#!/usr/bin/env ruby

require 'pathname'
require 'shellwords'
require 'yaml'

CONFIG_FILENAME = "~/.vpn"
PIDFILE = "/tmp/openconnect.pid"

class Vpn

    DEFAULTS = {
        "background" => true,
        "passwd-on-stdin" => true,
        "pid-file" => PIDFILE,
        "quiet" => true,
    }

    def up(config)
        abort "vpn is already up" if connected?
        opts = DEFAULTS.merge config.opts
        server = opts.delete("server") or abort "#{config.site} in #{config.filename} must specify a server"
        args = opts.map{ |key, val| val == true ? "--#{key}" : "--#{key}=#{Shellwords.escape val}"}.join(' ')
        sudo "openconnect #{args} #{server} <<< #{Shellwords.escape (passwd config.site)}"
    end

    def down
        abort "vpn is already down" unless connected?
        kill(:HUP)
    end

    def reset
        abort "vpn is not up" unless connected?
        kill(:USR2)
    end

    def connected?
        !!pid
    end

    private

    def pid
        @pid ||= begin
                     pid = File.read(PIDFILE).to_i # get process id
                     Process.kill 0, pid # probe process
                     pid
                 rescue Errno::ENOENT # no PIDFILE
                     nil
                 rescue Errno::EPERM # process exists but no permission (because of sudo)
                     pid
                 rescue SystemCallError => e # no process
                     nil
                 end
    end

    def sudo(cmd)
        system "sudo -p 'sudo password: ' #{cmd}"
    end

    def kill(signal)
        sudo "kill -s #{signal} #{pid}"
    end

    def passwd(site)
        $stdout.write "#{site} vpn password: "
        $stdout.flush
        begin
            system "stty -echo"
            @password = $stdin.gets.chomp
        ensure
            puts "\n"
            system "stty echo"
        end
    end


end

class ConfigData
    attr_reader :site, :opts, :filename
    def initialize(site)
        @filename = CONFIG_FILENAME
        begin
            @config = YAML.load Pathname(@filename).expand_path.read
        rescue Errno::ENOENT => e
            abort "Could not open config file #{@filename}"
        end
        @site = site || @config.keys.first
        @config.include? @site or abort "#{@site} not listed in #{CONFIG_FILENAME}"
        @opts = @config[@site]
    end

end
        
unless defined? RSpec

    vpn = Vpn.new

    case ARGV.shift
    when "up" then vpn.up ConfigData.new(ARGV.shift)
    when "down" then vpn.down
    when "reset" then vpn.reset
    when "status" then puts "vpn is #{vpn.connected? ? "up" : "down" }"
    else abort "usage: #{File.basename $0} up [site]|down|reset|status"
    end
end