dnest

#!/bin/bash
# Default to 3 day warning time just to give a heads-up before a weekend
WARN_HOURS=${DNEST_WARN_HOURS:-72}

# For testing purposes, let a leading 0 signify minutes so we can warn almost immediately
if [[ "$WARN_HOURS" == 0* ]]; then
    WARN_UNIT=minutes
    WARN_VAL=${WARN_HOURS#0}
else
    WARN_UNIT=hours
    WARN_VAL=$WARN_HOURS
fi

# Normalise to minutes for internal scheduling
WARN_MINS=$(( WARN_UNIT == "minutes" ? WARN_VAL : WARN_VAL * 60 ))
ATJOB_DIR=${XDG_DATA_HOME:-$HOME/.local/share}/dnest

mkdir -p "$ATJOB_DIR"

cancel_warning() {
    local atjob_file="$ATJOB_DIR/$1"
    [ -f "$atjob_file" ] && atrm "$(cat "$atjob_file")" 2>/dev/null && rm -f "$atjob_file"
}

# Schedule a warning at warn_minutes from now
schedule_warning() {
    local machine="$1"
    local warn_minutes="$2"

    cancel_warning "$machine"

    if (( warn_minutes > 0 )); then
        local job_id
        job_id=$(echo "notify-send -u critical 'DevNest Warning' 'Reservation for $machine expires in ${WARN_VAL} ${WARN_UNIT}'" \
            | at now + ${warn_minutes} minutes 2>&1 | awk '/^job/ {print $2}')
        [ -n "$job_id" ] && echo "$job_id" > "$ATJOB_DIR/$machine"
    fi
}

usage() {
    cat <<EOF
Usage: dnest [SUBCOMMAND] [OPTIONS] MACHINE

A wrapper around devnest that schedules a GNOME notification before your
reservation expires. All unrecognised subcommands are passed through to devnest.

Subcommands:
  reserve (default)  Reserve a machine. Same as omitting the subcommand.
  extend             Extend an existing reservation.
  release            Release a machine and cancel any pending warning.
  <anything else>    Passed through directly to devnest.

Options (reserve):
  -g GROUP           Node group (required by devnest)
  -t TIME            Reservation length in hours
  -j                 Output node info as JSON
  -f                 Force reserve even if a CI job is running

Options (extend):
  -t TIME            Number of hours to extend by

Warning behaviour:
  A persistent GNOME notification is sent DNEST_WARN_HOURS before the
  reservation expires (default: 72h). If you extend or release, any
  previously scheduled warning is cancelled and rescheduled as needed.

  DNEST_WARN_HOURS   Override the warning lead time (default: 72).
                     A value with a leading zero is treated as minutes,
                     which is useful for testing, e.g.:
                       DNEST_WARN_HOURS=059  ->  warn 59 minutes before expiry

Examples:
  dnest -g network -t 240 myhost
  dnest reserve -g network -t 240 myhost
  dnest extend -t 120 myhost
  dnest release myhost
  dnest list -g network
  DNEST_WARN_HOURS=059 dnest -g network -t1 myhost   # test: warn in 1 min
EOF
}

ACTION="${1}"

case "$ACTION" in
    -h | --help)
        usage
        exit 0
        ;;

    extend)
        shift
        while getopts ":t:" opt; do
            case "$opt" in
                t) ;;
            esac
        done
        machine="${@: -1}"
        output=$(devnest extend "$@" 2>&1)
        echo "$output"
        if echo "$output" | grep -q "reserved until"; then
            end_time=$(echo "$output" | grep -oP 'reserved until: \K[\d/]+, [\d:]+' | tr '/' '-' | tr -d ',')
            end_epoch=$(date -d "$end_time" +%s)
            remaining_minutes=$(( (end_epoch - $(date +%s)) / 60 ))
            [ -n "$machine" ] && schedule_warning "$machine" $(( remaining_minutes - WARN_MINS ))
        fi
        ;;
    reserve | -* | "")
        [ "$ACTION" = "reserve" ] && shift
        res_time=""
        while getopts ":t:g:jf" opt; do
            case "$opt" in
                t) res_time=$OPTARG ;;
            esac
        done
        machine="${@: -1}"
        if devnest reserve "$@"; then
            [ -n "$res_time" ] && [ -n "$machine" ] && \
                schedule_warning "$machine" $(( res_time * 60 - WARN_MINS ))
        fi
        ;;
    release)
        machine="${@: -1}"
        if devnest "$@"; then
            cancel_warning "$machine"
        fi
        ;;
    *)
        devnest "$@"
        ;;
esac