pdf_mailer.rb

# frozen_string_literal: true

# PdfMailer is responsible for sending emails that contain PDF attachments.
# It formats the email using the user's details and attaches the generated PDF.
class PdfMailer < ApplicationMailer
  # Sends an email with the generated PDF attachment.
  #
  # @param input [Hash] A hash containing input data including:
  #   - :user [User] The user receiving the email.
  #   - :template [Templates::Template] The template associated with the PDF.
  #   - :tmpfile [Tempfile] The temporary file containing the generated PDF.
  #
  # @return [Mail::Message] The mail object.
  def pdf_generated(input)
    after_inserting_attachments(input) do
      @user = input[:user]
      mail(**mailer_params_from_input(input))
    end
  end

  private

  # Prepares the parameters for the mailer from the input hash.
  #
  # @param input [Hash] The input data for generating the email.
  #
  # @return [Hash] A hash containing the parameters for the mailer.
  def mailer_params_from_input(input)
    {
      to: input[:user].email,
      from: "#{input[:user].first_name} <#{default_email_sender}>",
      template_path: 'pdf_mailer',
      template_name: 'basic_example',
      formats: [:html],
      subject: "#{input[:user].first_name}'s Invoice - #{formatted_todays_date}"
    }
  end

  # Inserts the PDF attachment into the email.
  #
  # @param input [Hash] The input data containing the PDF details.
  #
  # @yield [void] Yields control to the block after attachments are inserted.
  def after_inserting_attachments(input)
    attachments[input[:template].reference_file_name] = File.read(input[:tmpfile].path)
    yield
  end

  # Formats today's date into a string.
  #
  # @return [String] The formatted date string.
  def formatted_todays_date
    Date.today.strftime('%a, %b %e, %Y')
  end

  # Retrieves the default email sender address from the environment variable.
  #
  # @return [String] The default email sender address.
  def default_email_sender
    @default_email_sender ||= ENV["EMAIL_SENDER"]
  end
end