require 'logger'
require 'syslog'

module Byteback
  #
  # Translates Ruby's Logger calls to similar calls to Syslog
  # (implemented in Ruby 2.0 as Syslog::Logger).
  #
  # We need to neuter % signs which are taken as format strings.
  #
  class SyslogProxy
    class << self
      def debug(m)
        log_nopc(Syslog::LOG_DEBUG, m)
      end

      def info(m)
        log_nopc(Syslog::LOG_INFO, m)
      end

      def warn(m)
        log_nopc(Syslog::LOG_WARNING, m)
      end

      def error(m)
        log_nopc(Syslog::LOG_ERR, m)
      end

      #
      # syslog(3) says:
      #
      # LOG_EMERG means "system is unusable"
      # LOG_ERR   means "error conditions"
      #
      # Errors might be fatal to Byteback, but they're unlikely to make the
      # whole server unusable.  So lets dial this down to ERR from EMERG.
      #
      def fatal(m)
        log_nopc(Syslog::LOG_ERR, m)
      end

      def log_nopc(level, m)
        Syslog.log(level, m.gsub('%', '%%'))
      end
    end
  end

  # Log proxy class that we can include in our scripts for some simple
  # logging defaults.
  #
  module Log
    @@me = File.expand_path($PROGRAM_NAME).split('/').last

    #
    #  If we're running interactively then we have simple logging.
    #
    if STDIN.tty?

      #
      #  We log to the console.
      #
      logger = Logger.new(STDERR)
      logger.level = Logger::DEBUG
      logger.formatter = proc { |severity, _datetime, _progname, msg|
        if severity == 'FATAL' || severity == 'ERROR'
          "*** #{msg}\n"
        else
          "#{msg}\n"
        end
      }
      @@logger = logger
    else

      #
      #  Otherwise we log via our Syslog-proxy.
      #
      Syslog.open(@@me)
      @@logger = SyslogProxy
    end

    def debug(*a)
      @@logger.__send__(:debug, *a)
    end

    def info(*a)
      @@logger.__send__(:info, *a)
    end

    def warn(*a)
      @@logger.__send__(:warn, *a)
    end

    def fatal(*a)
      @@logger.__send__(:fatal, *a)
      exit 1
    end

    def error(*a)
      @@logger.__send__(:error, *a)
    end
  end
end