Hackathon Digest Mailer (#76)

Co-authored-by: Matt Almeida <matt7@hey.com>

Author: garyhtou

Gemfile

@@ -19,6 +19,7 @@ gem "sprockets-rails"
 gem "importmap-rails"
 gem "turbo-rails"
 gem "stimulus-rails"
+gem "premailer-rails" # Inline CSS for emails
 
 # Active Storage
 gem "aws-sdk-s3", require: false

Gemfile.lock

@@ -112,6 +112,8 @@ GEM
     countries (5.6.0)
       unaccent (~> 0.3)
     crass (1.0.6)
+    css_parser (1.14.0)
+      addressable
     date (3.3.3)
     debug (1.8.0)
       irb (>= 1.5.0)
@@ -136,6 +138,7 @@ GEM
       activerecord (>= 4.0)
       hashids (~> 1.0)
     hashids (1.0.6)
+    htmlentities (4.3.4)
     i18n (1.14.1)
       concurrent-ruby (~> 1.0)
     image_processing (1.12.2)
@@ -202,6 +205,14 @@ GEM
       ast (~> 2.4.1)
       racc
     pg (1.5.3)
+    premailer (1.21.0)
+      addressable
+      css_parser (>= 1.12.0)
+      htmlentities (>= 4.0.0)
+    premailer-rails (1.12.0)
+      actionmailer (>= 3)
+      net-smtp
+      premailer (~> 1.7, >= 1.7.9)
     public_suffix (5.0.1)
     puma (6.3.0)
       nio4r (~> 2.0)
@@ -350,6 +361,7 @@ DEPENDENCIES
   letter_opener_web
   pagy
   pg
+  premailer-rails
   puma
   rack-mini-profiler
   rails (~> 7.0.6)

app/assets/images/flag-orpheus-top.png

@@ -1,2 +1,37 @@
 module ApplicationHelper
+  # This method makes it easier to yield content with a default value.
+  #
+  # USAGE:
+  # ```
+  # <% yield_with_default_for :signature do %>
+  #   Default signature here
+  # <% end %>
+  # ```
+  #
+  # The same functionality can be achieved with the following code:
+  # ```
+  # <% if content_for?(:signature) %>
+  #   <%= yield :signature %>
+  # <% else %>
+  #   Default signature here
+  # <% end %>
+  # ```
+  #
+  # In helpers, `content_for` is used instead of `yield`.
+  #
+  # For more information regarding `yield` and `content_for`, see:
+  # - https://guides.rubyonrails.org/layouts_and_rendering.html#understanding-yield
+  # - https://apidock.com/rails/ActionView/Helpers/CaptureHelper/content_for
+  # - https://apidock.com/rails/v5.2.3/ActionView/Helpers/CaptureHelper/content_for%3F
+  def yield_with_default_for(key, &block)
+    default_key = :"default_#{key}"
+    before_key = :"before_#{key}"
+    after_key = :"after_#{key}"
+
+    content_for(default_key, &block)
+
+    concat content_for(before_key) if content_for?(before_key)
+    concat content_for?(key) ? content_for(key) : content_for(default_key)
+    concat content_for(after_key) if content_for?(after_key)
+  end
 end

app/helpers/application_helper.rb

@@ -0,0 +1,8 @@
+module MailerHelper
+  def recipient_name
+    return unless @_message&.to&.one? # Abort if there are multiple recipients
+
+    recipient = @recipient || @user || User.find_by_email_address(@_message&.to&.first)
+    recipient&.first_name
+  end
+end

app/helpers/mailer_helper.rb

@@ -1,4 +1,20 @@
 class ApplicationMailer < ActionMailer::Base
   default from: "hackathons@hackclub.com"
   layout "mailer"
+
+  helper :mailer, :application
+
+  before_action :set_default_unsubscribe_urls
+  after_action :set_unsubscribe_header
+
+  private
+
+  def set_default_unsubscribe_urls
+    @unsubscribe_url = root_url
+    @email_preferences_url = root_url
+  end
+
+  def set_unsubscribe_header
+    headers["List-Unsubscribe"] = "<#{@unsubscribe_url}>" if @unsubscribe_url
+  end
 end

app/mailers/application_mailer.rb

@@ -0,0 +1,12 @@
+class Hackathon::DigestMailer < ApplicationMailer
+  def digest
+    @digest = params[:digest]
+    @recipient = @digest.recipient
+
+    @listings_by_subscription = @digest.listings
+      .includes(:subscription, hackathon: {logo_attachment: :blob})
+      .group_by(&:subscription)
+
+    mail to: @recipient.email_address, subject: "Hackathons near you"
+  end
+end

app/mailers/hackathon/digest_mailer.rb

@@ -10,15 +10,6 @@ class Hackathon::Digest < ApplicationRecord
   private
 
   def delivery
-    # TODO: Implement
-    Class.new do
-      def method_missing(_)
-        # noop
-      end
-
-      def respond_to_missing?
-        true
-      end
-    end.new
+    Hackathon::DigestMailer.with(digest: self).digest
   end
 end

app/models/hackathon/digest.rb

@@ -1,22 +1,29 @@
 module Hackathon::Digest::Listings
   extend ActiveSupport::Concern
 
-  include ByLocation
-
   included do
     has_many :listings, dependent: :destroy
     has_many :listed_hackathons, through: :listings, source: :hackathon
     has_many :listed_subscriptions, through: :listings, source: :subscription
 
-    before_create :build_list_of_relevant_hackathons
+    before_validation :build_candidate_listings, on: :create
+    validates_length_of :listings, minimum: 1, on: :create, message: "must not be empty"
   end
 
   private
 
-  MAX_LISTINGS = 5
+  LISTING_CRITERIA = [Criterion::Location]
+  MAX_LISTINGS = 8
+
+  def applicable_listings(listing_criteria: LISTING_CRITERIA, max_listings: MAX_LISTINGS)
+    listing_criteria
+      .flat_map { |criterion| criterion.new(recipient:).candidate_listings }
+      .sort_by { |candidate| candidate[:hackathon].starts_at }
+      .first(max_listings)
+  end
 
-  def build_list_of_relevant_hackathons(max_listings: MAX_LISTINGS)
-    nearby_upcoming_hackathons.first(max_listings).each do |result|
+  def build_candidate_listings
+    applicable_listings.each do |result|
       listings.build hackathon: result[:hackathon], subscription: result[:subscription]
     end
   end