[Bugfix] Confirmed / Unconfirmed events over time for conference dashboard

db/migrate/20140701123203_add_events_per_week_to_conference.rb

@@ -0,0 +1,90 @@
+class AddEventsPerWeekToConference < ActiveRecord::Migration
+  class TempVersion < ActiveRecord::Base
+    self.table_name = 'versions'
+    serialize :object_changes, HashWithIndifferentAccess
+  end
+
+  class TempEvent < ActiveRecord::Base
+    self.table_name = 'events'
+  end
+
+  class TempConference < ActiveRecord::Base
+    self.table_name = 'conferences'
+    serialize :events_per_week, Hash
+  end
+
+  def up
+    add_column :conferences, :events_per_week, :text
+
+    TempVersion.where(item_type: 'Event').each do |event_version|
+      event = TempEvent.find(event_version.item_id)
+      conference = TempConference.find(event.conference_id)
+      week = event_version.created_at.end_of_week
+
+      no_events = {
+        new: 0,
+        withdrawn: 0,
+        unconfirmed: 0,
+        confirmed: 0,
+        canceled: 0,
+        rejected: 0,
+      }
+
+      if !conference.events_per_week
+        conference.events_per_week = {
+          week => no_events
+        }
+      elsif !conference.events_per_week[week]
+        conference.events_per_week[week] = no_events
+      end
+
+      if event_version.object_changes &&
+          event_version.event == 'create'
+
+        # Increment the new state
+        conference.events_per_week[week][:new] += 1
+      elsif event_version.object_changes &&
+          event_version.object_changes[:state]
+
+        prev_state = event_version.object_changes[:state][0].to_sym
+        next_state = event_version.object_changes[:state][1].to_sym
+
+        # Backward compatibility: deprecated state :review now :new
+        if prev_state == :review
+          prev_state = :new
+        elsif  next_state == :review
+          next_state = :new
+        end
+
+        # Increment the next state
+        conference.events_per_week[week][next_state] += 1
+
+        # Decrement the previous state
+        conference.events_per_week[week][prev_state] -= 1
+      end
+      conference.save
+    end
+
+
+    # Cumulate the previous weeks to get a snapshot
+    TempConference.all.each do |conference|
+      hash = conference.events_per_week.sort.to_h
+      previous = nil
+
+      hash.each do |week, values|
+        if previous
+          values.each do |state, value|
+            hash[week][state] += previous[state]
+          end
+        end
+        previous = values
+      end
+      conference.events_per_week = hash
+      conference.save
+    end
+  end
+
+  def down
+    remove_column :conferences, :events_per_week
+  end
+end