoundationaLLM.Common.Models.ResourceProviders.Vectorization;
-using FoundationaLLM.Common.Services.TokenReplacement;
 using FoundationaLLM.Orchestration.Core.Interfaces;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -41,6 +40,7 @@ public class OrchestrationBuilder
         /// <param name="resourceProviderServices">A dictionary of <see cref="IResourceProviderService"/> resource providers hashed by resource provider name.</param>
         /// <param name="llmOrchestrationServiceManager">The <see cref="ILLMOrchestrationServiceManager"/> that manages internal and external orchestration services.</param>
         /// <param name="cosmosDBService">The <see cref="IAzureCosmosDBService"/> used to interact with the Cosmos DB database.</param>
+        /// <param name="templatingService">The <see cref="ITemplatingService"/> used to render templates.</param>
         /// <param name="serviceProvider">The <see cref="IServiceProvider"/> provding dependency injection services for the current scope.</param>
         /// <param name="loggerFactory">The logger factory used to create new loggers.</param>
         /// <returns></returns>
@@ -54,6 +54,7 @@ public class OrchestrationBuilder
             Dictionary<string, IResourceProviderService> resourceProviderServices,
             ILLMOrchestrationServiceManager llmOrchestrationServiceManager,
             IAzureCosmosDBService cosmosDBService,
+            ITemplatingService templatingService,
             IServiceProvider serviceProvider,
             ILoggerFactory loggerFactory)
         {
@@ -65,6 +66,7 @@ public class OrchestrationBuilder
                 originalRequest.SessionId,
                 originalRequest.Settings?.ModelParameters,
                 resourceProviderServices,
+                templatingService,
                 callContext.CurrentUserIdentity!,
                 logger);
 
@@ -177,6 +179,7 @@ await cosmosDBService.PatchOperationsItemPropertiesAsync<LongRunningOperationCon
             string? sessionId,
             Dictionary<string, object>? modelParameterOverrides,
             Dictionary<string, IResourceProviderService> resourceProviderServices,
+            ITemplatingService templatingService,
             UnifiedUserIdentity currentUserIdentity,
             ILogger<OrchestrationBuilder> logger)
         {
@@ -264,8 +267,8 @@ await cosmosDBService.PatchOperationsItemPropertiesAsync<LongRunningOperationCon
                                     if (multipartPrompt is not null)
                                     {
 
-                                        multipartPrompt.Prefix = TokenReplacementEngine.ReplaceTokens(multipartPrompt.Prefix!);
-                                        multipartPrompt.Suffix = TokenReplacementEngine.ReplaceTokens(multipartPrompt.Suffix!);
+                                        multipartPrompt.Prefix = templatingService.Transform(multipartPrompt.Prefix!);
+                                        multipartPrompt.Suffix = templatingService.Transform(multipartPrompt.Suffix!);
                                     }
                                 }
                                 explodedObjectsManager.TryAdd(

src/dotnet/Orchestration/Services/OrchestrationService.cs

@@ -25,6 +25,7 @@ public class OrchestrationService : IOrchestrationService
 {
     private readonly ILLMOrchestrationServiceManager _llmOrchestrationServiceManager;
     private readonly IAzureCosmosDBService _cosmosDBService;
+    private readonly ITemplatingService _templatingService;
     private readonly ICallContext _callContext;
     private readonly IConfiguration _configuration;
     private readonly ILogger<OrchestrationService> _logger;
@@ -39,6 +40,7 @@ public class OrchestrationService : IOrchestrationService
     /// <param name="resourceProviderServices">A list of <see cref="IResourceProviderService"/> resource providers hashed by resource provider name.</param>
     /// <param name="llmOrchestrationServiceManager">The <see cref="ILLMOrchestrationServiceManager"/> managing the internal and external LLM orchestration services.</param>
     /// <param name="cosmosDBService">The <see cref="IAzureCosmosDBService"/> used to interact with the Cosmos DB database.</param>
+    /// <param name="templatingService">The <see cref="ITemplatingService"/> used to render templates.</param>
     /// <param name="callContext">The call context of the request being handled.</param>
     /// <param name="configuration">The <see cref="IConfiguration"/> used to retrieve app settings from configuration.</param>
     /// <param name="serviceProvider">The <see cref="IServiceProvider"/> provding dependency injection services for the current scope.</param>
@@ -47,6 +49,7 @@ public OrchestrationService(
         IEnumerable<IResourceProviderService> resourceProviderServices,
         ILLMOrchestrationServiceManager llmOrchestrationServiceManager,
         IAzureCosmosDBService cosmosDBService,
+        ITemplatingService templatingService,
         ICallContext callContext,
         IConfiguration configuration,
         IServiceProvider serviceProvider,
@@ -56,6 +59,7 @@ public OrchestrationService(
                 rps => rps.Name);
         _llmOrchestrationServiceManager = llmOrchestrationServiceManager;
         _cosmosDBService = cosmosDBService;
+        _templatingService = templatingService;
 
         _callContext = callContext;
         _configuration = configuration;
@@ -100,6 +104,7 @@ public async Task<CompletionResponse> GetCompletion(string instanceId, Completio
                 _resourceProviderServices,
                 _llmOrchestrationServiceManager,
                 _cosmosDBService,
+                _templatingService,
                 _serviceProvider,
                 _loggerFactory)
                 ?? throw new OrchestrationException($"The orchestration builder was not able to create an orchestration for agent [{completionRequest.AgentName ?? string.Empty}].");
@@ -139,6 +144,7 @@ public async Task<LongRunningOperation> StartCompletionOperation(string instance
                 _resourceProviderServices,
                 _llmOrchestrationServiceManager,
                 _cosmosDBService,
+                _templatingService,
                 _serviceProvider,
                 _loggerFactory)
                 ?? throw new OrchestrationException($"The orchestration builder was not able to create an orchestration for agent [{completionRequest.AgentName ?? string.Empty}].");
@@ -225,6 +231,7 @@ private async Task<CompletionResponse> GetCompletionForAgentConversation(
                 _resourceProviderServices,
                 _llmOrchestrationServiceManager,
                 _cosmosDBService,
+                _templatingService,
                 _serviceProvider,
                 _loggerFactory);
 

src/dotnet/OrchestrationAPI/Program.cs

@@ -117,6 +117,9 @@ public static void Main(string[] args)
             builder.AddGroupMembership();
             builder.AddAuthorizationServiceClient();
 
+            // Add the templating engine.
+            builder.AddRegexTemplatingEngine();
+
             //----------------------------
             // Resource providers
             //----------------------------