ucSellMedicine.cs

using DGVPrinterHelper;
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Pharmacy_Management_Sysytem.BusinessLogic;
using Pharmacy_Management_Sysytem.Models;
using Pharmacy_Management_Sysytem.Services;

namespace Pharmacy_Management_Sysytem
{
    public partial class ucSellMedicine : UserControl
    {
        private readonly IMedicineService _medicineService;
        private List<CartItem> _cartItems;
        
        public ucSellMedicine()
        {
            InitializeComponent();
            _medicineService = Program.Services.MedicineService;
            _cartItems = new List<CartItem>();
            InitializeCart();
            
            // Add input validation for numeric fields
            txtBoxNumsOfUnits.KeyPress += TxtBoxNumsOfUnits_KeyPress;
        }
        
        private void TxtBoxNumsOfUnits_KeyPress(object sender, KeyPressEventArgs e)
        {
            // Allow only digits, backspace, and delete
            if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
            {
                e.Handled = true;
            }
        }
        
        private void InitializeCart()
        {
            // Initialize the cart DataGridView
            dataGridView1.Columns.Clear();
            dataGridView1.Columns.Add("MedicineID", "Medicine ID");
            dataGridView1.Columns.Add("MedicineName", "Medicine Name");
            dataGridView1.Columns.Add("Quantity", "Quantity");
            dataGridView1.Columns.Add("PricePerUnit", "Price Per Unit");
            dataGridView1.Columns.Add("TotalPrice", "Total Price");
            
            // Set column widths
            dataGridView1.Columns[0].Width = 100;
            dataGridView1.Columns[1].Width = 200;
            dataGridView1.Columns[2].Width = 80;
            dataGridView1.Columns[3].Width = 100;
            dataGridView1.Columns[4].Width = 100;
        }
        
        private void RefreshCart()
        {
            dataGridView1.Rows.Clear();
            foreach (var item in _cartItems)
            {
                dataGridView1.Rows.Add(
                    item.MedicineId,
                    item.MedicineName,
                    item.Quantity,
                    item.PricePerUnit.ToString("C"),
                    item.TotalPrice.ToString("C")
                );
            }
        }
        
        public class CartItem
        {
            public string MedicineId { get; set; }
            public string MedicineName { get; set; }
            public int Quantity { get; set; }
            public decimal PricePerUnit { get; set; }
            public decimal TotalPrice => Quantity * PricePerUnit;
        }
        
        private void ClearForm()
        {
            txtBoxMedicineID.Text = "";
            txtBoxMedicineName.Text = "";
            txtBoxMedicineNumber.Text = "";
            txtBoxQuantity.Text = "";
            txtBoxPricePerUnit.Text = "";
            txtBoxNumsOfUnits.Text = "";
            txtBoxTotalPrice.Text = "";
        }
        void deleteMedicine(int PurchaseID)
        {
            try
            {
                // TODO: Implement purchase deletion using PurchaseService
                // For now, show a confirmation message
                var result = MessageBox.Show($"Are you sure you want to delete purchase ID {PurchaseID}?", 
                                           "Confirm Deletion", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
                
                if (result == DialogResult.Yes)
                {
                    // TODO: Call PurchaseService.DeletePurchase(PurchaseID)
                    MessageBox.Show($"Purchase ID {PurchaseID} would be deleted (PurchaseService not implemented yet)", 
                                  "Info", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error deleting purchase: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void ucSellMedicine_Load(object sender, EventArgs e)
        {
            listBox.Items.Clear();
            try
            {
                var result = _medicineService.GetValidMedicines();
                if (result.IsSuccess)
                {
                    foreach (var medicine in result.Data)
                    {
                        listBox.Items.Add(medicine.MedicineName);
                    }
                    if (listBox.Items.Count > 0)
                    {
                        listBox.SelectedIndex = 0;
                    }
                }
                else
                {
                    MessageBox.Show($"Error loading medicines: {result.ErrorMessage}", "Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error loading medicines: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void txtBoxSearch_TextChanged(object sender, EventArgs e)
        {
            listBox.Items.Clear();
            try
            {
                var result = _medicineService.GetMedicinesByName(txtBoxSearch.Text);
                if (result.IsSuccess)
                {
                    foreach (var medicine in result.Data)
                    {
                        listBox.Items.Add(medicine.MedicineName);
                    }
                    if (listBox.Items.Count > 0)
                    {
                        listBox.SelectedIndex = 0;
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error searching medicines: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void listBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                string selectedMedicineName = listBox.GetItemText(listBox.SelectedItem);
                txtBoxMedicineName.Text = selectedMedicineName;
                
                // Get medicine details by name
                var medicinesResult = _medicineService.GetMedicinesByName(selectedMedicineName);
                if (medicinesResult.IsSuccess && medicinesResult.Data.Count > 0)
                {
                    var medicine = medicinesResult.Data.First();
                    
                    // Populate all medicine details
                    txtBoxMedicineID.Text = medicine.MedicineId;
                    txtBoxMedicineNumber.Text = medicine.MedicineNumber;
                    txtBoxQuantity.Text = medicine.Quantity.ToString();
                    txtBoxPricePerUnit.Text = medicine.PricePerUnit.ToString();
                    
                    // Clear and reset other fields
                    txtBoxNumsOfUnits.Text = "";
                    txtBoxTotalPrice.Text = "";
                }
                else
                {
                    MessageBox.Show("Medicine details not found", "Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error loading medicine details: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void txtBoxNumsOfUnits_TextChanged(object sender, EventArgs e)
        {
            try
            {
                if (string.IsNullOrWhiteSpace(txtBoxNumsOfUnits.Text))
                {
                    txtBoxTotalPrice.Text = "";
                    return;
                }
                
                // Validate that the input is a valid number
                if (!int.TryParse(txtBoxNumsOfUnits.Text, out int units))
                {
                    txtBoxTotalPrice.Text = "";
                    return;
                }
                
                // Validate that price per unit is available and valid
                if (string.IsNullOrWhiteSpace(txtBoxPricePerUnit.Text) || 
                    !decimal.TryParse(txtBoxPricePerUnit.Text, out decimal pricePerUnit))
                {
                    txtBoxTotalPrice.Text = "";
                    return;
                }
                
                // Calculate total price
                decimal totalPrice = pricePerUnit * units;
                txtBoxTotalPrice.Text = totalPrice.ToString("F2");
            }
            catch (Exception ex)
            {
                // If any error occurs, clear the total price
                txtBoxTotalPrice.Text = "";
            }
        }

        private void btnAddToCart_Click(object sender, EventArgs e)
        {
            try
            {
                // Validate required fields
                if (string.IsNullOrWhiteSpace(txtBoxMedicineName.Text))
                {
                    MessageBox.Show("Please select a medicine first", "Validation Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                if (string.IsNullOrWhiteSpace(txtBoxNumsOfUnits.Text) || !int.TryParse(txtBoxNumsOfUnits.Text, out int units))
                {
                    MessageBox.Show("Please enter a valid number of units", "Validation Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                if (string.IsNullOrWhiteSpace(txtBoxQuantity.Text) || !int.TryParse(txtBoxQuantity.Text, out int availableQuantity))
                {
                    MessageBox.Show("Unable to determine available quantity", "Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
                
                if (units > availableQuantity)
                {
                    MessageBox.Show($"Not enough stock! Available: {availableQuantity}, Requested: {units}", 
                                  "Insufficient Stock", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                // Parse price per unit safely
                if (!decimal.TryParse(txtBoxPricePerUnit.Text, out decimal pricePerUnit))
                {
                    MessageBox.Show("Invalid price per unit", "Validation Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                // Add item to cart
                var cartItem = new CartItem
                {
                    MedicineId = txtBoxMedicineID.Text,
                    MedicineName = txtBoxMedicineName.Text,
                    Quantity = units,
                    PricePerUnit = pricePerUnit
                };
                
                // Check if item already exists in cart
                var existingItem = _cartItems.FirstOrDefault(x => x.MedicineId == cartItem.MedicineId);
                if (existingItem != null)
                {
                    // Update quantity if item already exists
                    existingItem.Quantity += cartItem.Quantity;
                }
                else
                {
                    // Add new item to cart
                    _cartItems.Add(cartItem);
                }
                
                // Refresh the cart display
                RefreshCart();
                
                // Clear the form for next item
                ClearForm();
                
                MessageBox.Show($"Added {units} units of {txtBoxMedicineName.Text} to cart\nTotal: ${txtBoxTotalPrice.Text}", 
                              "Added to Cart", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error adding to cart: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnBuy_Click(object sender, EventArgs e)
        {
            try
            {
                // Check if cart is empty
                if (_cartItems.Count == 0)
                {
                    MessageBox.Show("Your cart is empty. Please add some medicines first.", "Empty Cart", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                // Calculate total cart value
                decimal totalCartValue = _cartItems.Sum(item => item.TotalPrice);
                int totalItems = _cartItems.Sum(item => item.Quantity);
                
                // Show purchase summary
                string purchaseSummary = $"Purchase Summary:\n\n";
                foreach (var item in _cartItems)
                {
                    purchaseSummary += $"• {item.MedicineName} - {item.Quantity} units - ${item.TotalPrice:F2}\n";
                }
                purchaseSummary += $"\nTotal Items: {totalItems}\nTotal Amount: ${totalCartValue:F2}";
                
                var result = MessageBox.Show($"{purchaseSummary}\n\nDo you want to complete this purchase?", 
                                           "Confirm Purchase", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
                
                if (result == DialogResult.Yes)
                {
                    // TODO: Implement actual purchase completion with PurchaseService
                    // For now, just clear the cart and show success message
                    
                    // Print the bill before clearing the cart
                    PrintBill();
                    
                    _cartItems.Clear();
                    RefreshCart();
                    ClearForm();
                    
                    MessageBox.Show("Purchase completed successfully!\n\nThank you for your business!", 
                                  "Purchase Complete", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error completing purchase: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
        
        private void PrintBill()
        {
            try
            {
                // Use the existing cart DataGridView for printing
                if (dataGridView1.Rows.Count == 0)
                {
                    MessageBox.Show("No items in cart to print.", "Print Error", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                // Configure the printer with simpler settings
                DGVPrinter print = new DGVPrinter();
                print.Title = "PHARMACY MANAGEMENT SYSTEM";
                print.SubTitle = $"Bill Date: {DateTime.Now:dd/MM/yyyy HH:mm}";
                print.PageNumbers = true;
                print.PorportionalColumns = true;
                print.Footer = $"Total Amount: {_cartItems.Sum(item => item.TotalPrice):C}";
                
                // Print the cart DataGridView
                print.PrintDataGridView(dataGridView1);
            }
            catch (Exception ex)
            {
                // If DGVPrinter fails, show a simple text-based bill
                ShowTextBill();
            }
        }
        
        private void ShowTextBill()
        {
            try
            {
                string billText = "PHARMACY MANAGEMENT SYSTEM\n";
                billText += "================================\n";
                billText += $"Bill Date: {DateTime.Now:dd/MM/yyyy HH:mm}\n\n";
                billText += "Medicine ID\tMedicine Name\t\tQty\tPrice\tTotal\n";
                billText += "--------------------------------------------------------\n";
                
                foreach (var item in _cartItems)
                {
                    billText += $"{item.MedicineId}\t{item.MedicineName}\t\t{item.Quantity}\t{item.PricePerUnit:C}\t{item.TotalPrice:C}\n";
                }
                
                billText += "--------------------------------------------------------\n";
                billText += $"TOTAL AMOUNT: {_cartItems.Sum(item => item.TotalPrice):C}\n";
                billText += "================================\n";
                billText += "Thank you for your business!";
                
                MessageBox.Show(billText, "Bill Receipt", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error displaying bill: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            try
            {
                if (dataGridView1.SelectedRows.Count == 0)
                {
                    MessageBox.Show("Please select a medicine to remove from cart.", "No Selection", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    return;
                }
                
                var selectedRow = dataGridView1.SelectedRows[0];
                string medicineId = selectedRow.Cells["MedicineID"].Value.ToString();
                string medicineName = selectedRow.Cells["MedicineName"].Value.ToString();
                
                var result = MessageBox.Show($"Are you sure you want to remove '{medicineName}' from the cart?", 
                                           "Confirm Removal", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
                
                if (result == DialogResult.Yes)
                {
                    // Remove item from cart
                    _cartItems.RemoveAll(item => item.MedicineId == medicineId);
                    RefreshCart();
                    
                    MessageBox.Show($"'{medicineName}' has been removed from the cart.", "Item Removed", 
                                  MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error removing item from cart: {ex.Message}", "Error", 
                              MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
    }
}