#!/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 based on lsb_release id

	DISPLAY=:$DNum
	distro_id=$(lsb_release -i | awk '{print($3)}')

	if [ "${distro_id}" == "Ubuntu" ] || [ "${distro_id}" == "Debian" ]; then
		x-window-manager &
	else
		if [ "${XDG_SESSION_DESKTOP}" == "KDE" ]; then 
			startplasma-x11 &
		elif [ "${XDG_SESSION_DESKTOP}" == "GNOME" ]; then
			mutter &
		else
			printf "%s\n" "Could not find a suitable Window Manager"
			exit 1

		fi
 
	fi

fi

windowmanagerpid=$!

#detect podman or docker

if command -v docker; then
	engine_of_choice="docker"
	
elif command -v podman; then 
	engine_of_choice="podman"
else
	printf "%s\n" "Docker/Podman are not installed!"
	exit 1
fi

# then run the detected container engine

$engine_of_choice run --net=host \
		    --rm \
		    -e DISPLAY=:$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