class Format
  ZERO_WIDTH = "​"

  def self.i(str)
    "_#{str}_"
  end

  def self.b(str)
    "**#{str}**"
  end

  def self.bi(str)
    "***#{str}***"
  end

  def self.u(str)
    "__#{str}__"
  end

  def self.ui(str)
    "__*#{str}*__"
  end

  def self.ub(str)
    "__**#{str}**__"
  end

  def self.ubi(str)
    "__***#{str}***__"
  end

  def self.strike(str)
    "~~#{str}~~"
  end

  def self.inline(str)
    "`#{str.gsub("`", "'")}`"
  end

  def self.code(str, language: nil)
    str = str.gsub("`") { ZERO_WIDTH * 2 + "`" }
    "```#{language}\n#{str}\n```"
  end

  def self.margin(str, margin: 2)
    "\n" + str.lines.map { |l| " " * margin + l }.join + "\n" * 2
  end

  def self.escape(str)
    str = str.gsub('\\') { "\\\\" }.gsub("_") { '\\_' }
    str = str.gsub("*") { "\\*" }.gsub("`") { ZERO_WIDTH * 2 + "`" }
    str.gsub("~") { "\\~" }
  end

  def self.number(n)
    n = n.to_i if n.to_i == n

    ActiveSupport::NumberHelper.number_to_delimited(n)
  end
end