Add the database sizes into the sidebar (closes #21)

module/utils/fs.mjs

@@ -37,6 +37,30 @@ export async function lastModifiedAt(path) {
 	};
 };
 
+export async function getFileSize(path) {
+	try {
+		const response = await fetch(filePath(path), { method: `HEAD` });
+		const bytes = response.headers.get(`Content-Length`);
+		if (!bytes) { return null }
+
+		// round the non-bytes to 2 decimal places
+		const kilobytes = Math.floor(bytes / 10) / 100;
+		const megabytes = Math.floor(bytes / 10_000) / 100;
+
+		// determine the most appropriate unit to use
+		let friendly = `${bytes} bytes`;
+		if (megabytes > 0.25) {
+			friendly = `${megabytes}MB`;
+		} else if (kilobytes > 0) {
+			friendly = `${kilobytes}KB`;
+		};
+
+		return { bytes, kilobytes, megabytes, friendly };
+	} catch {
+		return null;
+	};
+};
+
 export async function getFile(path) {
 	try {
 		return fetchJsonWithTimeout(filePath(path));