#!/usr/bin/ruby -w

require 'yaml'
require 'cgi'

configuration_file = ENV['HOME'] + "/.bluesocket"

begin
  login = YAML.load( open( configuration_file, "r" ) )
  unless login.has_key? 'username'
    message = "Your username isn't specified in #{configuration_file}\n"
    message += "One of the lines should be 'username: sXXXXXXX'"
  end
  unless login.has_key? 'username'
    message = "Your password isn't specified in #{configuration_file}\n"
    message += "One of the lines should be 'password: blahblahblah'"
    raise message
  end
  unless login.has_key? 'url'
    message = "The base bluesocket URL isn't specified in "
    message += configuration_file + "\n"
    message += "One of the lines should be (e.g.): "
    message += "'url: https://wlangate.net.ed.ac.uk/'"
    raise message
  end
rescue
  puts"There was an error when trying to load the configuration file:"
  puts $!
  exit( -1 )
end

login_url = login['url'] + "/login.pl"
logout_popup_url = login['url'] + "/login.pl?action=logoutPopup"

def usage
  puts "Usage: bluesocket [ --logout ]"
end

if (ARGV.length == 1) && (ARGV[0] == "--logout")
  logout = true
elsif ARGV.empty?
  logout = false
else
  usage
  exit( -1 )
end

# To see whether the command actually succeeded or not, use $?.success?

def get_web_page( url, username = nil, password = nil )

  result = Array.new

  Kernel.open( "|-", "r" ) do |f|
    if f
      f.each_line { |line| result.push line }
    else
      begin
        exec( "curl", "-s", "-k", "-L", "-o", "-", url )
      rescue
        raise "Failed to invoke 'curl'"
      end
    end
  end

  result

end

if logout

  lines_in_logout_page = get_web_page( logout_popup_url )

  lines_in_logout_page.each do |line|
    if line =~ /\'(login.pl\?action=logout[^\']+)\'/
      # Then we found the logout URL, so use that.
      get_web_page( login['url'] + $1 )
      exit( 0 )
    end
  end

  # If we didn't find that line, then we're already logged out.

else
  
  lines_in_login_page = get_web_page( login_url )
 
  parameters = {
    '_FORM_SUBMIT' => '1',
    'which_form' => 'reg',
    'destination' => '',
    'error' => ''
  }

  # We need to add to those:
  #   source => IP address
  #   bs_name => bluesocket username
  #   bs_password => bluesocket password

  source_ip = nil

  lines_in_login_page.each do |line|
    if line =~ /\"source\" value=\"([0-9\.]+)\"/
      source_ip = $1
    end
  end 

  if source_ip # Otherwise we're probably logged in already...

    parameters['source'] = source_ip
    parameters['bs_name'] = login['username']
    parameters['bs_password'] = login['password']

    command = [ "curl", "-s", "-k", "-o", "/dev/null" ]

    parameters.each_pair do |key,value|
      command.concat [ "-d", key + "=" + CGI.escape(value) ]
    end

    command.push login['url'] + "login.pl"
    
    system( *command )

  end
  
end