Added LiteLLM as a new LLM provider (#909)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Provider/LiteLLM/ProviderLiteLLM.cs

@@ -0,0 +1,125 @@
+using System.Runtime.CompilerServices;
+
+using AIStudio.Chat;
+using AIStudio.Provider.OpenAI;
+using AIStudio.Settings;
+
+namespace AIStudio.Provider.LiteLLM;
+
+public sealed class ProviderLiteLLM(string hostname) : BaseProvider(LLMProviders.LITE_LLM, BuildBaseUri(hostname), ExternalHttpTrustPolicy.ALLOW_CUSTOM_ROOTS_WHEN_HOST_WHITELISTED, LOGGER)
+{
+    private static readonly ILogger<ProviderLiteLLM> LOGGER = Program.LOGGER_FACTORY.CreateLogger<ProviderLiteLLM>();
+
+    #region Implementation of IProvider
+
+    /// <inheritdoc />
+    public override string Id => LLMProviders.LITE_LLM.ToSecretId();
+
+    /// <inheritdoc />
+    public override string InstanceName { get; set; } = "LiteLLM";
+
+    /// <inheritdoc />
+    public override bool HasModelLoadingCapability => true;
+
+    /// <inheritdoc />
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    {
+        await foreach (var content in this.StreamOpenAICompatibleChatCompletion<ChatCompletionAPIRequest, ChatCompletionDeltaStreamLine, NoChatCompletionAnnotationStreamLine>(
+                           "LiteLLM",
+                           chatModel,
+                           chatThread,
+                           settingsManager,
+                           async (systemPrompt, apiParameters) =>
+                           {
+                               // Build the list of messages:
+                               var messages = await chatThread.Blocks.BuildMessagesUsingDirectImageUrlAsync(this.Provider, chatModel);
+
+                               return new ChatCompletionAPIRequest
+                               {
+                                   Model = chatModel.Id,
+
+                                   // Build the messages:
+                                   // - First of all the system prompt
+                                   // - Then none-empty user and AI messages
+                                   Messages = [systemPrompt, ..messages],
+
+                                   Stream = true,
+                                   AdditionalApiParameters = apiParameters
+                               };
+                           },
+                           token: token))
+            yield return content;
+    }
+
+    #pragma warning disable CS1998 // Async method lacks 'await' operators and will run synchronously
+    /// <inheritdoc />
+    public override async IAsyncEnumerable<ImageURL> StreamImageCompletion(Model imageModel, string promptPositive, string promptNegative = FilterOperator.String.Empty, ImageURL referenceImageURL = default, [EnumeratorCancellation] CancellationToken token = default)
+    {
+        yield break;
+    }
+    #pragma warning restore CS1998 // Async method lacks 'await' operators and will run synchronously
+
+    /// <inheritdoc />
+    public override async Task<TranscriptionResult> TranscribeAudioAsync(Model transcriptionModel, string audioFilePath, SettingsManager settingsManager, CancellationToken token = default)
+    {
+        var requestedSecret = await Program.RUST_SERVICE.GetAPIKey(this, SecretStoreType.TRANSCRIPTION_PROVIDER);
+        return await this.PerformStandardTranscriptionRequest(requestedSecret, transcriptionModel, audioFilePath, token: token);
+    }
+
+    /// <inheritdoc />
+    public override async Task<IReadOnlyList<IReadOnlyList<float>>> EmbedTextAsync(Model embeddingModel, SettingsManager settingsManager, CancellationToken token = default, params List<string> texts)
+    {
+        var requestedSecret = await Program.RUST_SERVICE.GetAPIKey(this, SecretStoreType.EMBEDDING_PROVIDER);
+        return await this.PerformStandardTextEmbeddingRequest(requestedSecret, embeddingModel, token: token, texts: texts);
+    }
+
+    /// <inheritdoc />
+    public override Task<ModelLoadResult> GetTextModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return this.LoadModels(SecretStoreType.LLM_PROVIDER, static model => model.IsChatModel(), token, apiKeyProvisional);
+    }
+
+    /// <inheritdoc />
+    public override Task<ModelLoadResult> GetImageModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return Task.FromResult(ModelLoadResult.FromModels([]));
+    }
+
+    /// <inheritdoc />
+    public override Task<ModelLoadResult> GetEmbeddingModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return this.LoadModels(SecretStoreType.EMBEDDING_PROVIDER, static model => model.IsEmbeddingModel(), token, apiKeyProvisional);
+    }
+
+    /// <inheritdoc />
+    public override Task<ModelLoadResult> GetTranscriptionModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return this.LoadModels(SecretStoreType.TRANSCRIPTION_PROVIDER, static model => model.IsTranscriptionModel(), token, apiKeyProvisional);
+    }
+
+    #endregion
+
+    private static Uri BuildBaseUri(string hostname)
+    {
+        // LiteLLM exposes an OpenAI-compatible API under the "/v1/" path. Users configure the
+        // base URL of their LiteLLM proxy (e.g. http://localhost:4000); we normalize any trailing
+        // slash and append the OpenAI-compatible path.
+        var normalizedHostname = hostname.TrimEnd('/');
+        return new Uri($"{normalizedHostname}/v1/");
+    }
+
+    private Task<ModelLoadResult> LoadModels(SecretStoreType storeType, Func<Model, bool> isWantedKind, CancellationToken token, string? apiKeyProvisional = null)
+    {
+        //
+        // The gateway serves every kind of model through one endpoint, so we have to sort
+        // them apart ourselves. We use the shared model kind detection for that, which every
+        // other provider uses as well:
+        //
+        return this.LoadModelsResponse<ModelsResponse>(
+            storeType,
+            "models",
+            modelResponse => modelResponse.Data.Where(isWantedKind),
+            token,
+            apiKeyProvisional);
+    }
+}