add geolocation search for public channels

Gemfile

@@ -35,6 +35,7 @@ gem 'em-http-request'
 gem 'tzinfo'
 gem 'tzinfo-data'
 gem 'turbolinks'
+gem 'geokit-rails'
 
 # to use debugger
 # gem 'ruby-debug'

Gemfile.lock

@@ -144,6 +144,9 @@ GEM
       actionpack (>= 3.0)
     geokit (1.8.4)
       multi_json (>= 1.3.2)
+    geokit-rails (2.0.1)
+      geokit (~> 1.5)
+      rails (>= 3.0)
     gravatarify (3.1.0)
     has_scope (0.6.0.rc)
       actionpack (>= 3.2, < 5)
@@ -362,6 +365,7 @@ DEPENDENCIES
   factory_girl_rails
   faker
   geokit
+  geokit-rails
   gravatarify
   i18n-tasks (~> 0.5.4)
   jquery-rails (= 3.0.4)

app/controllers/channels_controller.rb

@@ -6,6 +6,7 @@ class ChannelsController < ApplicationController
   layout 'application', :except => [:social_show, :social_feed]
   protect_from_forgery :except => [:realtime, :realtime_update, :post_data, :create, :destroy, :clear]
   require 'csv'
+  require 'will_paginate/array'
 
   # get list of all realtime channels
   def realtime
@@ -55,6 +56,10 @@ class ChannelsController < ApplicationController
     elsif params[:tag].present?
       @header = "#{t(:tag).capitalize}: #{params[:tag]}"
       @channels = Channel.public_viewable.active.order('ranking desc, updated_at DESC').with_tag(params[:tag]).paginate :page => params[:page]
+    # get channels by location
+    elsif params[:latitude].present? && params[:longitude].present? && params[:distance].present?
+      @header = "#{t(:channels_near)}: [#{params[:latitude]}, #{params[:longitude]}]"
+      @channels = Channel.location_search(params).paginate :page => params[:page]
     # normal channel list
     else
       @header = t(:featured_channels)

app/models/channel.rb

@@ -52,6 +52,11 @@
 
 class Channel < ActiveRecord::Base
   include KeyUtilities
+  # geolocation search: Channel.within(miles, :origin => [latitude, longitude]).to_a
+  # example: channels = Channel.within(4000, :origin => [4, 6]).to_a
+  # channels.sort_by{|s| s.distance_to([4, 6])}
+  acts_as_mappable :default_units => :kms, :default_formula => :sphere,
+    :distance_field_name => :distance, :lat_column_name => :latitude, :lng_column_name => :longitude
 
   belongs_to :user
   has_many :feeds
@@ -85,6 +90,18 @@ class Channel < ActiveRecord::Base
   cattr_reader :per_page
   @@per_page = 15
 
+  # search for public channels within a certain distance from the origin
+  # requires latitude, longitude, and distance to be present as options keys
+  # distance is in kilometers
+  def self.location_search(options = {})
+    # set the origin
+    origin = [options[:latitude].to_f, options[:longitude].to_f]
+    # query the database
+    channels = Channel.public_viewable.within(options[:distance].to_f, :origin => origin)
+    # sort channels by distance
+    return channels.sort_by{|c| c.distance_to(origin)}
+  end
+
   # how often the channel is updated
   def update_rate
     last_feeds = self.feeds.order('entry_id desc').limit(2)

app/views/docs/channels/_index.html.erb

@@ -16,6 +16,14 @@ Valid parameters:
   <li><b>username</b> (string) Person's username that you want to search Channels for (optional)</li>
 </ul>
 
+<br>
+You can also search for Channels within a certain distance of a location by including the following location parameters:
+<ul>
+  <li><b>latitude</b> (decimal) - Latitude of location in degrees. (optional)</li>
+  <li><b>longitude</b> (decimal) - Longitude of location in degrees. (optional)</li>
+  <li><b>distance</b> (decimal) - Distance in kilometers from location. (optional)</li>
+</ul>
+
 <br>
 Example GET:
 
@@ -163,6 +171,7 @@ Valid parameters:
   <li><b>api_key</b> (string) - Your Account API Key (this is different from a Channel API Key, and can be found in your Account settings). (required)</li>
 </ul>
 
+
 <br>
 Example GET:
 

config/locales/en.yml

@@ -55,6 +55,7 @@ en:
   channel_url: "URL"
   channels: "Channels"
   channels_my: "My Channels"
+  channels_near: "Channels Near"
   channels_public: "Public Channels"
   channels_public_view: "View Public Channels"
   channel_video_type_blank: "Either Youtube, or Vimeo, is required if a Video ID is specified."

db/migrate/20140804223739_add_geolocation_index_to_channels.rb

@@ -0,0 +1,6 @@
+class AddGeolocationIndexToChannels < ActiveRecord::Migration
+  def change
+    add_index :channels, [:latitude, :longitude]
+  end
+end
+

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20140801191621) do
+ActiveRecord::Schema.define(version: 20140804223739) do
 
   create_table "active_admin_comments", force: true do |t|
     t.string   "namespace"
@@ -107,6 +107,7 @@ ActiveRecord::Schema.define(version: 20140801191621) do
     t.text     "metadata"
   end
 
+  add_index "channels", ["latitude", "longitude"], name: "index_channels_on_latitude_and_longitude", using: :btree
   add_index "channels", ["public_flag", "last_entry_id", "updated_at"], name: "channels_public_viewable", using: :btree
   add_index "channels", ["ranking", "updated_at"], name: "index_channels_on_ranking_and_updated_at", using: :btree
   add_index "channels", ["realtime_io_serial_number"], name: "index_channels_on_realtime_io_serial_number", using: :btree

spec/controllers/channels_controller_spec.rb

@@ -125,6 +125,13 @@ describe ChannelsController do
         get :index, {:api_key => @user.api_key, :format => 'json'}
         response.should be_successful
       end
+
+      it "searches nearby public channels" do
+        channel1 = Channel.create(name: 'channel1', latitude: 10, longitude: 10, public_flag: true)
+        channel2 = Channel.create(name: 'channel2', latitude: 60, longitude: 60, public_flag: true)
+        get :public, {api_key: @user.api_key, latitude: 59.8, longitude: 60.2, distance: 100, format: 'json'}
+        JSON.parse(response.body)['channels'][0]['name'].should eq("channel2")
+      end
     end
 
     describe "create channel" do

spec/models/channel_spec.rb

@@ -134,5 +134,17 @@ describe Channel do
       channels.count.should == 1
     end
   end
+
+  describe 'geolocation' do
+    it 'should find nearby channels' do
+      channel1 = Channel.create(latitude: 10, longitude: 10, public_flag: true)
+      channel2 = Channel.create(latitude: 60, longitude: 60, public_flag: true)
+      channel3 = Channel.create(latitude: 60, longitude: 60, public_flag: false)
+      Channel.location_search({latitude: 9.8, longitude: 10.2, distance: 100}).first.should eq(channel1)
+      Channel.location_search({latitude: 60.2, longitude: 59.8, distance: 100}).first.should eq(channel2)
+      Channel.location_search({latitude: 60.2, longitude: 59.8, distance: 100}).count.should eq(1)
+      Channel.location_search({latitude: 30.8, longitude: 30.2, distance: 100}).count.should eq(0)
+    end
+  end
 end