Program.cs

using System;
using System.Text;
using System.Text.Json;
using Spectre.Console;

namespace BudgetManagementSystem
{

    class Program
    {
        static List<Transaction> transactions = new List<Transaction>();
        static List<Category> categories = new()
        {
            new Category { Name = "Food" },
            new Category { Name = "Transportation" },
            new Category { Name = "Shopping" },
            new Category { Name = "Travel" },
            new Category { Name = "Miscellaneous" }
        };

        static string transactionsFilePath = "transactions.json";
        static string categoriesFilePath = "categories.json";
        static bool exit = false;
        static void Main()
        {

            // Data persistence
            LoadData();
            Greeting();

            const int VIEW_TRANSACTIONS = 1;
            const int ADD_TRANSACTIONS = 2;
            const int REMOVE_TRANSACTIONS = 3;
            const int EDIT_TRANSACTIONS = 4;
            const int BUDGET = 5;
            const int VIEW_BUDGET = 6;
            const int EXPORT_TRANSACTIONS = 7;
            const int EXIT = 8;
            
            static bool runningProgram()
            {
                while (!exit)
                {
                    DisplayMenu();

                    var userChoice = Console.ReadLine();

                    int.TryParse(userChoice, out int intUserChoice);

                    switch (intUserChoice)
                    {
                        case VIEW_TRANSACTIONS:
                            ViewTransactions();
                            PromptUser();
                            break;
                        case ADD_TRANSACTIONS:
                            AddTransactions();
                            PromptUser();
                            break;
                        case REMOVE_TRANSACTIONS:
                            RemoveTransactions();
                            PromptUser();
                            break;
                        case EDIT_TRANSACTIONS:
                            EditTransactions();
                            PromptUser();
                            break;
                        case BUDGET:
                            Budget();
                            PromptUser();
                            break;
                        case VIEW_BUDGET:
                            ViewBudget();
                            PromptUser();
                            break;
                        case EXPORT_TRANSACTIONS:
                            ExportTransactions();
                            PromptUser();
                            break;
                        case EXIT:
                            // Data persistence
                            SaveData();
                            Environment.Exit(0);
                            break;
                        default:
                            AnsiConsole.MarkupLine("[red]Invalid choice. Please select a number between 1 and 8.[/]");
                            continue;
                    }

                    
                }

                return false;
            }
            runningProgram();
            Console.ReadKey();

            static void Greeting()
            {
                AnsiConsole.MarkupLine("\n[bold]Welcome to the 은행: Budget Tracker[/]");
                AnsiConsole.MarkupLine(@"[bold green]
............. ....      ............... 
... ............... ....................
.....#%######............-#%:....=##.=##
...%##:....-%#+......-##########.=##.=##
...##=......:##........##:..-##..=######
...*##-....-##=.......*#*....%#=.=##.=##
.....+######*..........##*..###..=##.=##
........................-###*:...=##.=##
##################=  .... ...-%######-..
..--................    .. .###.....*##.
..##:........ ......    ...:##.......##-
..##:.............. .   ....**#:...:##*.
..##############=..     ......=#####+...
...................     ............... [/]");
            }

            static void DisplayMenu()
            {
                Console.WriteLine("\n========================================");
                AnsiConsole.MarkupLine("[bold yellow]1. See all transactions[/]");
                AnsiConsole.MarkupLine("[bold green]2. Add a new transaction[/]");
                AnsiConsole.MarkupLine("[bold red]3. Remove a transaction[/]");
                AnsiConsole.MarkupLine("[bold hotpink]4. Edit a transaction[/]");
                AnsiConsole.MarkupLine("[bold deepskyblue1]5. Set a budget[/]");
                AnsiConsole.MarkupLine("[bold cyan]6. View budget[/]");
                AnsiConsole.MarkupLine("[bold pink1]7. Export transaction data[/]");
                AnsiConsole.MarkupLine("[bold deeppink1]8. Exit[/]");
                Console.WriteLine("========================================\n");
            }

            static void PromptUser()
            {
                Console.WriteLine("\nWhat do you want to do?");
            }

        }

        static bool ViewTransactions()
        {

            if (transactions.Count == 0)
            {
                AnsiConsole.MarkupLine("[red]No transactions have been added yet.[/]");
                return true;
            }
            for (int i = 0; i < transactions.Count; i++)
            {
                {
                    Console.WriteLine($"{i + 1}. \t Description: {transactions[i].Description} \n \t Amount: ${transactions[i].Amount} \n \t Category: {transactions[i].CategoryName.Name} \n \t Date: {transactions[i].Date} \n");

                }
            }

            return false;
        }

        static Category DisplayCategories()
        {

            while (true)
            {
                Console.WriteLine("\nPlease choose a category: ");


                for (int i = 0; i < categories.Count; i++)
                {
                    Console.WriteLine($"{i + 1}. {categories[i].Name}");

                }

                string userInput = Console.ReadLine();

                if (int.TryParse(userInput, out int selectedCategory) && selectedCategory > 0 && selectedCategory <= categories.Count)
                {
                    return categories[selectedCategory - 1];
                }
                else
                {
                    AnsiConsole.MarkupLine("[red]\nThe given index is not valid. Please choose a number between 1 and 5.\n[/]");
                    continue;
                }
            }

        }

        static void AddTransactions()
        {
            string description = "";
            decimal decimalAmount = 0;
            Category selectedCategory = null;
            DateTime currentTime = DateTime.Now;

            while (true)
            {
                Console.WriteLine("Enter the transaction description: ");
                description = Console.ReadLine();

                if (string.IsNullOrWhiteSpace(description))
                {
                    AnsiConsole.MarkupLine("[red]Description cannot be empty[/]");
                    continue;
                }

                break;
            }

            while (true)
            {
                Console.WriteLine("\nEnter the transaction amount: ");
                string amount = Console.ReadLine();

                if (decimal.TryParse(amount, out decimalAmount))
                {
                    break;
                }
                else
                {
                    AnsiConsole.MarkupLine("[red]Please input a decimal value.[/]");
                    continue;
                }
            }

            selectedCategory = DisplayCategories();


            // Time 
            AnsiConsole.MarkupLine($"\n[green]Transaction has been successfully saved at: {currentTime}[/]\n");


            // Add the transaction
            Transaction newTransaction = new Transaction()
            {
                Description = description,
                Amount = decimalAmount,
                CategoryName = selectedCategory,
                Date = currentTime
            };

            transactions.Add(newTransaction);


            if (selectedCategory.BudgetLimit == 0)
            {

            }
            else
            {
                TransactionReport(selectedCategory, newTransaction);
            }
        }

        static void TransactionReport(Category selectedCategoryName, Transaction transactionInfo)
        {

            decimal budget = selectedCategoryName.BudgetLimit;
            decimal amountSpent = DynamicBudget(selectedCategoryName);

            decimal remaining = budget - amountSpent;

            AnsiConsole.MarkupLine($"[green]Budget: ${budget}[/]");
            AnsiConsole.MarkupLine($"[red]Amount spent: ${amountSpent}[/]");
            if (remaining < 0)
            {
                AnsiConsole.MarkupLine($"[red]Remaining: ${remaining}[/]");
            }
            else
            {
                AnsiConsole.MarkupLine($"[yellow]Remaining: ${remaining}[/]");
            }

        }

        static void Budget()
        {
            // BudgetLimit
            Category selectedCategory = DisplayCategories();
            Console.WriteLine($"What is your budget for {selectedCategory.Name}?: ");
            string userBudget = Console.ReadLine();

            decimal transactionTotal = DynamicBudget(selectedCategory);

            if (decimal.TryParse(userBudget, out decimal budgetLimit))
            {
                selectedCategory.BudgetLimit = budgetLimit;
                decimal budgetTotal = budgetLimit - transactionTotal;

                AnsiConsole.MarkupLine($"[green] Your budget for the {selectedCategory.Name} category is: ${userBudget}[/]");

                if (transactionTotal > 0 && budgetTotal > 0)
                {
                    AnsiConsole.MarkupLine($"[green] You have ${budgetTotal} left to spend.[/]");
                }
                else if (budgetTotal < 0)
                {
                    AnsiConsole.MarkupLine($"[red] You are ${Math.Abs(budgetTotal)} over your budget.[/]");
                }
                else if (budgetTotal == 0)
                {
                    AnsiConsole.MarkupLine($"[yellow] Your budget is now ${budgetTotal}. You have reached your budget limit.[/]");
                }
            }


        }

        // This method is needed for transactionreport, budget, view budget, and export transactions
        static decimal DynamicBudget(Category categoryBudget)
        {
            decimal transactionTotal = 0;
            foreach (Transaction item in transactions)
            {
                if (item.CategoryName.Name.ToString() == categoryBudget.Name)
                {
                    transactionTotal += item.Amount;
                }
            }

            return transactionTotal;
        }

        static void ViewBudget()
        {
            Console.WriteLine("========================================");
            foreach (Category categoryName in categories)
            {
                AnsiConsole.MarkupLine($"[springgreen1]{categoryName.Name}: Budget: ${categoryName.BudgetLimit}[/] [white]|[/] [yellow] Amount spent: ${DynamicBudget(categoryName)}\n[/]");
            }
            Console.WriteLine("========================================");

        }

        static void EditTransactions()
        {


            if (ViewTransactions())
            {
                return;
            }

            Transaction transactionToEdit = null;

            while (true)
            {
                Console.WriteLine("Which transaction would you like to edit?");

                string selectedTransaction = Console.ReadLine();

                if (int.TryParse(selectedTransaction, out int selectedTransactionInt) && selectedTransactionInt > 0 && selectedTransactionInt <= transactions.Count)
                {
                    // Assign a new descripton
                    Console.WriteLine("Input a new description: ");
                    transactionToEdit = transactions[selectedTransactionInt - 1];
                    string transactionDescription = Console.ReadLine();
                    transactionToEdit.Description = transactionDescription;

                    // Assign a new category
                    Console.WriteLine("Choose a new category: ");
                    transactionToEdit.CategoryName = DisplayCategories();

                    // Assign a new amount
                    while (true)
                    {
                        Console.WriteLine("Input a new Amount: ");
                        string transactionAmount = Console.ReadLine();
                        if (decimal.TryParse(transactionAmount, out decimal transactionAmountDecimal))
                        {
                            transactionToEdit.Amount = transactionAmountDecimal;
                        }
                        else
                        {
                            AnsiConsole.MarkupLine("[red]Invalid amount.[/]");
                            continue;
                        }
                        break;
                    }

                }
                else
                {
                    continue;
                }

                transactionToEdit.UpdatedAt = DateTime.Now;

                AnsiConsole.MarkupLine($"[green]\ntransaction has been updated at: {transactionToEdit.UpdatedAt}\n[/]");

                if (transactionToEdit.CategoryName.BudgetLimit > 0)
                {
                    TransactionReport(transactionToEdit.CategoryName, transactionToEdit);
                }

                break;
            }

        }

        static void RemoveTransactions()
        {
            if (ViewTransactions())
            {
                return;
            }

            Transaction transactionToRemove = null;

            while (true)
            {
                Console.WriteLine("Select the index of the transaction you want to remove: ");
                string removeTransaction = Console.ReadLine();
                if (int.TryParse(removeTransaction, out int removeTransactionInt) && removeTransactionInt > 0 && removeTransactionInt <= transactions.Count)
                {
                    transactionToRemove = transactions[removeTransactionInt - 1];
                    transactions.RemoveAt(removeTransactionInt - 1);
                    AnsiConsole.MarkupLine($"[red]\ntransaction removed: {removeTransaction}\n[/]");
                    break;
                }
                else
                {
                    AnsiConsole.MarkupLine("[red]\nThe given index is not valid.\n[/]");
                    continue;
                }
            }


            if (transactionToRemove.CategoryName.BudgetLimit > 0)
            {
                TransactionReport(transactionToRemove.CategoryName, transactionToRemove);
            }
        }
        static void ExportTransactions()
        {

            try
            {
                string path = "budgettracker.csv";

                StringBuilder output = new StringBuilder();

                string header = "Description, Category, Amount, Date";
                output.AppendLine(header);

                for (int i = 0; i < transactions.Count; i++)
                {

                    string csvData = $"{transactions[i].Description}, {transactions[i].CategoryName.Name}, {transactions[i].Amount}, {transactions[i].Date}";

                    output.AppendLine(csvData);
                }

                File.WriteAllText(path, output.ToString());
                AnsiConsole.MarkupLine("[green]CSV file was successfully created.[/]");
            }
            catch (Exception ex)
            {
                AnsiConsole.MarkupLine("[red]Export failed[/]");
                AnsiConsole.WriteException(ex);
            }



        }

        static void SaveData()
        {
            string transactionJson = JsonSerializer.Serialize(transactions);
            string categoriesJson = JsonSerializer.Serialize(categories);
            File.WriteAllText(transactionsFilePath, transactionJson);
            File.WriteAllText(categoriesFilePath, categoriesJson);
        }

        static bool LoadData()
        {

            if (File.Exists(transactionsFilePath) && File.Exists(categoriesFilePath))
            {
                string transactionString = File.ReadAllText(transactionsFilePath);
                string categoryString = File.ReadAllText(categoriesFilePath);
                List<Transaction> transactionsList = JsonSerializer.Deserialize<List<Transaction>>(transactionString);
                List<Category> categoriesList = JsonSerializer.Deserialize<List<Category>>(categoryString);
                transactions = transactionsList;
                categories = categoriesList;

                foreach (Transaction transaction in transactions)
                {
                    transaction.CategoryName = categories.Find(c => c.Name == transaction.CategoryName.Name);

                }

                return true;
            }

            return false;
        }


    }
}