#!/usr/bin/env ruby
# vim: set noet sw=2 ts=2 sts=2:
require 'prometheus/client'
require 'prometheus/client/formats/text'
require 'ostruct'
require_relative 'probe'

module BlackboxSshd
end

class BlackboxSshd::Collector
	attr_reader :registry, :prober

  def initialize registry: nil, prober: nil
    @registry = registry || Prometheus::Client::Registry.new
    @registry.gauge :sshd_up, docstring: 'Server is up and connection from clients are generally possible', labels: %i[]
    @registry.gauge :sshd_host_certificate_serial, docstring: 'Host Certificates serial', labels: %i[]
    @registry.gauge :sshd_probe_duration, docstring: 'Time elapsed to probe the SSH-Server', labels: %i[]
		@registry.gauge :sshd_host, docstring: 'Provides informations about the remote host.', labels: %i[protocol software]
		@registry.gauge :sshd_host_key, docstring: 'Provides informations about the host key in labels.  1=key used, 0=no key (possible a certificate)', labels: %i[key]
    @registry.gauge :sshd_host_certificate, docstring: 'Provides informations about the host_certificate in labels.  1=certificate used, 0=no certificate used (possible simple key)', labels: %i[key ca id]
    @registry.gauge :sshd_host_certificate_valid_to, docstring: 'Certificate will usable till this time, then it will expire.'
    @registry.gauge :sshd_host_certificate_valid_from, docstring: 'Certificate is usable from this time.'
    @metrics = OpenStruct.new @registry.instance_variable_get( :@metrics)
    @prober = prober || BlackboxSshd::Prober.new
  end

  def collect hostident
    r = @prober.probe hostident
		@metrics.sshd_host.set 1, labels: {protocol: r[:protocol], software: r[:remote_software]}
    if hc = r[:host_cert]
			@metrics.sshd_host_certificate_serial.set hc.delete(:serial)
			@metrics.sshd_host_certificate_valid_from.set hc.delete(:valid_from).to_f
			@metrics.sshd_host_certificate_valid_to.set hc.delete(:valid_to).to_f
      @metrics.sshd_host_certificate.set 1, labels: hc
		else
      @metrics.sshd_host_certificate.set 0, labels: {key: '', ca: '', id: ''}
    end
		if hk = r[:host_key]
			@metrics.sshd_host_key.set 1, labels: {key: hk}
		else
			@metrics.sshd_host_key.set 0, labels: {key: ""}
		end
    @metrics.sshd_up.set 0 == r[:status].exitstatus ? 1 : 0
    @metrics.sshd_probe_duration.set r[:duration]
		self
  end

	def self.collect hostident, **opts
		new(**opts).collect hostident
	end
end

if __FILE__ == $0
  collector = BlackboxSshd::Collector.collect ARGV[0]
  puts Prometheus::Client::Formats::Text.marshal( collector.registry)
end