using System.Diagnostics;
using System.Runtime.InteropServices;
using AutoShutdown.Models;

namespace AutoShutdown.Services;

internal sealed class PowerService
{
    [DllImport("PowrProf.dll", SetLastError = true)]
    private static extern bool SetSuspendState(bool hibernate, bool forceCritical, bool disableWakeEvent);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool LockWorkStation();

    public void Execute(PowerAction action, int delaySeconds, bool forceApps)
    {
        switch (action)
        {
            case PowerAction.Shutdown:
                RunShutdownCommand($"/s /t {Math.Max(0, delaySeconds)}{ForceFlag(forceApps)}");
                break;
            case PowerAction.Restart:
                RunShutdownCommand($"/r /t {Math.Max(0, delaySeconds)}{ForceFlag(forceApps)}");
                break;
            case PowerAction.LogOff:
                if (delaySeconds > 0)
                {
                    using var timer = new System.Threading.Timer(_ => RunShutdownCommand($"/l{ForceFlag(forceApps)}"), null, TimeSpan.FromSeconds(delaySeconds), Timeout.InfiniteTimeSpan);
                    Thread.Sleep(TimeSpan.FromSeconds(delaySeconds + 1));
                }
                else
                {
                    RunShutdownCommand($"/l{ForceFlag(forceApps)}");
                }
                break;
            case PowerAction.Lock:
                DelayThen(delaySeconds, () => LockWorkStation());
                break;
            case PowerAction.Sleep:
                DelayThen(delaySeconds, () => SetSuspendState(false, forceApps, false));
                break;
            case PowerAction.Hibernate:
                DelayThen(delaySeconds, () => SetSuspendState(true, forceApps, false));
                break;
        }
    }

    public bool CancelShutdown()
    {
        var result = RunProcess("shutdown.exe", "/a", showWindow: false);
        return result == 0;
    }

    private static string ForceFlag(bool forceApps) => forceApps ? " /f" : string.Empty;

    private static void DelayThen(int delaySeconds, Action action)
    {
        if (delaySeconds > 0)
        {
            Task.Delay(TimeSpan.FromSeconds(delaySeconds)).ContinueWith(_ => action(), TaskScheduler.Default);
            return;
        }

        action();
    }

    private static void RunShutdownCommand(string arguments)
    {
        var code = RunProcess("shutdown.exe", arguments, showWindow: false);
        if (code != 0)
        {
            throw new InvalidOperationException($"shutdown.exe 执行失败，退出码 {code}。");
        }
    }

    private static int RunProcess(string fileName, string arguments, bool showWindow)
    {
        using var process = Process.Start(new ProcessStartInfo
        {
            FileName = fileName,
            Arguments = arguments,
            UseShellExecute = false,
            CreateNoWindow = !showWindow,
            WindowStyle = showWindow ? ProcessWindowStyle.Normal : ProcessWindowStyle.Hidden
        });

        if (process is null)
        {
            return -1;
        }

        process.WaitForExit();
        return process.ExitCode;
    }
}