MainForm.cs

using System.Diagnostics;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Text.Json;
using System.Windows.Forms;
using CUIckScan.Services;
using Microsoft.Web.WebView2.Core;
using Microsoft.Web.WebView2.WinForms;

namespace CUIckScan;

public sealed class MainForm : Form
{
    private const int GripSize = 6;

    private readonly WebView2 _webView;
    private bool _isMaximized;
    private bool _navigateStarted;
    private Rectangle _restoreBounds;
    private volatile bool _closeApprovedByReact;

    /// <summary>Set by Program.cs after construction so the form can prompt save-on-close.</summary>
    public ScanApiHost? ApiHost { get; set; }

    public MainForm()
    {
        Text = "CUIck Scan";
        FormBorderStyle = FormBorderStyle.None;
        StartPosition = FormStartPosition.CenterScreen;
        MinimumSize = new Size(960, 600);
        Size = new Size(1280, 800);
        BackColor = Color.FromArgb(19, 20, 26);
        DoubleBuffered = true;
        LoadAppIcon();

        // Padding creates a thin border around WebView2 that the form owns,
        // so WndProc can handle WM_NCHITTEST for resize grips on the edges.
        Padding = new Padding(GripSize);

        _webView = new WebView2
        {
            Dock = DockStyle.Fill,
            DefaultBackgroundColor = Color.FromArgb(19, 20, 26),
        };
        Controls.Add(_webView);
    }

    public async void NavigateTo(string url)
    {
        if (_navigateStarted) return;
        _navigateStarted = true;
        CrashLog.Debug($"NavigateTo called with url={url}");
        try
        {
            var udFolder = Path.Combine(Path.GetTempPath(), "CUIckScan_WebView2");
            CrashLog.Debug($"WebView2 userDataFolder={udFolder}");
            var env = await CoreWebView2Environment.CreateAsync(
                userDataFolder: udFolder);
            CrashLog.Debug("CoreWebView2Environment created — calling EnsureCoreWebView2Async...");
            await _webView.EnsureCoreWebView2Async(env);
            CrashLog.Debug($"CoreWebView2 initialized — BrowserVersion={_webView.CoreWebView2.Environment.BrowserVersionString}");

#if !DEBUG
            // In release builds, enable devtools only when --debug flag is passed
            _webView.CoreWebView2.Settings.AreDevToolsEnabled = CrashLog.DebugMode;
#endif
            _webView.CoreWebView2.Settings.AreDefaultContextMenusEnabled = false;
            _webView.CoreWebView2.Settings.IsStatusBarEnabled = false;
            _webView.CoreWebView2.Settings.IsZoomControlEnabled = false;

            // Debug: track navigation lifecycle
            _webView.CoreWebView2.NavigationStarting += (s, e) =>
            {
                CrashLog.Debug($"WebView2 NavigationStarting: Uri={e.Uri}");
                // Allowlist: only permit http/https to 127.0.0.1 or localhost
                if (!Uri.TryCreate(e.Uri, UriKind.Absolute, out var uri)
                    || (uri.Scheme != "http" && uri.Scheme != "https")
                    || (uri.Host != "127.0.0.1" && uri.Host != "localhost"))
                {
                    e.Cancel = true;
                    CrashLog.Warn($"Blocked navigation to: {e.Uri}");
                }
            };
            _webView.CoreWebView2.NavigationCompleted += (s, e) =>
                CrashLog.Debug($"WebView2 NavigationCompleted: IsSuccess={e.IsSuccess}, HttpStatusCode={e.HttpStatusCode}, WebErrorStatus={e.WebErrorStatus}");
            _webView.CoreWebView2.DOMContentLoaded += (s, e) =>
                CrashLog.Debug($"WebView2 DOMContentLoaded: NavigationId={e.NavigationId}");
            _webView.CoreWebView2.ContentLoading += (s, e) =>
                CrashLog.Debug($"WebView2 ContentLoading: NavigationId={e.NavigationId}, IsErrorPage={e.IsErrorPage}");
            _webView.CoreWebView2.ProcessFailed += (s, e) =>
                CrashLog.Error($"WebView2 ProcessFailed: Kind={e.ProcessFailedKind}, Reason={e.Reason}");

            // Block all new window requests (defense-in-depth against window.open)
            _webView.CoreWebView2.NewWindowRequested += (s, e) =>
            {
                e.Handled = true;
                CrashLog.Warn($"Blocked new window request: {e.Uri}");
            };

            _webView.CoreWebView2.WebMessageReceived += OnWebMessageReceived;
            CrashLog.Debug($"Navigating WebView2 to {url}");
            _webView.CoreWebView2.Navigate(url);
        }
        catch (Exception ex)
        {
            CrashLog.Error("WebView2 initialization failed", ex);
            MessageBox.Show(
                "WebView2 failed to initialize. The application will try to start in fallback mode.\n\n" +
                "If this persists, try deleting the CUIckScan_WebView2 folder in your temp directory.",
                "CUIckScan — Initialization Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        }
    }

    // --- Load application icon for title bar and taskbar ---

    private void LoadAppIcon()
    {
        var candidates = new[]
        {
            Path.Combine(AppContext.BaseDirectory, "Resources", "app.ico"),
            Path.Combine(AppContext.BaseDirectory, "app.ico"),
            Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "Resources", "app.ico"),
        };
        foreach (var path in candidates)
        {
            if (!File.Exists(path)) continue;
            try
            {
                var oldIcon = Icon;
                Icon = new Icon(path);
                oldIcon?.Dispose(); // M13: Dispose previous icon to prevent GDI handle leak
                return;
            }
            catch (Exception ex) { CrashLog.Debug($"Failed to load icon from {path}: {ex.Message}"); }
        }
    }

    // --- Native dialog helpers (called from API threads) ---

    public string? ShowFolderDialog(string? description = null, string? initialPath = null)
    {
        string? result = null;
        Invoke(() =>
        {
            using var dialog = new FolderBrowserDialog
            {
                Description = description ?? "Select folder",
                UseDescriptionForTitle = true,
                ShowNewFolderButton = true,
            };
            if (!string.IsNullOrEmpty(initialPath) && Directory.Exists(initialPath))
                dialog.InitialDirectory = initialPath;
            if (dialog.ShowDialog(this) == DialogResult.OK)
                result = dialog.SelectedPath;
        });
        return result;
    }

    public string? ShowOpenFileDialog(string? title = null, string? filter = null, string? initialDir = null)
    {
        string? result = null;
        Invoke(() =>
        {
            using var dialog = new OpenFileDialog
            {
                Title = title ?? "Open file",
                Filter = filter ?? "All files (*.*)|*.*",
                RestoreDirectory = true,
            };
            if (!string.IsNullOrEmpty(initialDir) && Directory.Exists(initialDir))
                dialog.InitialDirectory = initialDir;
            if (dialog.ShowDialog(this) == DialogResult.OK)
                result = dialog.FileName;
        });
        return result;
    }

    public string? ShowSaveFileDialog(string? title = null, string? filter = null, string? defaultName = null, string? initialDir = null)
    {
        string? result = null;
        Invoke(() =>
        {
            using var dialog = new SaveFileDialog
            {
                Title = title ?? "Save file",
                Filter = filter ?? "CSV files (*.csv)|*.csv|All files (*.*)|*.*",
                RestoreDirectory = true,
            };
            if (!string.IsNullOrEmpty(defaultName))
                dialog.FileName = defaultName;
            if (!string.IsNullOrEmpty(initialDir) && Directory.Exists(initialDir))
                dialog.InitialDirectory = initialDir;
            if (dialog.ShowDialog(this) == DialogResult.OK)
                result = dialog.FileName;
        });
        return result;
    }

    // --- Close handler: prompt to save scan database ---

    protected override void OnFormClosing(FormClosingEventArgs e)
    {
        // If React already handled the close prompt, skip the native dialog
        if (_closeApprovedByReact)
        {
            base.OnFormClosing(e);
            return;
        }

        // Fallback for Alt+F4, taskbar close, Windows shutdown — use native prompt
        if (ApiHost != null && !ApiHost.PromptSaveOnClose())
        {
            e.Cancel = true;
            return;
        }
        base.OnFormClosing(e);
    }

    // --- WebView2 message handler ---

    private void OnWebMessageReceived(object? sender, CoreWebView2WebMessageReceivedEventArgs e)
    {
        try
        {
            var json = e.WebMessageAsJson;
            using var doc = JsonDocument.Parse(json);
            var action = doc.RootElement.GetProperty("action").GetString();

            switch (action)
            {
                case "minimize":
                    Invoke(() => WindowState = FormWindowState.Minimized);
                    break;
                case "maximize":
                    Invoke(ToggleMaximize);
                    break;
                case "close":
                    Invoke(Close);
                    break;
                case "forceClose":
                    Invoke(() =>
                    {
                        _closeApprovedByReact = true;
                        Close();
                    });
                    break;
                case "switchToFallback":
                    Invoke(() =>
                    {
                        var exePath = Environment.ProcessPath;
                        if (exePath != null)
                        {
                            CrashLog.Log("Debug: switching to FallbackForm UI...");
                            Process.Start(exePath, "--debug --fallback");
                        }
                        _closeApprovedByReact = true;
                        Close();
                    });
                    break;
                case "drag":
                    Invoke(() =>
                    {
                        ReleaseCapture();
                        SendMessage(Handle, 0x00A1, 0x0002, 0);
                    });
                    break;
                case "titlebar-dblclick":
                    Invoke(ToggleMaximize);
                    break;
            }
        }
        catch (Exception ex) { CrashLog.Debug($"WebMessage handling error: {ex.GetType().Name}: {ex.Message}"); }
    }

    private void ToggleMaximize()
    {
        if (_isMaximized)
        {
            Padding = new Padding(GripSize);
            Bounds = _restoreBounds;
            _isMaximized = false;
        }
        else
        {
            _restoreBounds = Bounds;
            Padding = new Padding(0); // no grip when maximized
            Bounds = Screen.FromControl(this).WorkingArea;
            _isMaximized = true;
        }
        NotifyWindowState();
    }

    /// <summary>Update the window title (taskbar) and notify the React titlebar.</summary>
    public void SetTitleText(string? openedDbName)
    {
        var title = string.IsNullOrEmpty(openedDbName)
            ? "CUIck Scan"
            : $"CUIck Scan \u2014 {openedDbName}";

        try
        {
            Invoke(() =>
            {
                Text = title;
                try
                {
                    _webView.CoreWebView2?.PostWebMessageAsJson(
                        JsonSerializer.Serialize(new { type = "titleUpdate", openedDbName = openedDbName ?? "" }));
                }
                catch { }
            });
        }
        catch { }
    }

    private void NotifyWindowState()
    {
        try
        {
            var state = _isMaximized ? "maximized" : "normal";
            _webView.CoreWebView2?.PostWebMessageAsJson(
                $"{{\"type\":\"windowState\",\"state\":\"{state}\"}}");
        }
        catch { }
    }

    // --- WM_NCHITTEST: resize grips on the padding area ---

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == 0x0084 && !_isMaximized) // WM_NCHITTEST
        {
            // Use nint to avoid OverflowException on 64-bit multi-monitor setups
            var lp = (nint)m.LParam;
            var screenPt = new Point(unchecked((short)(lp & 0xFFFF)), unchecked((short)((lp >> 16) & 0xFFFF)));
            var pt = PointToClient(screenPt);
            var w = ClientSize.Width;
            var h = ClientSize.Height;

            if (pt.Y < GripSize)
            {
                if (pt.X < GripSize)        { m.Result = (IntPtr)13; return; } // HTTOPLEFT
                if (pt.X >= w - GripSize)    { m.Result = (IntPtr)14; return; } // HTTOPRIGHT
                m.Result = (IntPtr)12; return;                                   // HTTOP
            }
            if (pt.Y >= h - GripSize)
            {
                if (pt.X < GripSize)        { m.Result = (IntPtr)16; return; } // HTBOTTOMLEFT
                if (pt.X >= w - GripSize)    { m.Result = (IntPtr)17; return; } // HTBOTTOMRIGHT
                m.Result = (IntPtr)15; return;                                   // HTBOTTOM
            }
            if (pt.X < GripSize)            { m.Result = (IntPtr)10; return; } // HTLEFT
            if (pt.X >= w - GripSize)        { m.Result = (IntPtr)11; return; } // HTRIGHT
        }

        base.WndProc(ref m);
    }

    [DllImport("user32.dll")]
    private static extern bool ReleaseCapture();

    [DllImport("user32.dll")]
    private static extern nint SendMessage(IntPtr hWnd, int msg, nint wParam, nint lParam);
}