fix: determine correct projection from features at getProj (#1959)

* fix: determine correct projection from features at getProj

* chore: add test

* fix: test

* fix: another [0]

* fix: recursively search for number to get reference coordinate

Author: silvester-pari

elements/map/src/helpers/parse-text.js

@@ -11,24 +11,42 @@ import { READ_FEATURES_OPTIONS } from "../enums";
  * @param {string} text
  * @returns {string | undefined} - Returns the projection string if determined, otherwise undefined.
  */
-function getProj(formatReader, text) {
+export function getProj(formatReader, text) {
   const features = formatReader.readFeatures(text);
   const feature = features[0];
   const geometry = feature.getGeometry();
   // @ts-expect-error - Property 'getCoordinates' does not exist on type 'Geometry' but it does not showing
   const coordinates = geometry.getCoordinates();
   if (coordinates && coordinates.length > 0) {
-    const coord = coordinates[0][0][0];
-    if (coord >= -180 && coord <= 180) {
-      return "EPSG:4326";
-    } else {
-      return "EPSG:3857";
+    const coord = findFirstCoordinateValue(coordinates);
+    if (typeof coord === "number") {
+      if (coord >= -180 && coord <= 180) {
+        return "EPSG:4326"; // WGS 84 (Lon/Lat)
+      } else {
+        return "EPSG:3857"; // Web Mercator (X/Y)
+      }
     }
   }
 
   return undefined;
 }
 
+/**
+ * Recursively finds the first numerical coordinate value in a nested array.
+ *
+ * @param {any} coordinates - The coordinates array returned by geometry.getCoordinates().
+ * @returns {number | undefined} - The first numerical coordinate (longitude/x), or undefined.
+ */
+function findFirstCoordinateValue(coordinates) {
+  if (typeof coordinates === "number") {
+    return coordinates;
+  }
+  if (Array.isArray(coordinates) && coordinates.length > 0) {
+    return findFirstCoordinateValue(coordinates[0]);
+  }
+  return undefined;
+}
+
 /**
  * This function reads text and attempts to parse it as GeoJSON, KML, or TopoJSON.
  * If successful, it adds the parsed features to the map.

elements/map/test/cases/projection/check-get-proj.js

@@ -0,0 +1,54 @@
+import { getProj } from "../../../src/helpers/parse-text";
+import GeoJSON from "ol/format/GeoJSON";
+
+const checkGetProj = () => {
+  const geojson = JSON.stringify({
+    type: "FeatureCollection",
+    features: [
+      {
+        type: "Feature",
+        geometry: {
+          type: "Polygon",
+          coordinates: [
+            [
+              [10, 10],
+              [20, 10],
+              [20, 20],
+              [10, 20],
+              [10, 10],
+            ],
+          ],
+        },
+        properties: {},
+      },
+    ],
+  });
+  const proj = getProj(new GeoJSON(), geojson);
+  expect(proj).to.be.equal("EPSG:4326");
+
+  const geojson2 = JSON.stringify({
+    type: "FeatureCollection",
+    features: [
+      {
+        type: "Feature",
+        geometry: {
+          type: "Polygon",
+          coordinates: [
+            [
+              [200, 10],
+              [210, 10],
+              [210, 20],
+              [200, 20],
+              [200, 10],
+            ],
+          ],
+        },
+        properties: {},
+      },
+    ],
+  });
+  const proj2 = getProj(new GeoJSON(), geojson2);
+  expect(proj2).to.be.equal("EPSG:3857");
+};
+
+export default checkGetProj;

elements/map/test/cases/projection/index.js

@@ -5,3 +5,4 @@ export { default as changeProjection } from "./change-projection";
 export { default as specialProjection } from "./special-projection";
 export { default as fetchProjectionFromCode } from "./fetch-projection-from-code";
 export { default as getWgsCoordinates } from "./get-wgs-coordinates";
+export { default as checkGetProj } from "./check-get-proj";

elements/map/test/viewProjection.cy.js

@@ -5,6 +5,7 @@ import {
   getWgsCoordinates,
   initProjection,
   specialProjection,
+  checkGetProj,
 } from "./cases/projection";
 
 /**
@@ -36,4 +37,9 @@ describe("view projections", () => {
    */
   it("lonLatExtent delivering correct WGS coordinates", () =>
     getWgsCoordinates());
+
+  /**
+   * Test case to check getProj projection guessing logic
+   */
+  it("correctly guesses projection from coordinates", () => checkGetProj());
 });