Getting basics working

Auth/Services/UserService.cs

@@ -0,0 +1,32 @@
+using Auth.Models;
+using MongoDB.Driver;
+
+namespace Auth.Services;
+
+public class UserService
+{
+    private readonly IMongoCollection<User> _col;
+
+    public UserService(IConfiguration cfg)
+    {
+        var cs = cfg["MongoDB:ConnectionString"] ?? "mongodb://127.0.0.1:27017";
+        var dbName = cfg["MongoDB:DatabaseName"] ?? "GameDb";
+        var client = new MongoClient(cs);
+        var db = client.GetDatabase(dbName);
+        _col = db.GetCollection<User>("users");
+
+        var keys = Builders<User>.IndexKeys.Ascending(u => u.Username);
+        _col.Indexes.CreateOne(new CreateIndexModel<User>(keys, new CreateIndexOptions { Unique = true }));
+    }
+
+    public Task<User?> GetByUsernameAsync(string username) =>
+        _col.Find(u => u.Username == username).FirstOrDefaultAsync();
+
+    public Task CreateAsync(User user) => _col.InsertOneAsync(user);
+
+    public Task UpdateAsync(User user) =>
+        _col.ReplaceOneAsync(u => u.Id == user.Id, user);
+
+    public Task<List<User>> GetAllAsync() =>
+        _col.Find(FilterDefinition<User>.Empty).ToListAsync();
+}