#!/usr/bin/ruby
# tab-exporter - Prometheus exporter for statistics on browser tab usage

require 'rack'
require 'rack/handler/thin'

HOSTNAME = `hostname`.strip
USERNAME = `id -un`.strip

$last = Time.now - 1000
def tabs
  p [Time.now, $last, Time.now - $last]
  if Time.now - $last >= 30
    $last = Time.now
    # $result = `
    #  lz4jsoncat ~/.mozilla/firefox/*.default/sessionstore-backups/recovery.jsonlz4 |
    #  LANG=C sed 's/\\\\ud[89abcdef][0-9a-f][0-9a-f]/\\\\ufffd/g' | # invalid surrogates |
    #  jq '[.windows[].tabs | length] | add'
    # `.to_i
    $result = `
      wctab ~/.mozilla/firefox/*.default/sessionstore-backups/recovery.jsonlz4
    `.to_i
  end
  $result
end

class TabExporter
  def call(env)
    r = Rack::Response.new
    r.content_type = 'text/plain'
    r.write %Q|browser_open_tabs{hostname=#{HOSTNAME.dump},user=#{USERNAME.dump},browser="firefox"} #{tabs}\n|
    r.finish
  end
end

Rack::Handler::Thin.run(TabExporter.new, :Port => 9101, :Host => '::', :debug => true)