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

: << =cut

=head1 NAME

internode_usage - Plugin to monitor quota usage of an Internode service

The ideal usage is also used as an updated warning limit.

=head1 CONFIGURATION

  [internode_usage]
    env.internode_api_login LOGIN
    env.internode_api_password PASSWORD

An optional 'env.internode_api_url' can be used, but should not be needed.  It
will default to  https://customer-webtools-api.internode.on.net/api/v1.5.

If multiple services are available, the plugin will automatically pick the first
service from the list. To monitor other services, the plugin can be used
multiple times, by symlinking it as 'internode_usage_SERVICEID'.

=head1 CAVEATS

* The hourly rate are a bit spikey in the -day view, as the API seems to update
  every 20 to 30 minutes; it is fine in the -month and more aggregated views
* The daily rate is the _previous_ day, and does always lag by 24h
* Due to the way the API seems to update the data, values for the daily rate
  are missing for a short period every day

=head1 AUTHOR

Olivier Mehani

Copyright (C) 2019 Olivier Mehani <shtrom+munin@ssji.net>

=head1 LICENSE

SPDX-License-Identifier: GPL-3.0-or-later

=cut

# shellcheck disable=SC1090
. "${MUNIN_LIBDIR:-.}/plugins/plugin.sh"

if [ "${MUNIN_DEBUG:-0}" = 1 ]; then
    set -x
fi

if ! command -v curl >/dev/null; then
	echo "curl not found" >&2
	exit 1
fi
if ! command -v xpath >/dev/null; then
	echo "xpath (Perl XML::LibXML) not found" >&2
	exit 1
fi
if ! command -v bc >/dev/null; then
	echo "bc not found" >&2
	exit 1
fi

if [ -z "${internode_api_url:-}" ]; then
    internode_api_url="https://customer-webtools-api.internode.on.net/api/v1.5"
fi

xpath_extract() {
	xpath="$1"
	xpath -q -n -e "${xpath}" | \
		sed 's/<\([^>]*\)>\([^<]*\)<[^>]*>/\2/'
}

xpath_extract_attribute() {
	xpath="$1"
	xpath -q -n -e "${xpath}" | \
		sed 's/.*="\([^"]\+\)".*/\1/'
}

fetch() {
	# shellcheck disable=SC2154
	curl -u "${internode_api_login}:${internode_api_password}" -s "$@"
}

get_data() {
	SERVICE_XML="$(fetch "${internode_api_url}/${SERVICE_ID}/service")"
	SERVICE_USERNAME="$(echo "${SERVICE_XML}" | xpath_extract "internode/api/service/username")"
	SERVICE_QUOTA="$(echo "${SERVICE_XML}" | xpath_extract "internode/api/service/quota")"
	SERVICE_PLAN="$(echo "${SERVICE_XML}" | xpath_extract "internode/api/service/plan")"
	SERVICE_ROLLOVER="$(echo "${SERVICE_XML}" | xpath_extract "internode/api/service/rollover")"
	SERVICE_INTERVAL="$(echo "${SERVICE_XML}" | xpath_extract "internode/api/service/plan-interval" | sed 's/ly$//')"

	HISTORY_XML="$(fetch "${internode_api_url}/${SERVICE_ID}/history")"
	TODAY_TIMESTAMP="$(date +%s)"
	DAILY_DATE="$(date +%Y-%m-%d -d yesterday)"
	DAILY_TIMESTAMP="$(date -d "${DAILY_DATE} $(date +%H:%M:%S)" +%s)"
	DAILY_USAGE="$(echo "${HISTORY_XML}" | xpath_extract "internode/api/usagelist/usage[@day=\"${DAILY_DATE}\"]/traffic")"

	USAGE_XML="$(fetch "${internode_api_url}/${SERVICE_ID}/usage")"
	SERVICE_USAGE="$(echo "${USAGE_XML}" | xpath_extract "internode/api/traffic")"

	USAGE_CRITICAL="${SERVICE_QUOTA}"
	USAGE_WARNING="$(echo "${SERVICE_QUOTA}*.75" | bc -ql)"

	TODAY="$(date +%s)"
	FIRST_DAY="$(date +%s --date "${SERVICE_ROLLOVER} -1 ${SERVICE_INTERVAL}")"
	LAST_DAY="$(date +%s --date "${SERVICE_ROLLOVER}")"
	BILLING_PERIOD="(${LAST_DAY}-${FIRST_DAY})"
	IDEAL_USAGE="$(echo "${SERVICE_QUOTA}-(${SERVICE_QUOTA}*(${LAST_DAY}-${TODAY})/${BILLING_PERIOD})" | bc -ql)"
}

graph_config() {
	graph=""
	if [ -n "${1:-}" ]; then
		graph=".$1"
	fi

	echo "multigraph internode_usage_${SERVICE_ID}${graph}"

	case "$graph" in
		.current)
			echo "graph_title Hourly rate for ${SERVICE_USERNAME}"
			echo 'graph_category network'
			# ${graph_period} is not a shell variable
			# shellcheck disable=SC2016
			echo 'graph_vlabel bytes per ${graph_period}'
			# XXX: this seems to be updated twice per hour;
			# the data from this graph may be nonsense
			echo 'graph_period hour'

			echo "hourly_rate.label Hourly usage"
			echo "hourly_rate.type DERIVE"
			echo "hourly_rate.min 0"

			;;
		.daily)
			echo "graph_title Previous-day usage for ${SERVICE_USERNAME}"
			echo 'graph_category network'
			# ${graph_period} is not a shell variable
			# shellcheck disable=SC2016
			echo 'graph_vlabel bytes per ${graph_period}'
			echo 'graph_period day'

			echo "daily_rate.label Previous-day usage"
			echo "daily_rate.type GAUGE"

			;;
		*)
		#.usage)
			echo "graph_title Uplink usage for ${SERVICE_USERNAME}"
			echo 'graph_category network'
			echo 'graph_vlabel bytes'
			echo 'graph_period hour'

			echo "usage.label Total usage"
			echo "usage.draw AREA"
			echo "usage.extinfo ${SERVICE_PLAN}; rollover: ${SERVICE_ROLLOVER}"
			echo "ideal.label Ideal usage"
			echo "ideal.draw LINE"
			echo "ideal.colour FFA500"

			echo "usage.critical ${USAGE_CRITICAL}"
			echo "usage.warning ${IDEAL_USAGE}"
			echo "ideal.critical 0:"
			echo "ideal.warning 0:"
			;;
	esac
	echo
}

graph_data() {
	graph=""
	if [ -n "${1:-}" ]; then
		graph=".${1}"
	fi

	echo "multigraph internode_usage_${SERVICE_ID}${graph}"
	case "${graph}" in
		.current)
			echo "hourly_rate.value ${TODAY_TIMESTAMP}:${SERVICE_USAGE:-U}"
			;;
		.daily)
			echo "daily_rate.value ${DAILY_TIMESTAMP}:${DAILY_USAGE:-U}"
			;;
		*)
			echo "usage.value ${TODAY_TIMESTAMP}:${SERVICE_USAGE:-U}"
			echo "ideal.value ${TODAY_TIMESTAMP}:${IDEAL_USAGE:-U}"
			;;
	esac
	echo
}

main() {
	case ${1:-} in
		config)
			graph_config
			graph_config usage
			graph_config current
			graph_config daily
			if [ "${MUNIN_CAP_DIRTYCONFIG:-0}" = "1" ]; then
				main
			fi
			;;
		*)
			graph_data
			graph_data usage
			graph_data current
			graph_data daily
			;;
	esac
}

# Determine the service ID from the name of the symlink
SERVICE_ID="$(echo "${0}" | sed -n 's/^.*internode_usage_//p')"
if [ -z "${SERVICE_ID}" ]; then
	API_XML="$(fetch "${internode_api_url}")"
	# Otherwise, get the first service in the list
	SERVICE_ID="$(echo "${API_XML}" | xpath_extract "internode/api/services/service")"
fi

get_data

main ${1:-}