Implemented displaying errors.

ucalc.sln.DotSettings

@@ -0,0 +1,2 @@
+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:Boolean x:Key="/Default/CodeInspection/CodeAnnotations/NamespacesWithAnnotations/=ucalc_002EAnnotations/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

ucalc/BillingWindow.xaml

@@ -4,6 +4,7 @@
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:local="clr-namespace:UCalc"
+        xmlns:controls="clr-namespace:UCalc.Controls"
         mc:Ignorable="d"
         Title="MietRechner"
         Width="800"
@@ -21,7 +22,8 @@
         <TabControl Name="TabControl"
                     BorderBrush="White">
             <TabItem Visibility="Collapsed">
-                <Frame Source="Pages/LandlordPage.xaml"/>
+                <Frame Source="Pages/LandlordPage.xaml"
+                       LoadCompleted="OnLandlordFrameLoadCompleted"/>
             </TabItem>
             <TabItem Visibility="Collapsed">
                 <Frame Source="Pages/HousePage.xaml"/>

ucalc/BillingWindow.xaml.cs

@@ -1,22 +1,25 @@
 using System;
 using System.Windows;
+using System.Windows.Controls;
 using System.Windows.Navigation;
 using UCalc.Data;
+using UCalc.Models;
 using UCalc.Pages;
 
 namespace UCalc
 {
     public partial class BillingWindow
     {
-        private readonly Billing _savedBilling;
         public Billing Billing { get; }
+        public BillingModel Model { get; }
 
         public BillingWindow(Billing savedBilling, Billing billing)
         {
-            _savedBilling = savedBilling;
             Billing = billing;
             InitializeComponent();
 
+            Model = new BillingModel(Billing);
+
             Title =
                 $"MietRechner - Abrechnung von {billing.StartDate.ToShortDateString()} - {billing.EndDate.Date.ToShortDateString()}";
         }
@@ -28,9 +31,17 @@ namespace UCalc
 
         private void OnSideBarFrameLoadCompleted(object sender, NavigationEventArgs e)
         {
-            var sideBar = (SideBar) SideBarFrame.Content;
+            var sideBar = (SideBar) ((Frame) sender).Content;
             sideBar.TabControl = TabControl;
             sideBar.LandlordButton.Selected = true;
+
+            sideBar.Model = Model;
+        }
+
+        private void OnLandlordFrameLoadCompleted(object sender, NavigationEventArgs e)
+        {
+            var page = (LandlordPage) ((Frame) sender).Content;
+            page.Model = Model.LandlordModel;
         }
     }
 }

ucalc/Controls/ErrorCounter.xaml

@@ -5,5 +5,15 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:local="clr-namespace:UCalc.Controls"
              mc:Ignorable="d">
-    <Grid />
+
+    <Border CornerRadius="3"
+            BorderBrush="Red"
+            Background="Red">
+
+        <Label
+            Content="{Binding Path=Model.ErrorCount, RelativeSource={RelativeSource AncestorType=local:ErrorCounter}}"
+            Foreground="White" />
+
+    </Border>
+
 </UserControl>

ucalc/Controls/ErrorCounter.xaml.cs

@@ -1,7 +1,15 @@
-namespace UCalc.Controls
+using System.Windows;
+using UCalc.Models;
+
+namespace UCalc.Controls
 {
     public partial class ErrorCounter
     {
+        public Model Model { get; set; }
+
+        public static readonly DependencyProperty ModelProperty = DependencyProperty.Register(
+            "Model", typeof(Model), typeof(ErrorCounter), new PropertyMetadata((Model) null));
+
         public ErrorCounter()
         {
             InitializeComponent();

ucalc/Controls/ErrorIcon.xaml

@@ -0,0 +1,51 @@
+<UserControl x:Class="UCalc.Controls.ErrorIcon"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:local="clr-namespace:UCalc.Controls"
+             mc:Ignorable="d"
+             Width="16"
+             Height="16">
+
+    <UserControl.Resources>
+        <local:ErrorToVisibilityConverter x:Key="ErrorToVisibilityConverter" />
+        <local:ErrorToInVisibilityConverter x:Key="ErrorToInVisibilityConverter" />
+    </UserControl.Resources>
+    <StackPanel ToolTip="{Binding Path=Error, RelativeSource={RelativeSource AncestorType=local:ErrorIcon}}">
+        <Viewbox
+            Visibility="{Binding Path=Error, RelativeSource={RelativeSource AncestorType=local:ErrorIcon}, Converter={StaticResource ErrorToInVisibilityConverter}}"
+            Stretch="Uniform">
+            <Canvas Width="512" Height="512">
+                <Canvas.RenderTransform>
+                    <TranslateTransform X="0" Y="0" />
+                </Canvas.RenderTransform>
+                <Path Fill="DarkGreen">
+                    <Path.Data>
+                        <PathGeometry
+                            Figures="M504 256c0 136.967-111.033 248-248 248S8 392.967 8 256 119.033 8 256 8s248 111.033 248 248zM227.314 387.314l184-184c6.248-6.248 6.248-16.379 0-22.627l-22.627-22.627c-6.248-6.249-16.379-6.249-22.628 0L216 308.118l-70.059-70.059c-6.248-6.248-16.379-6.248-22.628 0l-22.627 22.627c-6.248 6.248-6.248 16.379 0 22.627l104 104c6.249 6.249 16.379 6.249 22.628.001z"
+                            FillRule="NonZero" />
+                    </Path.Data>
+                </Path>
+            </Canvas>
+        </Viewbox>
+
+        <Viewbox
+            Visibility="{Binding Path=Error, RelativeSource={RelativeSource AncestorType=local:ErrorIcon}, Converter={StaticResource ErrorToVisibilityConverter}}"
+            Stretch="Uniform">
+            <Canvas Width="512" Height="512">
+                <Canvas.RenderTransform>
+                    <TranslateTransform X="0" Y="0" />
+                </Canvas.RenderTransform>
+                <Path Fill="Red">
+                    <Path.Data>
+                        <PathGeometry
+                            Figures="M256 8C119 8 8 119 8 256s111 248 248 248 248-111 248-248S393 8 256 8zm121.6 313.1c4.7 4.7 4.7 12.3 0 17L338 377.6c-4.7 4.7-12.3 4.7-17 0L256 312l-65.1 65.6c-4.7 4.7-12.3 4.7-17 0L134.4 338c-4.7-4.7-4.7-12.3 0-17l65.6-65-65.6-65.1c-4.7-4.7-4.7-12.3 0-17l39.6-39.6c4.7-4.7 12.3-4.7 17 0l65 65.7 65.1-65.6c4.7-4.7 12.3-4.7 17 0l39.6 39.6c4.7 4.7 4.7 12.3 0 17L312 256l65.6 65.1z"
+                            FillRule="NonZero" />
+                    </Path.Data>
+                </Path>
+            </Canvas>
+        </Viewbox>
+    </StackPanel>
+
+</UserControl>

ucalc/Controls/ErrorIcon.xaml.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Windows;
+using System.Windows.Data;
+
+namespace UCalc.Controls
+{
+    public class ErrorToVisibilityConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+        {
+            if (value == null || "".Equals(value))
+            {
+                return Visibility.Collapsed;
+            }
+
+            return Visibility.Visible;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter,
+            System.Globalization.CultureInfo culture)
+        {
+            throw new InvalidOperationException();
+        }
+    }
+
+    public class ErrorToInVisibilityConverter : IValueConverter
+    {
+        private readonly ErrorToVisibilityConverter _converter = new ErrorToVisibilityConverter();
+
+        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+        {
+            var result = _converter.Convert(value, targetType, parameter, culture) as Visibility?;
+            return result == Visibility.Collapsed ? Visibility.Visible : Visibility.Collapsed;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter,
+            System.Globalization.CultureInfo culture)
+        {
+            throw new InvalidOperationException();
+        }
+    }
+
+    public partial class ErrorIcon
+    {
+        public string Error { get; set; }
+
+        public static readonly DependencyProperty ErrorProperty = DependencyProperty.Register(
+            "Error", typeof(string), typeof(ErrorIcon), new PropertyMetadata((string) null));
+
+        public ErrorIcon()
+        {
+            InitializeComponent();
+        }
+    }
+}

ucalc/Models/BillingModel.cs

@@ -0,0 +1,21 @@
+using UCalc.Data;
+
+namespace UCalc.Models
+{
+    public class BillingModel : Model
+    {
+        public LandlordModel LandlordModel { get; }
+
+        public BillingModel(Billing billing)
+        {
+            LandlordModel = new LandlordModel(billing.Landlord);
+
+            Properties = LandlordModel.Properties;
+        }
+
+        public override void Apply()
+        {
+            LandlordModel.Apply();
+        }
+    }
+}

ucalc/Models/HouseModel.cs

@@ -0,0 +1,20 @@
+using UCalc.Data;
+
+namespace UCalc.Models
+{
+    public class HouseModel : Model
+    {
+        private readonly House _data;
+        public ModelProperty<string> Street { get; }
+        public ModelProperty<string> HouseNumber { get; }
+        public ModelProperty<string> City { get; }
+        public ModelProperty<string> Postcode { get; }
+
+        // TODO: Flats?
+
+        public HouseModel(House data)
+        {
+            _data = data;
+        }
+    }
+}

ucalc/Models/LandlordModel.cs

@@ -0,0 +1,79 @@
+using UCalc.Data;
+
+namespace UCalc.Models
+{
+    public class LandlordModel : Model
+    {
+        private readonly Landlord _data;
+        public ModelProperty<int> Salutation { get; }
+        public ModelProperty<string> Name { get; }
+        public ModelProperty<string> MailAddress { get; }
+        public ModelProperty<string> Phone { get; }
+        public ModelProperty<string> Street { get; }
+        public ModelProperty<string> HouseNumber { get; }
+        public ModelProperty<string> City { get; }
+        public ModelProperty<string> Postcode { get; }
+        public ModelProperty<string> Iban { get; }
+        public ModelProperty<string> Bic { get; }
+        public ModelProperty<string> BankName { get; }
+
+        public LandlordModel(Landlord data)
+        {
+            _data = data;
+
+            Salutation = new ModelProperty<int>(this, (int) _data.Salutation, null);
+            Name = new ModelProperty<string>(this, _data.Name, ModelPropertyValidators.IsNotEmpty);
+            MailAddress = new ModelProperty<string>(this, _data.MailAddress, ModelPropertyValidators.IsNotEmpty);
+            Phone = new ModelProperty<string>(this, _data.Phone, ModelPropertyValidators.IsNotEmpty);
+            Street = new ModelProperty<string>(this, _data.Address.Street, ModelPropertyValidators.IsNotEmpty);
+            HouseNumber =
+                new ModelProperty<string>(this, _data.Address.HouseNumber, ModelPropertyValidators.IsNotEmpty);
+            City = new ModelProperty<string>(this, _data.Address.City, ModelPropertyValidators.IsNotEmpty);
+            Postcode = new ModelProperty<string>(this, _data.Address.Postcode, ModelPropertyValidators.IsNotEmpty);
+            Iban = new ModelProperty<string>(this, _data.BankAccount.Iban, ModelPropertyValidators.IsNotEmpty);
+            Bic = new ModelProperty<string>(this, _data.BankAccount.Bic, ModelPropertyValidators.IsNotEmpty);
+            BankName = new ModelProperty<string>(this, _data.BankAccount.BankName, ModelPropertyValidators.IsNotEmpty);
+
+            Properties = new ModelProperty[]
+                {Salutation, Name, MailAddress, Phone, Street, HouseNumber, City, Postcode, Iban, Bic, BankName};
+        }
+
+        public override void Apply()
+        {
+            base.Apply();
+
+            _data.Salutation = (Salutation) Salutation.Value;
+            Salutation.Modified = false;
+
+            _data.Name = Name.Value;
+            Name.Modified = false;
+
+            _data.MailAddress = MailAddress.Value;
+            MailAddress.Modified = false;
+
+            _data.Phone = Phone.Value;
+            Phone.Modified = false;
+
+            _data.Address.Street = Street.Value;
+            Street.Modified = false;
+
+            _data.Address.HouseNumber = HouseNumber.Value;
+            HouseNumber.Modified = false;
+
+            _data.Address.City = City.Value;
+            City.Modified = false;
+
+            _data.Address.Postcode = Postcode.Value;
+            Postcode.Modified = false;
+
+            _data.BankAccount.Iban = Iban.Value;
+            Iban.Modified = false;
+
+            _data.BankAccount.Bic = Bic.Value;
+            Bic.Modified = false;
+
+            _data.BankAccount.BankName = BankName.Value;
+            BankName.Modified = false;
+        }
+    }
+}

ucalc/Models/Model.cs

@@ -0,0 +1,118 @@
+using System;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using ucalc.Annotations;
+
+namespace UCalc.Models
+{
+    public class ModelProperty : INotifyPropertyChanged
+    {
+        private readonly Model _model;
+        private object _value;
+        private string _error;
+        private readonly Func<object, string> _validate;
+
+        public object Value
+        {
+            get => _value;
+            set
+            {
+                if (_value.Equals(value))
+                {
+                    return;
+                }
+
+                var oldError = Error;
+                Error = _validate?.Invoke(value);
+                if (oldError == null && Error != null || oldError != null && Error == null)
+                {
+                    _model.OnPropertyChanged("ErrorCount");
+                }
+
+                Modified = true;
+                _value = value;
+            }
+        }
+
+        public string Error
+        {
+            get => _error;
+            private set
+            {
+                if (_error == value)
+                {
+                    return;
+                }
+
+                _error = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public bool Modified { get; set; }
+
+        public ModelProperty(Model model, object value, Func<object, string> validate)
+        {
+            _model = model;
+            _value = value;
+            _error = validate?.Invoke(value);
+            _validate = validate;
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        [NotifyPropertyChangedInvocator]
+        private void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+
+    public class ModelProperty<T> : ModelProperty
+    {
+        public new T Value
+        {
+            get => (T) base.Value;
+            set => base.Value = value;
+        }
+
+        public ModelProperty(Model model, T value, Func<T, string> validate) : base(model, value,
+            validate == null ? (Func<object, string>) null : o => validate((T) o))
+        {
+        }
+    }
+
+    public static class ModelPropertyValidators
+    {
+        public static string IsNotEmpty(string data)
+        {
+            return string.IsNullOrEmpty(data) ? "Geben Sie einen Wert ein" : null;
+        }
+    }
+
+    public abstract class Model : INotifyPropertyChanged
+    {
+        public ModelProperty[] Properties { get; protected set; }
+
+        public bool Modified => Properties.Select(property => property.Modified).Any();
+
+        public int ErrorCount => Properties.Select(property => string.IsNullOrEmpty(property.Error) ? 0 : 1).Sum();
+
+        public virtual void Apply()
+        {
+            if (ErrorCount > 0)
+            {
+                throw new InvalidOperationException();
+            }
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        [NotifyPropertyChangedInvocator]
+        public void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}

ucalc/Pages/LandlordPage.xaml

@@ -4,6 +4,23 @@
       xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
       xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
       xmlns:local="clr-namespace:UCalc.Pages"
+      xmlns:controls="clr-namespace:UCalc.Controls"
       mc:Ignorable="d">
-    <Grid />
+
+    <ScrollViewer>
+        <StackPanel>
+
+            <DockPanel>
+                <Label DockPanel.Dock="Left" Content="Name:" />
+
+                <controls:ErrorIcon DockPanel.Dock="Right"
+                                    Error="{Binding Path=Model.Name.Error, RelativeSource={RelativeSource AncestorType=local:LandlordPage}}" />
+
+                <TextBox
+                    Text="{Binding Path=Model.Name.Value, RelativeSource={RelativeSource AncestorType=local:LandlordPage}, UpdateSourceTrigger=PropertyChanged}" />
+            </DockPanel>
+
+        </StackPanel>
+    </ScrollViewer>
+
 </Page>

ucalc/Pages/LandlordPage.xaml.cs

@@ -1,9 +1,11 @@
-using System.Windows.Controls;
+using UCalc.Models;
 
 namespace UCalc.Pages
 {
-    public partial class LandlordPage : Page
+    public partial class LandlordPage
     {
+        public LandlordModel Model { get; set; }
+
         public LandlordPage()
         {
             InitializeComponent();

ucalc/Pages/SideBar.xaml

@@ -5,6 +5,7 @@
       xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
       xmlns:local="clr-namespace:UCalc"
       xmlns:controls="clr-namespace:UCalc.Controls"
+      xmlns:pages="clr-namespace:UCalc.Pages"
       mc:Ignorable="d"
       Background="{x:Static local:Constants.SubMainColor}">
 
@@ -115,6 +116,12 @@
                 </Canvas>
             </Viewbox>
 
+            <controls:ErrorCounter x:Name="LandlordErrorCounter"
+                                   DockPanel.Dock="Right"
+                                   Margin="0, 12, 12, 12"
+                                   VerticalAlignment="Center"
+                                   Model="{Binding Path=Model.LandlordModel, RelativeSource={RelativeSource AncestorType=pages:SideBar}}"/>
+
             <Label Content="Vermieter"
                    Margin="0, 12, 12, 12"
                    VerticalAlignment="Center"

ucalc/Pages/SideBar.xaml.cs

@@ -2,12 +2,14 @@
 using System.Windows;
 using System.Windows.Controls;
 using UCalc.Controls;
+using UCalc.Models;
 
 namespace UCalc.Pages
 {
     public partial class SideBar
     {
         public TabControl TabControl { get; set; }
+        public BillingModel Model { get; set; }
 
         public SideBar()
         {

ucalc/ucalc.csproj

@@ -31,6 +31,9 @@
         <Page Update="Controls\ErrorCounter.xaml">
             <Generator></Generator>
         </Page>
+        <Page Update="Controls\ErrorIcon.xaml">
+            <Generator></Generator>
+        </Page>
     </ItemGroup>
 
     <ItemGroup>
@@ -58,6 +61,9 @@
         <Compile Update="Controls\ErrorCounter.xaml.cs">
             <DependentUpon>ErrorCounter.xaml</DependentUpon>
         </Compile>
+        <Compile Update="Controls\ErrorIcon.xaml.cs">
+            <DependentUpon>ErrorIcon.xaml</DependentUpon>
+        </Compile>
     </ItemGroup>
 
 </Project>