Implemented node system statistics

MoonlightServers.Api/Admin/Nodes/StatisticsController.cs

@@ -0,0 +1,40 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using MoonlightServers.Api.Infrastructure.Database;
+using MoonlightServers.Api.Infrastructure.Database.Entities;
+using MoonlightServers.Shared;
+using MoonlightServers.Shared.Admin.Nodes;
+
+namespace MoonlightServers.Api.Admin.Nodes;
+
+[ApiController]
+[Authorize(Policy = Permissions.Nodes.View)]
+[Route("api/admin/servers/nodes/{id:int}/statistics")]
+public class StatisticsController : Controller
+{
+    private readonly NodeService NodeService;
+    private readonly DatabaseRepository<Node> NodeRepository;
+
+    public StatisticsController(NodeService nodeService, DatabaseRepository<Node> nodeRepository)
+    {
+        NodeService = nodeService;
+        NodeRepository = nodeRepository;
+    }
+
+    [HttpGet]
+    public async Task<ActionResult<NodeStatisticsDto>> GetAsync([FromRoute] int id)
+    {
+        var node = await NodeRepository
+            .Query()
+            .FirstOrDefaultAsync(x => x.Id == id);
+
+        if (node == null)
+            return Problem("No node with this id found", statusCode: 404);
+
+        var statistics = await NodeService.GetStatisticsAsync(node);
+        var dto = NodeMapper.ToDto(statistics);
+
+        return dto;
+    }
+}