#!/bin/bash

set -uo pipefail

textfile_dir={{ node_exporter_textfile_dir }}
file=${textfile_dir}/hetzner.prom
tmp=${file}.$$
now=$(date +%s)

ssh_opts="-p {{ hetzner_port }} -i {{ user_home }}/.ssh/id_ed25519 -o UserKnownHostsFile={{ user_home }}/.ssh/known_hosts -o StrictHostKeyChecking=yes -o BatchMode=yes -o ConnectTimeout=15"

mkdir -p ${textfile_dir}

reachable=0
body=""

emit_path() {
    local label=$1
    local remote=$2
    local listing
    local files
    local bytes
    local pending
    local newest
    local age=-1

    if ! listing=$(sudo -u {{ user }} rsync --list-only -e "ssh ${ssh_opts}" {{ hetzner_user }}@{{ hetzner_host }}:${remote}/ 2>/dev/null)
    then
        body+="hetzner_remote_listing_ok{path=\"${label}\"} 0"$'\n'
        return
    fi

    reachable=1

    files=$(echo "${listing}" | awk '$1 ~ /^-/ && substr($5,1,1) != "." { c++ } END { print c + 0 }')
    bytes=$(echo "${listing}" | awk '$1 ~ /^-/ && substr($5,1,1) != "." { gsub(",", "", $2); s += $2 } END { printf "%.0f", s + 0 }')
    pending=$(echo "${listing}" | awk '$1 ~ /^-/ && substr($5,1,1) == "." { gsub(",", "", $2); s += $2 } END { printf "%.0f", s + 0 }')
    newest=$(echo "${listing}" | awk '$1 ~ /^-/ && substr($5,1,1) != "." { print $3" "$4 }' | sort -r | head -1)

    if [ -n "${newest}" ]
    then
        age=$((now - $(date -d "$(echo ${newest} | tr '/' '-')" +%s)))
    fi

    body+="hetzner_remote_listing_ok{path=\"${label}\"} 1"$'\n'
    body+="hetzner_remote_files{path=\"${label}\"} ${files}"$'\n'
    body+="hetzner_remote_bytes{path=\"${label}\"} ${bytes}"$'\n'
    body+="hetzner_remote_pending_bytes{path=\"${label}\"} ${pending}"$'\n'
    body+="hetzner_remote_newest_age_seconds{path=\"${label}\"} ${age}"$'\n'
}

{% for path in hetzner_paths %}
emit_path "{{ path.dest | replace('./', '') }}" "{{ path.dest }}"
{% endfor %}

{
    echo "# HELP hetzner_reachable Whether the storage box answered at least one listing."
    echo "# TYPE hetzner_reachable gauge"
    echo "hetzner_reachable ${reachable}"
    echo "# HELP hetzner_last_check_timestamp_seconds Unix time of the last storage box check."
    echo "# TYPE hetzner_last_check_timestamp_seconds gauge"
    echo "hetzner_last_check_timestamp_seconds ${now}"
    echo "# HELP hetzner_remote_listing_ok Whether this remote path could be listed."
    echo "# TYPE hetzner_remote_listing_ok gauge"
    echo "# HELP hetzner_remote_files Number of completed files stored at this remote path."
    echo "# TYPE hetzner_remote_files gauge"
    echo "# HELP hetzner_remote_bytes Bytes of completed files stored at this remote path."
    echo "# TYPE hetzner_remote_bytes gauge"
    echo "# HELP hetzner_remote_pending_bytes Bytes of in flight partial transfers at this remote path."
    echo "# TYPE hetzner_remote_pending_bytes gauge"
    echo "# HELP hetzner_remote_newest_age_seconds Age of the newest completed file at this remote path."
    echo "# TYPE hetzner_remote_newest_age_seconds gauge"
    printf '%s' "${body}"
} > "${tmp}"

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