Use helpers for repeated event dropdown links

app/helpers/events_helper.rb

@@ -54,4 +54,133 @@ module EventsHelper
   def rating_tooltip(event, max_rating)
     "#{event.average_rating}/#{max_rating}, #{pluralize(event.voters.length, 'vote')}"
   end
+
+  def event_type_dropdown(event, event_types, conference_id)
+    selection = event.event_type.try(:title) || 'Event Type'
+    options = event_types.collect do |event_type|
+      [
+        event_type.title,
+        admin_conference_program_event_path(
+          conference_id,
+          event,
+          event: { event_type_id: event_type.id }
+        )
+      ]
+    end
+    active_dropdown(selection, options)
+  end
+
+  def track_dropdown(event, tracks, conference_id)
+    selection = event.track.try(:name) || 'Track'
+    options = tracks.collect do |track|
+      [
+        track.name,
+        admin_conference_program_event_path(
+          conference_id,
+          event,
+          event: { track_id: track.id }
+        )
+      ]
+    end
+    active_dropdown(selection, options)
+  end
+
+  def difficulty_dropdown(event, difficulties, conference_id)
+    selection = event.difficulty_level.try(:title) || 'Difficulty'
+    options = difficulties.collect do |difficulty|
+      [
+        difficulty.title,
+        admin_conference_program_event_path(
+          conference_id,
+          event,
+          event: { difficulty_level_id: difficulty.id }
+        )
+      ]
+    end
+    active_dropdown(selection, options)
+  end
+
+  def state_dropdown(event, conference_id, email_settings)
+    selection = event.state.humanize
+    options = []
+    if event.transition_possible? :accept
+      options << [
+        'Accept',
+        accept_admin_conference_program_event_path(conference_id, event)
+      ]
+      if email_settings.send_on_accepted?
+        options << [
+          'Accept (without email)',
+          accept_admin_conference_program_event_path(
+            conference_id,
+            event,
+            send_mail: false
+          )
+        ]
+      end
+    end
+    if event.transition_possible? :reject
+      options << [
+        'Reject',
+        reject_admin_conference_program_event_path(conference_id, event)
+      ]
+      if email_settings.send_on_rejected?
+        options << [
+          'Reject (without email)',
+          reject_admin_conference_program_event_path(
+            conference_id,
+            event,
+            send_mail: false
+          )
+        ]
+      end
+    end
+    if event.transition_possible? :restart
+      options << [
+        'Start review',
+        restart_admin_conference_program_event_path(conference_id, event)
+      ]
+    end
+    if event.transition_possible? :confirm
+      options << [
+        'Confirm',
+        confirm_admin_conference_program_event_path(conference_id, event)
+      ]
+    end
+    if event.transition_possible? :cancel
+      options << [
+        'Cancel',
+        cancel_admin_conference_program_event_path(conference_id, event)
+      ]
+    end
+    active_dropdown(selection, options)
+  end
+
+  private
+
+  def active_dropdown(selection, options)
+    # Consistent rendering of dropdown lists that submit patched changes
+    #
+    # Selection is the string to show by default, which is clicked to expose the
+    # dropdown options.
+    # Options is a list of 2-item lists; for each entry:
+    # * [0] is the text of the option,
+    # * [1] is the link url for the options
+    content_tag('div', class: 'dropdown') do
+      content_tag(
+        'a',
+        class: 'dropdown-toggle',
+        href:  '#',
+        data:  { toggle: 'dropdown' }
+      ) do
+        content_tag('span', selection) +
+          content_tag('span', '', class: 'caret')
+      end +
+        content_tag('ul', class: 'dropdown-menu') do
+          options.collect do |option|
+            content_tag('li', link_to(option[0], option[1], method: :patch))
+          end.join.html_safe
+        end
+    end
+  end
 end