easy-going-rails/lib/formatters/ansi_formatter.rb

require_relative 'ansi_wrapper'
require_relative 'ansi_colors'

require 'io/console'
require 'amazing_print'
require 'json'

# wraps meanwhile takes care of ansi colors
class AnsiFormatter < SemanticLogger::Formatters::Color
  include AnsiColors

  ANSI_DEBUG = CLEAR + TEXT_GRAY_400
  ANSI_INFO = CLEAR + TEXT_GRAY_100
  ANSI_WARN = CLEAR + BG_YELLOW + TEXT_BLACK
  ANSI_ERROR = CLEAR + BG_RED + TEXT_WHITE
  ANSI_FATAL = CLEAR + BG_MAGENTA + BOLD + TEXT_WHITE
  NAME_MAX_SIZE = 20
  FOREMAN_PREFIX_LENGTH = 18
  DEFAULT_UNDETECTED_WRAP = 80

  def initialize
    super(color_map: ColorMap.new(
      debug: ANSI_DEBUG,
      info: ANSI_INFO,
      warn: ANSI_WARN,
      error: ANSI_ERROR,
      fatal: ANSI_FATAL
    ))
  end

  def call(log, logger)
    self.log = log
    self.logger = logger
    self.color = color_map[log.level]
    wrap_length = compute_useful_length
    wrap_level(wrap_length, message, payload, exception)
  end

  def origin
    origin = log.name.truncate(NAME_MAX_SIZE).center(NAME_MAX_SIZE)
    colorize(origin, AnsiColors::TEXT_CYAN)
  end

  def message
    return unless log.message

    colorize(log.message)
  end

  def exception
    return unless log.exception

    clazz = "#{log.exception.class}\n"
    message = log.exception.message.chomp('')
    backtrace = clean_backtrace(log.exception.backtrace)

    "#{colorize(clazz, ANSI_FATAL)}#{colorize(message, ANSI_ERROR)}#{backtrace}"
  end

  private

  def colorize(text, tint = color)    = "#{tint}#{text}#{AnsiColors::CLEAR}"
  def build_prefix                    = "#{origin} #{colorize(draw_rails(level_char))}  "
  def build_continuation              = "#{origin} #{colorize(draw_rails('┆'))}  "
  def draw_rails(char)                = "╣#{char}╠"

  def compute_useful_length
    IO.console.winsize[1] - FOREMAN_PREFIX_LENGTH
  rescue StandardError
    DEFAULT_UNDETECTED_WRAP
  end

  def clean_backtrace(backtrace)
    root_path = Rails.root.to_s
    backtrace = backtrace.select { |line| line.starts_with?(root_path) }
    backtrace = backtrace.map { |line| line.delete_prefix("#{root_path}/") }
    backtrace.compact.join("\n")
  end

  def level_char
    case log.level
    when :info, :debug then ' '
    else log.level.to_s.chr.upcase
    end
  end

  def wrap_level(length, *items)
    prefix = build_prefix
    continuation = build_continuation
    items.map do |item|
      AnsiWrapper.wrap(item, length, prefix, continuation)
    end.compact.join("\n")
  end
end