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

: << =cut

=head1 NAME

  switchbotmeter_multi - Munin plugin to monitor temperature and humidity with SwitchBot Meter

=head1 CONFIGURATION

  Obtain a token, secret and deviceid for SwitchBot API. See the following website.
  https://github.com/OpenWonderLabs/SwitchBotAPI

=head1 ENVIRONMENT VARIABLES

  env.token    : Token to access SwitchBot API. (Required)
  env.secret   : Secret to access SwitchBot API. (Required)
  env.deviceid : Device ID(s) of SwitchBot Meter separated by white space. (Required)
  env.interval : Interval in seconds for API access. (Optional, default is 0)

=head1 NOTES

  The amount of SwitchBot API calls per day is limited to 10000 times.
  If munin-node executes this plugin every 5 minutes, the API will be called 288 times a day.
  You can use env.interval parameter to prevent frequent API access. For example, if you set
  env.interval 900, the API response will be cached to local file for 900 seconds(15 minutes).

=head1 AUTHOR

  K.Cima https://github.com/shakemid

=head1 LICENSE

  GPLv2
  SPDX-License-Identifier: GPL-2.0-only

=head1 Magic markers

  #%# family=contrib
  #%# capabilities=

=cut

. "${MUNIN_LIBDIR}/plugins/plugin.sh"

set -o nounset
set -o pipefail

# Token to access SwitchBot API
token=${token:?}

# Secret to access SwitchBot API
secret=${secret:?}

# Device ID of SwitchBot Meter
deviceids=${deviceid:?}

# Interval for API access (second)
interval=${interval:-0}

# Plugin Name
pluginname=$( basename "$0" )

config() {
    local deviceid

    cat <<EOF
multigraph ${pluginname}_temperature
graph_title SwitchBot Meter Temperature
graph_category sensors
graph_scale no
graph_vlabel Temperature C
graph_args --base 1000
EOF
    for deviceid in ${deviceids}
    do
        echo ${deviceid}.label ${deviceid}
    done

    cat <<EOF
multigraph ${pluginname}_humidity
graph_title SwitchBot Meter Humidity
graph_category sensors
graph_scale no
graph_vlabel Humidity %
graph_args --base 1000 --lower-limit 0 --upper-limit 100
EOF
    for deviceid in ${deviceids}
    do
        echo ${deviceid}.label ${deviceid}
    done

    cat <<EOF
multigraph ${pluginname}_battery
graph_title SwitchBot Meter Battery
graph_category sensors
graph_scale no
graph_vlabel Battery %
graph_args --base 1000 --lower-limit 0 --upper-limit 100
EOF
    for deviceid in ${deviceids}
    do
        echo ${deviceid}.label ${deviceid}
    done
}

fetch() {
    local deviceid func val

    for deviceid in ${deviceids}
    do
        declare $( do_fetch ${deviceid} )
    done

    for func in temperature humidity battery
    do
        echo multigraph ${pluginname}_${func}

        for deviceid in ${deviceids}
        do
           val=${func}_${deviceid}
           echo ${deviceid}.value ${!val}
        done
    done
}

do_fetch() {
    local deviceid time_now time_modified
    deviceid=$1

    if [ "${interval}" -gt 0 ]; then
        time_now=$( date +%s )

        if [ -f "${MUNIN_STATEFILE}_${deviceid}" ]; then
            time_modified=$( stat --format=%Y "${MUNIN_STATEFILE}_${deviceid}" )
        else
            # initial run
            time_modified=0
        fi

        if [ $(( time_now - time_modified )) -le "${interval}" ]; then
            # read from cache
            cat "${MUNIN_STATEFILE}_${deviceid}"
        else
            # update cache
            fetch_api ${deviceid} | tee "${MUNIN_STATEFILE}_${deviceid}"
        fi
    else
        fetch_api ${deviceid}
    fi
}

fetch_api() {
    local deviceid temperature humidity battery t sign nonce response statusCode
    deviceid=$1

    t=$( date +'%s000' )
    nonce=$( openssl rand -base64 32 ) 
    sign=$( echo -n ${token}${t}${nonce} | openssl dgst -sha256 -hmac ${secret} -binary | base64 )

    response=$( curl -s -H "Content-Type:application/json;charset=utf8" -H "Authorization:${token}" -H "t:${t}" -H "nonce:${nonce}" -H "sign:${sign}" "https://api.switch-bot.com/v1.1/devices/${deviceid}/status" )

    statusCode=$( echo "${response}" | jq '.statusCode' )
    if [ "${statusCode}" -ne 100 ]; then
        echo Error with statusCode = "${statusCode}" 1>&2
        exit 1
    fi

    temperature=$( echo "${response}" | jq '.body.temperature' )
    humidity=$( echo "${response}" | jq '.body.humidity' )
    battery=$( echo "${response}" | jq '.body.battery' )

    echo temperature_${deviceid}=${temperature} humidity_${deviceid}=${humidity} battery_${deviceid}=${battery}
}

# Main
case ${1:-} in
config)
    config
    if [ "${MUNIN_CAP_DIRTYCONFIG:-}" = "1" ]; then
        fetch
    fi
    ;;
*)
    fetch
    ;;
esac

exit 0