Untitled

using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;

namespace CashManagerWPF
{
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private decimal _usdBalance;
        private decimal _kesBalance;
        public ObservableCollection<Transaction> Transactions { get; set; }

        public decimal USDBalance
        {
            get => _usdBalance;
            set { _usdBalance = value; OnPropertyChanged(); }
        }
        
        public decimal KESBalance
        {
            get => _kesBalance;
            set { _kesBalance = value; OnPropertyChanged(); }
        }
        
        public MainWindow()
        {
            InitializeComponent();
            Transactions = new ObservableCollection<Transaction>();
            DataContext = this;
        }

        private void AddTransaction(string type, decimal amount, string currency)
        {
            if (currency == "USD")
            {
                if (type == "IN") USDBalance += amount;
                else if (type == "OUT" && USDBalance >= amount) USDBalance -= amount;
            }
            else if (currency == "KES")
            {
                if (type == "IN") KESBalance += amount;
                else if (type == "OUT" && KESBalance >= amount) KESBalance -= amount;
            }

            Transactions.Add(new Transaction { Type = type, Amount = amount, Currency = currency, Date = DateTime.Now });
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public class Transaction
    {
        public string Type { get; set; } // IN or OUT
        public decimal Amount { get; set; }
        public string Currency { get; set; } // USD or KES
        public DateTime Date { get; set; }
    }
}