using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace UPSNet
{
    public static class WindowsShutdown
    {
        // Import Windows API functions
        [DllImport("user32.dll", SetLastError = true)]
        private static extern bool ExitWindowsEx(uint uFlags, uint dwReason);
		
        [DllImport("advapi32.dll", SetLastError = true)]
    	private static extern bool AbortSystemShutdown(string lpMachineName);
        
        [DllImport("advapi32.dll", SetLastError = true)]
        private static extern bool InitiateSystemShutdown(
            string lpMachineName,
            string lpMessage,
            uint dwTimeout,
            bool bForceAppsClosed,
            bool bRebootAfterShutdown);

        // Shutdown flags
        private const uint EWX_LOGOFF = 0x00;
        private const uint EWX_SHUTDOWN = 0x01;
        private const uint EWX_REBOOT = 0x02;
        private const uint EWX_FORCE = 0x04;
        private const uint EWX_POWEROFF = 0x08;

        /// <summary>
        /// Shutdown modes
        /// </summary>
        public enum ShutdownMode
        {
            Shutdown,
            Restart,
            LogOff,
            ForceShutdown,
            ForceRestart,
            PowerOff
        }

        /// <summary>
        /// Shuts down Windows with specified mode
        /// </summary>
        public static bool Shutdown(ShutdownMode mode)
        {
            uint flags = 0;

            switch (mode)
            {
                case ShutdownMode.Shutdown:
                    flags = EWX_SHUTDOWN;
                    break;
                case ShutdownMode.Restart:
                    flags = EWX_REBOOT;
                    break;
                case ShutdownMode.LogOff:
                    flags = EWX_LOGOFF;
                    break;
                case ShutdownMode.ForceShutdown:
                    flags = EWX_SHUTDOWN | EWX_FORCE;
                    break;
                case ShutdownMode.ForceRestart:
                    flags = EWX_REBOOT | EWX_FORCE;
                    break;
                case ShutdownMode.PowerOff:
                    flags = EWX_POWEROFF;
                    break;
            }

            return ExitWindowsEx(flags, 0);
        }

        /// <summary>
        /// Shuts down or restarts with a timeout and message
        /// </summary>
        public static bool TimedShutdown(bool restart, int timeoutSeconds = 30, string message = "") {
            return InitiateSystemShutdown(
                null,               // Local computer
                message,            // Display message
                (uint)timeoutSeconds, // Timeout period
                true,               // Force apps closed
                restart);           // Restart after shutdown
        }

        /// <summary>
	    /// Cancel pending shutdown
	    /// </summary>
	    public static bool CancelShutdown(){
	        return AbortSystemShutdown(null);  // Null for local computer
	    }

        /// <summary>
        /// Aborts a pending shutdown
        /// </summary>
        public static void AbortShutdown(){
            Process.Start("shutdown", "/a");
        }

        /// <summary>
        /// Executes shutdown via command line (alternative method)
        /// </summary>
        public static bool CmdShutdown(ShutdownMode mode, int timeoutSeconds = 0)
        {
            string args = "";

            switch (mode)
            {
                case ShutdownMode.Shutdown:
                case ShutdownMode.ForceShutdown:
                case ShutdownMode.PowerOff:
                    args = "/s";
                    break;
                case ShutdownMode.Restart:
                case ShutdownMode.ForceRestart:
                    args = "/r";
                    break;
                case ShutdownMode.LogOff:
                    args = "/l";
                    break;
            }

            if (timeoutSeconds > 0)
            {
                args += " /t " + timeoutSeconds;
            }

            if (mode == ShutdownMode.ForceShutdown || mode == ShutdownMode.ForceRestart)
            {
                args += " /f";
            }

            Process p = Process.Start("shutdown", args);
            if (p==null) return false;
            return true;
        }
    }
}