Program.cs

using System.Text.Json;

namespace Budgetering;

public class Income
{
    public required string Name { get; set; }
    public required decimal Amount { get; set; }
}

public class Expense
{
    public required string Name { get; set; }
    public required decimal Amount { get; set; }
}

public abstract class Program
{
    private const string IncomesFilePath = "incomes.json";
    private const string ExpensesFilePath = "expenses.json";

    static async Task Main(string[] args)
    {
        List<Income> incomes = await LoadIncomes();
        List<Expense> expenses = await LoadExpenses();
        

        var exitApp = false;
        while (!exitApp)
        {
            var selectedIndex = DisplayMenu(new string[]
            {
                "Tilføj Indkomst", "Se Indkomster", "Fjern Indkomst", "Tilføj Udgift", "Se Udgifter", "Fjern Udgift",
                "Statistik", "Exit"
            });

            switch (selectedIndex)
            {
                case 0:
                    var newIncome = IncomeQuestionnaire();
                    incomes.Add(newIncome);
                    await SaveIncomes(incomes);
                    Console.WriteLine("\nIndkomst tilføjet!");
                    break;

                case 1:
                    Console.Clear();
                    decimal totalIncome = 0;
                    Console.WriteLine("Indkomster:");
                    foreach (var income in incomes)
                    {
                        Console.WriteLine($"Indkomsten: {income.Name}, indtjener: {income.Amount}kr.");
                        totalIncome += income.Amount;
                    }

                    Console.WriteLine($"\nTotal Indkomst: {totalIncome}kr.");
                    Console.WriteLine("\nTryk på enhver knap for at vende tilbage...");
                    Console.ReadKey();
                    break;

                case 2:
                    RemoveIncome(incomes);
                    await SaveIncomes(incomes);
                    break;

                case 3:
                    var newExpense = ExpenseQuestionnaire();
                    expenses.Add(newExpense);
                    await SaveExpenses(expenses);
                    Console.WriteLine("\nUdgift tilføjet!");
                    break;

                case 4:
                    Console.Clear();
                    decimal totalExpense = 0;
                    Console.WriteLine("Udgift gemt:");
                    foreach (var expense in expenses)
                    {
                        Console.WriteLine($"Udgiften: {expense.Name}, koster dig: {expense.Amount}kr.");
                        totalExpense += expense.Amount;
                    }

                    Console.WriteLine($"\nTotal Udgift: {totalExpense}kr.");
                    Console.WriteLine("\nTryk på enhver knap for at vende tilbage...");
                    Console.ReadKey();
                    break;

                case 5:
                    RemoveExpense(expenses);
                    await SaveExpenses(expenses);
                    break;

                case 6:
                    ShowStatistics(incomes, expenses);
                    break;

                case 7:
                    exitApp = true;
                    break;
            }
        }
        Console.WriteLine("Vi ses!");
    }

    private static async Task SaveIncomes(List<Income> incomes)
    {
        string jsonString = JsonSerializer.Serialize(incomes, new JsonSerializerOptions { WriteIndented = true });
        await File.WriteAllTextAsync(IncomesFilePath, jsonString);
    }

    private static async Task<List<Income>> LoadIncomes()
    {
        if (!File.Exists(IncomesFilePath)) return new List<Income>();
        var jsonString = await File.ReadAllTextAsync(IncomesFilePath);
        return JsonSerializer.Deserialize<List<Income>>(jsonString) ?? new List<Income>();
    }

    private static async Task SaveExpenses(List<Expense> expenses)
    {
        var jsonString = JsonSerializer.Serialize(expenses, new JsonSerializerOptions { WriteIndented = true });
        await File.WriteAllTextAsync(ExpensesFilePath, jsonString);
    }

    private static async Task<List<Expense>> LoadExpenses()
    {
        if (!File.Exists(ExpensesFilePath)) return new List<Expense>();
        var jsonString = await File.ReadAllTextAsync(ExpensesFilePath);
        return JsonSerializer.Deserialize<List<Expense>>(jsonString) ?? new List<Expense>();
    }

    private static Income IncomeQuestionnaire()
    {
        Console.Clear();
        Console.WriteLine("Indtast navn på nye indkomst:");
        var incomeName = Console.ReadLine();
        Console.WriteLine($"Hvor meget tjener {incomeName} per måned?");
        var userInputAmount = Console.ReadLine() ?? throw new ArgumentNullException($"Console.ReadLine()");
        decimal.TryParse(userInputAmount, out var incomeAmount);
        Console.WriteLine($"Indkomsten {incomeName} tjener {incomeAmount}kr. per måned.");

        return new Income
        {
            Amount = incomeAmount,
            Name = incomeName ?? string.Empty
        };
    }

    private static Expense ExpenseQuestionnaire()
    {
        Console.Clear();
        Console.WriteLine("Indtast navn på nye udgift:");
        var expenseName = Console.ReadLine();
        Console.WriteLine($"Hvor meget koster {expenseName} per måned?");
        var userInputAmount = Console.ReadLine() ?? throw new ArgumentNullException($"Console.ReadLine()");
        decimal.TryParse(userInputAmount, out var expenseAmount);
        Console.WriteLine($"Udgiften {expenseName} koster {expenseAmount} per måned.");

        return new Expense
        {
            Amount = expenseAmount,
            Name = expenseName ?? string.Empty
        };
    }

    private static void RemoveIncome(List<Income> incomes)
    {
        if (incomes.Count == 0)
        {
            Console.WriteLine("Ingen indkomst at fjerne.");
            Console.ReadKey();
            return;
        }

        Console.Clear();
        Console.WriteLine("Vælg en indkomst at fjerne (tryk 0 for at gå tilbage):");
        for (var i = 0; i < incomes.Count; i++)
        {
            Console.WriteLine($"{i + 1}. {incomes[i].Name} - {incomes[i].Amount}kr.");
        }

        var choice = GetUserSelection(incomes.Count);

        if (choice == 0)
        {
            Console.WriteLine("Ingen indkomst blev fjernet.");
        }
        else
        {
            incomes.RemoveAt(choice - 1);
            Console.WriteLine("Indkomst fjernet!");
        }

        Console.ReadKey();
    }

    private static void RemoveExpense(List<Expense> expenses)
    {
        if (expenses.Count == 0)
        {
            Console.WriteLine("Ingen udgift at fjerne.");
            Console.ReadKey();
            return;
        }

        Console.Clear();
        Console.WriteLine("Vælg en udgift at fjerne (tryk 0 for at gå tilbage):");
        for (var i = 0; i < expenses.Count; i++)
        {
            Console.WriteLine($"{i + 1}. {expenses[i].Name} - {expenses[i].Amount}kr.");
        }

        var choice = GetUserSelection(expenses.Count);

        if (choice == 0)
        {
            Console.WriteLine("Ingen udgift blev fjernet.");
        }
        else
        {
            expenses.RemoveAt(choice - 1);
            Console.WriteLine("Udgift fjernet!");
        }

        Console.ReadKey();
    }

    private static int GetUserSelection(int max)
    {
        int choice;
        while (true)
        {
            Console.WriteLine($"Vælg et nummer mellem 0 og {max} (tryk 0 for at gå tilbage):");
            var input = Console.ReadLine();
            if (int.TryParse(input, out choice) && choice >= 0 && choice <= max)
                break;
            Console.WriteLine("Fejl, prøv igen.");
        }

        return choice;
    }

    private static void ShowStatistics(List<Income> incomes, List<Expense> expenses)
    {
        var totalIncome = incomes.Sum(income => income.Amount);
        var totalExpenses = expenses.Sum(expense => expense.Amount);
        var leftover = totalIncome - totalExpenses;

        Console.Clear();
        Console.WriteLine($"Total Indkomst: {totalIncome}kr.");
        Console.WriteLine($"Total Udgifter: {totalExpenses}kr.");
        Console.WriteLine($"Tilovers: {leftover}kr.");

        Console.WriteLine("\nTryk på enhver knap for at vende tilbage...");
        Console.ReadKey();
    }

    // Tryk på op og ned pilene for at bevæge sig i menuen
    private static int DisplayMenu(string[] options)
    {
        var selectedIndex = 0;
        ConsoleKey key;

        do
        {
            Console.Clear();
            Console.WriteLine("Brug piletasterne for at navigere, og Enter for at vælge:");

            for (var i = 0; i < options.Length; i++)
            {
                if (i == selectedIndex)
                {
                    Console.ForegroundColor = ConsoleColor.Green;
                    Console.WriteLine($"> {options[i]}");
                    Console.ResetColor();
                }
                else
                {
                    Console.WriteLine($"  {options[i]}");
                }
            }

            key = Console.ReadKey(true).Key;

            selectedIndex = key switch
            {
                ConsoleKey.UpArrow => (selectedIndex - 1 + options.Length) % options.Length,
                ConsoleKey.DownArrow => (selectedIndex + 1) % options.Length,
                _ => selectedIndex
            };
        } while (key != ConsoleKey.Enter);

        return selectedIndex;
    }
}