✨ Add geolocation service

src/modules/geolocation/geolocation.service.ts

@@ -1,5 +1,29 @@
-import { Injectable } from '@nestjs/common';
+import { Injectable, OnModuleDestroy } from '@nestjs/common';
+import maxmind, { Reader, CityResponse } from 'maxmind';
 import geolite2 from 'geolite2-redist';
 
 @Injectable()
-export class GeolocationService {}
+export class GeolocationService implements OnModuleDestroy {
+  lookup: Reader<CityResponse> | null = null;
+
+  onModuleDestroy() {
+    if (this.lookup) this.lookup = null;
+  }
+
+  /** Get the geolocation from an IP address */
+  async getLocation(ipAddress: string): Promise<Partial<CityResponse>> {
+    try {
+      return this.getUnsafeLocation(ipAddress);
+    } catch (error) {
+      return {};
+    }
+  }
+
+  private async getUnsafeLocation(ipAddress: string) {
+    if (this.lookup)
+      this.lookup = await geolite2.open<CityResponse>('GeoLite2-City', path => {
+        return maxmind.open(path);
+      });
+    return this.lookup.get(ipAddress);
+  }
+}