#!/usr/bin/env bash

if [ "$#" -lt 1 ]; then
    echo "Usage: ./run.sh command [arguments]"
    exit 1
fi

# Find free display number
for ((DNum=1 ; DNum <= 100 ; DNum++)) ; do
  [ -e /tmp/.X11-unix/X$DNum ] || break
done

RESOLUTION=1920x1080

# Start nested X Server
Xephyr :$DNum \
        -extension MIT-SHM \
	-extension XTEST \
	-nolisten tcp \
	-screen $RESOLUTION \
	-resizeable &

xephyrpid=$!

# If simple ratpoison window manager exists, run it
if command -v ratpoison; then
	sleep 1
	ratpoison -d :$DNum &
else # Use the default x window manager installed
	DISPLAY=:$DNum
	x-window-manager &
fi
windowmanagerpid=$!

docker run --net=host \
            --rm \
            -e DISPLAY=:$DNum \
            -v /tmp/.X11-unix/X$DNum:/tmp/.X11-unix/X$DNum:rw \
            --user $(id -u):$(id -g) \
	    --group-add audio \
	    --cap-drop=ALL \
	    --shm-size 2g \
    	    "$@"
kill $windowmanagerpid
kill $xephyrpid

## Explanation of docker parameters
# --net=host is to access the X server
# --rm is to remove the container when finished
# The next two lines is to pass along the X server socket and display
# --user is to set user to be non-root
# --cap-drop=ALL is to drop all priviledges
# --shm-size 2g is to increase shared memory
# $@ is to pass along the rest of the arguments