fallback support

Inspectron.Epson/PrintServer/JobSources/HttpPollingPrintJobSource.cs

@@ -0,0 +1,143 @@
+using System.Net.Http.Json;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Channels;
+using Inspectron.Epson.PrintServer.ConfigurationSources;
+using Inspectron.Epson.Queue;
+using Microsoft.Extensions.Logging;
+
+namespace Inspectron.Epson.PrintServer.JobSources;
+
+public class HttpPollingPrintJobSource : IPrintJobSource, IDisposable
+{
+    private readonly EpsonPrintServiceConfiguration _groupConfiguration;
+    private readonly ILogger _logger;
+    private readonly HttpClient _httpClient;
+    private readonly Channel<PrintJob> _printJobChannel = Channel.CreateUnbounded<PrintJob>();
+    private readonly CancellationTokenSource _pollingCts = new();
+    private readonly TimeSpan _pollingInterval;
+
+    public HttpPollingPrintJobSource(
+        EpsonPrintServiceConfiguration groupConfiguration,
+        ILogger logger
+)
+    {
+        _groupConfiguration = groupConfiguration;
+        _logger = logger;
+        _pollingInterval = TimeSpan.FromSeconds(3);
+
+        _httpClient = new HttpClient
+        {
+            BaseAddress = new Uri(groupConfiguration.ApiUrl?.TrimEnd('/') + "/")
+        };
+        _httpClient.DefaultRequestHeaders.Add("X-Printer-Server-Key", groupConfiguration.ApiKey);
+
+    }
+
+    private async Task StartPollingAsync(CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Starting HTTP polling for print jobs at {BaseUrl}", _httpClient.BaseAddress);
+
+        while (!cancellationToken.IsCancellationRequested)
+        {
+            try
+            {
+                await PollForJobsAsync(cancellationToken);
+            }
+            catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+            {
+                break;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error polling for print jobs. Retrying in {Interval}...", _pollingInterval);
+            }
+
+            try
+            {
+                await Task.Delay(_pollingInterval, cancellationToken);
+            }
+            catch (OperationCanceledException)
+            {
+                break;
+            }
+        }
+
+        _logger.LogInformation("HTTP polling stopped.");
+    }
+
+    private async Task PollForJobsAsync(CancellationToken cancellationToken)
+    {
+        var requestUrl = $"/api/printerServer/jobs";
+
+        var response = await _httpClient.GetAsync(requestUrl, cancellationToken);
+
+        if (!response.IsSuccessStatusCode)
+        {
+            _logger.LogWarning("Failed to fetch jobs. Status: {StatusCode}", response.StatusCode);
+            return;
+        }
+
+        var jobs = await response.Content.ReadFromJsonAsync<List<PrintJobDto>>(cancellationToken: cancellationToken);
+
+        if (jobs == null || jobs.Count == 0)
+        {
+            return;
+        }
+
+        _logger.LogInformation("Received {Count} print job(s) from HTTP endpoint.", jobs.Count);
+
+        foreach (var job in jobs)
+        {
+            _logger.LogInformation("Queuing print job: {PrintJob}", JsonSerializer.Serialize(job));
+            _printJobChannel.Writer.TryWrite(new PrintJob
+            {
+                JobId = job.JobId,
+                IP = job.PrinterIp,
+                Document = new SignalRPrintJobSource.PrintJobFromSignalR
+                {
+                    JobId = job.JobId,
+                    PrinterIp = job.PrinterIp,
+                    LogoUrl = job.LogoUrl,
+                    ReceiptType = job.ReceiptType,
+                    Content = job.Content
+                }
+            });
+        }
+    }
+
+    public Task StartAsync()
+    {
+        return StartPollingAsync(_pollingCts.Token);
+    }
+
+    public async Task<PrintJob> GetNextJobAsync(CancellationToken cancellationToken)
+    {
+        return await _printJobChannel.Reader.ReadAsync(cancellationToken);
+    }
+
+    public void Dispose()
+    {
+        _pollingCts.Cancel();
+        _pollingCts.Dispose();
+        _httpClient.Dispose();
+    }
+
+    public class PrintJobDto
+    {
+        [JsonPropertyName("jobId")]
+        public string JobId { get; set; } = "";
+
+        [JsonPropertyName("printerIp")]
+        public string PrinterIp { get; set; } = "";
+
+        [JsonPropertyName("logoUrl")]
+        public string? LogoUrl { get; set; }
+
+        [JsonPropertyName("receiptType")]
+        public int ReceiptType { get; set; }
+
+        [JsonPropertyName("content")]
+        public string Content { get; set; } = "";
+    }
+}