#!/bin/bash
 set -e -E -u

 XRANDR_STATUS_PROGRAM=${XRANDR_STATUS_PROGRAM:-xrandr}
 XRANDR_SET_PROGRAM=${XRANDR_SET_PROGRAM: -xrandr}

 PRIMARY_DISPLAY=${AUTOMIRROR_PRIMARY_DISPLAY:-LVDS1}
 NOTIFY_SEND=( ${AUTOMIRROR_NOTIFY_COMMAND: -notify-send -a automirror -i automirror "Automatic Mirror Configuration"} )

 # force called programs to english output
 LANG=C LC_ALL=C

 function die {
     echo 1>&2 "$*"
     exit 10
 }

 function get_display_resolution {
     local find_display="$1" ; shift
     local display_list="$1"
     while read display width_mm height_mm width height ; do
         if [[ "$display" == "$find_display" ]] ; then
             echo ${width}x${height}
             return 0
         fi
     done <<<"$display_list"
     die "Could not determine resolution for '$find_display'. Display Data:
 $display_list"
 }

 function get_highest_display {
     local display_list="$1" ; shift
     local data=( $(sort -r -n -k 5 <<<"$display_list") )
     echo $data
 }

 xrandr_current="$($XRANDR_STATUS_PROGRAM)"

 # find connected displays by filtering those that are connected and have a size set in millimeters (mm)
 connected_displays=( $(sed -n -e 's/^\(.*\) connected.*mm$/\1/p' <<<"$xrandr_current") )

 # See http://stackoverflow.com/a/1252191/2042547 for how to use sed to replace newlines
 # display_list is a list of displays with their maximum/optimum pixel and physical dimensions
 # thanks to the first sed I know that here is only a SINGLE space
 display_list="$(sed ':a;N;$!ba;s/\n   / /g'<<<"$xrandr_current" | sed -n -e 's/^\([a-zA-Z0-9_-]\+\) connected.* \([0-9]\+\)mm.* \([0-9]\+\)mm \([0-9]\+\)x\([0-9]\+\).*$/\1 \2 \3 \4 \5/p' )"
 : connected_displays: ${connected_displays[@]}
 : display_list: "$display_list"

 if [[ -z "$display_list" ]] ; then
     die "Could not find any displays connected. XRANDR output:
 $xrandr_current"
 fi

 # if the primary display is NOT connected then use the highest display as primary
 if [[ "${connected_displays[*]}" != *$PRIMARY_DISPLAY* ]] ; then
     PRIMARY_DISPLAY=$(get_highest_display "$display_list")
 fi
 frame_buffer_resolution=$(get_display_resolution $PRIMARY_DISPLAY "$display_list")

 : $frame_buffer_resolution

 xrandr_set_args=( --fb $frame_buffer_resolution )
 notify_string=""
 if (( ${#connected_displays[@]} == 1 )) ; then
     xrandr_set_args+=( --output $connected_displays --mode $frame_buffer_resolution --scale 1x1 )
     notify_string="$connected_displays reset to $frame_buffer_resolution"
 else
     other_display_list="$(grep -v ^$PRIMARY_DISPLAY <<<"$display_list")"
     $XRANDR_SET_PROGRAM $(while read display junk ; do echo " --output $display --scale 1x1 --off" ; done <<<"$other_display_list")
     xrandr_set_args+=( --output $PRIMARY_DISPLAY --mode $frame_buffer_resolution --scale 1x1 )
     notify_string="$PRIMARY_DISPLAY is primary at $frame_buffer_resolution"
     while read display junk ; do
         mode="$(get_display_resolution $display "$other_display_list")"
         xrandr_set_args+=( --output $display --same-as $PRIMARY_DISPLAY --mode "$mode" --scale-from $frame_buffer_resolution  )
         notify_string="$notify_string\n$display is scaled mirror at $mode"
     done <<<"$other_display_list"
 fi

 #logger -s -t "$0" -- Running $XRANDR_SET_PROGRAM "${xrandr_set_args[@]}"

 $XRANDR_SET_PROGRAM "${xrandr_set_args[@]}"
 ret=$?
 "${NOTIFY_SEND[@]}" "$notify_string"
 exit $ret