124 lines
3.9 KiB
C#
124 lines
3.9 KiB
C#
using Inspectron.Epson;
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using Inspectron.Epson.PrintServer.ConfigurationSources;
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using Inspectron.Epson.Queue;
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using Microsoft.Extensions.Logging;
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namespace EpsonPrintService;
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/// <summary>
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/// Background task that periodically discovers printers and notifies receivers when changes occur
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/// </summary>
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public class PrinterDiscoveryBackgroundTask
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{
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private readonly IDiscoveryService _discoveryService;
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private readonly IDiscoveredPrintersReceiver _receiver;
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private readonly ILogger _logger;
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private readonly PrintServer _printServer;
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private readonly TimeSpan _interval;
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private readonly TimeSpan _discoveryTimeout;
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private HashSet<string> _lastDiscoveredPrinterIps = new();
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private List<DiscoveredPrinter> _lastDiscoveredPrinters = new();
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public PrinterDiscoveryBackgroundTask(
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IDiscoveryService discoveryService,
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IDiscoveredPrintersReceiver receiver,
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ILogger logger,
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PrintServer printServer)
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{
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_discoveryService = discoveryService;
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_receiver = receiver;
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_logger = logger;
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_printServer = printServer;
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_interval = TimeSpan.FromSeconds(30);
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_discoveryTimeout = TimeSpan.FromSeconds(3);
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}
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/// <summary>
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/// Starts the background discovery task
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/// </summary>
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/// <param name="cancellationToken">Token to cancel the background task</param>
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public async Task StartAsync(CancellationToken cancellationToken)
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{
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_logger.LogInformation("Starting printer discovery background task (interval: {Interval}s)", _interval.TotalSeconds);
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// Run immediately on start
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await DiscoverAndNotifyAsync();
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// Scan once for now, then exit
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// By Reini, because we are loosing connection on frequent scans
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return;
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// Then run periodically
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while (!cancellationToken.IsCancellationRequested)
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{
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try
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{
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await Task.Delay(_interval, cancellationToken);
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await DiscoverAndNotifyAsync();
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}
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catch (TaskCanceledException)
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{
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break;
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Error during printer discovery");
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}
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}
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_logger.LogInformation("Printer discovery background task stopped");
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}
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private async Task DiscoverAndNotifyAsync()
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{
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List<DiscoveredPrinter> printers;
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HashSet<string> currentIps;
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bool configChanged;
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await _printServer.EnterDiscoveryLockAsync();
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try
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{
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printers = await _discoveryService.DiscoverPrintersAsync(_discoveryTimeout);
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currentIps = printers.Select(p => p.IPAddress).ToHashSet();
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configChanged = HasConfigurationChanged(currentIps);
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if (configChanged)
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{
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_lastDiscoveredPrinterIps = currentIps;
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_lastDiscoveredPrinters = printers;
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}
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}
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catch (Exception ex)
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{
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_logger.LogWarning(ex, "Failed to discover printers");
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return; // Exit early on error
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}
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finally
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{
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_printServer.ExitDiscoveryLock();
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}
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// Register printers AFTER releasing the lock
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foreach (string currentIp in currentIps)
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{
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_logger.LogDebug("Registering discovered printer with IP: {IP}", currentIp);
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_printServer.RegisterPrinter(currentIp);
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}
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if (configChanged)
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{
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_logger.LogInformation("Discovered printer configuration changed: {Count} printer(s)", printers.Count);
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await _receiver.OnPrintersDiscoveredAsync(printers.AsReadOnly());
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}
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}
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private bool HasConfigurationChanged(HashSet<string> currentIps)
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{
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if (currentIps.Count != _lastDiscoveredPrinterIps.Count)
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return true;
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return !currentIps.SetEquals(_lastDiscoveredPrinterIps);
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}
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}
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