require 'erb'
require 'tilt/erb'
require 'tuktuk'
require 'snails'

module Snails

  class Mailer
    include Snails::SimpleFormat
    Time.include(Snails::RelativeTime) unless Time.instance_methods.include?(:relative)

    @queue = :emails

    def initialize(opts)
      mail_config = (opts[:smtp] || opts[:mail]) or raise ":smtp options missing"

      if key = mail_config.dig(:dkim, :private_key) and File.exist?(key)
        mail_config[:dkim][:private_key] = IO.read(key)
      elsif mail_config[:dkim]
        puts "Private key for DKIM not found! Disabling..."
        mail_config.delete(:dkim)
      end

      Tuktuk.options = mail_config
      @debug         = mail_config[:debug]
      @from_email    = opts[:from] or raise ":from required"
      @base_subject  = opts[:base_subject] || ''
      @views         = opts[:views] || Snails.root.join('lib', 'views')
      @logfile       = opts[:logfile] # || Snails.root.join('log', 'mailer.log')
    end

    def email(name, &block)
      define_singleton_method(name) do |*args|
        instance_exec(*args, &block) 
      end
    end

    def helpers(&block)
      instance_eval(&block) 
    end

    def perform(method, *args)
      send(method, *args)
    end

    # e.g. Notifier.queue(:some_notification, @project, "arg1")
    def queue(method, obj, *args)
      return unless Snails.env.production?
      Resque.enqueue(self, method, obj.id, *args)
    end

    def send_error(to: @from_email, err:, env:, params: {})
      @exception, @env, @params = err, env, params
      @url = "#{env['REQUEST_METHOD']} #{env['REQUEST_URI']}"

      subject = "#{@url} :: (#{@exception.class}) \"#{@exception.message}\""
      content = %{
A <%= @exception.class %> occurred in <%= @url %>:

  -----------------

<%= @exception.message %>

<%= @exception.backtrace.join("\n") %>

  -----------------

- Request    : <%= @url %>
- Parameters : <%= @params.inspect %>
- IP address : <%= @env['REMOTE_ADDR'] %>
- User agent : <%= @env['HTTP_USER_AGENT'] %>
- Process    : <%= $$ %>
- Server     : <%= `hostname -s`.chomp %>

  -----------------
      }.strip

      send_email(to: to, subject: subject, body: content)
    end

    private

    def render(view)
      template = File.read(File.join(@views, "#{view}.erb"))
      ERB.new(template).result(binding)
    end

    def partial(name)
      partial_name = name.to_s["/"] ? name.to_s.reverse.sub("/", "_/").reverse : "_#{name}"
      render partial_name
    end

    def logger
      @logger ||= @logfile ? Logger.new(@logfile) : Snails.logger
    end

    def send_email(from: nil, to:, subject:, body: nil, template: nil, html_body: nil, html_template: nil)
      raise "No recipient given for mail: #{subject}!" if to.blank?

      message = {
        to:      to,
        from:    from || @from_email,
        subject: @base_subject + subject 
      }

      if body or template
        message[:body]  = template ? render(template) : body
      end

      if html_body or html_template
        message[:html_body] = html_template ? render(html_template) : html_body
      end

      logger.info "[#{to}] Delivering: #{subject}" 
      debug = @debug.nil? ? !Snails.env.production? : @debug # if debug isn't set, determine based on env
      resp, email = Tuktuk.deliver(message, debug: debug)

      if resp.is_a?(Tuktuk::Bounce)
        logger.info "[#{to}] Email bounced! [#{resp.code}] #{resp.message}"
      end

      return resp, email
    end

  end

end