Add dynamic variable substitution to conference descriptions

app/helpers/format_helper.rb

@@ -180,6 +180,15 @@ def restricted_markdown(text, truncate: 2000)
     truncate(sanitize(markdown.render(text), remove_elements: %w[a]), length: truncate)
   end
 
+  def markdown_with_variables(text, conference, escape_html = true)
+    return '' if text.nil?
+
+    parser = EmailTemplateParser.new(conference)
+    values = parser.retrieve_values
+    text = EmailTemplateParser.parse_template(text, values)
+    markdown(text, escape_html)
+  end
+
   def markdown(text, escape_html = true)
     return '' if text.nil?
 

app/services/email_template_parser.rb

@@ -1,14 +1,12 @@
 class EmailTemplateParser
-  def initialize(conference, user)
+  def initialize(conference, user = nil)
     @conference = conference
     @user = user
   end
 
   # rubocop:disable Metrics/AbcSize, Metrics/ParameterLists
   def retrieve_values(event = nil, booth = nil, quantity = nil, ticket = nil)
     h = {
-      'email'                  => @user.email,
-      'name'                   => @user.name,
       'conference'             => @conference.title,
       'conference_start_date'  => @conference.start_date,
       'conference_end_date'    => @conference.end_date,
@@ -23,6 +21,10 @@ def retrieve_values(event = nil, booth = nil, quantity = nil, ticket = nil)
         @conference.short_title, host: Rails.application.routes.default_url_options[:host]
       )
     }
+    if @user
+      h['email'] = @user.email
+      h['name']  = @user.name
+    end
     if @conference.program.cfp
       h['cfp_start_date'] = @conference.program.cfp.start_date
       h['cfp_end_date'] = @conference.program.cfp.end_date

app/views/admin/conferences/_form_fields.html.haml

@@ -23,10 +23,12 @@
     = f.label :description
     = f.text_area :description, rows: 5, data: { provide: 'markdown' }, class: 'form-control'
     .help-block= markdown_hint('Splash page content')
+    = render partial: 'shared/help', locals: { id: 'description_help', show_event_variables: false, show_ticket_variables: false, show_user_variables: false }
   .form-group
     = f.label :registered_attendees_message, 'Message for Registered Attendees'
     = f.text_area :registered_attendees_message, rows: 5, data: { provide: 'markdown' }, class: 'form-control'
     .help-block= markdown_hint('Splash page content')
+    = render partial: 'shared/help', locals: { id: 'registered_attendees_help', show_event_variables: false, show_ticket_variables: false, show_user_variables: false }
   .form-group
     = f.color_field :color, size: 6, class: 'form-control'
     %span.help-block

app/views/conferences/_about_and_happening_now.haml

@@ -9,8 +9,8 @@
 = content_for :about do
   #about
     -if @user_registered && conference.registered_attendees_message.present?
-      = markdown(conference.registered_attendees_message, false)
-    = markdown(conference.description, false)
+      = markdown_with_variables(conference.registered_attendees_message, conference, false)
+    = markdown_with_variables(conference.description, conference, false)
 
 %section#about-and-happening-now
   .container

app/views/conferences/_conference_details.html.haml

@@ -20,7 +20,7 @@
               %span>= conference.country_name
           - unless conference.description.blank?
             %p
-              = markdown(truncate(conference.description, length: 1000, separator: "\n", escape: false), escape_html=false)
+              = markdown_with_variables(truncate(conference.description, length: 1000, separator: "\n", escape: false), conference, escape_html=false)
         .col-md-2
           .btn-group-vertical
             - if !@conference || @conference != conference

app/views/shared/_help.html.haml

@@ -1,12 +1,13 @@
 .template-help{ id: id }
   Valid attributes:
   %table.table
-    %tr
-      %td {email}
-      %td The user's email address
-    %tr
-      %td {name}
-      %td The user's full name
+    - if local_assigns.fetch(:show_user_variables, true)
+      %tr
+        %td {email}
+        %td The user's email address
+      %tr
+        %td {name}
+        %td The user's full name
     %tr
       %td {conference}
       %td The full conference title

spec/helpers/format_helper_spec.rb

@@ -30,4 +30,35 @@
         .to eq "<p><a href=\"https://example.com/\" rel=\"nofollow\">a</a></p>\n"
     end
   end
+
+  describe 'markdown_with_variables' do
+    let(:conference) do
+      create(:conference, short_title: 'snap21', title: 'SnapCon 2021',
+             start_date: Date.new(2021, 7, 12), end_date: Date.new(2021, 7, 16))
+    end
+
+    it 'substitutes conference variables and renders markdown' do
+      text = 'Welcome to **{conference}**, running {conference_start_date} to {conference_end_date}.'
+      result = markdown_with_variables(text, conference, false)
+      expect(result).to include('Welcome to <strong>SnapCon 2021</strong>')
+      expect(result).to include('2021-07-12')
+      expect(result).to include('2021-07-16')
+    end
+
+    it 'returns empty string for nil text' do
+      expect(markdown_with_variables(nil, conference)).to eq ''
+    end
+
+    it 'renders normally when there are no placeholders' do
+      text = 'Just a regular description.'
+      expect(markdown_with_variables(text, conference, false)).to eq "<p>Just a regular description.</p>\n"
+    end
+
+    it 'includes venue when conference has one' do
+      conference.venue = create(:venue)
+      text = 'Join us at {venue}.'
+      result = markdown_with_variables(text, conference, false)
+      expect(result).to include(conference.venue.name)
+    end
+  end
 end

spec/services/email_template_parser_spec.rb

@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe EmailTemplateParser do
+  let(:conference) do
+    create(:conference, short_title: 'goto', start_date: Date.new(2014, 5, 1), end_date: Date.new(2014, 5, 6))
+  end
+  let(:user) { create(:user, username: 'johnd', email: '[email protected]', name: 'John Doe') }
+
+  describe '#retrieve_values' do
+    context 'without a user' do
+      let(:parser) { described_class.new(conference, nil) }
+
+      it 'returns conference values without user values' do
+        values = parser.retrieve_values
+        expect(values['conference']).to eq conference.title
+        expect(values['conference_start_date']).to eq Date.new(2014, 5, 1)
+        expect(values['conference_end_date']).to eq Date.new(2014, 5, 6)
+        expect(values).not_to have_key('email')
+        expect(values).not_to have_key('name')
+      end
+
+      it 'includes venue when conference has one' do
+        conference.venue = create(:venue)
+        values = parser.retrieve_values
+        expect(values['venue']).to eq conference.venue.name
+        expect(values['venue_address']).to eq conference.venue.address
+      end
+
+      it 'includes cfp dates when conference has cfp' do
+        create(:cfp, start_date: Date.new(2014, 4, 29), end_date: Date.new(2014, 5, 6),
+               program: conference.program)
+        values = parser.retrieve_values
+        expect(values['cfp_start_date']).to eq Date.new(2014, 4, 29)
+        expect(values['cfp_end_date']).to eq Date.new(2014, 5, 6)
+      end
+    end
+
+    context 'with a user' do
+      let(:parser) { described_class.new(conference, user) }
+
+      it 'includes user values' do
+        values = parser.retrieve_values
+        expect(values['email']).to eq '[email protected]'
+        expect(values['name']).to eq 'John Doe'
+        expect(values['conference']).to eq conference.title
+      end
+    end
+  end
+
+  describe '.parse_template' do
+    it 'substitutes conference variables in text' do
+      values = { 'conference' => 'SnapCon 2014', 'conference_start_date' => Date.new(2014, 5, 1) }
+      text = 'Welcome to {conference}, starting {conference_start_date}!'
+      result = described_class.parse_template(text, values)
+      expect(result).to eq 'Welcome to SnapCon 2014, starting 2014-05-01!'
+    end
+
+    it 'leaves unknown placeholders alone' do
+      values = { 'conference' => 'SnapCon 2014' }
+      text = 'Welcome to {conference}, dear {name}!'
+      result = described_class.parse_template(text, values)
+      expect(result).to eq 'Welcome to SnapCon 2014, dear {name}!'
+    end
+  end
+end