add support of query pagination with WillPaginate

lib/chewy/query/pagination.rb

@@ -13,3 +13,4 @@ def total_count
 end
 
 require 'chewy/query/pagination/kaminari' if defined?(::Kaminari)
+require 'chewy/query/pagination/will_paginate' if defined?(::WillPaginate)

lib/chewy/query/pagination/will_paginate.rb

@@ -0,0 +1,52 @@
+module Chewy
+  class Query
+    module Pagination
+      module WillPaginate
+        include ::WillPaginate::CollectionMethods
+
+        def paginate(options = {})
+          @current_page = ::WillPaginate::PageNumber(options[:page] || @current_page || 1)
+          @page_multiplier = @current_page - 1
+
+          pp = (options[:per_page] || per_page || ::WillPaginate.per_page).to_i
+
+          #call Chewy::Query methods to limit results
+          per_page(pp)
+          offset( @page_multiplier * pp )
+        end
+
+        def current_page(value=:non_given)
+          if value == :non_given
+            @current_page
+          else
+            @current_page = value
+          end
+        end
+
+        def per_page(value = :non_given)
+          if value == :non_given
+            @per_page
+          else
+            @per_page = value
+            limit(value)
+          end
+        end
+
+        def page(page)
+          paginate(page: page)
+        end
+
+        def total_pages
+          (total_entries / per_page.to_f).ceil
+        end
+
+        def total_entries
+          @total_entries ||= self.total_count
+        end
+
+      end
+    end
+  end
+end
+
+Chewy::Query::Pagination.send :include, Chewy::Query::Pagination::WillPaginate