1 files changed, 77 insertions, 0 deletions
diff --git a/Services/UserService.cs b/Services/UserService.cs
new file mode 100644
index 0000000..39b1963
--- /dev/null
+++ b/Services/UserService.cs
@@ -0,0 +1,77 @@
+using Microsoft.AspNetCore.Cryptography.KeyDerivation;
+using Microsoft.EntityFrameworkCore;
+
+namespace HyperBooru.Services;
+
+public interface IUserService {
+    public UserSessionState UserSessionState { get; }
+}
+
+public class UserService : IUserService {
+    public UserSessionState UserSessionState =>
+        globalUserService.GetSessionState(httpContext.Session.Id);
+
+    private IHttpContextAccessor         httpContextAccessor;
+    private IGlobalUserService           globalUserService;
+
+    private HttpContext httpContext =>
+        httpContextAccessor.HttpContext!;
+
+    public UserService(
+        IHttpContextAccessor httpContextAccessor,
+        IGlobalUserService globalUserService) {
+
+        this.httpContextAccessor = httpContextAccessor;
+        this.globalUserService   = globalUserService;
+
+        // HTTP context session states are discarded if no values
+        // are set. Set a dummy value so that the session state
+        // will not be discarded later when we actually need it.
+        httpContext.Session.SetInt32("Persist", 1);
+    }
+
+    public static string HashPassword(string password) =>
+        Convert.ToBase64String(
+            KeyDerivation.Pbkdf2(
+                password,
+                Array.Empty<byte>(),
+                KeyDerivationPrf.HMACSHA512,
+                100_000,
+                512 / 8));
+}
+
+public interface IGlobalUserService {
+    public UserSessionState GetSessionState(string id);
+}
+
+public class GlobalUserService : IGlobalUserService {
+    // TODO: prune this list periodically
+    private Dictionary<string, UserSessionState> sessionStates = new();
+
+    public UserSessionState GetSessionState(string id) {
+        sessionStates.TryGetValue(id, out var state);
+
+        if(state is null) {
+            state = new();
+            sessionStates[id] = state;
+        }
+
+        return state;
+    }
+}
+
+public record UserSessionState {
+    public event UserSessionStateChange OnStateChange;
+
+    public bool ShowNsfw {
+        get => showNsfw;
+        set {
+            showNsfw = value;
+            OnStateChange.Invoke(this);
+        }
+    }
+
+    private bool showNsfw = false;
+}
+
+public delegate void UserSessionStateChange(UserSessionState sessionState);