Implement plaintext description method in Event model and update ApiController to use it for event descriptions

Author: edsaperia

app/controllers/api_controller.rb

@@ -29,7 +29,7 @@ def events
         e.dtstart     = Icalendar::Values::DateTime.new(ev.start_at.utc, tzid: 'UTC')
         e.dtend       = Icalendar::Values::DateTime.new(ev.end_at.utc, tzid: 'UTC')
         e.summary     = ev.name
-        e.description = "Register: #{ev.url}\n\n#{ev.description}"
+        e.description = "Register: #{ev.url}\n\n#{ev.description_plaintext}"
         e.location    = 'Newspeak House, 133 Bethnal Green Road, London, E2 7DG, UK'
         e.url         = ev.url
         e.organizer   = Icalendar::Values::CalAddress.new("mailto:#{ev.organiser_email}", cn: ev.organiser_name)

app/models/event.rb

@@ -24,4 +24,24 @@ def formatted_date_details
       "#{start_date} • #{start_time} – #{end_time} • #{location}"
     end
   end
+
+  def description_plaintext
+    text = description.to_s.dup
+    # Convert Markdown links and images to "text (url)"
+    text.gsub!(/!\[([^\]]*)\]\(([^\)]+)\)/, '\\1 (\\2)')
+    text.gsub!(/\[([^\]]+)\]\(([^\)]+)\)/, '\\1 (\\2)')
+    # Remove emphasis/strong/code markers
+    text.gsub!(/[*_]{1,3}([^*_]+)[*_]{1,3}/, '\\1')
+    text.gsub!(/`{1,3}([^`]+)`{1,3}/m, '\\1')
+    # Strip headings and blockquotes markers
+    text.gsub!(/^\s{0,3}#+\s*/, '')
+    text.gsub!(/^>\s?/, '')
+    # Normalize list markers
+    text.gsub!(/^\s*[-*+]\s+/, '- ')
+    text.gsub!(/^\s*\d+\.\s+/, '- ')
+    # Collapse excessive blank lines
+    text.gsub!(/\r\n?/, "\n")
+    text.gsub!(/\n{3,}/, "\n\n")
+    text.strip
+  end
 end