feat: add Resend email delivery method and configuration (#11)

* feat: add Resend email delivery method and configuration

* chore: simplify ResendProvider initialization by removing settings parameter

* test: update ResendProvider initialization in tests by removing unnecessary settings parameter

* chore: improvements

.env.example

@@ -262,3 +262,5 @@ AZURE_APP_SECRET=
 BAILEYS_PROVIDER_DEFAULT_CLIENT_NAME=Chatwoot
 BAILEYS_PROVIDER_DEFAULT_URL=http://localhost:3025
 BAILEYS_PROVIDER_DEFAULT_API_KEY=
+
+RESEND_API_KEY=

Gemfile

@@ -178,6 +178,8 @@ gem 'ruby-openai'
 
 gem 'shopify_api'
 
+gem 'resend', '~> 0.19.0'
+
 ### Gems required only in specific deployment environments ###
 ##############################################################
 

Gemfile.lock

@@ -634,6 +634,8 @@ GEM
       uber (< 0.2.0)
     request_store (1.5.1)
       rack (>= 1.4)
+    resend (0.19.0)
+      httparty (>= 0.21.0)
     responders (3.1.1)
       actionpack (>= 5.2)
       railties (>= 5.2)
@@ -957,6 +959,7 @@ DEPENDENCIES
   rails (~> 7.0.8.4)
   redis
   redis-namespace
+  resend (~> 0.19.0)
   responders (>= 3.1.1)
   rest-client
   reverse_markdown

app/views/devise/mailer/reset_password_instructions.html.erb

@@ -4,5 +4,7 @@
 
 <p><%= link_to 'Change my password', frontend_url('auth/password/edit', reset_password_token: @token) %></p>
 
+<p style="color: #999999; font-size: 12px;">Copy and paste the URL into your browser if the link above doesn't work: <%= frontend_url('auth/password/edit', reset_password_token: @token) %></p>
+
 <p>If you didn't request this, please ignore this email.</p>
 <p>Your password won't change until you access the link above and create a new one.</p>

config/initializers/mailer.rb

@@ -1,3 +1,5 @@
+require_relative '../../lib/mail/resend_provider'
+
 Rails.application.configure do
   #########################################
   # Configuration Related to Action Mailer
@@ -36,6 +38,9 @@ Rails.application.configure do
   # You can use letter opener for your local development by setting the environment variable
   config.action_mailer.delivery_method = :letter_opener if Rails.env.development? && ENV['LETTER_OPENER']
 
+  config.action_mailer.delivery_method = :resend if ENV['RESEND_API_KEY'].present?
+  ActionMailer::Base.add_delivery_method :resend, Mail::ResendProvider
+
   #########################################
   # Configuration Related to Action MailBox
   #########################################

config/initializers/resend.rb

@@ -0,0 +1,3 @@
+require 'resend'
+
+Resend.api_key = ENV.fetch('RESEND_API_KEY', nil)

lib/mail/resend_provider.rb

@@ -0,0 +1,29 @@
+module Mail # rubocop:disable Style/ClassAndModuleChildren
+  class ResendProvider
+    class DeliveryError < StandardError; end
+
+    def initialize(_settings); end # rubocop:disable Style/RedundantInitialize
+
+    def deliver!(mail)
+      Resend::Emails.send(
+        from: mail.smtp_envelope_from,
+        to: mail.smtp_envelope_to,
+        subject: mail.subject,
+        html: mail.decoded,
+        text: sanitize_html(mail.decoded)
+      )
+    rescue Resend::Error => e
+      raise DeliveryError, "Failed to send email: #{e.message}"
+    rescue StandardError => e
+      raise DeliveryError, "An error occurred while sending email: #{e.message}"
+    end
+
+    private
+
+    def sanitize_html(html)
+      sanitized = ActionView::Base.full_sanitizer.sanitize(html)
+      # NOTE: Remove more than two consecutive newlines
+      sanitized.lines.map(&:strip).join("\n").gsub(/\n{3,}/, "\n\n").strip
+    end
+  end
+end

spec/lib/mail/resend_provider_spec.rb

@@ -0,0 +1,57 @@
+require 'rails_helper'
+
+describe Mail::ResendProvider do
+  let(:provider) { described_class.new({}) }
+  let(:mail) do
+    instance_double(Mail::Message,
+                    smtp_envelope_from: 'sender@example.com',
+                    smtp_envelope_to: ['receiver@example.com'],
+                    subject: 'Test Email',
+                    decoded: '<p>This is a test email message.</p>')
+  end
+
+  describe '#deliver!' do
+    it 'calls Resend with the correct parameters' do
+      response = instance_double(HTTParty::Response, success?: true)
+      allow(Resend::Emails).to receive(:send)
+        .with(
+          from: 'sender@example.com',
+          to: ['receiver@example.com'],
+          subject: 'Test Email',
+          html: '<p>This is a test email message.</p>',
+          text: 'This is a test email message.'
+        )
+        .and_return(response)
+
+      provider.deliver!(mail)
+
+      expect(Resend::Emails).to have_received(:send)
+    end
+
+    context 'when response is not successful' do
+      it 'raises a DeliveryError with the error message' do
+        allow(Resend::Emails).to receive(:send)
+          .with(
+            from: 'sender@example.com',
+            to: ['receiver@example.com'],
+            subject: 'Test Email',
+            html: '<p>This is a test email message.</p>',
+            text: 'This is a test email message.'
+          )
+          .and_raise(Resend::Error.new('Service unavailable'))
+
+        expect { provider.deliver!(mail) }
+          .to raise_error(described_class::DeliveryError, 'Failed to send email: Service unavailable')
+      end
+    end
+
+    context 'when an exception occurs during sending' do
+      it 'raises a DeliveryError with the exception message' do
+        allow(Resend::Emails).to receive(:send).and_raise(StandardError, 'Connection timed out')
+
+        expect { provider.deliver!(mail) }
+          .to raise_error(described_class::DeliveryError, 'An error occurred while sending email: Connection timed out')
+      end
+    end
+  end
+end