From 5c838908eb2050350a9657bd117cdcbeed7c3716 Mon Sep 17 00:00:00 2001
From: Ankitkumar Satapara <Ankitkumar_Satapara@epam.com>
Date: Sat, 18 Apr 2026 17:24:55 +0530
Subject: [PATCH] Added function in the panel for user to be added new function

---
 .../CreateFunctionDialog.xaml                 |  97 ++++++++++++++
 .../CreateFunctionDialog.xaml.cs              |  52 ++++++++
 Examples/Nodify.Calculator/EditorView.xaml    |  47 +++++++
 Examples/Nodify.Calculator/Executor.cs        |  89 +++++++++++--
 .../FunctionOperationViewModel.cs             | 119 ++++++++++++++++++
 .../OperationInfoViewModel.cs                 |   3 +
 .../Operations/OperationFactory.cs            |  18 +++
 .../OperationsMenuViewModel.cs                |  34 +++++
 .../SystemOperationViewModel.cs               |   3 +-
 9 files changed, 454 insertions(+), 8 deletions(-)
 create mode 100644 Examples/Nodify.Calculator/CreateFunctionDialog.xaml
 create mode 100644 Examples/Nodify.Calculator/CreateFunctionDialog.xaml.cs
 create mode 100644 Examples/Nodify.Calculator/FunctionOperationViewModel.cs

diff --git a/Examples/Nodify.Calculator/CreateFunctionDialog.xaml b/Examples/Nodify.Calculator/CreateFunctionDialog.xaml
new file mode 100644
index 0000000..cf46ca6
--- /dev/null
+++ b/Examples/Nodify.Calculator/CreateFunctionDialog.xaml
@@ -0,0 +1,97 @@
+<Window x:Class="Nodify.Calculator.CreateFunctionDialog"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Create New Function"
+        Width="500"
+        Height="520"
+        WindowStartupLocation="CenterOwner"
+        ResizeMode="NoResize"
+        Background="#2D2D30"
+        Foreground="White">
+    <Grid Margin="15">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+
+        <!-- Function Name -->
+        <TextBlock Text="Function Name:" Grid.Row="0" Margin="0 0 0 4" />
+        <TextBox x:Name="FunctionNameBox" Grid.Row="1" Margin="0 0 0 10"
+                 Background="#3E3E42" Foreground="White" Padding="4" />
+
+        <!-- Input Parameters -->
+        <StackPanel Orientation="Horizontal" Grid.Row="2" Margin="0 0 0 4">
+            <TextBlock Text="Input Parameters:" FontWeight="Bold" />
+            <Button Content="➕ Add" Margin="10 0 0 0" Padding="8 2" Click="AddInput_Click"
+                    Background="#3E3E42" Foreground="White" Cursor="Hand" />
+        </StackPanel>
+        <DataGrid x:Name="InputParamsGrid" Grid.Row="3" Margin="0 0 0 10"
+                  AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="True"
+                  Background="#3E3E42" Foreground="White" RowBackground="#3E3E42"
+                  AlternatingRowBackground="#333337" GridLinesVisibility="None"
+                  HeadersVisibility="Column" BorderBrush="#555">
+            <DataGrid.Columns>
+                <DataGridTextColumn Header="Name" Binding="{Binding Name}" Width="*" />
+                <DataGridComboBoxColumn Header="Type" SelectedItemBinding="{Binding Type}" Width="120">
+                    <DataGridComboBoxColumn.ItemsSource>
+                        <x:Array Type="sys:String" xmlns:sys="clr-namespace:System;assembly=System.Runtime">
+                            <sys:String>string</sys:String>
+                            <sys:String>int</sys:String>
+                            <sys:String>double</sys:String>
+                            <sys:String>bool</sys:String>
+                            <sys:String>float</sys:String>
+                            <sys:String>decimal</sys:String>
+                            <sys:String>long</sys:String>
+                            <sys:String>DateTime</sys:String>
+                            <sys:String>object</sys:String>
+                        </x:Array>
+                    </DataGridComboBoxColumn.ItemsSource>
+                </DataGridComboBoxColumn>
+            </DataGrid.Columns>
+        </DataGrid>
+
+        <!-- Output Parameters -->
+        <StackPanel Orientation="Horizontal" Grid.Row="4" Margin="0 0 0 4">
+            <TextBlock Text="Output Parameters:" FontWeight="Bold" />
+            <Button Content="➕ Add" Margin="10 0 0 0" Padding="8 2" Click="AddOutput_Click"
+                    Background="#3E3E42" Foreground="White" Cursor="Hand" />
+        </StackPanel>
+        <DataGrid x:Name="OutputParamsGrid" Grid.Row="5" Margin="0 0 0 10"
+                  AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="True"
+                  Background="#3E3E42" Foreground="White" RowBackground="#3E3E42"
+                  AlternatingRowBackground="#333337" GridLinesVisibility="None"
+                  HeadersVisibility="Column" BorderBrush="#555">
+            <DataGrid.Columns>
+                <DataGridTextColumn Header="Name" Binding="{Binding Name}" Width="*" />
+                <DataGridComboBoxColumn Header="Type" SelectedItemBinding="{Binding Type}" Width="120">
+                    <DataGridComboBoxColumn.ItemsSource>
+                        <x:Array Type="sys:String" xmlns:sys="clr-namespace:System;assembly=System.Runtime">
+                            <sys:String>string</sys:String>
+                            <sys:String>int</sys:String>
+                            <sys:String>double</sys:String>
+                            <sys:String>bool</sys:String>
+                            <sys:String>float</sys:String>
+                            <sys:String>decimal</sys:String>
+                            <sys:String>long</sys:String>
+                            <sys:String>DateTime</sys:String>
+                            <sys:String>object</sys:String>
+                        </x:Array>
+                    </DataGridComboBoxColumn.ItemsSource>
+                </DataGridComboBoxColumn>
+            </DataGrid.Columns>
+        </DataGrid>
+
+        <!-- Buttons -->
+        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Grid.Row="6">
+            <Button Content="Create" Width="80" Margin="0 0 10 0" Padding="4"
+                    Click="OnCreateClick" IsDefault="True" />
+            <Button Content="Cancel" Width="80" Padding="4"
+                    Click="OnCancelClick" IsCancel="True" />
+        </StackPanel>
+    </Grid>
+</Window>
diff --git a/Examples/Nodify.Calculator/CreateFunctionDialog.xaml.cs b/Examples/Nodify.Calculator/CreateFunctionDialog.xaml.cs
new file mode 100644
index 0000000..845456c
--- /dev/null
+++ b/Examples/Nodify.Calculator/CreateFunctionDialog.xaml.cs
@@ -0,0 +1,52 @@
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Windows;
+
+namespace Nodify.Calculator
+{
+    public partial class CreateFunctionDialog : Window
+    {
+        public string FunctionName { get; private set; } = string.Empty;
+        public List<FunctionParameterInfo> InputParameters { get; } = new List<FunctionParameterInfo>();
+        public List<FunctionParameterInfo> OutputParameters { get; } = new List<FunctionParameterInfo>();
+
+        private readonly ObservableCollection<FunctionParameterInfo> _inputs = new ObservableCollection<FunctionParameterInfo>();
+        private readonly ObservableCollection<FunctionParameterInfo> _outputs = new ObservableCollection<FunctionParameterInfo>();
+
+        public CreateFunctionDialog()
+        {
+            InitializeComponent();
+            InputParamsGrid.ItemsSource = _inputs;
+            OutputParamsGrid.ItemsSource = _outputs;
+        }
+
+        private void AddInput_Click(object sender, RoutedEventArgs e)
+        {
+            _inputs.Add(new FunctionParameterInfo { Name = $"param{_inputs.Count + 1}", Type = "string" });
+        }
+
+        private void AddOutput_Click(object sender, RoutedEventArgs e)
+        {
+            _outputs.Add(new FunctionParameterInfo { Name = $"result{_outputs.Count + 1}", Type = "string" });
+        }
+
+        private void OnCreateClick(object sender, RoutedEventArgs e)
+        {
+            if (string.IsNullOrWhiteSpace(FunctionNameBox.Text))
+            {
+                MessageBox.Show("Please enter a function name.", "Validation", MessageBoxButton.OK, MessageBoxImage.Warning);
+                return;
+            }
+
+            FunctionName = FunctionNameBox.Text.Trim();
+            InputParameters.AddRange(_inputs);
+            OutputParameters.AddRange(_outputs);
+            DialogResult = true;
+        }
+
+        private void OnCancelClick(object sender, RoutedEventArgs e)
+        {
+            DialogResult = false;
+        }
+    }
+}
diff --git a/Examples/Nodify.Calculator/EditorView.xaml b/Examples/Nodify.Calculator/EditorView.xaml
index a56e430..d24b30f 100644
--- a/Examples/Nodify.Calculator/EditorView.xaml
+++ b/Examples/Nodify.Calculator/EditorView.xaml
@@ -433,6 +433,21 @@
                     </nodify:Node>
                 </DataTemplate>
 
+                <DataTemplate DataType="{x:Type local:FunctionOperationViewModel}">
+                    <nodify:Node Header="{Binding Title}"
+                                 Input="{Binding Input}"
+                                 Output="{Binding Output}"
+                                 ToolTip="Double click to edit function"
+                                 BorderBrush="#FF9800"
+                                 BorderThickness="2">
+                        <nodify:Node.InputBindings>
+                            <MouseBinding Gesture="LeftDoubleClick"
+                                          Command="{Binding DataContext.OpenCalculatorCommand, RelativeSource={RelativeSource AncestorType=UserControl}}"
+                                          CommandParameter="{Binding InnerCalculator}" />
+                        </nodify:Node.InputBindings>
+                    </nodify:Node>
+                </DataTemplate>
+
                 <DataTemplate DataType="{x:Type local:CalculatorOperationViewModel}">
                     <nodify:Node Header="{Binding Title}"
                                  Input="{Binding Input}"
@@ -691,6 +706,38 @@
                             </DataTemplate>
                         </ItemsControl.ItemTemplate>
                     </ItemsControl>
+
+                    <!-- Functions Section -->
+                    <TextBlock Text="Functions" FontWeight="Bold" Margin="0 8 0 4" />
+                    <Button Content="➕ Create New Function"
+                            Command="{Binding Calculator.OperationsMenu.CreateFunctionCommand}"
+                            Margin="0 0 0 6"
+                            Padding="6 3"
+                            Cursor="Hand"
+                            Background="#FF9800"
+                            Foreground="White" />
+                    <ItemsControl ItemsSource="{Binding Calculator.OperationsMenu.AvailableFunctions}"
+                          Focusable="False">
+                        <ItemsControl.ItemContainerStyle>
+                            <Style>
+                                <Setter Property="FrameworkElement.Margin" Value="3" />
+                                <Setter Property="FrameworkElement.HorizontalAlignment" Value="Left" />
+                                <Setter Property="FrameworkElement.Cursor" Value="Hand" />
+                                <Setter Property="FrameworkElement.ToolTip" Value="Drag and drop to add this function to the flow" />
+                            </Style>
+                        </ItemsControl.ItemContainerStyle>
+                        <ItemsControl.ItemTemplate>
+                            <DataTemplate DataType="{x:Type local:OperationInfoViewModel}">
+                                <Border Background="#3E3E42" CornerRadius="3" Padding="6 4"
+                                        MouseMove="OnNodeDrag" Cursor="Hand">
+                                    <StackPanel Orientation="Horizontal">
+                                        <TextBlock Text="ƒ " Foreground="#FF9800" FontWeight="Bold" />
+                                        <TextBlock Text="{Binding Title}" Foreground="Orange" FontWeight="SemiBold" />
+                                    </StackPanel>
+                                </Border>
+                            </DataTemplate>
+                        </ItemsControl.ItemTemplate>
+                    </ItemsControl>
                 </StackPanel>
             </ScrollViewer>
             </DockPanel>
diff --git a/Examples/Nodify.Calculator/Executor.cs b/Examples/Nodify.Calculator/Executor.cs
index ffb806a..9d3ec6e 100644
--- a/Examples/Nodify.Calculator/Executor.cs
+++ b/Examples/Nodify.Calculator/Executor.cs
@@ -428,6 +428,14 @@ namespace Nodify.Calculator
                 OnLogMe?.Invoke($"Auth node resolved. Base URL: {_authBaseUrl}, Auth Type: {_authType}");
                 return;
             }
+
+            // Handle Function nodes — execute the inner flow
+            if (op is FunctionOperationViewModel funcOp)
+            {
+                OnLogMe?.Invoke($"Executing function: {funcOp.FunctionName}");
+                ExecuteFunction(funcOp, connections);
+                return;
+            }
             OnLogMe?.Invoke($"Starting Execution : {url}");
             var res = GetResponse(url, "get");
             if (!string.IsNullOrEmpty(res))
@@ -509,16 +517,83 @@ namespace Nodify.Calculator
 
         private static string GetConnectorTextValue(ConnectorViewModel connector)
         {
-            // When the connector is not connected, the user enters text in the Value text box.
-            // Value is a double, so we try to use it as a string representation.
-            // However, for string inputs (URL, token, etc.) the value won't be meaningful as a double.
-            // The user-typed string is actually stored in the Title field for unconnected inputs in some cases,
-            // but here we rely on the ConnectorViewModel.Value being 0 (default) and the actual string 
-            // is not captured as double. So we return empty — the AuthOperationViewModel properties are the 
-            // primary source set via the node's text boxes.
             return string.Empty;
         }
 
+        private void ExecuteFunction(FunctionOperationViewModel funcOp, ICollection<ConnectionViewModel> connections)
+        {
+            // Propagate outer input values into the function
+            for (int i = 0; i < funcOp.InputParameters.Count; i++)
+            {
+                var outerInputIndex = i + 1; // skip flow triangle
+                if (outerInputIndex < funcOp.Input.Count)
+                {
+                    var outerConnector = funcOp.Input[outerInputIndex];
+                    var inputCon = connections.FirstOrDefault(c => c.Input == outerConnector);
+                    if (inputCon != null)
+                    {
+                        var sourceNodeId = inputCon.Output.Operation.NodeId;
+                        if (outputs.TryGetValue(sourceNodeId, out var val))
+                        {
+                            outerConnector.Value = double.TryParse(val, out var d) ? d : 0;
+                        }
+                    }
+                }
+            }
+
+            // Trigger propagation of input values to inner Begin node
+            funcOp.PropagateInputsToInner();
+
+            // Execute the inner calculator's flow (Begin -> End)
+            var innerOps = funcOp.InnerCalculator.Operations;
+            var innerConns = funcOp.InnerCalculator.Connections;
+
+            OnLogMe?.Invoke($"  [Function '{funcOp.FunctionName}'] Resolving inner GET variables...");
+            ResolveGetVariableNodes(innerOps, innerConns);
+
+            OnLogMe?.Invoke($"  [Function '{funcOp.FunctionName}'] Executing inner chain...");
+            var innerStart = innerOps.FirstOrDefault(n => n.Title?.Equals("Begin", StringComparison.OrdinalIgnoreCase) == true);
+            if (innerStart == null)
+            {
+                OnLogMe?.Invoke($"  [Function '{funcOp.FunctionName}'] No Begin node found inside function!", logType.Error);
+                return;
+            }
+
+            var visited = new HashSet<string>();
+            TraverseChain(innerStart, "end", innerConns, visited, true);
+
+            // Collect outputs from the inner End node
+            var innerEnd = innerOps.FirstOrDefault(n => n.Title?.Equals("End", StringComparison.OrdinalIgnoreCase) == true);
+            if (innerEnd != null)
+            {
+                for (int i = 0; i < funcOp.OutputParameters.Count; i++)
+                {
+                    var endInputIndex = i + 1; // skip flow triangle
+                    if (endInputIndex < innerEnd.Input.Count)
+                    {
+                        var endConnector = innerEnd.Input[endInputIndex];
+                        var endCon = innerConns.FirstOrDefault(c => c.Input == endConnector);
+                        if (endCon != null)
+                        {
+                            var sourceId = endCon.Output.Operation.NodeId;
+                            if (outputs.TryGetValue(sourceId, out var resultVal))
+                            {
+                                var outerOutputIndex = i + 1; // skip flow triangle
+                                if (outerOutputIndex < funcOp.Output.Count)
+                                {
+                                    funcOp.Output[outerOutputIndex].Value = double.TryParse(resultVal, out var dv) ? dv : 0;
+                                }
+                                outputs[funcOp.NodeId] = resultVal;
+                                OnLogMe?.Invoke($"  [Function '{funcOp.FunctionName}'] Output '{funcOp.OutputParameters[i].Name}' = {resultVal}");
+                            }
+                        }
+                    }
+                }
+            }
+
+            OnLogMe?.Invoke($"Function '{funcOp.FunctionName}' execution completed.");
+        }
+
         private string GetResponse(string url, string type)
         {
             string baseURL = !string.IsNullOrWhiteSpace(_authBaseUrl) ? _authBaseUrl : "https://localhost:7107";
diff --git a/Examples/Nodify.Calculator/FunctionOperationViewModel.cs b/Examples/Nodify.Calculator/FunctionOperationViewModel.cs
new file mode 100644
index 0000000..7d0b98b
--- /dev/null
+++ b/Examples/Nodify.Calculator/FunctionOperationViewModel.cs
@@ -0,0 +1,119 @@
+using System.Collections.Generic;
+using System.Windows;
+
+namespace Nodify.Calculator
+{
+    public class FunctionOperationViewModel : CalculatorOperationViewModel
+    {
+        private string _functionName = "Function";
+        public string FunctionName
+        {
+            get => _functionName;
+            set
+            {
+                if (SetProperty(ref _functionName, value))
+                {
+                    Title = value;
+                }
+            }
+        }
+
+        public List<FunctionParameterInfo> InputParameters { get; } = new List<FunctionParameterInfo>();
+        public List<FunctionParameterInfo> OutputParameters { get; } = new List<FunctionParameterInfo>();
+
+        private OperationViewModel InnerBegin { get; }
+        private OperationViewModel InnerEnd { get; }
+
+        public FunctionOperationViewModel()
+        {
+            // Add Begin and End nodes inside the inner calculator for flow-based editing
+            InnerBegin = new SystemOperationViewModel
+            {
+                Title = "Begin",
+                SystemOperationType = SystemOperations.BEGIN,
+                Location = new Point(50, 150)
+            };
+            InnerBegin.Output.Add(new ConnectorViewModel { Title = "", Shape = ConnectorShape.Triangle, IsInput = false });
+
+            InnerEnd = new SystemOperationViewModel
+            {
+                Title = "End",
+                SystemOperationType = SystemOperations.END,
+                Location = new Point(600, 150)
+            };
+            InnerEnd.Input.Add(new ConnectorViewModel { Title = "", Shape = ConnectorShape.Triangle });
+
+            InnerCalculator.Operations.Add(InnerBegin);
+            InnerCalculator.Operations.Add(InnerEnd);
+        }
+
+        public void ConfigureParameters(List<FunctionParameterInfo> inputs, List<FunctionParameterInfo> outputs)
+        {
+            InputParameters.Clear();
+            InputParameters.AddRange(inputs);
+            OutputParameters.Clear();
+            OutputParameters.AddRange(outputs);
+
+            // Add data output connectors to InnerBegin (these feed the inner flow with input values)
+            foreach (var inp in inputs)
+            {
+                InnerBegin.Output.Add(new ConnectorViewModel
+                {
+                    Title = $"{inp.Name} ({inp.Type})",
+                    Shape = ConnectorShape.Circle,
+                    IsInput = false
+                });
+
+                // Also add an outer input connector on the function node
+                Input.Add(new ConnectorViewModel
+                {
+                    Title = $"{inp.Name} ({inp.Type})"
+                });
+            }
+
+            // Add data input connectors to InnerEnd (these collect inner flow results)
+            foreach (var outp in outputs)
+            {
+                InnerEnd.Input.Add(new ConnectorViewModel
+                {
+                    Title = $"{outp.Name} ({outp.Type})",
+                    Shape = ConnectorShape.Circle
+                });
+
+                // Also add an outer output connector on the function node
+                Output.Add(new ConnectorViewModel
+                {
+                    Title = $"{outp.Name} ({outp.Type})",
+                    IsInput = false
+                });
+            }
+        }
+
+        protected override void OnInputValueChanged()
+        {
+            PropagateInputsToInner();
+        }
+
+        public void PropagateInputsToInner()
+        {
+            // Propagate outer input values into the InnerBegin's data output connectors
+            // The first output of InnerBegin is the flow triangle, data starts at index 1
+            for (var i = 0; i < InputParameters.Count; i++)
+            {
+                var outerIndex = i; // outer Input: first is flow triangle (index 0), data starts at 1
+                var innerIndex = i + 1; // InnerBegin Output: first is flow triangle, data starts at 1
+
+                if (outerIndex + 1 < Input.Count && innerIndex < InnerBegin.Output.Count)
+                {
+                    InnerBegin.Output[innerIndex].Value = Input[outerIndex + 1].Value;
+                }
+            }
+        }
+    }
+
+    public class FunctionParameterInfo
+    {
+        public string Name { get; set; } = string.Empty;
+        public string Type { get; set; } = "string";
+    }
+}
diff --git a/Examples/Nodify.Calculator/OperationInfoViewModel.cs b/Examples/Nodify.Calculator/OperationInfoViewModel.cs
index 171e743..e038130 100644
--- a/Examples/Nodify.Calculator/OperationInfoViewModel.cs
+++ b/Examples/Nodify.Calculator/OperationInfoViewModel.cs
@@ -32,5 +32,8 @@ namespace Nodify.Calculator
         public string VariableType { get; set; } = string.Empty;
         public string DefaultValue { get; set; } = string.Empty;
         public bool IsSimpleVariable { get; set; }
+        public bool IsFunction { get; set; }
+        public List<FunctionParameterInfo> FunctionInputs { get; set; } = new List<FunctionParameterInfo>();
+        public List<FunctionParameterInfo> FunctionOutputs { get; set; } = new List<FunctionParameterInfo>();
     }
 }
diff --git a/Examples/Nodify.Calculator/Operations/OperationFactory.cs b/Examples/Nodify.Calculator/Operations/OperationFactory.cs
index 9a88ab6..70a082c 100644
--- a/Examples/Nodify.Calculator/Operations/OperationFactory.cs
+++ b/Examples/Nodify.Calculator/Operations/OperationFactory.cs
@@ -275,6 +275,24 @@ namespace Nodify.Calculator
                     //_o.Input.AddRange(input);
                     return _o;
                 case OperationType.System:
+                    if (info.sysOp == SystemOperations.FUNCTION)
+                    {
+                        var funcOp = new FunctionOperationViewModel
+                        {
+                            Title = info.Title,
+                            FunctionName = info.Title
+                        };
+                        // Add flow connectors (triangle)
+                        var funcFlowIn = new ConnectorViewModel { Title = "", Shape = ConnectorShape.Triangle };
+                        var funcFlowOut = new ConnectorViewModel { Title = "", Shape = ConnectorShape.Triangle, IsInput = false };
+                        funcOp.Input.Add(funcFlowIn);
+                        funcOp.Output.Add(funcFlowOut);
+
+                        // Configure typed input/output parameters
+                        funcOp.ConfigureParameters(info.FunctionInputs, info.FunctionOutputs);
+                        return funcOp;
+                    }
+
                     if (info.sysOp == SystemOperations.AUTH)
                     {
                         var authOp = new AuthOperationViewModel
diff --git a/Examples/Nodify.Calculator/OperationsMenuViewModel.cs b/Examples/Nodify.Calculator/OperationsMenuViewModel.cs
index 1509a75..5e382bd 100644
--- a/Examples/Nodify.Calculator/OperationsMenuViewModel.cs
+++ b/Examples/Nodify.Calculator/OperationsMenuViewModel.cs
@@ -113,6 +113,7 @@ namespace Nodify.Calculator
         public NodifyObservableCollection<OperationInfoViewModel> SwaggerOperations { get; }
         public NodifyObservableCollection<OperationInfoViewModel> AvailableModels { get; }
         public NodifyObservableCollection<OperationInfoViewModel> AvailableVariables { get; }
+        public NodifyObservableCollection<OperationInfoViewModel> AvailableFunctions { get; }
         public INodifyCommand CreateOperationCommand { get; }
 
         [Newtonsoft.Json.JsonIgnore]
@@ -125,6 +126,7 @@ namespace Nodify.Calculator
             List<OperationInfoViewModel> operations = new List<OperationInfoViewModel>();
             AvailableModels = new NodifyObservableCollection<OperationInfoViewModel>();
             AvailableVariables = new NodifyObservableCollection<OperationInfoViewModel>();
+            AvailableFunctions = new NodifyObservableCollection<OperationInfoViewModel>();
             LoadVariablesFromDb();
 
             var customModelDir = "CustomModels";
@@ -158,6 +160,7 @@ namespace Nodify.Calculator
             CreateOperationCommand = new DelegateCommand<OperationInfoViewModel>(CreateOperation);
             ImportSwaggerCommand = new DelegateCommand(ImportSwagger);
             AddVariableCommand = new DelegateCommand(AddVariable);
+            CreateFunctionCommand = new DelegateCommand(CreateFunction);
         }
 
         
@@ -180,6 +183,37 @@ namespace Nodify.Calculator
 
         public INodifyCommand ImportSwaggerCommand { get; }
         public INodifyCommand AddVariableCommand { get; }
+        public INodifyCommand CreateFunctionCommand { get; }
+
+        private void CreateFunction()
+        {
+            var dialog = new CreateFunctionDialog();
+            dialog.Owner = System.Windows.Application.Current.MainWindow;
+            if (dialog.ShowDialog() != true)
+                return;
+
+            var funcName = dialog.FunctionName;
+
+            if (AvailableFunctions.Any(f => f.Title == funcName))
+            {
+                MessageBox.Show($"A function named '{funcName}' already exists.", "Duplicate Function", MessageBoxButton.OK, MessageBoxImage.Warning);
+                return;
+            }
+
+            var funcInfo = new OperationInfoViewModel
+            {
+                Title = funcName,
+                Type = OperationType.System,
+                sysOp = SystemOperations.FUNCTION,
+                IsFlowNode = true,
+                IsFunction = true,
+                FunctionInputs = new System.Collections.Generic.List<FunctionParameterInfo>(dialog.InputParameters),
+                FunctionOutputs = new System.Collections.Generic.List<FunctionParameterInfo>(dialog.OutputParameters)
+            };
+
+            AvailableFunctions.Add(funcInfo);
+            AvailableOperations.Add(funcInfo);
+        }
 
         private void AddVariable()
         {
diff --git a/Examples/Nodify.Calculator/SystemOperationViewModel.cs b/Examples/Nodify.Calculator/SystemOperationViewModel.cs
index 5100d2c..3be161b 100644
--- a/Examples/Nodify.Calculator/SystemOperationViewModel.cs
+++ b/Examples/Nodify.Calculator/SystemOperationViewModel.cs
@@ -17,7 +17,8 @@ namespace Nodify.Calculator
         GET_SET,
         PARSEJSON,
         SPLIT,
-        AUTH
+        AUTH,
+        FUNCTION
     }
 
     public class SystemOperationViewModel : OperationViewModel