fleshout backend

backend/Data/InMemory/InMemoryUserRepository.cs

@@ -0,0 +1,58 @@
+using System.Collections.Concurrent;
+
+namespace Backend.Data.InMemory;
+
+/// <summary>
+/// Default implementation so the skeleton runs with no database. State is per-process
+/// and lost on restart.
+/// </summary>
+public sealed class InMemoryUserRepository : IUserRepository
+{
+    private readonly ConcurrentDictionary<Guid, User> _users = new();
+
+    public Task<IReadOnlyList<User>> GetAllAsync(CancellationToken cancellationToken = default)
+    {
+        IReadOnlyList<User> users = _users.Values
+            .OrderBy(user => user.CreatedAt)
+            .ToList();
+
+        return Task.FromResult(users);
+    }
+
+    public Task<User?> GetByIdAsync(Guid id, CancellationToken cancellationToken = default)
+    {
+        _users.TryGetValue(id, out var user);
+
+        return Task.FromResult(user);
+    }
+
+    public Task<User?> GetByEmailAsync(string email, CancellationToken cancellationToken = default)
+    {
+        var user = _users.Values
+            .FirstOrDefault(candidate => string.Equals(candidate.Email, email, StringComparison.OrdinalIgnoreCase));
+
+        return Task.FromResult(user);
+    }
+
+    public Task<User> AddAsync(User user, CancellationToken cancellationToken = default)
+    {
+        _users[user.Id] = user;
+
+        return Task.FromResult(user);
+    }
+
+    public Task<User?> UpdateAsync(User user, CancellationToken cancellationToken = default)
+    {
+        if (!_users.ContainsKey(user.Id))
+        {
+            return Task.FromResult<User?>(null);
+        }
+
+        _users[user.Id] = user;
+
+        return Task.FromResult<User?>(user);
+    }
+
+    public Task<bool> DeleteAsync(Guid id, CancellationToken cancellationToken = default)
+        => Task.FromResult(_users.TryRemove(id, out _));
+}