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using Enmarcha.Backend.Configuration;
using Enmarcha.Backend.Data;
using Enmarcha.Backend.Data.Models;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using System.Text.Json;
using WebPush;
namespace Enmarcha.Backend.Services;
public interface IPushNotificationService
{
Task SubscribeAsync(string endpoint, string p256dh, string auth);
Task UnsubscribeAsync(string endpoint);
Task SendAlertAsync(ServiceAlert alert);
}
public class PushNotificationService(
AppDbContext db,
IOptions<AppConfiguration> options,
ILogger<PushNotificationService> logger
) : IPushNotificationService
{
private readonly WebPushClient? _client = BuildClient(options.Value.Vapid);
private static WebPushClient? BuildClient(VapidConfiguration? vapid)
{
if (vapid is null) return null;
var client = new WebPushClient();
client.SetVapidDetails(vapid.Subject, vapid.PublicKey, vapid.PrivateKey);
return client;
}
public async Task SubscribeAsync(string endpoint, string p256dh, string auth)
{
var existing = await db.PushSubscriptions
.FirstOrDefaultAsync(s => s.Endpoint == endpoint);
if (existing is null)
{
db.PushSubscriptions.Add(new Data.Models.PushSubscription
{
Id = Guid.NewGuid(),
Endpoint = endpoint,
P256DhKey = p256dh,
AuthKey = auth,
CreatedAt = DateTime.UtcNow,
});
}
else
{
// Refresh keys in case they changed (e.g. after re-subscription)
existing.P256DhKey = p256dh;
existing.AuthKey = auth;
}
await db.SaveChangesAsync();
}
public async Task UnsubscribeAsync(string endpoint)
{
var subscription = await db.PushSubscriptions
.FirstOrDefaultAsync(s => s.Endpoint == endpoint);
if (subscription is not null)
{
db.PushSubscriptions.Remove(subscription);
await db.SaveChangesAsync();
}
}
public async Task SendAlertAsync(ServiceAlert alert)
{
if (_client is null)
{
logger.LogWarning("VAPID not configured — skipping push notification for alert {AlertId}", alert.Id);
return;
}
var now = DateTime.UtcNow;
var phase = alert.GetPhase(now);
alert.Version++;
if (phase == AlertPhase.PreNotice)
alert.PreNoticeNotifiedAt = now;
else if (phase == AlertPhase.Active)
alert.ActiveNotifiedAt = now;
var payload = JsonSerializer.Serialize(new
{
alertId = alert.Id,
version = alert.Version,
phase = phase.ToString(),
cause = alert.Cause.ToString(),
effect = alert.Effect.ToString(),
header = (Dictionary<string, string>)alert.Header,
description = (Dictionary<string, string>)alert.Description,
selectors = alert.Selectors.Select(s => s.Raw).ToList(),
eventStart = alert.EventStartDate,
eventEnd = alert.EventEndDate,
});
var subscriptions = await db.PushSubscriptions.ToListAsync();
var expired = new List<Data.Models.PushSubscription>();
foreach (var sub in subscriptions)
{
try
{
var pushSub = new WebPush.PushSubscription(sub.Endpoint, sub.P256DhKey, sub.AuthKey);
await _client.SendNotificationAsync(pushSub, payload);
}
catch (WebPushException ex) when (
ex.StatusCode is System.Net.HttpStatusCode.Gone or System.Net.HttpStatusCode.NotFound)
{
// Subscription expired or was revoked — remove it
expired.Add(sub);
}
catch (Exception ex)
{
logger.LogWarning(ex, "Failed to deliver push notification to endpoint {Endpoint}", sub.Endpoint[..Math.Min(40, sub.Endpoint.Length)]);
}
}
if (expired.Count > 0)
{
db.PushSubscriptions.RemoveRange(expired);
logger.LogInformation("Removed {Count} expired push subscription(s)", expired.Count);
}
await db.SaveChangesAsync();
}
}
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