require "logger"
require "pp"

#== MonoLogger
# A subclass of Ruby's stdlib Logger with all the mutex and logrotation stuff
# ripped out.
class MonoLogger < Logger

  #
  # === Synopsis
  #
  #   Logger.new(name, shift_age = 7, shift_size = 1048576)
  #   Logger.new(name, shift_age = 'weekly')
  #
  # === Args
  #
  # +logdev+::
  #   The log device.  This is a filename (String) or IO object (typically
  #   +STDOUT+, +STDERR+, or an open file).
  # +shift_age+::
  #   Number of old log files to keep, *or* frequency of rotation (+daily+,
  #   +weekly+ or +monthly+).
  # +shift_size+::
  #   Maximum logfile size (only applies when +shift_age+ is a number).
  #
  # === Description
  #
  # Create an instance.
  #
  def initialize(logdev)
    @progname = nil
    @level = DEBUG
    @default_formatter = Formatter.new
    @formatter = nil
    @logdev = nil
    if logdev
      @logdev = LocklessLogDevice.new(logdev)
    end
  end

  class LocklessLogDevice < LogDevice

    def initialize(log = nil)
      @dev = @filename = @shift_age = @shift_size = nil
      if log.respond_to?(:write) and log.respond_to?(:close)
        @dev = log
      else
        @dev = open_logfile(log)
        @filename = log
      end
      @dev.sync = true
    end

    def write(message)
      @dev.write(message)
    rescue Exception => ignored
      warn("log writing failed. #{ignored}")
    end

    def close
      @dev.close rescue nil
    end

  private

    def open_logfile(filename)
      if FileTest.exist?(filename)
        open(filename, (File::WRONLY | File::APPEND))
      else
        create_logfile(filename)
      end
    end

    def create_logfile(filename)
      logdev = open(filename, (File::WRONLY | File::APPEND | File::CREAT))
      add_log_header(logdev)
      logdev
    end

    def add_log_header(file)
      file.write(
        "# Logfile created on %s by %s\n" % [Time.now.to_s, Logger::ProgName]
      )
    end

  end

end