Added support for Perplexity (#545)

Co-authored-by: Thorsten Sommer <mail@tsommer.org>

app/MindWork AI Studio/Provider/Perplexity/ProviderPerplexity.cs

@@ -0,0 +1,148 @@
+using System.Net.Http.Headers;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Text.Json;
+
+using AIStudio.Chat;
+using AIStudio.Provider.OpenAI;
+using AIStudio.Settings;
+
+namespace AIStudio.Provider.Perplexity;
+
+public sealed class ProviderPerplexity(ILogger logger) : BaseProvider("https://api.perplexity.ai/", logger)
+{
+    private static readonly Model[] KNOWN_MODELS =
+    [
+        new("sonar", "Sonar"),
+        new("sonar-pro", "Sonar Pro"),
+        new("sonar-reasoning", "Sonar Reasoning"),
+        new("sonar-reasoning-pro", "Sonar Reasoning Pro"),
+        new("sonar-deep-research", "Sonar Deep Research"),
+    ];
+    
+    #region Implementation of IProvider
+
+    /// <inheritdoc />
+    public override string Id => LLMProviders.PERPLEXITY.ToName();
+
+    /// <inheritdoc />
+    public override string InstanceName { get; set; } = "Perplexity";
+    
+    /// <inheritdoc />
+    public override async IAsyncEnumerable<ContentStreamChunk> StreamChatCompletion(Model chatModel, ChatThread chatThread, SettingsManager settingsManager, [EnumeratorCancellation] CancellationToken token = default)
+    {
+        // Get the API key:
+        var requestedSecret = await RUST_SERVICE.GetAPIKey(this);
+        if(!requestedSecret.Success)
+            yield break;
+        
+        // Prepare the system prompt:
+        var systemPrompt = new Message
+        {
+            Role = "system",
+            Content = chatThread.PrepareSystemPrompt(settingsManager, chatThread, this.logger),
+        };
+        
+        // Prepare the Perplexity HTTP chat request:
+        var perplexityChatRequest = JsonSerializer.Serialize(new ChatRequest
+        {
+            Model = chatModel.Id,
+            
+            // Build the messages:
+            // - First of all the system prompt
+            // - Then none-empty user and AI messages
+            Messages = [systemPrompt, ..chatThread.Blocks.Where(n => n.ContentType is ContentType.TEXT && !string.IsNullOrWhiteSpace((n.Content as ContentText)?.Text)).Select(n => new Message
+            {
+                Role = n.Role switch
+                {
+                    ChatRole.USER => "user",
+                    ChatRole.AI => "assistant",
+                    ChatRole.AGENT => "assistant",
+                    ChatRole.SYSTEM => "system",
+
+                    _ => "user",
+                },
+
+                Content = n.Content switch
+                {
+                    ContentText text => text.Text,
+                    _ => string.Empty,
+                }
+            }).ToList()],
+            Stream = true,
+        }, JSON_SERIALIZER_OPTIONS);
+
+        async Task<HttpRequestMessage> RequestBuilder()
+        {
+            // Build the HTTP post request:
+            var request = new HttpRequestMessage(HttpMethod.Post, "chat/completions");
+
+            // Set the authorization header:
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", await requestedSecret.Secret.Decrypt(ENCRYPTION));
+
+            // Set the content:
+            request.Content = new StringContent(perplexityChatRequest, Encoding.UTF8, "application/json");
+            return request;
+        }
+        
+        await foreach (var content in this.StreamChatCompletionInternal<ResponseStreamLine>("Perplexity", RequestBuilder, 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 Task<IEnumerable<Model>> GetTextModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return this.LoadModels();
+    }
+
+    /// <inheritdoc />
+    public override Task<IEnumerable<Model>> GetImageModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return Task.FromResult(Enumerable.Empty<Model>());
+    }
+    
+    /// <inheritdoc />
+    public override Task<IEnumerable<Model>> GetEmbeddingModels(string? apiKeyProvisional = null, CancellationToken token = default)
+    {
+        return Task.FromResult(Enumerable.Empty<Model>());
+    }
+    
+    public override IReadOnlyCollection<Capability> GetModelCapabilities(Model model)
+    {
+        var modelName = model.Id.ToLowerInvariant().AsSpan();
+        
+        if(modelName.IndexOf("reasoning") is not -1 ||
+           modelName.IndexOf("deep-research") is not -1)
+            return
+            [
+                Capability.TEXT_INPUT,
+                Capability.MULTIPLE_IMAGE_INPUT,
+                
+                Capability.TEXT_OUTPUT,
+                Capability.IMAGE_OUTPUT,
+                
+                Capability.ALWAYS_REASONING,
+            ];
+        
+        return
+        [
+            Capability.TEXT_INPUT,
+            Capability.MULTIPLE_IMAGE_INPUT,
+            
+            Capability.TEXT_OUTPUT,
+            Capability.IMAGE_OUTPUT,
+        ];
+    }
+    
+    #endregion
+
+    private Task<IEnumerable<Model>> LoadModels() => Task.FromResult<IEnumerable<Model>>(KNOWN_MODELS);
+}

app/MindWork AI Studio/Provider/Perplexity/ResponseStreamLine.cs

@@ -0,0 +1,45 @@
+namespace AIStudio.Provider.Perplexity;
+
+/// <summary>
+/// Data model for a line in the response stream, for streaming completions.
+/// </summary>
+/// <param name="Id">The id of the response.</param>
+/// <param name="Object">The object describing the response.</param>
+/// <param name="Created">The timestamp of the response.</param>
+/// <param name="Model">The model used for the response.</param>
+/// <param name="SystemFingerprint">The system fingerprint; together with the seed, this allows you to reproduce the response.</param>
+/// <param name="Choices">The choices made by the AI.</param>
+public readonly record struct ResponseStreamLine(string Id, string Object, uint Created, string Model, string SystemFingerprint, IList<Choice> Choices, IList<SearchResult> SearchResults) : IResponseStreamLine
+{
+    /// <inheritdoc />
+    public bool ContainsContent() => this != default && this.Choices.Count > 0;
+
+    /// <inheritdoc />
+    public ContentStreamChunk GetContent() => new(this.Choices[0].Delta.Content, this.GetSources());
+    
+    /// <inheritdoc />
+    public bool ContainsSources() => this != default && this.SearchResults.Count > 0;
+
+    /// <inheritdoc />
+    public IList<ISource> GetSources() => this.SearchResults.Cast<ISource>().ToList();
+}
+
+/// <summary>
+/// Data model for a choice made by the AI.
+/// </summary>
+/// <param name="Index">The index of the choice.</param>
+/// <param name="Delta">The delta text of the choice.</param>
+public readonly record struct Choice(int Index, Delta Delta);
+
+/// <summary>
+/// The delta text of a choice.
+/// </summary>
+/// <param name="Content">The content of the delta text.</param>
+public readonly record struct Delta(string Content);
+
+/// <summary>
+/// Data model for a search result.
+/// </summary>
+/// <param name="Title">The title of the search result.</param>
+/// <param name="URL">The URL of the search result.</param>
+public sealed record SearchResult(string Title, string URL) : Source(Title, URL);