Add connection test and command-line display

SqlcmdGuiApp/CommandLineWindow.xaml

@@ -0,0 +1,8 @@
+<Window x:Class="SqlcmdGuiApp.CommandLineWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Command Line" Height="200" Width="600">
+    <Grid Margin="5">
+        <TextBox x:Name="CommandTextBox" IsReadOnly="True" TextWrapping="Wrap" VerticalScrollBarVisibility="Auto"/>
+    </Grid>
+</Window>

SqlcmdGuiApp/CommandLineWindow.xaml.cs

@@ -0,0 +1,15 @@
+using System.Windows;
+
+namespace SqlcmdGuiApp
+{
+    public partial class CommandLineWindow : Window
+    {
+        public CommandLineWindow(string commandLine)
+        {
+            InitializeComponent();
+            CommandTextBox.Text = commandLine;
+            CommandTextBox.Focus();
+            CommandTextBox.SelectAll();
+        }
+    }
+}

SqlcmdGuiApp/MainWindow.xaml

@@ -71,6 +71,10 @@
             </ScrollViewer>
         </GroupBox>
 
-        <Button Content="Execute" Grid.Row="3" Grid.ColumnSpan="2" Height="30" Click="ExecuteButton_Click"/>
+        <StackPanel Grid.Row="3" Grid.ColumnSpan="2" Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 5 0 0">
+            <Button Content="Test Connection" Margin="5" Width="120" Click="TestConnectionButton_Click"/>
+            <Button Content="View Command-Line" Margin="5" Width="120" Click="ViewCommandLineButton_Click"/>
+            <Button Content="Execute" Margin="5" Width="80" Click="ExecuteButton_Click"/>
+        </StackPanel>
     </Grid>
 </Window>

SqlcmdGuiApp/MainWindow.xaml.cs

@@ -66,68 +66,94 @@ private void LoadParameters(string path)
             }
         }
 
-        private void ExecuteButton_Click(object sender, RoutedEventArgs e)
+        private List<string> BuildSqlcmdArguments(bool includeInputFile)
         {
-            if (!File.Exists(FilePathTextBox.Text))
-            {
-                MessageBox.Show("SQL file not found.");
-                return;
-            }
+            var args = new List<string> { "-S", ServerTextBox.Text };
 
-            var psi = new ProcessStartInfo("sqlcmd")
-            {
-                RedirectStandardOutput = true,
-                RedirectStandardError = true,
-                UseShellExecute = false,
-                CreateNoWindow = true
-            };
-            psi.ArgumentList.Add("-S");
-            psi.ArgumentList.Add(ServerTextBox.Text);
             if (!string.IsNullOrEmpty(DatabaseTextBox.Text))
             {
-                psi.ArgumentList.Add("-d");
-                psi.ArgumentList.Add(DatabaseTextBox.Text);
+                args.Add("-d");
+                args.Add(DatabaseTextBox.Text);
             }
 
             if (AuthComboBox.SelectedIndex == 1)
             {
-                psi.ArgumentList.Add("-U");
-                psi.ArgumentList.Add(UserTextBox.Text);
-                psi.ArgumentList.Add("-P");
-                psi.ArgumentList.Add(PasswordBox.Password);
+                args.Add("-U");
+                args.Add(UserTextBox.Text);
+                args.Add("-P");
+                args.Add(PasswordBox.Password);
             }
             else
             {
-                psi.ArgumentList.Add("-E");
+                args.Add("-E");
             }
 
             var encrypt = (EncryptComboBox.SelectedItem as ComboBoxItem)?.Content?.ToString()?.ToLower();
             if (!string.IsNullOrEmpty(encrypt))
             {
-                psi.ArgumentList.Add("-N");
-                psi.ArgumentList.Add(encrypt);
+                args.Add("-N");
+                args.Add(encrypt);
             }
 
             if (TrustServerCertificateCheckBox.IsChecked == true)
             {
-                psi.ArgumentList.Add("-C");
+                args.Add("-C");
             }
 
             if (ReadOnlyIntentCheckBox.IsChecked == true)
             {
-                psi.ArgumentList.Add("-K");
-                psi.ArgumentList.Add("ReadOnly");
+                args.Add("-K");
+                args.Add("ReadOnly");
             }
 
-
             foreach (var p in Parameters)
             {
-                psi.ArgumentList.Add("-v");
-                psi.ArgumentList.Add($"{p.Name}={p.Value}");
+                args.Add("-v");
+                args.Add($"{p.Name}={p.Value}");
+            }
+
+            if (includeInputFile)
+            {
+                args.Add("-i");
+                args.Add(FilePathTextBox.Text);
+            }
+
+            return args;
+        }
+
+        private ProcessStartInfo BuildSqlcmdProcessInfo(bool includeInputFile)
+        {
+            var psi = new ProcessStartInfo("sqlcmd")
+            {
+                RedirectStandardOutput = true,
+                RedirectStandardError = true,
+                UseShellExecute = false,
+                CreateNoWindow = true
+            };
+            foreach (var arg in BuildSqlcmdArguments(includeInputFile))
+            {
+                psi.ArgumentList.Add(arg);
+            }
+            return psi;
+        }
+
+        private static string Quote(string arg) => arg.Contains(' ') ? $"\"{arg}\"" : arg;
+
+        private string BuildCommandLine()
+        {
+            var args = BuildSqlcmdArguments(true).Select(Quote);
+            return "sqlcmd " + string.Join(" ", args);
+        }
+
+        private void ExecuteButton_Click(object sender, RoutedEventArgs e)
+        {
+            if (!File.Exists(FilePathTextBox.Text))
+            {
+                MessageBox.Show("SQL file not found.");
+                return;
             }
 
-            psi.ArgumentList.Add("-i");
-            psi.ArgumentList.Add(FilePathTextBox.Text);
+            var psi = BuildSqlcmdProcessInfo(true);
 
             try
             {
@@ -149,6 +175,45 @@ private void ExecuteButton_Click(object sender, RoutedEventArgs e)
                 MessageBox.Show("Failed to execute sqlcmd. See error.log for details.");
             }
         }
+
+        private void TestConnectionButton_Click(object sender, RoutedEventArgs e)
+        {
+            var psi = BuildSqlcmdProcessInfo(false);
+            psi.ArgumentList.Add("-Q");
+            psi.ArgumentList.Add("SELECT 1");
+
+            try
+            {
+                var process = Process.Start(psi);
+                if (process == null)
+                {
+                    throw new InvalidOperationException("Failed to start sqlcmd process.");
+                }
+                process.WaitForExit();
+                var error = process.StandardError.ReadToEnd();
+
+                if (process.ExitCode == 0)
+                {
+                    MessageBox.Show("Connection successful.");
+                }
+                else
+                {
+                    MessageBox.Show(string.IsNullOrWhiteSpace(error) ? "Connection failed." : error);
+                }
+            }
+            catch (Exception ex)
+            {
+                App.LogError(ex.ToString());
+                MessageBox.Show("Failed to execute sqlcmd. See error.log for details.");
+            }
+        }
+
+        private void ViewCommandLineButton_Click(object sender, RoutedEventArgs e)
+        {
+            var cmd = BuildCommandLine();
+            var window = new CommandLineWindow(cmd);
+            window.ShowDialog();
+        }
     }
 
     public class SqlParameter