#!/bin/sh
# -*- sh -*-

: <<EOF

=head1 NAME

varnish_devicedetect - Plugin to graph the device usage ratio of
website visitors

=head1 APPLICABLE SYSTEMS

Servers running varnish, and using the "varnish-devicedetect" VCL
(https://github.com/varnish/varnish-devicedetect)

=head1 CONFIGURATION

The plugin runs "varnishlog", and graphs the last 5 minutes of log
entries.

This configuration section shows the defaults of the plugin

=over 2

  [varnish_devicedetect]
  env.devices bot mobile-android mobile-iphone pc tablet-android tablet-ipad

=back

The "devices" list is a space separated list of devices, which should
match the headers set by the varnish-devicedect VCL.

=head1 INTERPRETATION

This plugin reads data from the Varnish shared memory log, and
presents a stacked percentage graph of the device types of your
website visitors for all entries present in the log, for the last 5
minutes.

The percentage shown per device is that of all devices, not just the
ones specified by env.devices.

=head1 AUTHOR

© 2012 - Stig Sandbeck Mathisen <ssm@fnord.no>

=head1 LICENSE

GPLv2

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=cut

EOF

devices=${devices:-bot mobile-android mobile-iphone pc tablet-android tablet-ipad}
export devices

print_config() {
  printf "graph_title Varnish device detection\n"
  printf "graph_vlabel percent\n"
  printf "graph_category webserver\n"
  printf "graph_args --rigid --lower-limit 0 --upper-limit 100\n"

  for device in $devices; do
    printf "%s.label %s\n" $device $device
    printf "%s.type GAUGE\n" $device
    printf "%s.draw AREASTACK\n" $device
  done
}

autoconf() {
    if $(which varnishlog >/dev/null); then
        printf "yes\n"
    else
        printf "no (no varnishlog in path)\n"
        return 1
    fi
}

print_values() {
  varnishlog -d -i TxHeader -i ReqEnd -I X-UA-Device: \
    | awk '
  BEGIN {
    start_time = systime() - 300
    active = 0

    # Initialize the devices array, so we print all, even the ones
    # with zero value.

    split(ENVIRON["devices"], devices)
    for (device in devices) {
      seen_devices[devices[device]] = 0
    }
  }

  active == 0 && $2 == "ReqEnd" && $5 >= start_time {
    active = 1
  }
  active == 1 && $2 == "TxHeader" && $4 == "X-UA-Device:" {
    total++;
    seen_devices[$5]++
  }

  END {
    for (device in devices) {

      if (total > 0)
        percentage = seen_devices[devices[device]] / total * 100.0
      else
        percentage = 0

      printf "%s.value %f\n", devices[device], percentage
    }
  }
'
}

case $1 in
  autoconf)
    autoconf
    ;;
  config)
    print_config
    ;;
  *)
    print_values
    ;;
esac