storage interface and implementation

Author: Zonnex

src/ActiveLogin.Authentication.BankId.Core/IStateStorage.cs

@@ -0,0 +1,8 @@
+namespace ActiveLogin.Authentication.BankId.Core;
+
+public interface IStateStorage
+{
+    ValueTask<Guid> WriteAsync(object value);
+    ValueTask<bool> TryReadAsync<T>(Guid key, out T? value);
+    ValueTask<T?> RemoveAsync<T>(Guid key);
+}

src/ActiveLogin.Authentication.BankId.Core/InMemoryStateStorage.cs

@@ -0,0 +1,34 @@
+using System.Collections.Concurrent;
+
+namespace ActiveLogin.Authentication.BankId.Core;
+
+public class InMemoryStateStorage : IStateStorage
+{
+    private static readonly ConcurrentDictionary<Guid, object> _storage = new();
+
+    public ValueTask<Guid> WriteAsync(object value)
+    {
+        var key = Guid.NewGuid();
+        _ = _storage.TryAdd(key, value);
+        return new ValueTask<Guid>(key);
+    }
+
+    public ValueTask<T?> RemoveAsync<T>(Guid key)
+    {
+        return _storage.TryRemove(key, out var value)
+            ? new ValueTask<T?>((T)value)
+            : new ValueTask<T?>(default(T));
+    }
+
+    public ValueTask<bool> TryReadAsync<T>(Guid key, out T? value)
+    {
+        if (_storage.TryGetValue(key, out var obj))
+        {
+            value = (T)obj;
+            return new ValueTask<bool>(true);
+        }
+
+        value = default;
+        return new ValueTask<bool>(false);
+    }
+}