feat: add aggregated resource usage chart to dashboard

src/Controllers/DashboardController.php

@@ -34,12 +34,15 @@ class DashboardController
             return in_array((int) $s['id'], $accessibleIds, true);
         })) : [];
 
+        $aggregatedMetrics = $this->monitoringService->getAggregatedHistoricalMetrics($accessibleIds ?? []);
+
         $recentActivity = $this->auditService->getRecentActivity(10, $userId);
 
         $this->view->display('dashboard.index', [
             'title' => 'Dashboard - ServerManager',
             'stats' => $stats,
             'servers' => $servers,
+            'aggregatedMetrics' => $aggregatedMetrics,
             'recentActivity' => $recentActivity,
         ]);
     }
@@ -65,4 +68,16 @@ class DashboardController
             'message' => 'Metrics refreshed',
         ]);
     }
+
+    public function chartData(): void
+    {
+        $serverModel = new Server();
+        $accessibleIds = $serverModel->getAccessibleServerIds((int) Session::get('user_id'));
+        $data = $this->monitoringService->getAggregatedHistoricalMetrics($accessibleIds ?? []);
+
+        $this->view->json([
+            'success' => true,
+            'data' => $data,
+        ]);
+    }
 }

src/Services/MonitoringService.php

@@ -173,6 +173,29 @@ class MonitoringService
         );
     }
 
+    public function getAggregatedHistoricalMetrics(array $serverIds, int $hours = 24): array
+    {
+        if (empty($serverIds)) {
+            return [];
+        }
+        $placeholders = implode(',', array_fill(0, count($serverIds), '?'));
+        $params = $serverIds;
+        $params[] = $hours;
+        return $this->db->fetchAll(
+            "SELECT
+                DATE_FORMAT(created_at, '%Y-%m-%d %H:%i:00') as time_bucket,
+                AVG(cpu_usage) as avg_cpu,
+                AVG(ram_usage) as avg_ram,
+                AVG(disk_usage) as avg_disk
+             FROM monitoring_history
+             WHERE server_id IN ({$placeholders})
+               AND created_at >= DATE_SUB(NOW(), INTERVAL ? HOUR)
+             GROUP BY time_bucket
+             ORDER BY time_bucket ASC",
+            $params
+        );
+    }
+
     public function getDashboardStats(?array $serverIds = null): array
     {
         $where = '';