Added tool calling support (#731)

Co-authored-by: krut_ni <nils.kruthoff@dlr.de>
Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Provider/OpenAI/ResponsesResponse.cs

@@ -0,0 +1,77 @@
+using System.Text.Json;
+
+namespace AIStudio.Provider.OpenAI;
+
+/// <summary>
+/// Non-streaming OpenAI Responses API result used during local tool execution.
+/// </summary>
+public sealed record ResponsesResponse
+{
+    public string Id { get; init; } = string.Empty;
+
+    public string Model { get; init; } = string.Empty;
+
+    public string? OutputText { get; init; }
+
+    public IList<JsonElement> Output { get; init; } = [];
+
+    public IReadOnlyList<ResponsesFunctionCallItem> GetFunctionCalls() => this.Output
+        .Where(x => ReadString(x, "type").Equals("function_call", StringComparison.Ordinal))
+        .Select(x => new ResponsesFunctionCallItem
+        {
+            Type = ReadString(x, "type"),
+            CallId = ReadString(x, "call_id"),
+            Name = ReadString(x, "name"),
+            Arguments = ReadString(x, "arguments"),
+        })
+        .ToList();
+
+    public string GetTextOutput()
+    {
+        if (!string.IsNullOrWhiteSpace(this.OutputText))
+            return this.OutputText;
+
+        return string.Concat(this.Output
+            .Where(x => ReadString(x, "type").Equals("message", StringComparison.Ordinal))
+            .SelectMany(ReadContentItems)
+            .Select(x => ReadString(x, "type") switch
+            {
+                "output_text" => ReadString(x, "text"),
+                "refusal" => ReadString(x, "refusal"),
+                _ => string.Empty,
+            }));
+    }
+
+    public IReadOnlyList<Source> GetSources() => this.Output
+        .Where(x => ReadString(x, "type").Equals("message", StringComparison.Ordinal))
+        .SelectMany(ReadContentItems)
+        .SelectMany(x => ReadArrayItems(x, "annotations"))
+        .Where(x => ReadString(x, "type").Equals("url_citation", StringComparison.Ordinal))
+        .Select(x => new Source(ReadString(x, "title"), ReadString(x, "url"), SourceOrigin.LLM))
+        .Where(x => !string.IsNullOrWhiteSpace(x.Title) && !string.IsNullOrWhiteSpace(x.URL))
+        .ToList();
+
+    private static IEnumerable<JsonElement> ReadContentItems(JsonElement outputItem)
+        => ReadArrayItems(outputItem, "content");
+
+    private static IEnumerable<JsonElement> ReadArrayItems(JsonElement item, string propertyName)
+    {
+        if (item.ValueKind is not JsonValueKind.Object ||
+            !item.TryGetProperty(propertyName, out var array) ||
+            array.ValueKind is not JsonValueKind.Array)
+            yield break;
+
+        foreach (var arrayItem in array.EnumerateArray())
+            yield return arrayItem;
+    }
+
+    private static string ReadString(JsonElement item, string propertyName)
+    {
+        if (item.ValueKind is not JsonValueKind.Object ||
+            !item.TryGetProperty(propertyName, out var property) ||
+            property.ValueKind is not JsonValueKind.String)
+            return string.Empty;
+
+        return property.GetString() ?? string.Empty;
+    }
+}