feat: Implement event RSVP functionality with ICS export

- Added RSVP actions (interested, going, cancel) in EventsController.
- Created EventAttendance model to track RSVPs with validations.
- Introduced EventAttendancePolicy for access control on RSVP actions.
- Implemented ICS export functionality for events.
- Updated routes to include RSVP and ICS endpoints for events.
- Enhanced Event and Calendar models to support associations with EventAttendance and CalendarEntry.
- Added views for RSVP actions and ICS download link in event show page.
- Created tests for EventsController, EventAttendance model, and policies.
- Updated documentation to reflect new features and usage.

Author: rsmithlal

app/controllers/better_together/calendars_controller.rb

@@ -4,6 +4,12 @@ module BetterTogether
   # CRUD for calendars
   class CalendarsController < FriendlyResourceController
     # GET /better_together/calendars
+    def show
+      @calendar = set_resource_instance
+      authorize @calendar
+      @upcoming_events = @calendar.events.upcoming.order(:starts_at)
+      @past_events = @calendar.events.past.order(starts_at: :desc)
+    end
 
     # GET /better_together/calendars/new
     def new

app/controllers/better_together/events_controller.rb

@@ -14,10 +14,52 @@ def index
       @past_events = @events.past
     end
 
+    def show
+      super
+    end
+
+    def ics
+      send_data @event.to_ics,
+                filename: "#{@event.slug}.ics",
+                type: 'text/calendar; charset=UTF-8'
+    end
+
+    # RSVP actions
+    def rsvp_interested
+      rsvp_update('interested')
+    end
+
+    def rsvp_going
+      rsvp_update('going')
+    end
+
+    def rsvp_cancel
+      @event = set_resource_instance
+      authorize @event, :show?
+      attendance = BetterTogether::EventAttendance.find_by(event: @event, person: helpers.current_person)
+      attendance&.destroy
+      redirect_to @event, notice: t('better_together.events.rsvp_cancelled', default: 'RSVP cancelled')
+    end
+
     protected
 
     def resource_class
       ::BetterTogether::Event
     end
+
+    private
+
+    def rsvp_update(status)
+      @event = set_resource_instance
+      authorize @event, :show?
+      attendance = BetterTogether::EventAttendance.find_or_initialize_by(event: @event, person: helpers.current_person)
+      attendance.status = status
+      authorize attendance
+      if attendance.save
+        redirect_to @event, notice: t('better_together.events.rsvp_saved', default: 'RSVP saved')
+      else
+        redirect_to @event, alert: attendance.errors.full_messages.to_sentence
+      end
+    end
   end
 end

app/controllers/better_together/resource_controller.rb

@@ -3,8 +3,8 @@
 module BetterTogether
   # Abstracts the retrieval of resources
   class ResourceController < ApplicationController # rubocop:todo Metrics/ClassLength
-    before_action :set_resource_instance, only: %i[show edit update destroy]
-    before_action :authorize_resource, only: %i[new show edit update destroy]
+    before_action :set_resource_instance, only: %i[show edit update destroy ics]
+    before_action :authorize_resource, only: %i[new show edit update destroy ics]
     before_action :resource_collection, only: %i[index]
     before_action :authorize_resource_class, only: %i[index]
     after_action :verify_authorized, except: :index

app/models/better_together/calendar.rb

@@ -12,6 +12,9 @@ class Calendar < ApplicationRecord
 
     belongs_to :community, class_name: '::BetterTogether::Community'
 
+    has_many :calendar_entries, class_name: 'BetterTogether::CalendarEntry', dependent: :destroy
+    has_many :events, through: :calendar_entries
+
     slugged :name
 
     translates :name

app/models/better_together/calendar_entry.rb

@@ -1,6 +1,11 @@
 # frozen_string_literal: true
 
 module BetterTogether
+  # Join model between Calendar and Event for future calendar organization
   class CalendarEntry < ApplicationRecord
+    belongs_to :calendar, class_name: 'BetterTogether::Calendar'
+    belongs_to :event, class_name: 'BetterTogether::Event'
+
+    validates :event_id, uniqueness: { scope: :calendar_id }
   end
 end

app/models/better_together/event.rb

@@ -2,6 +2,7 @@
 
 module BetterTogether
   # A Schedulable Event
+  # rubocop:disable Metrics/ClassLength
   class Event < ApplicationRecord
     include Attachments::Images
     include Categorizable
@@ -16,6 +17,12 @@ class Event < ApplicationRecord
 
     attachable_cover_image
 
+    has_many :event_attendances, class_name: 'BetterTogether::EventAttendance', dependent: :destroy
+    has_many :attendees, through: :event_attendances, source: :person
+
+    has_many :calendar_entries, class_name: 'BetterTogether::CalendarEntry', dependent: :destroy
+    has_many :calendars, through: :calendar_entries
+
     categorizable(class_name: 'BetterTogether::EventCategory')
 
     # belongs_to :address, -> { where(physical: true, primary_flag: true) }
@@ -27,7 +34,6 @@ class Event < ApplicationRecord
     translates :description, backend: :action_text
 
     validates :name, presence: true
-    validates :starts_at, presence: true
     validates :registration_url, format: { with: URI::DEFAULT_PARSER.make_regexp(%w[http https]) }, allow_blank: true,
                                  allow_nil: true
     validate :ends_at_after_starts_at
@@ -75,15 +81,88 @@ def to_s
       name
     end
 
+    # Minimal iCalendar representation for export
+    def to_ics
+      lines = ics_header_lines + ics_event_lines + ics_footer_lines
+      "#{lines.join("\r\n")}\r\n"
+    end
+
     configure_attachment_cleanup
 
     private
 
+    def ics_header_lines
+      [
+        'BEGIN:VCALENDAR',
+        'VERSION:2.0',
+        'PRODID:-//Better Together Community Engine//EN',
+        'CALSCALE:GREGORIAN',
+        'METHOD:PUBLISH',
+        'BEGIN:VEVENT'
+      ]
+    end
+
+    def ics_event_lines
+      lines = []
+      lines.concat(ics_basic_event_info)
+      lines << ics_description_line if ics_description_present?
+      lines.concat(ics_timing_info)
+      lines << "URL:#{url}"
+      lines
+    end
+
+    def ics_basic_event_info
+      [
+        "DTSTAMP:#{ics_timestamp}",
+        "UID:event-#{id}@better-together",
+        "SUMMARY:#{name}"
+      ]
+    end
+
+    def ics_timing_info
+      lines = []
+      lines << "DTSTART:#{ics_start_time}" if starts_at
+      lines << "DTEND:#{ics_end_time}" if ends_at
+      lines
+    end
+
+    def ics_footer_lines
+      ['END:VEVENT', 'END:VCALENDAR']
+    end
+
+    def ics_timestamp
+      Time.current.utc.strftime('%Y%m%dT%H%M%SZ')
+    end
+
+    def ics_start_time
+      starts_at&.utc&.strftime('%Y%m%dT%H%M%SZ')
+    end
+
+    def ics_end_time
+      ends_at&.utc&.strftime('%Y%m%dT%H%M%SZ')
+    end
+
+    def ics_description_present?
+      respond_to?(:description) && description
+    end
+
+    def ics_description_line
+      desc_text = ActionView::Base.full_sanitizer.sanitize(description.to_plain_text)
+      desc_text += "\n\n#{I18n.t('better_together.events.ics.view_details_url', url: url)}"
+      "DESCRIPTION:#{desc_text}"
+    end
+
     def ends_at_after_starts_at
       return if ends_at.blank? || starts_at.blank?
       return if ends_at > starts_at
 
       errors.add(:ends_at, I18n.t('errors.models.ends_at_before_starts_at'))
     end
+
+    # Public URL to this event for use in ICS export
+    def url
+      BetterTogether::Engine.routes.url_helpers.event_url(self, locale: I18n.locale)
+    end
   end
+  # rubocop:enable Metrics/ClassLength
 end

app/models/better_together/event_attendance.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module BetterTogether
+  # Tracks a person's RSVP to an event
+  class EventAttendance < ApplicationRecord
+    STATUS = {
+      interested: 'interested',
+      going: 'going'
+    }.freeze
+
+    belongs_to :event, class_name: 'BetterTogether::Event'
+    belongs_to :person, class_name: 'BetterTogether::Person'
+
+    validates :status, inclusion: { in: STATUS.values }
+    validates :event_id, uniqueness: { scope: :person_id }
+  end
+end

app/policies/better_together/event_attendance_policy.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module BetterTogether
+  # Access control for event attendance (RSVPs)
+  class EventAttendancePolicy < ApplicationPolicy
+    def create?
+      user.present?
+    end
+
+    def update?
+      user.present? && record.person_id == agent&.id
+    end
+
+    alias rsvp_interested? update?
+    alias rsvp_going? update?
+
+    def destroy?
+      update?
+    end
+  end
+end

app/policies/better_together/event_policy.rb

@@ -11,6 +11,8 @@ def show?
       record.privacy_public? || creator_or_manager
     end
 
+    alias ics? show?
+
     def update?
       creator_or_manager
     end

app/views/better_together/events/show.html.erb

@@ -35,6 +35,9 @@
                    destroy_path: policy(@resource).destroy? ? event_path(@resource) : nil,
                    destroy_confirm: t('globals.confirm_delete'),
                    destroy_aria_label: 'Delete Record' %>
+        <div class="mt-2 text-end">
+          <%= link_to t('better_together.events.add_to_calendar', default: 'Add to calendar (.ics)'), ics_event_path(@event), class: 'btn btn-outline-secondary btn-sm' %>
+        </div>
       </div>
     </div>
   </div>
@@ -43,6 +46,27 @@
     <!-- Membership section -->
     <hr aria-hidden="true">
 
+    <!-- RSVP Actions -->
+    <% if current_person %>
+      <% attendance = BetterTogether::EventAttendance.find_by(event: @event, person: current_person) %>
+      <div class="container my-3">
+        <div class="d-flex gap-2">
+          <%= button_to t('better_together.events.rsvp_interested', default: 'Interested'), rsvp_interested_event_path(@event), method: :post, class: "btn btn-outline-primary #{'active' if attendance&.status == 'interested'}" %>
+          <%= button_to t('better_together.events.rsvp_going', default: 'Going'), rsvp_going_event_path(@event), method: :post, class: "btn btn-primary #{'active' if attendance&.status == 'going'}" %>
+          <% if attendance %>
+            <%= button_to t('better_together.events.rsvp_cancel', default: 'Cancel RSVP'), rsvp_cancel_event_path(@event), method: :delete, class: 'btn btn-outline-danger' %>
+          <% end %>
+        </div>
+        <div class="text-muted mt-2">
+          <% going_count = BetterTogether::EventAttendance.where(event: @event, status: 'going').count %>
+          <% interested_count = BetterTogether::EventAttendance.where(event: @event, status: 'interested').count %>
+          <small>
+            <%= t('better_together.events.rsvp_counts', default: 'Going: %{going} · Interested: %{interested}', going: going_count, interested: interested_count) %>
+          </small>
+        </div>
+      </div>
+    <% end %>
+
     <!-- Event tabbed section with members -->
     <section class="card tabbed-section">
       <div class="card-header">
@@ -94,4 +118,4 @@
   </div>
 
   <%= share_buttons(shareable: @event) if @event.privacy_public? %>
-</div>
+</div>