using System;
using System.Runtime.InteropServices;

namespace TeamsISO.App.WinUI.Probe;

/// <summary>
/// Tiny diagnostic console — calls the native MddBootstrapInitialize2
/// export from Microsoft.WindowsAppRuntime.Bootstrap.dll directly and
/// reports the HResult.
///
/// Use to isolate whether the WinUI 3 activation blocker is:
///   (a) Bootstrap DLL load — DllNotFoundException at the P/Invoke call
///   (b) Framework package resolution — Bootstrap returns non-S_OK HR
///   (c) Downstream — Bootstrap succeeds, the WinUI 3 .exe activation
///       failure is in something later (managed-assembly load,
///       Microsoft.WinUI.dll native imports, etc.)
/// </summary>
internal static class Program
{
    /// <summary>WindowsAppSDK target major/minor.</summary>
    private const uint WindowsAppSdkMajorMinor = 0x00010006;

    [DllImport("Microsoft.WindowsAppRuntime.Bootstrap.dll", CharSet = CharSet.Unicode, ExactSpelling = true)]
    private static extern int MddBootstrapInitialize2(
        uint majorMinorVersion,
        string? versionTag,
        PackageVersion minVersion,
        int options);

    [DllImport("Microsoft.WindowsAppRuntime.Bootstrap.dll", ExactSpelling = true)]
    private static extern void MddBootstrapShutdown();

    [StructLayout(LayoutKind.Sequential)]
    private struct PackageVersion
    {
        public ushort Revision;
        public ushort Build;
        public ushort Minor;
        public ushort Major;
    }

    public static int Main(string[] args)
    {
        Console.WriteLine("TeamsISO WinUI 3 bootstrap probe");
        Console.WriteLine("───────────────────────────────────────────");
        Console.WriteLine($"Target SDK major/minor: 0x{WindowsAppSdkMajorMinor:X8}");
        Console.WriteLine();

        try
        {
            // Try with both null and "" for versionTag; report both.
            var minVersion = new PackageVersion();
            Console.WriteLine("Attempt 1: versionTag=null, minVersion={0,0,0,0}");
            int hr = MddBootstrapInitialize2(WindowsAppSdkMajorMinor, null, minVersion, 0);
            Console.WriteLine($"  HR=0x{hr:X8} ({Describe(hr)})");

            if (hr != 0)
            {
                Console.WriteLine();
                Console.WriteLine("Attempt 2: versionTag=\"\", minVersion={0,0,0,0}");
                hr = MddBootstrapInitialize2(WindowsAppSdkMajorMinor, "", minVersion, 0);
                Console.WriteLine($"  HR=0x{hr:X8} ({Describe(hr)})");
            }

            if (hr != 0)
            {
                Console.WriteLine();
                Console.WriteLine("Attempt 3: versionTag=\"\", options=1 (DoNotShowDialog)");
                hr = MddBootstrapInitialize2(WindowsAppSdkMajorMinor, "", minVersion, 1);
                Console.WriteLine($"  HR=0x{hr:X8} ({Describe(hr)})");
            }

            if (hr == 0)
            {
                Console.WriteLine();
                Console.WriteLine("Bootstrap succeeded.");
                Console.WriteLine("The WinUI 3 .exe activation failure is NOT in the bootstrap.");
                Console.WriteLine("Suspect: downstream managed-assembly load (Microsoft.WinUI.dll");
                Console.WriteLine("native imports during JIT).");
                MddBootstrapShutdown();
            }
            else
            {
                Console.WriteLine();
                Console.WriteLine("Bootstrap failed. Decode the HResult:");
                DescribeHResult(hr);
            }
        }
        catch (DllNotFoundException ex)
        {
            Console.WriteLine($"DllNotFoundException: {ex.Message}");
            Console.WriteLine();
            Console.WriteLine("Microsoft.WindowsAppRuntime.Bootstrap.dll couldn't be located by");
            Console.WriteLine("the loader. Check that the file is alongside the .exe and that the");
            Console.WriteLine("process architecture matches (x64 .exe loads x64 DLLs).");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Unexpected: {ex.GetType().Name}: {ex.Message}");
        }

        Console.WriteLine();
        Console.WriteLine("Press any key to exit.");
        Console.ReadKey(true);
        return 0;
    }

    private static string Describe(int hr) => hr switch
    {
        0 => "S_OK",
        unchecked((int)0x80073B17) => "ERROR_INSTALL_PACKAGE_NOT_FOUND",
        unchecked((int)0x80073B19) => "ERROR_PACKAGES_REPUTATION_CHECK_FAILED",
        unchecked((int)0x80004005) => "E_FAIL",
        unchecked((int)0x80670016) => "MDD_E_BOOTSTRAP_INITIALIZE_DDLM_NOT_FOUND",
        unchecked((int)0x80670017) => "MDD_E_BOOTSTRAP_INITIALIZE_LIFECYCLE_MANAGER_FAILURE",
        _ => "(unknown HR)",
    };

    private static void DescribeHResult(int hr)
    {
        var description = (uint)hr switch
        {
            0x80670016 =>
                "DDLM (Dynamic Dependency Lifetime Manager) for this WindowsAppSDK major.minor\n" +
                "  is NOT installed on this machine. The framework package (Microsoft.WindowsApp\n" +
                "  Runtime.1.6) may be present but its DDLM sibling — MicrosoftCorporationII.\n" +
                "  WinAppRuntime.Main.1.6 — is missing. Run \"Get-AppxPackage | Where Name -like\n" +
                "  '*WinAppRuntime.Main*'\" to see which versions have DDLM coverage. Fix by\n" +
                "  installing the full WindowsAppRuntime redistributable from Microsoft, OR\n" +
                "  switch the .csproj to a major.minor whose Main package IS installed.",
            0x80670017 =>
                "Lifecycle manager start failed. The DDLM is installed but couldn't be activated.\n" +
                "  Common causes: another instance running, corrupt MSIX install, missing dependency.",
            0x80073B17 => "Framework package not found. Install Microsoft.WindowsAppRuntime.<x.y>.",
            0x80073B18 => "Framework package version mismatch.",
            0x80073B19 => "Framework package not present for current user.",
            0x80073B26 => "Framework package architecture mismatch.",
            _ => $"Unknown HResult. Look up in WindowsAppSDK source BootstrapErrorCodes.h.",
        };
        Console.WriteLine($"  {description}");
    }
}
