Add implementation of facebook api

Author: nalabjp

lib/statistics/client.rb

@@ -101,5 +101,30 @@ def fetch_events(group_id:, since_at: @default_since, until_at: @default_until)
         events
       end
     end
+
+    class Facebook
+      def initialize
+        @client = Koala::Facebook::API.new(ENV.fetch('FACEBOOK_ACCESS_TOKEN'))
+      end
+
+      def fetch_events(group_id:, since_at: nil, until_at: nil)
+        params = {
+          fields: %i(attending_count start_time owner),
+          limit: 100,
+          since: since_at,
+          until: until_at
+        }.compact!
+
+        events = []
+
+        collection = @client.get_object("#{group_id}/events", params)
+        events.push(*collection.to_a)
+        while collection.paging['next'] do
+          events.push(*collection.next_page.to_a)
+        end
+
+        events
+      end
+    end
   end
 end

spec/lib/statistics/client_spec.rb

@@ -56,4 +56,19 @@
       end
     end
   end
+
+  context 'Facebook' do
+    include_context 'Use stubs for Facebook'
+
+    describe '#fetch_events' do
+      subject { Statistics::Client::Facebook.new.fetch_events(group_id: 123451234512345) }
+
+      it do
+        expect(subject).to be_instance_of(Array)
+        expect(subject.size).to eq 1
+        expect(subject.first['id']).to eq '125500978166443'
+        expect(subject.first.dig('owner', 'id')).to eq '123451234512345'
+      end
+    end
+  end
 end

spec/support/shared_contexts/statistics.rb

@@ -41,3 +41,24 @@
     ]
   end
 end
+
+RSpec.shared_context 'Use stubs for Facebook' do
+  let(:facebook_response) do
+    resp = OpenStruct.new(data: {
+      "data" => [
+        {"attending_count"=>1, "start_time"=>"2017-10-29T13:00:00+0900", "owner"=>{"name"=>"CoderDojo ひばりヶ丘", "id"=>"123451234512345"}, "id"=>"125500978166443"}
+      ],
+      "paging" => {
+        "cursors" => {
+          "before" => "QVFIUjVOd2tKSmZA6S01fR0NFNWN2aFJlc01JUnpqRW5aMFFkeHdBS3NTcUt1b3JfazUzM3FtVGhCYlN6bE1OS1lxZAzQ0YjVSNWRRVWRfd182SXh3LUN6VXZAB",
+          "after" => "QVFIUmZA1cEk5QlV0VFc2Ri1BT3JEOWl3M1gzemRZAZAkpkaFdjNTEwUDdtaERLdFpwYV9CejVuX3hLV2kyVm5Gem9KSTAzTGg0dUd4SjNLXzBlSTZAJMVAtdmln"
+        }
+      }
+    })
+    Koala::Facebook::API::GraphCollection.new(resp, nil)
+  end
+
+  before do
+    allow_any_instance_of(Koala::Facebook::API).to receive(:get_object).and_return(facebook_response)
+  end
+end