#!/bin/bash
#
# This program takes one argument: the amount of time your computer takes before it puts the monitor to sleep (in seconds or minutes).
# It will press the left shift key for you before it happens.
# If you have dimming enabled and want to prevent that, enter the time it takes to dim the monitor.

function usage(){
    echo "Usage: ./dont_sleep.sh [-s timeinseconds]"
    echo "       ./dont_sleep.sh [-m timeinminutes]"
    echo "Values in seconds must be integers and higher than 5."
    echo "Values in minutes must be integers and at least 1."
    exit 0
}

if [ "$#" -ne 2 ] || ! [[ "$1" =~ -{1}. ]]; then
    usage
fi

while getopts ":s:m:" opt; do
    case $opt in
        s)  if  ! [[ "$OPTARG" =~ ^[0-9]+$ ]] || [ "$OPTARG" -lt 5 ]; then
                usage
            fi
            secs=$OPTARG
            ;;

        m)  if  ! [[ "$OPTARG" =~ ^[0-9]+$ ]] || [ "$OPTARG" -lt 5 ]; then
                usage 
            fi
            mins=$OPTARG
            ;;

        ?)  usage
            ;;
    esac
done

if [ "$mins" ]; then
    time=$(((60*$mins)-5)) 
elif [ "$secs" ]; then
    time=$(($secs-5))
fi

echo "Will press left Shift every $time seconds."

while [ true ] 
do
    sleep $time
    # Switch the comment between the next 2 lines if you prefer the mouse is moved instead.
    # Check the manpage for xte for more ideas.
    #xte 'mousermove 1 1'
    xte 'key Shift_L' 
done