Add notifications API for PostIt home page

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/Yavsc.Api/Controllers/Administration/NotificationsApiController.cs

@@ -0,0 +1,50 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using Yavsc.Abstract.Models.Messaging;
+using Yavsc.Models;
+using Yavsc.Server.Helpers;
+
+namespace Yavsc.ApiControllers.Administration;
+
+[Produces("application/json")]
+[Route(Constants.APIPrefix + "/" + Constants.NotificationsPath)]
+public sealed class NotificationsApiController : Controller
+{
+    private readonly ApplicationDbContext _dbContext;
+
+    public NotificationsApiController(ApplicationDbContext dbContext)
+    {
+        _dbContext = dbContext;
+    }
+
+    [HttpGet]
+    [HttpGet(Constants.NotificationsCurrentUserRoute)]
+    [AllowAnonymous]
+    public async Task<ActionResult<List<Notification>>> GetCurrentUserNotifications()
+    {
+        var currentUserId = User.GetUserId();
+        var isAdmin = User.IsInRole(Constants.AdminGroupName);
+
+        var dismissedIds = string.IsNullOrWhiteSpace(currentUserId)
+            ? new HashSet<long>()
+            : await _dbContext.DismissClicked
+                .AsNoTracking()
+                .Where(d => d.UserId == currentUserId)
+                .Select(d => d.NotificationId)
+                .ToHashSetAsync();
+
+        var notifications = await _dbContext.Notification
+            .AsNoTracking()
+            .Where(n => !dismissedIds.Contains(n.Id))
+            .Where(n =>
+                string.IsNullOrWhiteSpace(n.Target)
+                || (n.Target != null && n.Target.StartsWith("pub/"))
+                || (!string.IsNullOrWhiteSpace(currentUserId) && n.Target == $"user/{currentUserId}")
+                || (isAdmin && n.Target == "administration"))
+            .OrderByDescending(n => n.Id)
+            .ToListAsync();
+
+        return Ok(notifications);
+    }
+}