Struktur av MVVM

Controller

namespace My_WPF_Project
{
    public class Controller
    {
        vmHeader Vm { get; set; }
        
        public Controller(vmHeader vm)
        {
            Vm = vm;
            
            Vm.Save.CallBack = Save();
            Vm.Save.Enable = _ => DateTime.Now.Hour => 5;
            
            Vm.Changed.Callback = Changed;
        }
        
        private void Save()
        {
        }
        
        private void Changed()
        {
        }
    }
}

Header.xaml

<UserControl x:Class="My_WPF_Project.Views.Header">
    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:My_WPF_Project.Views"
    xmlns:viewModels="clr-namespace:My_WPF_Project.ViewModels"
    xmlns:interactivity="http://schemas.microsoft.com/expression/2010/interactivity"
    mc:Ignorable="d" 
    d:DesignHeight="450" d:DesignWidth="450">
    
    <UserControl.DataContect>
        <viewModels: vmHeader />
    </UserControl.DataContect>
    
    <Grid>
        <Button Command="{Binding Save}" Content=Save />
      
        <ComboBox>
           <interactivity:Interaction.Triggers>
                <interactivity:EventTrigger EventName="SelectionChanged">
                    <interactivity:InvokeCommandAction Command="{Binding Changed}" />
                </interactivity:EventTrigger>
            </interactivity:Interaction.Triggers>
        </ComboBox>
    </Grid>

</Usercontrol>

MainWindow.xaml

<Window x:Class="My_WPF_Project.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:My_WPF_Project"
        xmlns:views="clr-namespace:My_WPF_Project.Views"
        mc:Ignorable="d"
        Title="Main Window" Height="850" Width="800">
    
    <DockPanel LastChildFill="True">
        
        <!-- Header -->
        <views:Header x:Name="viewHeader" DockPanel.Dock="Top" Margin="6,0,6,0" />

        <!-- Footer -->
        <views:Footer x:Name="viewFooter" DockPanel.Dock="Bottom" Margin="6,0,6,0" />
        
        <!-- Body -->
        <views:Body x:Name="viewBody" Margin="6,0,6,0" />
    </DockPanel>
    
</Window>

MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace My_WPF_Project
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        vmHeader vmHeader;
        vmBody vmBody;
        vmFooter;
    
        public MainWindow()
        {
            InitializeComponent();

            SetupViewModels();
            SetupControls();
            SetupRouter();
            SetupVMS();
        }

        private void SetupViewModels()
        {
            vmHeader = viewHeader.DataContext as ViewModels.vmHeader;
            vmBody = viewBody.DataContext as ViewModels.vmBody;
            vmFooter = viewFooter.DataContext as ViewModels.vmFooter;
        }

        private void SetupControls()
        {
            new Controls.Header(vmHeader);
            new Controls.Body(vmBody);
            new Controls.Footer(vmFooter);
        }
        
        private void SetupRouter()
        {
            new Router(vmHeader, vmBody, vmFooter);
        }
        
        private void SetupVMS()
        {
            vms.Header = vmHeader;
            vms.Body = vmBody;
            vms.Footer = vmFooter;
        }
    }
}

RelayCommand

namespace My_WPF_Project
{
    class RelayCommand : ICommand
    {
        public Action CallBack { get; set; }
        public Predicate<object> Enable { get; set; }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public bool CanExecute(object parameter)
        {
            return Enable == null ? true : Enable(parameter);
        }

        public void Execute(object parameter = null)
        {
            CallBack();
        }
    }
}

Router

namespace My_WPF_Project
{
    public Router
    {
        vmHeader Header { get; set; }
        vmBody Body { get; set; }
        vmFooter Footer { get; set; }
    
        public Router(vmHeader header, vmBody body, vmFooter footer)
        {
            Header = header;
            Body = body;
            Footer = footer;
            
            Header.Save.Callback = Save();
            Header.Enable = _ => DateTime.Now.Hour => 5;
            
            Header.Changed.Callback = Changed;
        }
        
        private void Save()
        {
        }
        
        private void Changed()
        {
        }
    }
}

vmHeader

using System;

namespace My_WPF_Project.ViewModels
{
    class vmHeader
    {
        public RelayCommand Save { get; private set; }
        public RelayCommand Changed { get; private set; }
        
        public vmHeader()
        {
            Save = new RelayCommand();
            Save.CallBack = Save;
            Save.Enable = _ => Datetime.Now.Hour => 5;
            
            Changed = new RelayCommand();
        }
        
        private void Save()
        {
        }
    }
}

vms

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using My_WPF_Project.ViewModels;

namespace My_WPF_Project
{
    static class vms
    {
        public static vmHeader Header { get; set; }
        public static vmBody Body { get; set; }
        public static vmFooter Footer { get; set; }
    }
}