client/Services/Printing/WindowsPrinterStatusReader.cs

using CloudPrint.Client.Models;
using System.Management;

namespace CloudPrint.Client.Services.Printing;

public sealed class WindowsPrinterStatusReader : IPrinterStatusReader
{
    public PrinterStatusSnapshot Read(string printerName)
    {
        if (string.IsNullOrWhiteSpace(printerName))
        {
            return new PrinterStatusSnapshot { Status = PrinterStatus.Unknown, Message = "打印机名称为空" };
        }

        try
        {
            return ReadCore(printerName);
        }
        catch (Exception ex)
        {
            return new PrinterStatusSnapshot
            {
                Status = PrinterStatus.Unknown,
                Message = $"状态读取失败：{ex.Message}"
            };
        }
    }

    private static PrinterStatusSnapshot ReadCore(string printerName)
    {
        using var searcher = new ManagementObjectSearcher(
            "SELECT Name, WorkOffline, PrinterStatus, DetectedErrorState FROM Win32_Printer");

        foreach (ManagementObject printer in searcher.Get())
        {
            var name = Convert.ToString(printer["Name"]);
            if (!string.Equals(name, printerName, StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }

            var workOffline = Convert.ToBoolean(printer["WorkOffline"] ?? false);
            var printerStatus = Convert.ToUInt32(printer["PrinterStatus"] ?? 2u);
            var errorState = Convert.ToUInt32(printer["DetectedErrorState"] ?? 0u);
            var queueCount = CountQueueJobs(printerName);

            var status = MapStatus(workOffline, printerStatus, errorState, queueCount);
            return new PrinterStatusSnapshot
            {
                Status = status,
                QueueCount = queueCount,
                Message = BuildMessage(workOffline, printerStatus, errorState)
            };
        }

        return new PrinterStatusSnapshot
        {
            Status = PrinterStatus.Offline,
            Message = "未找到打印机"
        };
    }

    private static int CountQueueJobs(string printerName)
    {
        var escapedName = printerName.Replace("\\", "\\\\", StringComparison.Ordinal).Replace("'", "''", StringComparison.Ordinal);
        using var searcher = new ManagementObjectSearcher($"SELECT Name FROM Win32_PrintJob WHERE Name LIKE '{escapedName},%'");
        return searcher.Get().Count;
    }

    private static PrinterStatus MapStatus(bool workOffline, uint printerStatus, uint errorState, int queueCount)
    {
        if (workOffline || printerStatus == 7)
        {
            return PrinterStatus.Offline;
        }

        if (errorState is >= 3 and <= 11 || printerStatus == 6)
        {
            return PrinterStatus.Error;
        }

        if (printerStatus == 4 || queueCount > 0)
        {
            return PrinterStatus.Printing;
        }

        return printerStatus == 3 ? PrinterStatus.Idle : PrinterStatus.Unknown;
    }

    private static string BuildMessage(bool workOffline, uint printerStatus, uint errorState)
    {
        if (workOffline)
        {
            return "脱机";
        }

        return errorState switch
        {
            3 => "缺纸",
            4 => "卡纸",
            5 => "碳粉不足",
            6 => "门打开",
            7 => "需要人工干预",
            8 => "离线",
            9 => "维修中",
            10 => "输出纸盘已满",
            11 => "缺纸",
            _ => printerStatus switch
            {
                3 => "就绪",
                4 => "打印中",
                5 => "预热中",
                6 => "已停止",
                7 => "离线",
                _ => string.Empty
            }
        };
    }
}