From 8b8a0f1f3049b6cd908c3e2273ed71be7fca0dae Mon Sep 17 00:00:00 2001
From: Esteban Ceron <restebance@gmail.com>
Date: Thu, 29 Nov 2018 17:36:27 -0500
Subject: [PATCH] [FEATURE] include redshift adapter to support geolocation

---
 geokit-rails.gemspec                  |  1 +
 lib/geokit-rails/acts_as_mappable.rb  |  5 ++++-
 lib/geokit-rails/adapters/redshift.rb | 22 ++++++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 lib/geokit-rails/adapters/redshift.rb

diff --git a/geokit-rails.gemspec b/geokit-rails.gemspec
index 1cbba93..27b0dad 100644
--- a/geokit-rails.gemspec
+++ b/geokit-rails.gemspec
@@ -26,6 +26,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'test-unit'
   spec.add_development_dependency "mocha", "~> 0.9"
   spec.add_development_dependency 'coveralls'
+  spec.add_development_dependency 'activerecord5-redshift-adapter', '~> 1.0'
   spec.add_development_dependency "mysql2", "~> 0.2"
   spec.add_development_dependency "activerecord-mysql2spatial-adapter"
   spec.add_development_dependency "pg", "~> 0.10"
diff --git a/lib/geokit-rails/acts_as_mappable.rb b/lib/geokit-rails/acts_as_mappable.rb
index a31b0a6..de2a2e6 100644
--- a/lib/geokit-rails/acts_as_mappable.rb
+++ b/lib/geokit-rails/acts_as_mappable.rb
@@ -11,7 +11,10 @@ module Glue # :nodoc:
       extend ActiveSupport::Concern
 
       module ClassMethods # :nodoc:
-        OPTION_SYMBOLS = [ :distance_column_name, :default_units, :default_formula, :lat_column_name, :lng_column_name, :qualified_lat_column_name, :qualified_lng_column_name, :skip_loading ]
+        OPTION_SYMBOLS = [ :distance_column_name, :default_units, 
+                           :default_formula, :lat_column_name, 
+                           :lng_column_name, :qualified_lat_column_name, 
+                           :qualified_lng_column_name, :skip_loading ]
 
         def acts_as_mappable(options = {})
           metaclass = (class << self; self; end)
diff --git a/lib/geokit-rails/adapters/redshift.rb b/lib/geokit-rails/adapters/redshift.rb
new file mode 100644
index 0000000..0afc331
--- /dev/null
+++ b/lib/geokit-rails/adapters/redshift.rb
@@ -0,0 +1,22 @@
+module Geokit
+  module Adapters
+    class Redshift < Abstract
+      
+      def sphere_distance_sql(lat, lng, multiplier)
+        %|
+          (ACOS(least(1,COS(#{lat})*COS(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*COS(RADIANS(#{qualified_lng_column_name}))+
+          COS(#{lat})*SIN(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*SIN(RADIANS(#{qualified_lng_column_name}))+
+          SIN(#{lat})*SIN(RADIANS(#{qualified_lat_column_name}))))*#{multiplier})
+         |
+      end
+      
+      def flat_distance_sql(origin, lat_degree_units, lng_degree_units)
+        %|
+          SQRT(POW(#{lat_degree_units}*(#{origin.lat}-#{qualified_lat_column_name}),2)+
+          POW(#{lng_degree_units}*(#{origin.lng}-#{qualified_lng_column_name}),2))
+         |
+      end
+      
+    end
+  end
+end