Store Medicine with StreamWriter in C# (5)

Question

Код для Form1.cs

using System.Text.Json;
using System.Xml.Linq;

namespace AnyaTask5
{
    public partial class Form1 : Form
    {
        private List<Medicine> medicines = new List<Medicine>();
        private string filePath = "medicines.txt";
        private string departmentName = "Отделение терапии";

        public Form1()
        {
            InitializeComponent();
            LoadMedicines();
            UpdateMedicineList();
            lblDepartment.Text = departmentName;
        }

        private void LoadMedicines()
        {
            if (File.Exists(filePath))
            {
                string[] lines = File.ReadAllLines(filePath);
                foreach (string line in lines)
                {
                    string[] med = line.Split("-", StringSplitOptions.TrimEntries);
                    Medicine me = new Medicine();
                    me.Name = med[0];
                    me.Quantity = int.Parse(med[1]);
                    medicines.Add(me);
                }

                UpdateMedicineList();
            }
        }

        private void SaveMedicines()
        {
            using (StreamWriter writer = new StreamWriter(filePath))
            {
                foreach (var med in medicines)
                {
                    writer.WriteLine(med);
                }
            }
            MessageBox.Show("Список лекарств сохранён");
        }

        private void UpdateMedicineList()
        {
            listBoxAll.Items.Clear();
            listBoxZero.Items.Clear();

            foreach (var med in medicines)
            {
                listBoxAll.Items.Add(med);
                if (med.Quantity == 0)
                    listBoxZero.Items.Add(med);
            }
        }

        private void btnAdd_Click(object sender, EventArgs e)
        {
            string name = txtName.Text.Trim();
            if (!int.TryParse(txtQuantity.Text, out int quantity)) return;

            var existing = medicines.FirstOrDefault(m => m.Name.Equals(name, StringComparison.OrdinalIgnoreCase));
            if (existing != null)
                existing.Quantity += quantity;
            else
                medicines.Add(new Medicine { Name = name, Quantity = quantity });

            UpdateMedicineList();
        }

        private void btnRemove_Click(object sender, EventArgs e)
        {
            if (listBoxAll.SelectedItem is Medicine selected)
            {
                medicines.Remove(selected);
                UpdateMedicineList();
            }
        }

        private void btnDecrement_Click(object sender, EventArgs e)
        {
            if (listBoxAll.SelectedItem is Medicine selected &&
                int.TryParse(txtQuantity.Text, out int amount))
            {
                if (selected.Quantity < amount)
                {
                    MessageBox.Show("Недостаточно лекарств на складе");
                    return;
                }

                selected.Quantity -= amount;
                UpdateMedicineList();
            }
        }

        private void btnEdit_Click(object sender, EventArgs e)
        {
            if (listBoxAll.SelectedItem is Medicine selected)
            {
                string name = txtName.Text.Trim();
                if (int.TryParse(txtQuantity.Text, out int qty))
                {
                    selected.Name = name;
                    selected.Quantity = qty;
                    UpdateMedicineList();
                }
            }
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            SaveMedicines();
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            SaveMedicines();
        }

        private void btnChangeDept_Click(object sender, EventArgs e)
        {
            string newName = Microsoft.VisualBasic.Interaction.InputBox("Введите название отделения", "Изменение", departmentName);
            if (!string.IsNullOrWhiteSpace(newName))
            {
                departmentName = newName;
                lblDepartment.Text = departmentName;
            }
        }
    }
}

Код для Form1.Designer.cs

namespace AnyaTask5
{
    partial class Form1
    {
        private System.ComponentModel.IContainer components = null;
        private Label lblDepartment;
        private TextBox txtName;
        private TextBox txtQuantity;
        private ListBox listBoxAll;
        private ListBox listBoxZero;
        private Button btnAdd;
        private Button btnRemove;
        private Button btnDecrement;
        private Button btnEdit;
        private Button btnChangeDept;
        private Button btnSave;
        private Label lblAll;
        private Label lblZero;

        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
                components.Dispose();
            base.Dispose(disposing);
        }

        private void InitializeComponent()
        {
            lblDepartment = new Label();
            txtName = new TextBox();
            txtQuantity = new TextBox();
            listBoxAll = new ListBox();
            listBoxZero = new ListBox();
            btnAdd = new Button();
            btnRemove = new Button();
            btnDecrement = new Button();
            btnEdit = new Button();
            btnChangeDept = new Button();
            btnSave = new Button();
            lblAll = new Label();
            lblZero = new Label();
            SuspendLayout();
            //
            // lblDepartment
            //
            lblDepartment.AutoSize = true;
            lblDepartment.Font = new Font("Segoe UI", 9F, FontStyle.Regular, GraphicsUnit.Point, 204);
            lblDepartment.Location = new Point(20, 15);
            lblDepartment.Name = "lblDepartment";
            lblDepartment.Size = new Size(154, 20);
            lblDepartment.TabIndex = 0;
            lblDepartment.Text = "Название отделения";
            //
            // txtName
            //
            txtName.Location = new Point(20, 50);
            txtName.Name = "txtName";
            txtName.PlaceholderText = "Наименование";
            txtName.Size = new Size(150, 27);
            txtName.TabIndex = 1;
            //
            // txtQuantity
            //
            txtQuantity.Location = new Point(180, 50);
            txtQuantity.Name = "txtQuantity";
            txtQuantity.PlaceholderText = "Кол-во";
            txtQuantity.Size = new Size(80, 27);
            txtQuantity.TabIndex = 2;
            //
            // listBoxAll
            //
            listBoxAll.FormattingEnabled = true;
            listBoxAll.Location = new Point(20, 100);
            listBoxAll.Name = "listBoxAll";
            listBoxAll.Size = new Size(399, 84);
            listBoxAll.TabIndex = 9;
            //
            // listBoxZero
            //
            listBoxZero.FormattingEnabled = true;
            listBoxZero.Location = new Point(20, 220);
            listBoxZero.Name = "listBoxZero";
            listBoxZero.Size = new Size(399, 64);
            listBoxZero.TabIndex = 10;
            //
            // btnAdd
            //
            btnAdd.Location = new Point(270, 50);
            btnAdd.Name = "btnAdd";
            btnAdd.Size = new Size(149, 27);
            btnAdd.TabIndex = 3;
            btnAdd.Text = "Добавить";
            btnAdd.Click += btnAdd_Click;
            //
            // btnRemove
            //
            btnRemove.Location = new Point(20, 310);
            btnRemove.Name = "btnRemove";
            btnRemove.Size = new Size(91, 34);
            btnRemove.TabIndex = 4;
            btnRemove.Text = "Удалить";
            btnRemove.Click += btnRemove_Click;
            //
            // btnDecrement
            //
            btnDecrement.Location = new Point(117, 310);
            btnDecrement.Name = "btnDecrement";
            btnDecrement.Size = new Size(89, 34);
            btnDecrement.TabIndex = 5;
            btnDecrement.Text = "Списать";
            btnDecrement.Click += btnDecrement_Click;
            //
            // btnEdit
            //
            btnEdit.Location = new Point(212, 310);
            btnEdit.Name = "btnEdit";
            btnEdit.Size = new Size(130, 34);
            btnEdit.TabIndex = 6;
            btnEdit.Text = "Редактировать";
            btnEdit.Click += btnEdit_Click;
            //
            // btnChangeDept
            //
            btnChangeDept.Location = new Point(20, 356);
            btnChangeDept.Name = "btnChangeDept";
            btnChangeDept.Size = new Size(186, 27);
            btnChangeDept.TabIndex = 7;
            btnChangeDept.Text = "Изменить отделение";
            btnChangeDept.Click += btnChangeDept_Click;
            //
            // btnSave
            //
            btnSave.Location = new Point(212, 356);
            btnSave.Name = "btnSave";
            btnSave.Size = new Size(130, 27);
            btnSave.TabIndex = 8;
            btnSave.Text = "Сохранить";
            btnSave.Click += btnSave_Click;
            //
            // lblAll
            //
            lblAll.AutoSize = true;
            lblAll.Location = new Point(20, 80);
            lblAll.Name = "lblAll";
            lblAll.Size = new Size(109, 20);
            lblAll.TabIndex = 11;
            lblAll.Text = "Все лекарства:";
            //
            // lblZero
            //
            lblZero.AutoSize = true;
            lblZero.Location = new Point(20, 200);
            lblZero.Name = "lblZero";
            lblZero.Size = new Size(102, 20);
            lblZero.TabIndex = 12;
            lblZero.Text = "Закончились:";
            //
            // Form1
            //
            ClientSize = new Size(438, 400);
            Controls.Add(lblDepartment);
            Controls.Add(txtName);
            Controls.Add(txtQuantity);
            Controls.Add(btnAdd);
            Controls.Add(btnRemove);
            Controls.Add(btnDecrement);
            Controls.Add(btnEdit);
            Controls.Add(btnChangeDept);
            Controls.Add(btnSave);
            Controls.Add(listBoxAll);
            Controls.Add(listBoxZero);
            Controls.Add(lblAll);
            Controls.Add(lblZero);
            FormBorderStyle = FormBorderStyle.FixedDialog;
            MaximizeBox = false;
            Name = "Form1";
            Text = "Учёт лекарств";
            ResumeLayout(false);
            PerformLayout();
        }
    }
}

Код для Medicine.cs

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

namespace AnyaTask5
{

    public class Medicine
    {
        public string Name { get; set; }
        public int Quantity { get; set; }

        public override string ToString()
        {
            return $"{Name} - {Quantity}";
        }
    }
}