// Copyright(c) 2019-2022 pypy, Natsumi and individual contributors.
// All rights reserved.
//
// This work is licensed under the terms of the MIT license.
// For a copy, see <https://opensource.org/licenses/MIT>.

using System;
using System.Runtime.InteropServices;

namespace VRCX
{
    public static class WinApi
    {
        [DllImport("kernel32.dll", SetLastError = false)]
        public static extern void CopyMemory(IntPtr destination, IntPtr source, uint length);

        [DllImport("user32.dll", SetLastError = true)]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll", SetLastError = true)]
        public static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
        [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
        public static extern int SHParseDisplayName([MarshalAs(UnmanagedType.LPWStr)] string pszName, IntPtr pbc, out IntPtr ppidl, uint sfgaoIn, out uint psfgaoOut);
        [DllImport("shell32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr SHOpenFolderAndSelectItems(IntPtr pidlFolder, uint cidl, IntPtr[] apidl, uint dwFlags);
        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);

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

        /// <summary>
        /// Flag that specifies the access rights to query limited information about a process.
        /// This won't throw an exception when we try to access info about an elevated process
        /// </summary>
        private const int PROCESS_QUERY_LIMITED_INFORMATION = 0x1000;

        /// <summary>
        /// Determines whether the specified process has exited using WinAPI's GetExitCodeProcess running with PROCESS_QUERY_LIMITED_INFORMATION.
        /// We do this because Process.HasExited in .net framework opens a handle with PROCESS_QUERY_INFORMATION, which will throw an exception if the process is elevated.
        /// GetExitCodeProcess works with PROCESS_QUERY_LIMITED_INFORMATION, which will not throw an exception if the process is elevated.
        /// https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getexitcodeprocess
        /// </summary>
        /// <param name="process">The process to check.</param>
        /// <returns>true if the process has exited; otherwise, false.</returns>
        internal static bool HasProcessExited(int processId)
        {
            IntPtr hProcess = WinApi.OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, false, processId);
            if (hProcess == IntPtr.Zero)
            {
                // this is probably fine
                return true;
                //throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
            }

            bool exited;
            if (!WinApi.GetExitCodeProcess(hProcess, out uint exitCode))
            {
                throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
            }

            // Fun fact, If a program uses STILL_ACTIVE (259) as an exit code, GetExitCodeProcess will return 259, since it returns... the exit code. This would break this function.
            exited = exitCode != 259;
            return exited;
        }
    }
}