Backend-scheudler for telegram notifications by new contact requests

RazorPagesMovie/Models/ContactMessage.cs

@@ -33,4 +33,6 @@ public class ContactMessage
     [Display(Name = "Gesendet am")]
     [DataType(DataType.DateTime)]
     public DateTime SentAt { get; set; } = DateTime.Now;
+
+    public bool NotificationSent { get; set; } = false;
 }

RazorPagesMovie/Program.cs

@@ -2,6 +2,7 @@ using Microsoft.AspNetCore.Authentication.Cookies;
 using Microsoft.EntityFrameworkCore;
 using RazorPagesMovie.Data;
 using RazorPagesMovie.Models;
+using RazorPagesMovie.Services;
 
 var builder = WebApplication.CreateBuilder(args);
 builder.Configuration.AddJsonFile("appsettings.Local.json", optional: true, reloadOnChange: true);
@@ -21,6 +22,9 @@ builder.Services.AddRazorPages(options =>
     options.Conventions.AuthorizeFolder("/Admin");
 });
 
+builder.Services.AddHttpClient();
+builder.Services.AddHostedService<ContactMessageNotificationService>();
+
 var app = builder.Build();
 
 using (var scope = app.Services.CreateScope())

RazorPagesMovie/Services/ContactMessageNotificationService.cs

@@ -0,0 +1,95 @@
+using System.Net.Http.Json;
+using Microsoft.EntityFrameworkCore;
+using RazorPagesMovie.Data;
+
+namespace RazorPagesMovie.Services;
+
+public class ContactMessageNotificationService : BackgroundService
+{
+    private static readonly TimeSpan CheckInterval = TimeSpan.FromMinutes(5);
+
+    private readonly IServiceScopeFactory _scopeFactory;
+    private readonly IHttpClientFactory _httpClientFactory;
+    private readonly IConfiguration _configuration;
+    private readonly ILogger<ContactMessageNotificationService> _logger;
+
+    public ContactMessageNotificationService(
+        IServiceScopeFactory scopeFactory,
+        IHttpClientFactory httpClientFactory,
+        IConfiguration configuration,
+        ILogger<ContactMessageNotificationService> logger)
+    {
+        _scopeFactory = scopeFactory;
+        _httpClientFactory = httpClientFactory;
+        _configuration = configuration;
+        _logger = logger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            await CheckForNewContactMessagesAsync(stoppingToken);
+            await Task.Delay(CheckInterval, stoppingToken);
+        }
+    }
+
+    private async Task CheckForNewContactMessagesAsync(CancellationToken stoppingToken)
+    {
+        var botToken = _configuration["Telegram:BotToken"];
+        var chatId = _configuration["Telegram:ChatId"];
+
+        if (string.IsNullOrWhiteSpace(botToken) || string.IsNullOrWhiteSpace(chatId))
+        {
+            return;
+        }
+
+        using var scope = _scopeFactory.CreateScope();
+        var context = scope.ServiceProvider.GetRequiredService<RazorPagesMovieContext>();
+
+        var neueEintraege = await context.ContactMessage
+            .Where(c => !c.NotificationSent)
+            .OrderBy(c => c.SentAt)
+            .ToListAsync(stoppingToken);
+
+        if (neueEintraege.Count == 0)
+        {
+            return;
+        }
+
+        var httpClient = _httpClientFactory.CreateClient();
+        var sendMessageUrl = $"https://api.telegram.org/bot{botToken}/sendMessage";
+
+        foreach (var eintrag in neueEintraege)
+        {
+            var text = $"Neue Kontaktanfrage von {eintrag.Name}\n"
+                + $"E-Mail: {eintrag.Email}\n"
+                + (string.IsNullOrWhiteSpace(eintrag.Phone) ? "" : $"Telefon: {eintrag.Phone}\n")
+                + (string.IsNullOrWhiteSpace(eintrag.Subject) ? "" : $"Betreff: {eintrag.Subject}\n")
+                + $"\n{eintrag.Message}";
+
+            try
+            {
+                var response = await httpClient.PostAsJsonAsync(
+                    sendMessageUrl,
+                    new { chat_id = chatId, text },
+                    stoppingToken);
+
+                if (response.IsSuccessStatusCode)
+                {
+                    eintrag.NotificationSent = true;
+                }
+                else
+                {
+                    _logger.LogWarning("Telegram-Versand fehlgeschlagen für ContactMessage {Id}: {StatusCode}", eintrag.Id, response.StatusCode);
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Telegram-Versand fehlgeschlagen für ContactMessage {Id}", eintrag.Id);
+            }
+        }
+
+        await context.SaveChangesAsync(stoppingToken);
+    }
+}