#!/bin/bash

read label dimensions rest <<<"$(xdpyinfo | grep dimensions)"
IFS='x' read width height <<<"$dimensions"
half=$((width/2))
margin=4     # allowance to ensure windows don't overlap

case $1 in
left)
    coords=0,0,0,$((half-margin)),-1
    ;;
right)
    coords=0,$half,0,$((half-margin)),-1
    ;;
*)
    echo "Usage: snapleft {left|right}" 1>&2
    exit 1
    ;;
esac
wmctrl -r :ACTIVE: -b remove,maximized_horz
wmctrl -r :ACTIVE: -b add,maximized_vert
wmctrl -r :ACTIVE: -e $coords