#!/usr/bin/env bash

# Performs borgmatic backups and checks, given that
# enough time has elapsed since the last one performed.
# cerberus, 2022-02-03-1

set -o pipefail

[ -f /opt/borg/bin/borg ] && borg=/opt/borg/bin/borg || borg="$(command -v borg)"
[ -f /opt/borg/bin/borgmatic ] && borgmatic=/opt/borg/bin/borgmatic || borgmatic="$(command -v borgmatic)"

export LOG_FILE="/var/log/borgmatic-wrapper.log"
export STATE_DIR="/var/tmp/borgmatic-wrapper"
LIB_DIR="${LIB_DIR:-/usr/local/jilits}"

script_name="$(basename -- "$0")"
max_minutes_since_last_backup=""
max_minutes_since_last_check=720

. "$LIB_DIR/libverbosity.sh" || exit 127
. "$LIB_DIR/libcommon.sh" || exit 127
. "$LIB_DIR/libdatatype.sh" || exit 127
. "$LIB_DIR/libdatetime.sh" || exit 127
. "$LIB_DIR/libstate.sh" || exit 127

eggsit() {
    rc=$?
    [ $rc -eq 0 ] && echlog "Script exiting ($rc)..."
    [ $rc -ne 0 ] && errlog "Script exiting ($rc)..."
    exit $rc
}
trap "eggsit" EXIT

get_last_backup_ts() {
    local ts state_ttl="$((6 * 60 * 60))"
    ts="$(get_state CachedLastBackupTimestamp)"

    if [ -n "$ts" ]; then
        echo "$ts"
        return 0
    fi

    ts="$(sudo "$borgmatic" list --last 1 --successful --json | jq -r '.[0].archives[0].start')"
    set_state CachedLastBackupTimestamp "$ts" "$state_ttl"
    echo "$ts"
}

minutes_since_last_backup() {
    local ue
    ue="$(dt_to_ue "$(get_last_backup_ts)")"
    echo "$((($(current_ue) - ue) / 60))"
}

remote_is_online() {
    local host port
    host="$(cut -d: -f1 <<<"$1")"
    port="$(cut -d: -f2 <<<"$1")"
    nc -zvw1 "${host:?Missing remote host}" "${port:?Missing remote port}" | tee -a "$LOG_FILE" >/dev/null
}

perform_backup() {
    echlog "Running backup."

    rm_state CachedLastBackupTimestamp
    rm_state LastBackupPrettyTimestamp

    "$borgmatic" create --files --stats --verbosity 2 --syslog-verbosity -1 2>&1 | tee -a "$LOG_FILE" || return 1
    set_state LastBackupPrettyTimestamp "$(dt_to_pretty "$(get_last_backup_ts)")" "$((4 * 60 * 60))"

    "$borgmatic" prune --files --stats --verbosity 2 --syslog-verbosity -1 2>&1 | tee -a "$LOG_FILE" || return 2
}

perform_check() {
    echlog "Running check."

    rm_state LastCheckUnixEpoch

    "$borgmatic" check --progress --verbosity 2 --syslog-verbosity -1 2>&1 | tee -a "$LOG_FILE" || return 1
    set_state LastCheckUnixEpoch "$(current_ue)" "$((24 * 60 * 60))"
}

function usage() {
    echo "Usage: $script_name [OPTIONS]"
    echo
    echo "Options:"
    echo "  -h              Display help."
    echo "  -b [MINUTES]    Max minutes since last backup. "
    echo "  -c [MINUTES]    Max minutes since last check."
    echo "  -r [HOST:PORT]  Ensure remote is online before running actions."
}

while getopts ":b:c:r:h" arg; do
    case $arg in
    b) max_minutes_since_last_backup=$OPTARG ;;
    c) max_minutes_since_last_check=$OPTARG ;;
    r) remote_host_port=$OPTARG ;;
    h)
        usage
        exit 0
        ;;
    :)
        echo "$script_name: Must supply a value with -$OPTARG." >&2
        usage
        exit 1
        ;;
    ?)
        echo "Invalid option: -${OPTARG}."
        echo
        usage
        exit 2
        ;;
    esac
done

rotlog 10000000

if ! is_int "$max_minutes_since_last_backup"; then
    usage
    echlog
    echxit "ERROR: Invalid or unset value for argument -b: '$max_minutes_since_last_backup'" 2
fi

for bin in jq nc; do
    if ! command -v "$bin" >/dev/null; then
        echxit "ERROR: '$bin' not installed" 3
    fi
done

if ! im_root; then
    echxit "ERROR: This script must be run as root" 1
elif pgrep -f "$borg" >/dev/null; then
    echxit "ERROR: Borg seems to be active already" 11
elif [ -n "$remote_host_port" ]; then
    if ! remote_is_online "$remote_host_port"; then
        echxit "ERROR: Unable to reach $remote_host_port" 12
    fi
fi

echlog "The last backup was carried out $(minutes_since_last_backup) minutes ago (>=$max_minutes_since_last_backup)."
if [[ "$(minutes_since_last_backup)" -ge "$max_minutes_since_last_backup" ]]; then
    perform_backup || echxit "ERROR: Backup returned errors" 21
fi

last_check_unixepoch="$(get_state LastCheckUnixEpoch)" || last_check_unixepoch=0
minutes_since_last_check="$((($(current_ue) - last_check_unixepoch) / 60))"
echo "The last check was carried out $minutes_since_last_check minutes ago (>=$max_minutes_since_last_check)." | tee -a "$LOG_FILE"

if [[ "$minutes_since_last_check" -ge "$max_minutes_since_last_check" ]]; then
    perform_check || echxit "ERROR: Check returned errors" 21
fi

echo "Script finished."