refactor(backend): replace coravel with hangfire for background jobs

for *some reason*, coravel locks a persistent job queue behind a
paywall. this means that if the server ever crashes, all pending jobs
are lost. this is... not good, so we're switching to hangfire for that
instead.

coravel is still used for emails, though.

BREAKING CHANGE: Foxnouns.NET now requires Redis to work. the EFCore
storage for hangfire doesn't work well enough, unfortunately.

Foxnouns.Backend/Services/KeyCacheService.cs

@@ -17,94 +17,42 @@ using Foxnouns.Backend.Database.Models;
 using Microsoft.EntityFrameworkCore;
 using Newtonsoft.Json;
 using NodaTime;
+using StackExchange.Redis;
 
 namespace Foxnouns.Backend.Services;
 
-public class KeyCacheService(DatabaseContext db, IClock clock, ILogger logger)
+public class KeyCacheService(Config config)
 {
-    private readonly ILogger _logger = logger.ForContext<KeyCacheService>();
+    public ConnectionMultiplexer Multiplexer { get; } =
+        // ConnectionMultiplexer.Connect(config.Database.Redis);
+        ConnectionMultiplexer.Connect("127.0.0.1:6379");
 
-    public Task SetKeyAsync(
-        string key,
-        string value,
-        Duration expireAfter,
-        CancellationToken ct = default
-    ) => SetKeyAsync(key, value, clock.GetCurrentInstant() + expireAfter, ct);
+    public async Task SetKeyAsync(string key, string value, Duration expireAfter) =>
+        await Multiplexer
+            .GetDatabase()
+            .StringSetAsync(key, value, expiry: expireAfter.ToTimeSpan());
 
-    public async Task SetKeyAsync(
-        string key,
-        string value,
-        Instant expires,
-        CancellationToken ct = default
-    )
-    {
-        db.TemporaryKeys.Add(
-            new TemporaryKey
-            {
-                Expires = expires,
-                Key = key,
-                Value = value,
-            }
-        );
-        await db.SaveChangesAsync(ct);
-    }
+    public async Task<string?> GetKeyAsync(string key, bool delete = false) =>
+        delete
+            ? await Multiplexer.GetDatabase().StringGetDeleteAsync(key)
+            : await Multiplexer.GetDatabase().StringGetAsync(key);
 
-    public async Task<string?> GetKeyAsync(
-        string key,
-        bool delete = false,
-        CancellationToken ct = default
-    )
-    {
-        TemporaryKey? value = await db.TemporaryKeys.FirstOrDefaultAsync(k => k.Key == key, ct);
-        if (value == null)
-            return null;
+    public async Task DeleteKeyAsync(string key) =>
+        await Multiplexer.GetDatabase().KeyDeleteAsync(key);
 
-        if (delete)
-            await db.TemporaryKeys.Where(k => k.Key == key).ExecuteDeleteAsync(ct);
+    public Task DeleteExpiredKeysAsync(CancellationToken ct) => Task.CompletedTask;
 
-        return value.Value;
-    }
-
-    public async Task DeleteKeyAsync(string key, CancellationToken ct = default) =>
-        await db.TemporaryKeys.Where(k => k.Key == key).ExecuteDeleteAsync(ct);
-
-    public async Task DeleteExpiredKeysAsync(CancellationToken ct)
-    {
-        int count = await db
-            .TemporaryKeys.Where(k => k.Expires < clock.GetCurrentInstant())
-            .ExecuteDeleteAsync(ct);
-        if (count != 0)
-            _logger.Information("Removed {Count} expired keys from the database", count);
-    }
-
-    public Task SetKeyAsync<T>(
-        string key,
-        T obj,
-        Duration expiresAt,
-        CancellationToken ct = default
-    )
-        where T : class => SetKeyAsync(key, obj, clock.GetCurrentInstant() + expiresAt, ct);
-
-    public async Task SetKeyAsync<T>(
-        string key,
-        T obj,
-        Instant expires,
-        CancellationToken ct = default
-    )
+    public async Task SetKeyAsync<T>(string key, T obj, Duration expiresAt)
         where T : class
     {
         string value = JsonConvert.SerializeObject(obj);
-        await SetKeyAsync(key, value, expires, ct);
+        await SetKeyAsync(key, value, expiresAt);
     }
 
-    public async Task<T?> GetKeyAsync<T>(
-        string key,
-        bool delete = false,
-        CancellationToken ct = default
-    )
+    public async Task<T?> GetKeyAsync<T>(string key, bool delete = false)
         where T : class
     {
-        string? value = await GetKeyAsync(key, delete, ct);
+        string? value = await GetKeyAsync(key, delete);
         return value == null ? default : JsonConvert.DeserializeObject<T>(value);
     }
 }