chore: init backend and ignore local artifacts

utils/bbox.js

@@ -0,0 +1,45 @@
+function getBBox(geometry) {
+    let minLng = Infinity, minLat = Infinity;
+    let maxLng = -Infinity, maxLat = -Infinity;
+
+    function process(coords) {
+        if (typeof coords[0] === "number") {
+            const [lng, lat] = coords;
+
+            minLng = Math.min(minLng, lng);
+            minLat = Math.min(minLat, lat);
+            maxLng = Math.max(maxLng, lng);
+            maxLat = Math.max(maxLat, lat);
+        } else {
+            coords.forEach(process);
+        }
+    }
+
+    // 🔥 handle theo type cho rõ ràng
+    switch (geometry.type) {
+        case "Point":
+            process(geometry.coordinates);
+            break;
+
+        case "MultiPoint":
+        case "LineString":
+            process(geometry.coordinates);
+            break;
+
+        case "MultiLineString":
+        case "Polygon":
+            process(geometry.coordinates);
+            break;
+
+        case "MultiPolygon":
+            process(geometry.coordinates);
+            break;
+
+        default:
+            throw new Error("Unsupported geometry type: " + geometry.type);
+    }
+
+    return { minLng, minLat, maxLng, maxLat };
+}
+
+module.exports = { getBBox };