VRFS-3276 : Calendar Manager - initial checkin

* Create ICS events given individual parameters
* Create calendar from music session
* Also will create ICS “delete” events

ruby/lib/jam_ruby/calendar_manager.rb

@@ -0,0 +1,43 @@
+module JamRuby
+  class CalendarManager
+    class << self
+      def ics_from_music_session(music_session, delete=false)
+        uid = "#{music_session.user_id}_#{music_session.id}@JamKazam"
+        text = "JamKazam Session #{music_session.description}"
+        case music_session.recurring_mode
+          when NO_RECURRING
+            create_ics_event(uid, text, scheduled_start, scheduled_start+scheduled_duration, delete)
+          when RECURRING_WEEKLY
+            create_ics_event(uid, text, scheduled_start, scheduled_start+scheduled_duration, delete)
+          else
+            raise ArgumentError("Recurring mode not supported: #{music_session.recurring_mode}")
+        end
+      end
+
+      # @return calendar (as ICS string) for specified user
+      def create_ics_feed(user)
+      end
+
+      def create_ics_event(uuid, summary, start_at, end_at, delete=false, sequence=0)
+        uuid ||= UUID.timestamp_create
+        event = "BEGIN:VEVENT\r\n"
+        event << "UID:#{uuid}\r\n"
+        event << "DTSTAMP:#{Time.now.utc().strftime(DATE_FORMAT)}\r\n"
+        event << "DTSTART:#{start_at.utc().strftime(DATE_FORMAT)}\r\n"
+        event << "DTEND:#{end_at.utc().strftime(DATE_FORMAT)}\r\n"
+        event << "SUMMARY:#{summary}\r\n"
+        if delete
+          event << "METHOD:CANCEL\r\n"
+          event << "STATUS:CANCELLED\r\n"
+        end
+        event << "SEQUENCE:#{sequence}\r\n" if sequence
+        event << "END:VEVENT"
+      end
+
+      def create_ics_cal(ics_events)
+        "BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:JamKazam\r\n#{ics_events}\r\nEND:VCALENDAR"
+      end
+
+    end
+  end
+end