#!/bin/bash

set -uo pipefail

textfile_dir={{ node_exporter_textfile_dir }}
file=${textfile_dir}/services.prom
tmp=${file}.$$

mkdir -p ${textfile_dir}

declare -A active_count
declare -A unit_count
units=""

record() {
    local service=$1
    local unit=$2
    local kind=$3
    local state=$4

    units+="service_unit_active{service=\"${service}\",unit=\"${unit}\",kind=\"${kind}\"} ${state}"$'\n'
    unit_count[${service}]=$(( ${unit_count[${service}]:-0} + 1 ))
    active_count[${service}]=$(( ${active_count[${service}]:-0} + state ))
}

check_user_unit() {
    local service=$1
    local owner=$2
    local unit=$3
    local state=0

    if systemctl --user --machine ${owner}@.host is-active --quiet ${unit} 2>/dev/null
    then
        state=1
    fi

    record ${service} ${unit} rootless ${state}
}

check_system_unit() {
    local service=$1
    local unit=$2
    local state=0

    if systemctl is-active --quiet ${unit} 2>/dev/null
    then
        state=1
    fi

    record ${service} ${unit} system ${state}
}

check_container() {
    local service=$1
    local container=$2
    local state=0

    if [ "$(podman container inspect -f '{% raw %}{{.State.Running}}{% endraw %}' ${container} 2>/dev/null)" = "true" ]
    then
        state=1
    fi

    record ${service} ${container} container ${state}
}

{% for service in monitored_services %}
{% for unit in service.units | default([]) %}
check_user_unit {{ service.name }} {{ service.owner }} {{ unit }}
{% endfor %}
{% for unit in service.system_units | default([]) %}
check_system_unit {{ service.name }} {{ unit }}
{% endfor %}
{% for container in service.containers | default([]) %}
check_container {{ service.name }} {{ container }}
{% endfor %}
{% endfor %}

{
    echo "# HELP service_unit_active Whether a unit or container backing a service is running."
    echo "# TYPE service_unit_active gauge"
    printf '%s' "${units}"

    echo "# HELP service_enabled Whether a service is expected to be running."
    echo "# TYPE service_enabled gauge"
{% for service in monitored_services %}
    echo "service_enabled{service=\"{{ service.name }}\",group=\"{{ service.group }}\"} {{ 1 if service.enabled else 0 }}"
{% endfor %}

    echo "# HELP service_units_total Number of units or containers backing a service."
    echo "# TYPE service_units_total gauge"
    for service in "${!unit_count[@]}"
    do
        echo "service_units_total{service=\"${service}\"} ${unit_count[${service}]}"
    done

    echo "# HELP service_units_active Number of running units or containers backing a service."
    echo "# TYPE service_units_active gauge"
    for service in "${!active_count[@]}"
    do
        echo "service_units_active{service=\"${service}\"} ${active_count[${service}]}"
    done
} > "${tmp}"

chmod 0644 "${tmp}"
mv "${tmp}" "${file}"