#!/usr/bin/env ruby

# Files
pid_file = "/tmp/#{File.basename($PROGRAM_NAME)}.pid"
log_file = "/tmp/#{File.basename($PROGRAM_NAME)}.log"

# Run only run one daemon at a time.
if File.exists?(pid_file)
  puts "PID file exists already!" 
  exit
end

# Daemonize
if RUBY_VERSION < "1.9"
  exit if fork
  Process.setsid
  exit if fork
  STDIN.reopen "/dev/null"
  STDOUT.reopen "/dev/null", "a"
  STDERR.reopen "/dev/null", "a"
else
  Process.daemon
end

# Register signal handlers.
at_exit { File.delete(pid_file) }
[:TERM, :INT, :QUIT, :HUP].each do |signal|
  trap(signal) do
    File.open(log_file, 'a') do |f|
      f.puts "Daemon received #{signal} signal."
      f.puts "Daemon #{(signal == :HUP && 'refreshed') || 'stopped'}."
    end
    exit unless signal == :HUP
  end
end

# Forked childs write a PID file on startup.
File.open(pid_file, 'w') { |f| f.puts(Process.pid) }

# Overwrite log file.
File.open(log_file, 'w') { |f| f.puts 'Daemon started...' }

# Finally run the lazy daemon
loop { sleep 1 }