using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;

namespace WebhookServer.Core.Execution.Native;

/// <summary>
/// Win32 P/Invoke layer for launching processes in another user's session.
/// Used by <see cref="InteractiveProcessLauncher"/>; not intended for general use.
/// </summary>
[SupportedOSPlatform("windows")]
internal static class NativeMethods
{
    public const uint INVALID_SESSION_ID = 0xFFFFFFFF;
    public const int MAXIMUM_ALLOWED = 0x02000000;

    public const uint CREATE_UNICODE_ENVIRONMENT = 0x00000400;
    public const uint CREATE_NO_WINDOW = 0x08000000;
    public const uint CREATE_NEW_CONSOLE = 0x00000010;
    public const uint NORMAL_PRIORITY_CLASS = 0x00000020;

    public const int STARTF_USESTDHANDLES = 0x00000100;

    public const int HANDLE_FLAG_INHERIT = 1;

    public const uint INFINITE = 0xFFFFFFFF;

    public enum SECURITY_IMPERSONATION_LEVEL
    {
        SecurityAnonymous = 0,
        SecurityIdentification = 1,
        SecurityImpersonation = 2,
        SecurityDelegation = 3,
    }

    public enum TOKEN_TYPE
    {
        TokenPrimary = 1,
        TokenImpersonation = 2,
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct SECURITY_ATTRIBUTES
    {
        public int nLength;
        public IntPtr lpSecurityDescriptor;
        public int bInheritHandle;
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct STARTUPINFO
    {
        public int cb;
        public string? lpReserved;
        public string? lpDesktop;
        public string? lpTitle;
        public uint dwX;
        public uint dwY;
        public uint dwXSize;
        public uint dwYSize;
        public uint dwXCountChars;
        public uint dwYCountChars;
        public uint dwFillAttribute;
        public uint dwFlags;
        public ushort wShowWindow;
        public ushort cbReserved2;
        public IntPtr lpReserved2;
        public IntPtr hStdInput;
        public IntPtr hStdOutput;
        public IntPtr hStdError;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct PROCESS_INFORMATION
    {
        public IntPtr hProcess;
        public IntPtr hThread;
        public uint dwProcessId;
        public uint dwThreadId;
    }

    [DllImport("kernel32.dll")]
    public static extern uint WTSGetActiveConsoleSessionId();

    [DllImport("wtsapi32.dll", SetLastError = true)]
    public static extern bool WTSQueryUserToken(uint sessionId, out IntPtr phToken);

    [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    public static extern bool DuplicateTokenEx(
        IntPtr hExistingToken,
        uint dwDesiredAccess,
        IntPtr lpTokenAttributes,
        SECURITY_IMPERSONATION_LEVEL impersonationLevel,
        TOKEN_TYPE tokenType,
        out IntPtr phNewToken);

    [DllImport("userenv.dll", SetLastError = true)]
    public static extern bool CreateEnvironmentBlock(
        out IntPtr lpEnvironment,
        IntPtr hToken,
        bool bInherit);

    [DllImport("userenv.dll", SetLastError = true)]
    public static extern bool DestroyEnvironmentBlock(IntPtr lpEnvironment);

    [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    public static extern bool CreateProcessAsUser(
        IntPtr hToken,
        string? lpApplicationName,
        string? lpCommandLine,
        IntPtr lpProcessAttributes,
        IntPtr lpThreadAttributes,
        bool bInheritHandles,
        uint dwCreationFlags,
        IntPtr lpEnvironment,
        string? lpCurrentDirectory,
        ref STARTUPINFO lpStartupInfo,
        out PROCESS_INFORMATION lpProcessInformation);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool CreatePipe(
        out IntPtr hReadPipe,
        out IntPtr hWritePipe,
        ref SECURITY_ATTRIBUTES lpPipeAttributes,
        uint nSize);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool SetHandleInformation(IntPtr hObject, int dwMask, int dwFlags);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool CloseHandle(IntPtr hObject);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool GetExitCodeProcess(IntPtr hProcess, out uint lpExitCode);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern uint WaitForSingleObject(IntPtr hHandle, uint dwMilliseconds);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool TerminateProcess(IntPtr hProcess, uint uExitCode);

    public static Win32Exception LastError(string what) =>
        new(Marshal.GetLastWin32Error(), $"{what} failed");
}