Attempt to not use a timezone when it is not recognized

app/models/region.rb

@@ -23,6 +23,7 @@ class Region < ApplicationRecord
   def tzid
     country = TZInfo::Country.get region.try(:code) || code
     if country.present? && country.zone_identifiers.length.positive?
+      # Get arbitrarily the first zone for this country
       country.zone_identifiers[0]
     else
       Time.now.zone

app/views/events/index.ics.haml

@@ -5,6 +5,7 @@
   cal = Icalendar::Calendar.new
   @events.each do |event|
     tzid = event.region.tzid
+    use_timezone = true
     if cal.timezones.none? { |t| tzid == t.tzid }
       # Only add this zone once
       begin
@@ -13,14 +14,21 @@
         cal.add_timezone timezone
       rescue TZInfo::InvalidTimezoneIdentifier
         # No need to add this tz
+        use_timezone = false
       end
     end
 
     cal.event do |e|
-      e.dtstamp     = Icalendar::Values::DateTime.new event.decision_time, tzid: tzid
+      if use_timezone
+        e.dtstamp   = Icalendar::Values::DateTime.new event.decision_time, tzid: tzid
+        e.dtstart   = Icalendar::Values::DateTime.new event.start_time, tzid: tzid
+        e.dtend     = Icalendar::Values::DateTime.new event.end_time, tzid: tzid
+      else
+        e.dtstamp   = Icalendar::Values::DateTime.new event.decision_time.localtime
+        e.dtstart   = Icalendar::Values::DateTime.new event.start_time.localtime
+        e.dtend     = Icalendar::Values::DateTime.new event.end_time.localtime
+      end
       e.uid         = "#{event.id}@#{request.domain}"
-      e.dtstart     = Icalendar::Values::DateTime.new event.start_time, tzid: tzid
-      e.dtend       = Icalendar::Values::DateTime.new event.end_time, tzid: tzid
       e.summary     = event.title
       e.description = to_markdown event.description.tr '\'', '’'
       e.location    = event.full_address.tr '\'', '’'

test/models/region_test.rb

@@ -12,6 +12,6 @@ class RegionTest < ActiveSupport::TestCase
   end
 
   test 'check other timezone is local timezone' do
-    assert regions(:region_other).tzid == Time.now.zone
+    assert regions(:region_other).tzid == 'CEST'
   end
 end