Towel Shop

using System;
using System.Collections.Generic;
using System.Text;

namespace TowelShop
{
    class Program
    {
        /// <summary>
        /// Sell Towels Command
        /// </summary>
        /// <param name="stk">Stack</param>
        /// <param name="amount">Amount of towels</param>
        /// <param name="price">Price of towels</param>
        static void Sell(Stack.Stack<string> stk, int amount, double price)
        {
            //str = string in stack
            //S_amount = Stack_amount (amount of towels in stack) //temp_amount = keeps amount to sell //x = index of x in string
            //S_price = Stack_price (price of towels in stack) //profit = overall profit from sale
            //sale = if a sale was made - true, if not - false
            string str;
            int S_amount, temp_amount, x;
            double S_price, profit;
            bool sale = false;
            profit = 0;
            temp_amount = amount;
            while (!stk.IsEmpty()) //Checks if there is inventory
            {
                if (amount > 0 && price >= 0) //Checks if the amount / price entered is valid
                {
                    sale = true;
                    str = stk.Pop();
                    x = str.IndexOf("x"); //Find X representing distinction between amount and price
                    S_amount = Convert.ToInt32(str.Substring(0, x)); //Turn amount in string to int
                    S_price = Convert.ToDouble(str.Substring(x + 1)); //Turn price in string to double
                    if (amount >= S_amount) //Checks if amount to sell is greater or equal to amount in stack
                    {
                        profit += ((price * S_amount) - (S_price * S_amount)); //Calculate profit
                        amount -= S_amount;
                    }
                    else if (amount < S_amount) //Checks if amount to sell is lower than amount in stack
                    {
                        profit += ((price * amount) - (S_price * S_amount)); //Calculate profit
                        S_amount -= amount;
                        stk.Push(S_amount + "x" + S_price); //Return remaining towels into stack
                        amount = 0;
                        break;
                    }
                }
                else //Breaks the while loop if amount / price entered is invalid
                    break;
            }
            if (sale) //Prints detailed message if sale was made
            {
                amount = temp_amount - amount;
                Console.WriteLine("Sold " + amount + " towels for: $" + (amount * price) + " (Profit: $" + profit + ")");
            }
            else //Prints error message if invalid
                Console.WriteLine("Sale not made - No inventory / Invalid towel amount or price.");

        }
        /// <summary>
        /// Buy Towels Command
        /// </summary>
        /// <param name="stk">Stack</param>
        /// <param name="amount">Amount of towels</param>
        /// <param name="price">Price of towels</param>
        static void Buy(Stack.Stack<string> stk, int amount, double price)
        {
            if (amount > 0 && price >= 0) //Checks if the amount / price entered is valid & prints detailed message if purchase was made
            {
                stk.Push(amount + "x" + price);
                Console.WriteLine("Added " + amount + " towels for: $" + (amount * price) + " ($" + price + " each)");
            }
            else //Prints error message if invalid
                Console.WriteLine("Purchase not made - Invalid towel amount or price");
        }
        /// <summary>
        /// Main program & User Interface
        /// </summary>
        /// <param name="args"></param>
        static void Main(string[] args)
        {
            Stack.Stack<string> stk = new Stack.Stack<string>();
            int amount; //Amount of towels
            double price; //Price of towels
            char x; //Command holder
            do
            {
                Console.Clear(); //Clear the console
                Console.WriteLine("---Towel Manager Program---");
                Console.WriteLine("What would you like to do?\n");
                Console.WriteLine("B: Buy Towels\nS: Sell Towels\nI: Show Inventory\nQ: Quit Program"); //Available commands
                x = char.Parse(Console.ReadLine()); //Enter command
                Console.WriteLine();
                switch (x)
                {
                    case 'B': //Checks if buy / sale commands activated
                    case 'b':
                    case 'S':
                    case 's':
                        Console.WriteLine("Enter amount of towels:");
                        amount = int.Parse(Console.ReadLine());
                        Console.WriteLine("Enter price of each towel:");
                        price = double.Parse(Console.ReadLine());
                        if (x == 'B' || x == 'b') //Checks if buy command
                            Buy(stk, amount, price);
                        else //Checks if sell command
                            Sell(stk, amount, price);
                        Console.ReadKey();
                        break;
                    case 'I': //Checks if inventory command activated
                    case 'i':
                        Console.WriteLine("AMOUNTxPRICE");
                        Console.WriteLine(stk);
                        Console.ReadKey();
                        break;
                    case 'Q': //Checks if quit command activated
                    case 'q':
                        Console.WriteLine("Are you sure you want to exit? (y/n)"); //Safety measure to prevent accidental quit
                        x = char.Parse(Console.ReadLine());
                        if (x == 'Y' || x == 'y') //Chekcs if yes / no
                            x = 'Q';
                        break;
                    default: //Prints error message if invalid command
                        Console.WriteLine("ERROR: Invalid Command");
                        Console.ReadKey();
                        break;
                }
            }
            while (x != 'Q' && x != 'q'); //Infinite loop until Quit command is activated
        }
    }
}