#!/bin/sh
#
# (C) Matthew Slowe, 2014
#
# This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License
# http://creativecommons.org/licenses/by-sa/4.0/
#
# Wildcard-script to monitor a river system's catchment area. To monitor a
# particular catchment aread, link river_levels_<id> to this file. E.g.
#
#    ln /usr/share/munin/node/plugins-contrib/river_levels_ /etc/munin/node.d/river_levels_123
#
# ...will monitor catchment area 123.
#
# Parameters:
#
#   config
#
#%# family=manual

# Expects a config file to specify which stations to include in the data check and name the catchment
#
# [river_levels_]
# env.urlbase http://path.to.service/path
# 
# [river_levels_123]
# env.stations 23 24 25 26
# env.catchmentname Great River
# 
# The station list can be generated by using getstations.pl:

# host$ perl getstations.pl 123 </tmp/river_level_.dat
# 23 24 25 26


CACHE=/tmp/river_level_.dat
checkdata () {
    if [ ! -f $CACHE ] || test `find "$CACHE" -mtime +1`
    then
        curl -o $CACHE -Ss $urlbase || exit 1
    fi
}

CATCHMENT=$(basename $0 | sed 's/^river_levels_//g' | cut -d_ -f 3)

if [ "$1" = "autoconf" ]; then
    echo "no"
    exit 0
fi

if [ "$1" = "suggest" ]; then
    exit 0
fi

if [ "$1" = "config" ]; then
    echo "graph_title River Levels for $catchmentname [$CATCHMENT]"
    echo 'graph_args --base 1000 -l 0 '
    echo 'graph_vlabel station level (metres)'
    echo 'graph_category rivers'
    echo 'graph_info This graph shows river levels'

    checkdata
    perl -e '
        use JSON::PP;
        $CatchmentId = shift @ARGV;
        $in = decode_json(<>) or die;
        foreach $station (@{$in->{data}}) {
                if ($station->{url} =~ /CatchmentId=$CatchmentId$/) {
                        $id    = $station->{id};
                        $river = $station->{watercourse};
                        $name  = $station->{station};
                        print "river_level_$id.label $name on $river ($id)\n";
                        print "river_level_$id.info Current river level (metres)\n";
                }
        }
' $CATCHMENT <$CACHE
    exit 0
fi

for STATION in $stations ; do
    curl -m 5 -sS $urlbase/$STATION |
        perl -MJSON::PP -e '$id=shift(@ARGV); $d=decode_json(<>) or die "error decoding station $id"; print "river_level_$id.value ", $d->{data}->{current}->{level} || "U", "\n";' $STATION
done