class EcoRake
  module Utils
    # Mailer helper that uses `aws-sdk-ses` **gem** (`Aws::SES::Client`)
    # Several ENV vars should be configured for it to work (i.e. in the `.env` file):
    #   1. `MAILER_REGION`
    #   2. `MAILER_KEY_ID`
    #   3. `MAILER_ACCESS_KEY`
    #   4. `MAILER_FROM`
    class Mailer
      # Sends an email
      # @param to [String] destination email address
      # @param subject [String] subject of the email
      # @param body [String] `html` or plain text message
      # @param from [String] the email address this is send **from**
      def mail(to:, subject:, body:, from: nil, cc: nil, bcc: nil)
        unless configured?
          puts "Mailer: You are missing configuration parameters. Review your .env file"
          return false
        end
        ses.send_email(
          destination: fetch_to(to: to, cc: cc, bcc: bcc),
          source:      fetch_from(from),
          message:     {
            subject: {
              charset: "UTF-8",
              data:    subject
            },
            body:    {
              # NOTEL: `html:` will let you send html instead
              # you can use both at once if you like
              text: {
                charset: "UTF-8",
                data:    body
              }
            }
          }
        ).tap do |response|
          puts "Sent email to #{to} (MessageId: #{response.message_id})"
        end
      end

      # @return [Boolean] whether or not the mailer is configured for usage.
      def configured?
        fetch_access_key_id && fetch_secret_access_key && fetch_region
      end

      private

      def ses
        require 'aws-sdk-ses'
        begin
          @ses ||= Aws::SES::Client.new(
            access_key_id:     fetch_access_key_id,
            secret_access_key: fetch_secret_access_key,
            region:            fetch_region
          )
        rescue StandardError => e
          puts "Trying to send an email with wrong email configuration: #{e}"
        end
        @ses
      end

      def fetch_to(to: nil, cc: nil, bcc: nil)
        {
          to_addresses: [to].flatten.compact.uniq
        }.tap do |dest|
          cc  = [cc].flatten.compact.uniq
          bcc = [bcc].flatten.compact.uniq
          dest.merge!(cc_addresses: cc)   unless cc.empty?
          dest.merge!(bcc_addresses: bcc) unless bcc.empty?
        end
      end

      def fetch_from(value = nil)
        value || ENV['MAILER_FROM']
      end

      def fetch_access_key_id
        ENV['MAILER_KEY_ID']
      end

      def fetch_secret_access_key
        ENV['MAILER_ACCESS_KEY']
      end

      def fetch_region
        ENV['MAILER_REGION']
      end
    end
  end
end