Migrate email mapping keys

VoidCat/Services/Migrations/IMigration.cs

@@ -9,5 +9,6 @@ public static class Migrations
 {
     public static void AddVoidMigrations(this IServiceCollection svc)
     {
+        svc.AddTransient<IMigration, UserLookupKeyHashMigration>();
     }
 }

VoidCat/Services/Migrations/UserLookupKeyHashMigration.cs

@@ -0,0 +1,44 @@
+using Newtonsoft.Json;
+using StackExchange.Redis;
+using VoidCat.Model;
+
+namespace VoidCat.Services.Migrations;
+
+public class UserLookupKeyHashMigration : IMigration
+{
+    private readonly IDatabase _database;
+
+    public UserLookupKeyHashMigration(IDatabase database)
+    {
+        _database = database;
+    }
+    
+    public async ValueTask Migrate()
+    {
+        var users = await _database.SetMembersAsync("users");
+        foreach (var userId in users)
+        {
+            if (!Guid.TryParse(userId, out var gid)) continue;
+
+            var userJson = await _database.StringGetAsync($"user:{gid}");
+            var user = JsonConvert.DeserializeObject<UserEmail>(userJson);
+            if (user == default) continue;
+
+            if (await _database.KeyExistsAsync(MapOld(user.Email)))
+            {
+                await _database.KeyDeleteAsync(MapOld(user.Email));
+                await _database.StringSetAsync(MapNew(user.Email), $"\"{userId}\"");
+            }
+        }
+    }
+
+    private static RedisKey MapOld(string email) => $"user:email:{email}";
+    private static RedisKey MapNew(string email) => $"user:email:{email.Hash("md5")}";
+
+    internal class UserEmail
+    {
+        public UserEmail(string email) => Email = email;
+
+        public string Email { get; init; }
+    }
+}