fix von viel errors in GUI und logik dahinter

SkyTeam/verfuegbareFluge.xaml.cs

@@ -2,15 +2,25 @@
 using System.Data;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Navigation;
 using MySql.Data.MySqlClient;
 
 namespace SkyTeam
 {
     public partial class verfuegbareFluge : Page
     {
-        public verfuegbareFluge()
+        private string _fromCity;
+        private string _toCity;
+        private DateTime? _flightDate;
+
+        public verfuegbareFluge(string from = "", string to = "", DateTime? date = null)
         {
             InitializeComponent();
+
+            _fromCity = from;
+            _toCity = to;
+            _flightDate = date;
+
             LoadFlights();
         }
 
@@ -19,15 +29,52 @@ namespace SkyTeam
             string query = @"SELECT f.Id, f.Flugnummer, f.Abflugort AS 'From', f.Zielort AS 'To', 
                              z.Modell AS Plane, f.Abflugdatum AS Date
                              FROM fluege f
-                             JOIN flugzeuge z ON f.FlugzeugId = z.Id";
+                             JOIN flugzeuge z ON f.FlugzeugId = z.Id
+                             WHERE 1=1"; 
 
-            using (MySqlConnection conn = new MySqlConnection(DatenbankServices.GetConnection()))
+            if (!string.IsNullOrWhiteSpace(_fromCity))
             {
-                conn.Open();
-                MySqlDataAdapter adapter = new MySqlDataAdapter(query, conn);
-                DataTable dt = new DataTable();
-                adapter.Fill(dt);
-                AvailableFlightsDataGrid.ItemsSource = dt.DefaultView;
+                query += " AND f.Abflugort LIKE @from";
+            }
+            if (!string.IsNullOrWhiteSpace(_toCity))
+            {
+                query += " AND f.Zielort LIKE @to";
+            }
+            if (_flightDate.HasValue)
+            {
+                query += " AND DATE(f.Abflugdatum) = @date";
+            }
+
+            try
+            {
+                using (MySqlConnection conn = new MySqlConnection(DatenbankServices.GetConnection()))
+                {
+                    conn.Open();
+                    MySqlCommand cmd = new MySqlCommand(query, conn);
+
+                    if (!string.IsNullOrWhiteSpace(_fromCity))
+                        cmd.Parameters.AddWithValue("@from", "%" + _fromCity + "%");
+
+                    if (!string.IsNullOrWhiteSpace(_toCity))
+                        cmd.Parameters.AddWithValue("@to", "%" + _toCity + "%");
+
+                    if (_flightDate.HasValue)
+                        cmd.Parameters.AddWithValue("@date", _flightDate.Value.ToString("yyyy-MM-dd"));
+
+                    MySqlDataAdapter adapter = new MySqlDataAdapter(cmd);
+                    DataTable dt = new DataTable();
+                    adapter.Fill(dt);
+                    AvailableFlightsDataGrid.ItemsSource = dt.DefaultView;
+
+                    if (dt.Rows.Count == 0)
+                    {
+                        MessageBox.Show("Keine Flüge gefunden.");
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show("Fehler beim Laden: " + ex.Message);
             }
         }
 
@@ -42,6 +89,12 @@ namespace SkyTeam
             DataRowView row = (DataRowView)AvailableFlightsDataGrid.SelectedItem;
             int flightId = Convert.ToInt32(row["Id"]);
 
+            if (SessionManager.CurrentUserId == 0)
+            {
+                MessageBox.Show("Fehler: Nicht eingeloggt.");
+                return;
+            }
+
             string query = "INSERT INTO buchungen (UserId, FlugId) VALUES (@uid, @fid)";
 
             try
@@ -50,13 +103,13 @@ namespace SkyTeam
                 {
                     conn.Open();
                     MySqlCommand cmd = new MySqlCommand(query, conn);
-                    cmd.Parameters.AddWithValue("@uid",SessionManager.CurrentUserId);
+                    cmd.Parameters.AddWithValue("@uid", SessionManager.CurrentUserId);
                     cmd.Parameters.AddWithValue("@fid", flightId);
                     cmd.ExecuteNonQuery();
                 }
 
                 MessageBox.Show("Erfolgreich gebucht!");
-                ((MainWindow)Application.Current.MainWindow).MainFrame.Navigate(new BuchungenPage());
+                NavigationService.Navigate(new BuchungenPage());
             }
             catch (Exception ex)
             {