#!/usr/bin/ruby -w

def log( message, prefix = "" )
  open( "/var/log/switch-network.log", "a" ) { |f|
    message.split( /\n/ ).each { |e|
      f.puts prefix + " " + e.rstrip
    }
  }
end

log( "------ switch-network run at: " + `date` )

$situations = Array.new

interfaces_directory = "/etc/network/"

Dir.new(interfaces_directory).entries.each do |e|
  if e =~ /^interfaces\.(.*[^~])$/
    $situations.push $1
  end
end

$situations.sort!

def usage
  puts "Usage: switch-network <situation>"
  puts "... where <situation> is one of:"
  $situations.each do |s|
    puts " * " + s
  end
end

unless ARGV.length == 1
  usage
  log( "Bad usage: switch-network #{ARGV.join(' ')}", '-' )
  exit( -1 )
end

log( "Available situations:", '-' )
$situations.each do |s|
  log( s, '*' )
end

new_situation = ARGV[0]

unless $situations.index( new_situation )
  usage
  exit( -1 )
end

log( "Switching to network: #{new_situation}", "#" )

unless system( "/sbin/ifdown", "-a" )
  log "Warning: Couldn't lower all the interfaces.", '-'
  puts "Warning: Couldn't lower all the interfaces."
end

# Sometimes it seems it's better to unload the wireless modules
# as well when switching network.

unless new_situation == "loopback"

  log( "Removing ipw2200 module...", '-' )
  system "/sbin/rmmod", "ipw2200"

  log( "Modprobing ipw2200 module...", '-' )
  system "/sbin/modprobe", "ipw2200"

end

log( "Copying interfaces file...", '-' )

system( "/bin/cp",
        "#{interfaces_directory}/interfaces.#{new_situation}",
        "#{interfaces_directory}/interfaces" )

log( "Raising interfaces again...", '-' )

system "/sbin/ifup", "-a"

log( "Done switching networks.", '-' )