dalrm

#!/usr/bin/env bash
# Diox' Alarm, first draft
# Warning: Requires both bash and possibly also GNU date

read_timeout=10 # Must be in seconds
 snooze_time="10 minutes"
human_format="%A%e, %H:%M"

           ansi_red="\e[1;31m" # bold + red
         ansi_green="\e[1;32m" # bold + green
        ansi_yellow="\e[1;33m" # bold + yellow
      ansi_clr_line="\e[K"
    ansi_clr_colors="\e[0m"
   ansi_save_cursor="\e[s"
ansi_restore_cursor="\e[u"

if [ -z "$BASH_VERSION" ]; then
    echo "Bash is required"! >&2
    exit 1
fi

print_remaining() {
    local total_seconds=$1
    local dd hh mm ss ut
    let dd="$total_seconds / 60 / 60 / 24"
    let hh="$total_seconds / 60 / 60 % 24"
    let mm="($total_seconds / 60 % 60)"
    let ss="$total_seconds % 60"

    if [ $dd -ne 0 ]; then
        ut[1]="$dd day"
        [[ $dd -gt 1 ]] && ut[0]+="s"
    fi

    if [ $hh -ne 0 ]; then
        ut[1]="$hh hour"
        [[ $hh -gt 1 ]] && ut[1]+="s"
    fi

    if [ $mm -ne 0 ]; then
        ut[2]="$mm minute"
        [[ $mm -gt 1 ]] && ut[2]+="s"
    else
        if [ $dd -eq 0 -a $hh -eq 0 ]; then
            if [ $ss -lt 1 ]; then
                ut[2]="now"
            else
                ut[2]="less than 1 minute"
            fi
        fi
    fi

    echo -en "${ut[@]}"
}

wakeup() {
    $arg_script &

    local bg_pid=$!
    local user_input

    echo -en "\n[${ansi_green}q${ansi_clr_colors}] to stop, "
    echo -en "[${ansi_yellow}s${ansi_clr_colors}] to snooze\n\n"

    read -N 1 -t ${read_timeout} user_input
    pkill -P $bg_pid

    case "$user_input" in
        "q")
            echo
            exit
        ;;
        "s")
            unixtime_alarm=$(date +"%s" -d "$snooze_time")
            human_alarm="$(date +"${human_format}" -d "$snooze_time")"
            clear
        ;;
    esac

    alrm
}

alrm() {
    local let seconds=2 # Anything greater than 1
    while [ $seconds -gt 1 ]
    do
        unixtime_now="$(date +%s)"
        human_now="$(date +"${human_format}")"
        let seconds="$unixtime_alarm - $unixtime_now"

        echo -en "${ansi_restore_cursor}"
        echo -e "${human_now}${ansi_clr_line}\n${ansi_clr_line}"
        echo -e "$arg_script will run for ${read_timeout}s on${ansi_clr_line}"
        echo -en "${ansi_red}${human_alarm}${ansi_clr_colors} "
        echo -n '('; print_remaining $seconds; echo -e ")${ansi_clr_line}"

        sleep 1
    done

    wakeup
}

if [ $# -ne 2 ]; then
    me="$(basename $0)"
    echo "Usage: $me <script filename> <time>"
    echo
    echo "Examples:"
    echo "  $me ./test.bash 06:30"
    echo "  $me ./test.bash \"Friday 13:00\""
    echo "  $me \$(which ls) \"1 minute 10 seconds\""
    echo
    echo "^C exits"
    exit 0
fi

arg_script="$1"
arg_time="$2"

# Sanity checks
if [ ! -x "$arg_script" ]; then
    echo "\"$arg_script\": not executable, or doesn't exist" >&2
    exit 1
fi

date +"${human_format}" -d "$arg_time" > /dev/null 2>&1 || {
    echo -n "Failed to run \`date\` command: " >&2
    echo "date +\"${human_format}\" -d \"$arg_time\"" >&2
    date --version 2>&1 | head -n1 >&2
    exit 1
}

which pkill || exit 1

unixtime_alarm=$(date +"%s" -d "$arg_time")
human_alarm="$(date +"${human_format}" -d "$arg_time")"

clear
echo -e "${ansi_save_cursor}"
alrm