Add StationDataModule, implementing getNearestStations & a Geohash generator method

src/lib/validation.ts

@@ -1,6 +1,7 @@
 /**
-* Checks if a string is a valid CRS
+* Checks if a string is a valid CRS (Syntactically Only)
 * using byte level checking for max performance
+* @param CRS The CRS Code to be validated
 */
 export const IsValidCrs = (CRS: string): boolean => {
     if (CRS.length !== 3) return false;
@@ -15,8 +16,9 @@ export const IsValidCrs = (CRS: string): boolean => {
 }
 
 /**
- * Checks if a string is a valid TIPLOC
+ * Checks if a string is a valid TIPLOC (Syntactically Only)
  * using byte level checking for max performance
+ * @param TIPLOC The TIPLOC to be validated
  */
 export const IsValidTiploc = (TIPLOC: string): boolean => {
     const l = TIPLOC.length;
@@ -33,9 +35,10 @@ export const IsValidTiploc = (TIPLOC: string): boolean => {
 }
 
 /**
- * Checks if a string is a valid PIS Code
+ * Checks if a string is a valid PIS Code (Syntactically Only)
  * using byte level checking for max performance
  * ONLY GWR (4-digit) CODES SUPPORTED
+ * @param PIS The PIS Code to be validated
  */
 export const IsValidPis = (PIS: string): boolean => {
     if (PIS.length !== 4) return false;
@@ -44,4 +47,15 @@ export const IsValidPis = (PIS: string): boolean => {
         if (!(char >= 48 && char <= 57)) return false;
     }
     return true;
+}
+
+/**
+ * Validates Geohash string against standard b32 alphabet
+ * (Syntactically Only validation)
+ * @param hash The geohash to be validated
+ * @param maxLen Defaults to 6 - which is enforced by the server, should not need changing
+ */
+export const IsValidGeoHash = (hash: string, maxLen: number = 6): boolean => {
+    const geoHashRegex = new RegExp(`^[0-9bcdefghjkmnpqrstuvwxyz]{1,${maxLen}}$`, 'i');
+    return geoHashRegex.test(hash);
 }