Program.cs

using System;
using System.Linq;
using System.Windows.Forms;
using Microsoft.Web.WebView2.Core;
using CUIckScan.Services;

namespace CUIckScan;

internal static class Program
{
    [STAThread]
    private static void Main(string[] args)
    {
        // ── Single-instance enforcement — prevent multiple instances from competing
        // for the same SQLite database or scan state ──
        using var mutex = new Mutex(true, @"Local\CUIckScan_SingleInstance", out var createdNew);
        if (!createdNew)
        {
            MessageBox.Show(
                "CUIckScan is already running.\n\nOnly one instance can run at a time to prevent database conflicts.",
                "CUIckScan",
                MessageBoxButtons.OK,
                MessageBoxIcon.Information);
            return;
        }

        // ── Parse command line flags ──
        var debug = args.Any(a => a.Equals("--debug", StringComparison.OrdinalIgnoreCase)
                              || a.Equals("-debug", StringComparison.OrdinalIgnoreCase)
                              || a.Equals("/debug", StringComparison.OrdinalIgnoreCase));
        CrashLog.DebugMode = debug;

        // ── Global exception handlers — catch everything, log to disk ──
        AppDomain.CurrentDomain.UnhandledException += (_, e) =>
        {
            var ex = e.ExceptionObject as Exception;
            CrashLog.Fatal($"Unhandled AppDomain exception (isTerminating={e.IsTerminating})", ex);
        };

        Application.ThreadException += (_, e) =>
        {
            CrashLog.Fatal("Unhandled UI thread exception", e.Exception);
            MessageBox.Show(
                $"CUIckScan encountered an unexpected error.\n\nDetails have been logged to:\n{CrashLog.CurrentLogPath}",
                "CUIckScan Error",
                MessageBoxButtons.OK,
                MessageBoxIcon.Error);
        };

        TaskScheduler.UnobservedTaskException += (_, e) =>
        {
            CrashLog.Error("Unobserved Task exception (non-fatal)", e.Exception);
            e.SetObserved(); // Prevent process termination
        };

        Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);

        ApplicationConfiguration.Initialize();

        // Prune old logs on startup and resume audit hash chain for tamper-evidence continuity
        CrashLog.PruneOldLogs();
        CrashLog.PruneOldAuditLogs();
        CrashLog.InitAuditHashChain();

        // --fallback: force WinForms UI even when WebView2 is available (debug mode only)
        var fallback = debug && args.Any(a => a.Equals("--fallback", StringComparison.OrdinalIgnoreCase)
                                           || a.Equals("-fallback", StringComparison.OrdinalIgnoreCase)
                                           || a.Equals("/fallback", StringComparison.OrdinalIgnoreCase));

        var version = ReadVersion();
        CrashLog.Log($"CUIckScan v{version} starting{(debug ? " [DEBUG MODE]" : "")}{(fallback ? " [FALLBACK UI]" : "")}");
        CrashLog.Debug($"Args: [{string.Join(", ", args)}]");
        CrashLog.Debug($"BaseDirectory: {AppContext.BaseDirectory}");
        CrashLog.Debug($"OS: {Environment.OSVersion}, .NET: {Environment.Version}, 64bit: {Environment.Is64BitProcess}");
        CrashLog.Debug($"User: {Environment.UserDomainName}\\{Environment.UserName}");

        try
        {
            CrashLog.Debug("Checking WebView2 availability...");
            if (!fallback && IsWebView2Available())
            {
                CrashLog.Debug("WebView2 available — creating MainForm...");
                var mainForm = new MainForm();
                CrashLog.Debug("MainForm created — creating ScanApiHost...");
                var apiHost = new ScanApiHost(mainForm);
                mainForm.ApiHost = apiHost;
                CrashLog.Debug("ScanApiHost created — starting API server...");
                var apiUrl = apiHost.Start();
                CrashLog.Log($"API server started at {apiUrl}");
                CrashLog.Debug("Navigating WebView2 to API URL...");
                mainForm.NavigateTo(apiUrl);
                CrashLog.Debug("Application.Run() — entering WinForms message loop");
                Application.Run(mainForm);
                CrashLog.Debug("Message loop exited — stopping API server...");
                apiHost.Stop();
            }
            else
            {
                CrashLog.Warn(fallback
                    ? "Debug --fallback flag active — using FallbackForm"
                    : "WebView2 not available — showing fallback form");
                Application.Run(new FallbackForm(version, debug));
            }
        }
        catch (Exception ex)
        {
            CrashLog.Fatal("Fatal exception in Main()", ex);
            MessageBox.Show(
                $"CUIckScan failed to start.\n\nDetails have been logged to:\n{CrashLog.CurrentLogPath}",
                "CUIckScan Fatal Error",
                MessageBoxButtons.OK,
                MessageBoxIcon.Error);
        }

        CrashLog.Log("CUIckScan shutting down normally");
    }

    private static bool IsWebView2Available()
    {
        try
        {
            var versionInfo = CoreWebView2Environment.GetAvailableBrowserVersionString();
            return !string.IsNullOrEmpty(versionInfo);
        }
        catch
        {
            return false;
        }
    }

    private static string ReadVersion()
    {
        var candidates = new[]
        {
            Path.Combine(AppContext.BaseDirectory, "release_version.txt"),
            Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "release_version.txt"),
        };
        foreach (var path in candidates)
        {
            try
            {
                if (File.Exists(path))
                    return File.ReadAllText(path).Trim();
            }
            catch (IOException) { }
        }
        return "0.0.0";
    }
}