Add support for Nominatim

This adds support for Nominatim-based reverse geocoding, along with
Photon and Geofi. To use it, set the environment variables:

NOMINATIM_API_HOST - the host name of the OSM Nominatim server
NOMINATIM_API_USE_HTTPS - use the HTTPS to connect
NOMINATIM_API_KEY - the API key

config/initializers/01_constants.rb

@@ -13,5 +13,9 @@
 PHOTON_API_KEY = ENV.fetch('PHOTON_API_KEY', nil)
 PHOTON_API_USE_HTTPS = ENV.fetch('PHOTON_API_USE_HTTPS', 'true') == 'true'
 
+NOMINATIM_API_HOST = ENV.fetch('NOMINATIM_API_HOST', nil)
+NOMINATIM_API_KEY = ENV.fetch('NOMINATIM_API_KEY', nil)
+NOMINATIM_API_USE_HTTPS = ENV.fetch('NOMINATIM_API_USE_HTTPS', 'true') == 'true'
+
 GEOAPIFY_API_KEY = ENV.fetch('GEOAPIFY_API_KEY', nil)
 # /Reverse geocoding settings

config/initializers/03_dawarich_settings.rb

@@ -3,7 +3,7 @@
 class DawarichSettings
   class << self
     def reverse_geocoding_enabled?
-      @reverse_geocoding_enabled ||= photon_enabled? || geoapify_enabled?
+      @reverse_geocoding_enabled ||= photon_enabled? || geoapify_enabled? || nominatim_enabled?
     end
 
     def photon_enabled?
@@ -17,5 +17,9 @@ def photon_uses_komoot_io?
     def geoapify_enabled?
       @geoapify_enabled ||= GEOAPIFY_API_KEY.present?
     end
+
+    def nominatim_enabled?
+      @nominatim_enabled ||= NOMINATIM_API_HOST.present?
+    end
   end
 end

config/initializers/geocoder.rb

@@ -19,6 +19,12 @@
 elsif GEOAPIFY_API_KEY.present?
   settings[:lookup] = :geoapify
   settings[:api_key] = GEOAPIFY_API_KEY
+elsif NOMINATIM_API_HOST.present?
+  settings[:lookup] = :nominatim
+  settings[:nominatim] = { use_https: NOMINATIM_API_USE_HTTPS, host: NOMINATIM_API_HOST }
+  if NOMINATIM_API_KEY.present?
+    settings[:api_key] = NOMINATIM_API_KEY
+  end
 end
 
 Geocoder.configure(settings)