Updated the logic for Stat/Metric tracking in the dashboard more robust. (#365)

* Updated the logic for Stat/Metric tracking in the dashboard more robust.

* Show used/total for stats.

* Added the ability to configure the update interval of metrics in the dashboard.

services/Storage.ts

@@ -0,0 +1,61 @@
+// TODO: Convert to a real service
+
+// @ts-expect-error: This import is a special directive that tells the compiler to use the GTop library
+import GTop from 'gi://GTop';
+
+import { pollVariable } from 'customModules/PollVar';
+import { GenericResourceData } from 'lib/types/customModules/generic';
+
+class Storage {
+    private updateFrequency = Variable(2000);
+    private shouldRound = false;
+
+    public storage = Variable<GenericResourceData>({ total: 0, used: 0, percentage: 0, free: 0 });
+
+    constructor() {
+        this.calculateUsage = this.calculateUsage.bind(this);
+        pollVariable(this.storage, [], this.updateFrequency.bind('value'), this.calculateUsage);
+    }
+
+    public calculateUsage(): GenericResourceData {
+        try {
+            const currentFsUsage = new GTop.glibtop_fsusage();
+
+            GTop.glibtop_get_fsusage(currentFsUsage, '/');
+
+            const total = currentFsUsage.blocks * currentFsUsage.block_size;
+            const available = currentFsUsage.bavail * currentFsUsage.block_size;
+            const used = total - available;
+
+            return {
+                total,
+                used,
+                free: available,
+                percentage: this.divide([total, used]),
+            };
+        } catch (error) {
+            console.error('Error calculating Storage usage:', error);
+            return { total: 0, used: 0, percentage: 0, free: 0 };
+        }
+    }
+
+    public setShouldRound(round: boolean): void {
+        this.shouldRound = round;
+    }
+
+    private divide([total, used]: number[]): number {
+        const percentageTotal = (used / total) * 100;
+
+        if (this.shouldRound) {
+            return total > 0 ? Math.round(percentageTotal) : 0;
+        }
+
+        return total > 0 ? parseFloat(percentageTotal.toFixed(2)) : 0;
+    }
+
+    public updateTimer(timerInMs: number): void {
+        this.updateFrequency.value = timerInMs;
+    }
+}
+
+export default Storage;