<!-- MainWindow.xaml -->
<Window x:Class="MyApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Мое первое WPF приложение" 
        Height="450" Width="800">
    
    <Grid>
        <Button Content="Нажми меня!" 
                Width="150" Height="50" 
                Click="Button_Click"/>
    </Grid>
</Window>

// MainWindow.xaml.cs
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }
    
    private void Button_Click(object sender, RoutedEventArgs e)
    {
        MessageBox.Show("Привет, WPF!");
    }
}

<Window ...>
    <StackPanel Margin="20">
        <Label Content="Имя:"/>
        <TextBox x:Name="txtName" Margin="0,0,0,10"/>
        
        <Label Content="Возраст:"/>
        <TextBox x:Name="txtAge" Margin="0,0,0,10"/>
        
        <Label Content="Пол:"/>
        <StackPanel Orientation="Horizontal">
            <RadioButton x:Name="rbMale" Content="Мужской" GroupName="Gender"/>
            <RadioButton x:Name="rbFemale" Content="Женский" GroupName="Gender"/>
        </StackPanel>
        
        <CheckBox x:Name="chkAgree" Content="Согласен с условиями" Margin="0,10,0,10"/>
        
        <Button Content="Зарегистрироваться" Click="Register_Click" 
                Background="#667eea" Foreground="White" Height="40"/>
    </StackPanel>
</Window>

<Grid>
    <!-- Определяем строки и столбцы -->
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>     <!-- Авто (по содержимому) -->
        <RowDefinition Height="*"/>         <!-- Звездочка (пропорционально) -->
        <RowDefinition Height="50"/>        <!-- Фиксированная высота -->
    </Grid.RowDefinitions>
    
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*"/>
        <ColumnDefinition Width="2*"/>
    </Grid.ColumnDefinitions>
    
    <!-- Элементы -->
    <Label Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" 
           Content="Заголовок"/>
    <TextBox Grid.Row="1" Grid.Column="0"/>
    <Button Grid.Row="1" Grid.Column="1" Content="OK"/>
    <StatusBar Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2"/>
</Grid>

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>
    
    <!-- Заголовок -->
    <TextBlock Grid.Row="0" Text="Калькулятор" 
               FontSize="24" HorizontalAlignment="Center"/>
    
    <!-- Кнопки (5 строк по 4 столбца) -->
    <Grid Grid.Row="1">
        <Grid.RowDefinitions>
            <RowDefinition/><RowDefinition/>
            <RowDefinition/><RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/><ColumnDefinition/>
            <ColumnDefinition/><ColumnDefinition/>
        </Grid.ColumnDefinitions>
        
        <!-- Цифры -->
        <Button Grid.Row="0" Grid.Column="0" Content="7"/>
        <Button Grid.Row="0" Grid.Column="1" Content="8"/>
        <Button Grid.Row="0" Grid.Column="2" Content="9"/>
        <Button Grid.Row="0" Grid.Column="3" Content="/"/>
        <!-- ... остальные кнопки -->
    </Grid>
    
    <!-- Результат -->
    <TextBox Grid.Row="2" Text="0" FontSize="20" Margin="10"/>
</Grid>

<!-- XAML -->
<TextBox Text="{Binding UserName}" />
<Label Content="{Binding UserName}" />

// C# (ViewModel)
public class MainViewModel
{
    private string _userName;
    public string UserName
    {
        get => _userName;
        set
        {
            _userName = value;
            OnPropertyChanged(); // Оповещаем UI об изменении!
        }
    }
}

// Базовый класс для ViewModel
public class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
    
    // Упрощенный метод для установки значений
    protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
    {
        if (Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }
}

// Использование
public class PersonViewModel : ViewModelBase
{
    private string _name;
    public string Name
    {
        get => _name;
        set => SetProperty(ref _name, value);
    }
}

<Window x:Class="BindingDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        Title="Binding Demo" Height="300" Width="400">
    
    <Window.DataContext>
        <local:PersonViewModel/>
    </Window.DataContext>
    
    <StackPanel Margin="20">
        <Label Content="Имя:"/>
        <TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged}"/>
        
        <Label Content="Возраст:"/>
        <TextBox Text="{Binding Age}"/>
        
        <Label Content="Приветствие:"/>
        <Label Content="{Binding Greeting}" FontWeight="Bold"/>
        
        <Button Content="Обновить" Command="{Binding UpdateCommand}" Margin="0,20,0,0"/>
    </StackPanel>
</Window>

// RelayCommand - простая реализация ICommand
public class RelayCommand : ICommand
{
    private readonly Action _execute;
    private readonly Func _canExecute;
    
    public RelayCommand(Action execute, Func canExecute = null)
    {
        _execute = execute;
        _canExecute = canExecute;
    }
    
    public bool CanExecute(object parameter) => _canExecute == null || _canExecute();
    public void Execute(object parameter) => _execute();
    public event EventHandler CanExecuteChanged;
    
    public void RaiseCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
}

// Использование в ViewModel
public class MainViewModel : ViewModelBase
{
    public ICommand SaveCommand { get; }
    
    public MainViewModel()
    {
        SaveCommand = new RelayCommand(Save, CanSave);
    }
    
    private bool CanSave() => !string.IsNullOrEmpty(Name);
    private void Save() => MessageBox.Show("Сохранено!");
}

<!-- Определение стиля -->
<Window.Resources>
    <Style x:Key="ModernButton" TargetType="Button">
        <Setter Property="Background" Value="#667eea"/>
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="FontSize" Value="16"/>
        <Setter Property="Height" Value="40"/>
        <Setter Property="Width" Value="150"/>
        <Setter Property="Cursor" Value="Hand"/>
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Background" Value="#764ba2"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</Window.Resources>

<!-- Применение стиля -->
<Button Style="{StaticResource ModernButton}" Content="Нажми меня!"/>

<!-- Шаблон для кнопки -->
<Style TargetType="Button">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Border Background="{TemplateBinding Background}"
                        CornerRadius="10"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="1">
                    <ContentPresenter HorizontalAlignment="Center" 
                                      VerticalAlignment="Center"/>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<!-- Шаблон для ListBoxItem -->
<DataTemplate x:Key="PersonTemplate">
    <StackPanel Orientation="Horizontal">
        <Ellipse Width="40" Height="40" Fill="{Binding AvatarColor}"/>
        <StackPanel>
            <TextBlock Text="{Binding Name}" FontWeight="Bold"/>
            <TextBlock Text="{Binding Age}" FontSize="10"/>
        </StackPanel>
    </StackPanel>
</DataTemplate>

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

public class MainViewModel : ViewModelBase
{
    private ObservableCollection<Person> _people;
    private Person _selectedPerson;
    
    public MainViewModel()
    {
        LoadCommand = new RelayCommand(LoadPeople);
        AddCommand = new RelayCommand(AddPerson);
        DeleteCommand = new RelayCommand(DeletePerson, CanDelete);
        
        _people = new ObservableCollection<Person>();
    }
    
    public ObservableCollection<Person> People
    {
        get => _people;
        set => SetProperty(ref _people, value);
    }
    
    public Person SelectedPerson
    {
        get => _selectedPerson;
        set => SetProperty(ref _selectedPerson, value);
    }
    
    public ICommand LoadCommand { get; }
    public ICommand AddCommand { get; }
    public ICommand DeleteCommand { get; }
    
    private void LoadPeople()
    {
        People.Clear();
        foreach(var p in Database.GetPeople())
            People.Add(p);
    }
}

<Window x:Class="MyApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        Title="MVVM Demo" Height="450" Width="600">
    
    <Window.DataContext>
        <local:MainViewModel/>
    </Window.DataContext>
    
    <Grid Margin="10">
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        
        <!-- Список людей -->
        <DataGrid Grid.Row="0" 
                  ItemsSource="{Binding People}"
                  SelectedItem="{Binding SelectedPerson}"
                  AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTextColumn Header="ID" Binding="{Binding Id}" Width="50"/>
                <DataGridTextColumn Header="Имя" Binding="{Binding Name}" Width="150"/>
                <DataGridTextColumn Header="Возраст" Binding="{Binding Age}" Width="100"/>
            </DataGrid.Columns>
        </DataGrid>
        
        <!-- Кнопки управления -->
        <StackPanel Grid.Row="1" Orientation="Horizontal" Margin="0,10,0,0">
            <Button Content="Загрузить" Command="{Binding LoadCommand}" 
                    Width="100" Margin="5" Padding="8"/>
            <Button Content="Добавить" Command="{Binding AddCommand}" 
                    Width="100" Margin="5" Padding="8"/>
            <Button Content="Удалить" Command="{Binding DeleteCommand}" 
                    Width="100" Margin="5" Padding="8"/>
        </StackPanel>
    </Grid>
</Window>

// TaskItem.cs (Model)
public class TaskItem : ViewModelBase
{
    private bool _isCompleted;
    public int Id { get; set; }
    public string Title { get; set; }
    public bool IsCompleted
    {
        get => _isCompleted;
        set => SetProperty(ref _isCompleted, value);
    }
}

// MainViewModel.cs
public class MainViewModel : ViewModelBase
{
    private ObservableCollection<TaskItem> _tasks;
    private string _newTaskTitle;
    
    public ObservableCollection<TaskItem> Tasks { get; set; }
    public string NewTaskTitle { get; set; }
    public ICommand AddTaskCommand { get; }
    public ICommand DeleteTaskCommand { get; }
    
    public int CompletedCount => Tasks.Count(t => t.IsCompleted);
    public int TotalCount => Tasks.Count;
}