Implemented better CRS handling for "unknown" EPSG codes

package.json

@@ -35,6 +35,7 @@
     "ajv": "^6.12.2",
     "axios": "^0.19.2",
     "check-disk-space": "^2.1.0",
+    "epsg-index": "^1.0.0",
     "fs-extra": "^8.0.1",
     "nedb": "^1.8.0",
     "object-hash": "^1.3.1",

src/processes/anomaly.json

@@ -4,7 +4,7 @@
     "description": "Computes anomalies based on normals for a specific temporal frequency.",
     "categories": [
         "climatology",
-        "cube",
+        "cubes",
         "math"
     ],
     "parameters": [

src/processgraph/datacube.js

@@ -225,23 +225,27 @@ module.exports = class DataCube {
 			return coords;
 		}
 
-		/* Inspiration from: https://github.com/geotiffjs/cog-explorer/blob/master/src/components/mapview.jsx
-		const epsg = `EPSG:${code}`;
-		if (!proj4.defs(epsg)) {
-			const response = await fetch(`//epsg.io/${code}.proj4`);
-			proj4.defs(epsg, await response.text());
+		this.loadCrsDef(fromCrs);
+		this.loadCrsDef(toCrs);
+
+		return proj4(fromCrs, toCrs, coords);
+	}
+
+	loadCrsDef(crs) {
+		if (proj4.defs(crs)) {
+			return; // CRS already available
+		}
+		if (!crs.startsWith('EPSG:')) {
+			throw new Error("CRS " + crs + " not supported");
 		}
-		*/
 
-		// ToDo: Check this is correct; maybe find better way to convert 180/90 to Web Mercator
-		if (fromCrs === 'EPSG:4326' && toCrs === 'EPSG:3857' && Math.abs(coords[1]) > 85.051129) {
-			return [
-				coords[0],
-				Math.sign(coords[1]) * 85.051129
-			];
+		try {
+			let code = crs.substring(5);
+			const def = require('epsg-index/s/' + code + '.json');
+			proj4.defs(crs, def.proj4);
+		} catch (error) {
+			throw new Error("CRS " + crs + " not available for reprojection");
 		}
-
-		return proj4(fromCrs, toCrs, coords);
 	}
 
 	setSpatialExtent(extent) {