#!/bin/sh
state_dir="${XDG_STATE_HOME:-$HOME/.local/state}"
contexts_dir="$state_dir/contexts"
mkdir -p "$contexts_dir"

link() {
  ln -nsf "${1:?}" "${2:?}"
}

new_context() {
  echo new_context 1>&2
  : "${1:?I require a context name}"
  dir="${contexts_dir}/${1}"
  if [ -d "${dir}" ]
  then notify-send "ctx" "${dir} already exists!"
  else mkdir -p "${dir}"
       echo "$1" > "${dir}/name"
       link "${dir}" "${state_dir}/context"
  fi
}
set_context() {
  echo set_context 1>&2
  : "${1:?I require a context name}"
  dir="${contexts_dir}/${1}"
  if [ -d "${dir}" ]
  then link "${dir}" "${state_dir}/context"
  else notify-send "ctx" "${dir} does not exists!"
  fi
}

{
if [ "$1" ]
then echo "$1"
else ls "$contexts_dir" | dmenu -p "switch to contex: " -l 20
fi
} |
  while read -r context
  do case "$context" in
    +*) new_context "${context#+}" ;;
    *[![:space:]]*) set_context "$context" ;;
  esac
  done