update-csshx-config

#!/usr/bin/env ruby

require 'erb'

Cluster = Struct.new(:name, :hosts)

class Host
  
  attr_accessor :fqdn, :port, :user, :name, :proxy
  
  def proxied?
    !!@proxy
  end
  
  def ip?
    !(IPAddr.new(@fqdn) rescue nil).nil?
  end
end

class ERBContext
  def initialize(hash)
    hash.each_pair do |key, value|
      instance_variable_set('@' + key.to_s, value)
    end
  end
  
  def get_binding
    binding
  end
end

FQDN_RE = /(.+?)(?=\.)/
HOST_SPEC_RE = /(?:(?<proxy>[^\s]+)\s+->\s+)?(?:(?<user>[^@]+)@)?(?<fqdn>[^\s:]+)(?:\:(?<port>\d+))?(?:\s+\((?<name>[^\)]+)\))?/

CSSHRC = <<EOS
clusters = <%= @clusters.map(&:name).join(' ') %>
<% @clusters.each do |cluster| %>
  <%= cluster.name %> = <%= cluster.hosts.map(&:name).join(' ') %>
<% end %>
EOS

def parse_host_spec(spec)
  data = HOST_SPEC_RE.match(spec)
  host = Host.new
  host.fqdn = data['fqdn']
  host.proxy = data['proxy']
  host.port = data['port'] || 22
  host.user = data['user']
  host.name = 
    if data['name']
      data['name']
    else
      FQDN_RE.match(data['fqdn'])[1]
    end
  
  host
end

def get_clusters
  Dir.glob(File.expand_path('~/.ssh/hosts.d/*.hosts')).map do |hosts_file|
    cluster = Cluster.new(File.basename(hosts_file, '.hosts'))
    cluster.hosts = File.readlines(hosts_file).map(&:chomp).map { |spec| parse_host_spec(spec) }
    
    cluster
  end
end

File.open(File.expand_path('~/.csshrc'), File::CREAT|File::TRUNC|File::RDWR, 0644) do |io|
  io.puts ERB.new(CSSHRC, nil, '%').result(ERBContext.new(clusters: get_clusters).get_binding)
end