AddPurchase

AddPurchaseModel.cs

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

namespace ArbitrageClient
{
    class AddPurchaseModel
    {
        private DateTime purchaseDate;

        private string sellerName;
        private string sellerStreet;
        private string sellerCity;
        private string sellerTelephoneNumber;
        private string sellerComments;

        private decimal sellingPrice;
        private decimal fuelCost;
        private decimal shippingCost;
        private bool shippingIncluded;
        private decimal totalPrice;

        public DateTime PurchaseDate
        {
            get
            {
                return purchaseDate;
            }

            set
            {
                purchaseDate = value;
            }
        }

        public string SellerName
        {
            get
            {
                return sellerName;
            }

            set
            {
                sellerName = value;
            }
        }

        public string SellerStreet
        {
            get
            {
                return sellerStreet;
            }

            set
            {
                sellerStreet = value;
            }
        }

        public string SellerCity
        {
            get
            {
                return sellerCity;
            }

            set
            {
                sellerCity = value;
            }
        }

        public string SellerTelephoneNumber
        {
            get
            {
                return sellerTelephoneNumber;
            }

            set
            {
                sellerTelephoneNumber = value;
            }
        }

        public string SellerComments
        {
            get
            {
                return sellerComments;
            }

            set
            {
                sellerComments = value;
            }
        }

        public decimal SellingPrice
        {
            get
            {
                return sellingPrice;
            }

            set
            {
                sellingPrice = value;
            }
        }

        public decimal FuelCost
        {
            get
            {
                return fuelCost;
            }

            set
            {
                fuelCost = value;
            }
        }

        public decimal ShippingCost
        {
            get
            {
                return shippingCost;
            }

            set
            {
                shippingCost = value;
            }
        }

        public bool ShippingIncluded
        {
            get
            {
                return shippingIncluded;
            }

            set
            {
                shippingIncluded = value;
            }
        }

        public decimal TotalPrice
        {
            get
            {
                return totalPrice;
            }

            set
            {
                totalPrice = value;
            }
        }
    }
}

AddPurchaseUserControl.xaml

<UserControl x:Class="ArbitrageClient.AddPurchaseUserControl"
             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:ArbitrageClient"
             mc:Ignorable="d" 
             d:DesignHeight="600" d:DesignWidth="800">
    <UserControl.DataContext>
        <local:AddPurchaseViewModel />
    </UserControl.DataContext>
    <Grid Margin="10">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.Resources>
            <Style TargetType="{x:Type TextBox}">
                <Setter Property="Margin" Value="0,2,0,2" />
            </Style>
            <Style TargetType="{x:Type ComboBox}">
                <Setter Property="Margin" Value="0,2,0,2" />
            </Style>
            <Style TargetType="{x:Type DatePicker}">
                <Setter Property="Margin" Value="0,2,0,2" />
            </Style>
        </Grid.Resources>
        <Label Grid.Row="0" Grid.ColumnSpan="2" FontWeight="Bold" HorizontalContentAlignment="Center">General</Label>
        <Label Grid.Row="1" Grid.Column="0">Purchase date: </Label>
        <DatePicker Grid.Row="1" Grid.Column="1" Text="{Binding PurchaseDate}" />
        <Label Grid.Row="2" Grid.ColumnSpan="2" Visibility="Hidden">Placeholder</Label>
        <Label Grid.Row="3" Grid.ColumnSpan="2" FontWeight="Bold" HorizontalContentAlignment="Center">Seller</Label>
        <Label Grid.Row="4" Grid.Column="0">Name: </Label>
        <TextBox Grid.Row="4" Grid.Column="1" Text="{Binding SellerName}" />
        <Label Grid.Row="5" Grid.Column="0">Street: </Label>
        <TextBox Grid.Row="5" Grid.Column="1" Text="{Binding SellerStreet}" />
        <Label Grid.Row="6" Grid.Column="0">City: </Label>
        <TextBox Grid.Row="6" Grid.Column="1" Text="{Binding SellerCity}" />
        <Label Grid.Row="7" Grid.Column="0">Tel. number: </Label>
        <TextBox Grid.Row="7" Grid.Column="1" Text="{Binding SellerTelephoneNumber}" />
        <Label Grid.Row="8" Grid.Column="0">Comments: </Label>
        <TextBox Grid.Row="8" Grid.Column="1" Text="{Binding SellerComments}" />
        <Label Grid.Row="9" Grid.ColumnSpan="2" Visibility="Hidden">Placeholder</Label>
        <Label Grid.Row="10" Grid.ColumnSpan="2" FontWeight="Bold" HorizontalContentAlignment="Center">Pricing</Label>
        <Label Grid.Row="11" Grid.Column="0">Selling price: </Label>
        <TextBox Grid.Row="11" Grid.Column="1" Text="{Binding SellingPrice}" />
        <Label Grid.Row="12" Grid.Column="0">Extra cost: </Label>
        <ComboBox Grid.Row="12" Grid.Column="1" x:Name="extraCost">
            <ComboBoxItem Tag="FuelCost">Fuel cost</ComboBoxItem>
            <ComboBoxItem Tag="ShippingCost">Shipping cost</ComboBoxItem>
            <ComboBoxItem Tag="ShippingIncluded">Shipping included</ComboBoxItem>
        </ComboBox>
        <Label Grid.Row="13" Grid.Column="0">Cost: </Label>
        <TextBox Grid.Row="13" Grid.Column="1" Text="{Binding FuelCost}">
            <TextBox.Style>
                <Style TargetType="{x:Type TextBox}" BasedOn="{StaticResource {x:Type TextBox}}">
                    <Setter Property="TextBlock.Visibility" Value="Collapsed"></Setter>
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding ElementName=extraCost, Path=SelectedItem.Tag}" Value="FuelCost">
                            <Setter Property="TextBlock.Visibility" Value="Visible" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </TextBox.Style>
        </TextBox>
        <TextBox Grid.Row="13" Grid.Column="1" Text="{Binding ShippingCost}">
            <TextBox.Style>
                <Style TargetType="{x:Type TextBox}" BasedOn="{StaticResource {x:Type TextBox}}">
                    <Setter Property="TextBlock.Visibility" Value="Collapsed"></Setter>
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding ElementName=extraCost, Path=SelectedItem.Tag}" Value="ShippingCost">
                            <Setter Property="TextBlock.Visibility" Value="Visible" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </TextBox.Style>
        </TextBox>
        <TextBox Grid.Row="13" Grid.Column="1" IsEnabled="False">
            <TextBox.Style>
                <Style TargetType="{x:Type TextBox}" BasedOn="{StaticResource {x:Type TextBox}}">
                    <Setter Property="TextBox.Visibility" Value="Collapsed"></Setter>
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding ElementName=extraCost, Path=SelectedItem.Tag}" Value="ShippingIncluded">
                            <Setter Property="TextBox.Visibility" Value="Visible" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </TextBox.Style>
        </TextBox>
        <Label Grid.Row="14" Grid.Column="0">Total price:</Label>
        <TextBox Grid.Row="14" Grid.Column="1" IsEnabled="False" Text="{Binding TotalPrice}" />
    </Grid>
</UserControl>

AddPurchaseUserControl.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 ArbitrageClient
{
    /// <summary>
    /// Interaction logic for AddPurchaseUserControl.xaml
    /// </summary>
    public partial class AddPurchaseUserControl : UserControl
    {
        public AddPurchaseUserControl()
        {
            InitializeComponent();
        }
    }
}

AddPurchaseViewModel.cs

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

namespace ArbitrageClient
{
    class AddPurchaseViewModel : INotifyPropertyChanged
    {
        private AddPurchaseModel addPurchaseModel;

        public AddPurchaseViewModel()
        {
            AddPurchaseModel = new AddPurchaseModel { };
        }

        public AddPurchaseModel AddPurchaseModel
        {
            get
            {
                return addPurchaseModel;
            }

            set
            {
                addPurchaseModel = value;
            }
        }

        public DateTime PurchaseDate
        {
            get
            {
                return AddPurchaseModel.PurchaseDate;
            }

            set
            {
                if (AddPurchaseModel.PurchaseDate != value)
                {
                    AddPurchaseModel.PurchaseDate = value;
                    RaisePropertyChanged("PurchaseDate");
                }
            }
        }

        public string SellerName
        {
            get
            {
                return AddPurchaseModel.SellerName;
            }

            set
            {
                if (AddPurchaseModel.SellerName != value)
                {
                    AddPurchaseModel.SellerName = value;
                    RaisePropertyChanged("SellerName");
                }
            }
        }

        public string SellerStreet
        {
            get
            {
                return AddPurchaseModel.SellerStreet;
            }

            set
            {
                if (AddPurchaseModel.SellerStreet != value)
                {
                    AddPurchaseModel.SellerStreet = value;
                    RaisePropertyChanged("SellerStreet");
                }
            }
        }

        public string SellerCity
        {
            get
            {
                return AddPurchaseModel.SellerCity;
            }

            set
            {
                if (AddPurchaseModel.SellerCity != value)
                {
                    AddPurchaseModel.SellerCity = value;
                    RaisePropertyChanged("SellerCity");
                }
            }
        }

        public string SellerTelephoneNumber
        {
            get
            {
                return AddPurchaseModel.SellerTelephoneNumber;
            }

            set
            {
                if (AddPurchaseModel.SellerTelephoneNumber != value)
                {
                    AddPurchaseModel.SellerTelephoneNumber = value;
                    RaisePropertyChanged("SellerTelephoneNumber");
                }
            }
        }

        public string SellerComments
        {
            get
            {
                return AddPurchaseModel.SellerComments;
            }

            set
            {
                if (AddPurchaseModel.SellerComments != value)
                {
                    AddPurchaseModel.SellerComments = value;
                    RaisePropertyChanged("SellerComments");
                }
            }
        }

        public decimal SellingPrice
        {
            get
            {
                return AddPurchaseModel.SellingPrice;
            }

            set
            {
                if (AddPurchaseModel.SellingPrice != value)
                {
                    AddPurchaseModel.SellingPrice = value;
                    RaisePropertyChanged("SellingPrice");
                }
            }
        }

        public decimal FuelCost
        {
            get
            {
                return AddPurchaseModel.FuelCost;
            }

            set
            {
                if (AddPurchaseModel.FuelCost != value)
                {
                    AddPurchaseModel.FuelCost = value;
                    RaisePropertyChanged("FuelCost");
                }
            }
        }

        public decimal ShippingCost
        {
            get
            {
                return AddPurchaseModel.ShippingCost;
            }

            set
            {
                if (AddPurchaseModel.ShippingCost != value)
                {
                    AddPurchaseModel.ShippingCost = value;
                    RaisePropertyChanged("ShippingCost");
                }
            }
        }

        public bool ShippingIncluded
        {
            get
            {
                return AddPurchaseModel.ShippingIncluded;
            }

            set
            {
                if (AddPurchaseModel.ShippingIncluded != value)
                {
                    AddPurchaseModel.ShippingIncluded = value;
                    RaisePropertyChanged("ShippingIncluded");
                }
            }
        }

        public decimal TotalPrice
        {
            get
            {
                return AddPurchaseModel.TotalPrice;
            }

            set
            {
                if (AddPurchaseModel.TotalPrice != value)
                {
                    AddPurchaseModel.TotalPrice = value;
                    RaisePropertyChanged("TotalPrice");
                }
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void RaisePropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            handler?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}