using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Security.Principal;
using System.Xml.Linq;

namespace AutoShutdown.Services;

internal sealed class WakeService
{
    private const string TaskName = "AutoShutdown Wake";

    public void ScheduleWake(DateTime wakeAt)
    {
        var taskXmlPath = Path.Combine(Path.GetTempPath(), $"AutoShutdown-Wake-{Guid.NewGuid():N}.xml");

        try
        {
            File.WriteAllText(taskXmlPath, CreateWakeTaskXml(wakeAt));
            RunProcess("schtasks.exe", $"/Create /TN \"{TaskName}\" /XML \"{taskXmlPath}\" /F");
        }
        finally
        {
            TryDelete(taskXmlPath);
        }
    }

    public void CancelWake()
    {
        RunProcess("schtasks.exe", $"/Delete /TN \"{TaskName}\" /F", ignoreErrors: true);
    }

    private static string CreateWakeTaskXml(DateTime wakeAt)
    {
        XNamespace ns = "http://schemas.microsoft.com/windows/2004/02/mit/task";
        var startBoundary = wakeAt.ToString("yyyy-MM-dd'T'HH:mm:ss", CultureInfo.InvariantCulture);
        var userId = WindowsIdentity.GetCurrent().User?.Value ?? Environment.UserName;

        var task = new XDocument(
            new XElement(ns + "Task",
                new XAttribute("version", "1.4"),
                new XElement(ns + "RegistrationInfo",
                    new XElement(ns + "Description", "AutoShutdown wake timer")),
                new XElement(ns + "Triggers",
                    new XElement(ns + "TimeTrigger",
                        new XElement(ns + "StartBoundary", startBoundary),
                        new XElement(ns + "Enabled", "true"))),
                new XElement(ns + "Principals",
                    new XElement(ns + "Principal",
                        new XAttribute("id", "Author"),
                        new XElement(ns + "UserId", userId),
                        new XElement(ns + "LogonType", "InteractiveToken"),
                        new XElement(ns + "RunLevel", "LeastPrivilege"))),
                new XElement(ns + "Settings",
                    new XElement(ns + "MultipleInstancesPolicy", "IgnoreNew"),
                    new XElement(ns + "DisallowStartIfOnBatteries", "false"),
                    new XElement(ns + "StopIfGoingOnBatteries", "false"),
                    new XElement(ns + "AllowHardTerminate", "true"),
                    new XElement(ns + "StartWhenAvailable", "true"),
                    new XElement(ns + "RunOnlyIfNetworkAvailable", "false"),
                    new XElement(ns + "IdleSettings",
                        new XElement(ns + "StopOnIdleEnd", "false"),
                        new XElement(ns + "RestartOnIdle", "false")),
                    new XElement(ns + "AllowStartOnDemand", "true"),
                    new XElement(ns + "Enabled", "true"),
                    new XElement(ns + "Hidden", "true"),
                    new XElement(ns + "RunOnlyIfIdle", "false"),
                    new XElement(ns + "WakeToRun", "true"),
                    new XElement(ns + "ExecutionTimeLimit", "PT1M"),
                    new XElement(ns + "Priority", "7")),
                new XElement(ns + "Actions",
                    new XAttribute("Context", "Author"),
                    new XElement(ns + "Exec",
                        new XElement(ns + "Command", "cmd.exe"),
                        new XElement(ns + "Arguments", "/c exit")))));

        return task.ToString(SaveOptions.DisableFormatting);
    }

    private static void RunProcess(string fileName, string arguments, bool ignoreErrors = false)
    {
        using var process = Process.Start(new ProcessStartInfo
        {
            FileName = fileName,
            Arguments = arguments,
            UseShellExecute = false,
            CreateNoWindow = true,
            RedirectStandardOutput = true,
            RedirectStandardError = true
        });

        if (process is null)
        {
            throw new InvalidOperationException("无法启动 Windows 任务计划程序命令。");
        }

        var output = process.StandardOutput.ReadToEnd();
        var error = process.StandardError.ReadToEnd();
        process.WaitForExit();

        if (!ignoreErrors && process.ExitCode != 0)
        {
            var message = string.Join(Environment.NewLine, new[] { error, output }.Where(item => !string.IsNullOrWhiteSpace(item)));
            throw new InvalidOperationException(string.IsNullOrWhiteSpace(message) ? "创建唤醒计划失败。" : message.Trim());
        }
    }

    private static void TryDelete(string path)
    {
        try
        {
            File.Delete(path);
        }
        catch
        {
            // 临时任务 XML 删除失败不影响计划本身。
        }
    }
}