Bangun Aplikasi MangsIpul

# Buka Tools → NuGet Package Manager → Package Manager Console

Install-Package Newtonsoft.Json -Version 13.0.3
Install-Package RestSharp -Version 110.2.0
Install-Package Microsoft.Extensions.Configuration.Json -Version 7.0.0

using System;
using System.Windows.Forms;

namespace MangsIpulApp
{
    internal static class Program
    {
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            
            // Form login tampil pertama
            Application.Run(new LoginForm());
        }
    }
}

private void chkShowPassword_CheckedChanged(object sender, EventArgs e)
{
    // Centang = tampilkan teks; kosong = tampilkan bullet
    txtPassword.UseSystemPasswordChar = !chkShowPassword.Checked;
}

using System;

namespace MangsIpulApp.Services
{
    public static class SessionManager
    {
        public static string BearerToken { get; set; }
        public static string CurrentUserId { get; set; }
        public static string CurrentUsername { get; set; }
        public static string CurrentUserEmail { get; set; }
        public static string CurrentUserRole { get; set; }
        
        public static bool IsLoggedIn => !string.IsNullOrEmpty(BearerToken);
        
        public static void Logout()
        {
            BearerToken = null;
            CurrentUserId = null;
            CurrentUsername = null;
            CurrentUserEmail = null;
            CurrentUserRole = null;
        }
    }
}

using System;
using System.Net.Http;
using System.Net.Http.Headers;

namespace MangsIpulApp.Services
{
    public class ApiService
    {
        private static HttpClient _client;
        private static readonly object _lock = new object();
        
        public static HttpClient Client
        {
            get
            {
                lock (_lock)
                {
                    if (_client == null)
                    {
                        _client = new HttpClient();
                        _client.BaseAddress = new Uri("http://localhost:8000/api/");
                        _client.DefaultRequestHeaders.Accept.Clear();
                        _client.DefaultRequestHeaders.Accept.Add(
                            new MediaTypeWithQualityHeaderValue("application/json"));
                        _client.Timeout = TimeSpan.FromSeconds(30);
                    }
                    return _client;
                }
            }
        }
        
        public static void SetAuthorizationHeader()
        {
            if (SessionManager.IsLoggedIn)
                Client.DefaultRequestHeaders.Authorization =
                    new AuthenticationHeaderValue("Bearer", SessionManager.BearerToken);
        }
        
        public static void RemoveAuthorizationHeader()
        {
            Client.DefaultRequestHeaders.Authorization = null;
        }
    }
}

using Newtonsoft.Json;

namespace MangsIpulApp.Models
{
    public class LoginRequest
    {
        public string email { get; set; }
        public string password { get; set; }
    }
    
    public class LoginResponse
    {
        [JsonProperty("token")]
        public string Token { get; set; }
        
        [JsonProperty("user")]
        public User User { get; set; }
        
        [JsonProperty("message")]
        public string Message { get; set; }
    }
    
    public class User
    {
        [JsonProperty("id")]
        public int Id { get; set; }
        
        [JsonProperty("username")]
        public string Username { get; set; }
        
        [JsonProperty("email")]
        public string Email { get; set; }
        
        [JsonProperty("role")]
        public string Role { get; set; }
    }
    
    public class ErrorResponse
    {
        [JsonProperty("message")]
        public string Message { get; set; }
    }
}

private async void btnLogin_Click(object sender, EventArgs e)
{
    if (string.IsNullOrWhiteSpace(txtUsername.Text))
    {
        MessageBox.Show("Username/Email tidak boleh kosong!", "Validasi",
            MessageBoxButtons.OK, MessageBoxIcon.Warning);
        txtUsername.Focus();
        return;
    }
    
    if (string.IsNullOrWhiteSpace(txtPassword.Text))
    {
        MessageBox.Show("Password tidak boleh kosong!", "Validasi",
            MessageBoxButtons.OK, MessageBoxIcon.Warning);
        txtPassword.Focus();
        return;
    }
    
    btnLogin.Enabled = false;
    btnLogin.Text = "Memproses...";
    
    var loginRequest = new LoginRequest
    {
        email = txtUsername.Text.Trim(),
        password = txtPassword.Text
    };
    
    try
    {
        var json = JsonConvert.SerializeObject(loginRequest);
        var content = new StringContent(json, Encoding.UTF8, "application/json");
        var response = await _httpClient.PostAsync("login", content);
        var responseBody = await response.Content.ReadAsStringAsync();
        
        if (response.IsSuccessStatusCode)
        {
            var result = JsonConvert.DeserializeObject<LoginResponse>(responseBody);
            
            SessionManager.BearerToken = result.Token;
            SessionManager.CurrentUserId = result.User.Id.ToString();
            SessionManager.CurrentUsername = result.User.Username;
            SessionManager.CurrentUserEmail = result.User.Email;
            SessionManager.CurrentUserRole = result.User.Role;
            ApiService.SetAuthorizationHeader();
            
            MessageBox.Show($"Selamat datang, {result.User.Username}!",
                "Login Berhasil", MessageBoxButtons.OK, MessageBoxIcon.Information);
            
            new MainDashboard().Show();
            this.Hide();
        }
        else
        {
            var err = JsonConvert.DeserializeObject<ErrorResponse>(responseBody);
            MessageBox.Show($"Login gagal: {err?.Message ?? "Username atau password salah"}",
                "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }
    catch (HttpRequestException ex)
    {
        MessageBox.Show($"Tidak dapat terhubung ke server.\n{ex.Message}",
            "Network Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
    catch (TaskCanceledException)
    {
        MessageBox.Show("Request timeout. Coba lagi.", "Timeout",
            MessageBoxButtons.OK, MessageBoxIcon.Warning);
    }
    finally
    {
        btnLogin.Enabled = true;
        btnLogin.Text = "LOGIN";
    }
}

{
  "id": 101,
  "kode_transaksi": "TRX-20260115-001",
  "tanggal": "2026-01-15T10:30:00",
  "jumlah": 2,
  "total_harga": 500000,
  "status": "completed",
  "user": {
    "id": 5,
    "username": "john_doe",
    "alamat": "Jl. Merdeka No. 10"
  },
  "barang": {
    "id": 12,
    "nama": "Laptop Gaming",
    "harga": 250000
  }
}

private async Task LoadTransaksiData()
{
    try
    {
        dgvTransaksi.DataSource = null;
        lblStatus.Text = "Loading data...";
        
        var response = await _httpClient.GetAsync("transaksi");
        var jsonResponse = await response.Content.ReadAsStringAsync();
        
        if (response.IsSuccessStatusCode)
        {
            var list = JsonConvert.DeserializeObject<List<dynamic>>(jsonResponse);
            
            var flatList = new List<TransaksiViewModel>();
            foreach (var item in list)
            {
                flatList.Add(new TransaksiViewModel
                {
                    KodeTransaksi = item.kode_transaksi,
                    Tanggal = DateTime.Parse(item.tanggal.ToString()),
                    Pembeli = item.user.username,
                    Alamat = item.user.alamat,
                    NamaBarang = item.barang.nama,
                    Jumlah = item.jumlah,
                    TotalHarga = item.total_harga,
                    Status = item.status
                });
            }
            
            dgvTransaksi.DataSource = flatList;
            
            // Format kolom
            dgvTransaksi.Columns["TotalHarga"].DefaultCellStyle.Format = "Rp #,0";
            dgvTransaksi.Columns["Tanggal"].DefaultCellStyle.Format = "dd MMM yyyy HH:mm";
            
            // Warna status
            dgvTransaksi.CellFormatting += (s, e) => {
                if (dgvTransaksi.Columns[e.ColumnIndex].Name == "Status" && e.Value != null)
                {
                    string st = e.Value.ToString().ToLower();
                    if (st == "completed")
                        e.CellStyle.BackColor = Color.LightGreen;
                    else if (st == "pending")
                        e.CellStyle.BackColor = Color.LightYellow;
                    else if (st == "cancelled")
                        e.CellStyle.BackColor = Color.LightPink;
                }
            };
            
            lblStatus.Text = $"Menampilkan {flatList.Count} transaksi";
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show($"Error: {ex.Message}");
    }
}

// ViewModel untuk flatten data nested
public class TransaksiViewModel
{
    public string KodeTransaksi { get; set; }
    public DateTime Tanggal { get; set; }
    public string Pembeli { get; set; }
    public string Alamat { get; set; }
    public string NamaBarang { get; set; }
    public int Jumlah { get; set; }
    public decimal TotalHarga { get; set; }
    public string Status { get; set; }
}

namespace MangsIpulApp.Models
{
    public class Produk
    {
        public int id { get; set; }
        public string nama { get; set; }
        public string kode_produk { get; set; }
        public decimal harga { get; set; }
        public int stok { get; set; }
        public string kategori { get; set; }
        public string deskripsi { get; set; }
        public DateTime created_at { get; set; }
    }
}

private async Task LoadProdukData()
{
    try
    {
        var response = await _httpClient.GetAsync("produk");
        var json = await response.Content.ReadAsStringAsync();
        
        if (response.IsSuccessStatusCode)
        {
            var list = JsonConvert.DeserializeObject<List<Produk>>(json);
            dgvProduk.DataSource = list;
            
            dgvProduk.Columns["harga"].DefaultCellStyle.Format = "Rp #,0";
            
            // Warning stok rendah
            dgvProduk.CellFormatting += (s, e) => {
                if (dgvProduk.Columns[e.ColumnIndex].Name == "stok" && e.Value != null)
                {
                    int stok = Convert.ToInt32(e.Value);
                    if (stok < 10)
                        e.CellStyle.ForeColor = Color.Red;
                }
            };
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show($"Error load produk: {ex.Message}");
    }
}

private void transaksiToolStripMenuItem_Click(object sender, EventArgs e)
{
    OpenChildForm(new TransaksiForm());
    lblModuleTitle.Text = "Modul Transaksi";
}

private void produkToolStripMenuItem_Click(object sender, EventArgs e)
{
    OpenChildForm(new ProdukForm());
    lblModuleTitle.Text = "Modul Manajemen Produk";
}

private void logoutToolStripMenuItem_Click(object sender, EventArgs e)
{
    var confirm = MessageBox.Show("Yakin ingin logout?", "Konfirmasi",
        MessageBoxButtons.YesNo, MessageBoxIcon.Question);
    
    if (confirm == DialogResult.Yes)
    {
        SessionManager.Logout();
        ApiService.RemoveAuthorizationHeader();
        
        new LoginForm().Show();
        this.Close();
    }
}

static class Program
{
    [STAThread]
    static void Main()
    {
        Application.ThreadException +=
            new ThreadExceptionEventHandler(Application_ThreadException);
        
        AppDomain.CurrentDomain.UnhandledException +=
            new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException);
        
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new LoginForm());
    }
    
    private static void Application_ThreadException(object sender, ThreadExceptionEventArgs e)
    {
        LogException(e.Exception);
        MessageBox.Show($"Terjadi kesalahan: {e.Exception.Message}\n\nSilakan hubungi support.",
            "Kesalahan Aplikasi", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
    
    private static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
    {
        var ex = (Exception)e.ExceptionObject;
        LogException(ex);
        MessageBox.Show($"Kesalahan fatal: {ex.Message}\nAplikasi akan ditutup.",
            "Kesalahan Kritis", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
    
    private static void LogException(Exception ex)
    {
        string logPath = Path.Combine(Application.StartupPath, "logs",
            $"error_{DateTime.Now:yyyyMMdd}.log");
        Directory.CreateDirectory(Path.GetDirectoryName(logPath));
        
        string log = $"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] " +
            $"Message: {ex.Message}\n" +
            $"Stack: {ex.StackTrace}\n" +
            $"Source: {ex.Source}\n" +
            new string('-', 50) + "\n";
        
        File.AppendAllText(logPath, log);
    }
}