#!/usr/bin/ruby
# card10-bme680-exporter - Prometheus exporter for card10 BME680 env sensor

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

HOSTNAME = `hostname`.strip
TTY = ARGV[1] || "/dev/ttyACM0"

$data = {}

Thread.new {
  File.open(TTY) { |tty|
    while line = tty.gets
      if line =~ /^BSECData\((.*)\)/
        new_data = {}
        $1.split(/,\s+/).each { |s|
          k, v = s.split("=", 2)
          new_data[k] = v.to_f
        }
        $data = new_data
      end
      
    end
  }
}

class BME680Exporter
  def call(env)
    r = Rack::Response.new
    r.content_type = 'text/plain'
    $data.each { |k,v|
      r.write %Q|cardio_bsecdata_#{k}{hostname=#{HOSTNAME.dump}} #{v}\n|
    }
    r.finish
  end
end

Rack::Handler::Thin.run(BME680Exporter.new, :Port => 9882, :Host => '::', :debug => true)