#!/usr/bin/env bash

set -u

CHECK_SPACE_APIKEY="<API-KEY>"
HEALTCHECKSIO_UPTIMEKUMA_UUID="<HEALTCHECKSIO_UPTIMEKUMA_UUID>"

UPTIMEKUMA_URL="https://uptime-kuma.golem.linux.it"
PUSH_PATH="/api/push/"

UK_PING_TIMEOUT=2
UK_PING_RETRY=3
UK_STATUS_UP="up"
UK_STATUS_DOWN="down"

HC_PING_TIMEOUT=10
HC_PING_RETRY=5
HC_FAIL_PATH="/fail"

ROOTFS_USED_THRESHOLD=75

# uptime-kuma ###########################################################

get-push-url() {
    local apikey="$1"
    echo "${UPTIMEKUMA_URL}${PUSH_PATH}${apikey}"
}

ping-url() {
    local url="${1}"
    echo "Ping to ${url}: "
    curl -m "$UK_PING_TIMEOUT" --retry "$UK_PING_RETRY" "${url}"
    echo
}

ping-status-msg() {
    local apikey="${1}"
    local status="${2}"
    local msg="${3}"
    local url
    url=$(get-push-url "${apikey}")"?status=${status}&msg=${msg}"
    ping-url "${url}"
}

urlencode() {
    echo "${1}" | jq -s -R -r @uri
}

# healthchecks.io #######################################################

hc-ping() {
    local url="$1"
    echo "Ping to ${url}: "
    curl -m $HC_PING_TIMEOUT --retry $HC_PING_RETRY "${url}"
    echo
}

# checks ################################################################

check-site-hc() {
    local hcurl="$1"
    local site="$2"
    local hcpath=""
    echo "Checking ${site}:"
    # shellcheck disable=SC2015
    curl -m 3 -fSs -o /dev/null "${site}"
    if test $? -ne 0; then
        hcpath=$HC_FAIL_PATH
    fi
    hc-ping "${hcurl}${hcpath}"
}

check-space() {
    local apikey=$CHECK_SPACE_APIKEY
    local status=$UK_STATUS_UP
    local msg

    local rootfs_used
    rootfs_used="$(df --output=pcent / | tail -n1 | sed 's/\%//')"
    if test "$rootfs_used" -ge $ROOTFS_USED_THRESHOLD; then
        status=$UK_STATUS_DOWN
        msg="WARN / : ${rootfs_used}%"
    else
        msg="OK / : ${rootfs_used}%"
    fi

    echo "$msg"
    msg=$(urlencode "$msg")
    ping-status-msg "$apikey" "$status" "$msg"
}

#########################################################################

check-space
check-site-hc "https://hc-ping.com/${HEALTCHECKSIO_UPTIMEKUMA_UUID}" uptime-kuma.golem.linux.it