class IpHelper

# File lib/ip-helper.rb, line 26
def get_current_machine_ipv4s
  loopback_regex = /^localhost$|^127(?:\.[0-9]+){0,2}\.[0-9]+$|^(?:0*\:)*?:?0*1$/

  potential_ips = Socket.ip_address_list.map{|info| info.ip_address}
                        .select {|info| not loopback_regex.match(info)}

  potential_ips.select { |info| is_valid_v4_ip info}
end

# File lib/ip-helper.rb, line 44
def get_event_store_ips_from_dns(dns_name)
  Resolv::DNS.open { |dns|
    resources = dns.getresources dns_name, Resolv::DNS::Resource::IN::A
    resources.map { |res| res.address.to_s }
  }
end

# File lib/ip-helper.rb, line 16
def get_ips_in_cluster(cluster_dns)
  event_store_ips = get_event_store_ips_from_dns cluster_dns
  return event_store_ips.count unless event_store_ips == nil
  return 0
end

# File lib/ip-helper.rb, line 7
def get_local_ip_that_also_on_cluster(cluster_dns)
  current_machine_ips = get_current_machine_ipv4s
  event_store_ips = get_event_store_ips_from_dns cluster_dns

  return no_event_store_ips_error cluster_dns unless event_store_ips.any?

  get_matching_ips current_machine_ips, event_store_ips
end

# File lib/ip-helper.rb, line 35
def get_matching_ips(machine_ips, event_store_ips)
  matched_ips = machine_ips.select do |ip_to_look_for|
    event_store_ips.find { |ip_to_match| ip_to_look_for == ip_to_match }
  end
  return no_matching_ip_error machine_ips, event_store_ips unless matched_ips.one?

  matched_ips[0]
end

# File lib/ip-helper.rb, line 22
def is_valid_v4_ip(potential_ip)
  /^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$/.match potential_ip
end

# File lib/ip-helper.rb, line 55
def no_event_store_ips_error(dns_name)
  "could not find any ips at dns name #{dns_name} so cannot check gossips"
end

# File lib/ip-helper.rb, line 51
def no_matching_ip_error(machine_ips, event_store_ips)
  "this machine has ips of #{machine_ips}, event store (according to dns lookup) has ips of #{event_store_ips}. There should be exactly one match, but wasn't. "
end