module Mentionable
  extend ActiveSupport::Concern

  module ClassMethods
    # options:
    # - message_field
    # - user_field
    def mentionable(options = {})
      @mentionable_options = options

      after_create :queue_mention_messages
    end

    def mentionable_option(key)
      @mentionable_options[key]
    end
  end

  def strip_quote_blocks(str)
    stripped = ""
    str.gsub!(/\s*\[quote\](?!\])\s*/m, "\n\n[quote]\n\n")
    str.gsub!(/\s*\[\/quote\]\s*/m, "\n\n[/quote]\n\n")
    str.gsub!(/(?:\r?\n){3,}/, "\n\n")
    str.strip!
    nest = 0
    str.split(/\n{2}/).each do |block|
      if block == "[quote]"
        nest += 1

      elsif block == "[/quote]"
        nest -= 1

      elsif nest == 0
        stripped << "#{block}\n"
      end
    end

    stripped
  end

  def queue_mention_messages
    from_id = read_attribute(self.class.mentionable_option(:user_field))
    text = strip_quote_blocks(read_attribute(self.class.mentionable_option(:message_field)))

    names = text.scan(DText::MENTION_REGEXP).map do |mention|
      mention.gsub!(/(?:^\s*@)|(?:[:;,.!?\)\]<>]$)/, "")
    end

    names.uniq.each do |name|
      body  = self.instance_exec(name, &self.class.mentionable_option(:body))
      title = self.instance_exec(name, &self.class.mentionable_option(:title))

      Dmail.create_automated(to_name: name, title: title, body: body)
    end
  end
end