#!/usr/bin/env bash
# Performs a standard screen lock, with an extra bit of style. Before locking
# the screen, takes a screenshot of the current display and blurs and
# desaturates the image, using that for the lock screen background. A mighty
# neat effect. 
#
# Requirements: sway-lock grim imagemagick
#
export IFS=$'\n\t'
set -euo pipefail


# Generates the command to execute for taking a screenshot and applying affects
# for use as the lockscreen wallpaper. Note that this does not execute the
# command. It only generates it.
#
# @out_file   Path to save the lockscreen wallpaper to
gen_wallpaper_cmd() {
  local out_file="${1:?}"
  local cmd=""

  if type -p grim 1>/dev/null 2>/dev/null; then
    cmd="$(type -p grim) -c -l 0 -"
  else
    return 2
  fi

  # Generate the wallpaper gen command (with blurring and desaturation)
  printf '%s | convert - -scale 50%% -blur 0x3 -modulate 110,50 %s\n' \
    "${cmd}" "${out_file}"
}


# Locks the screen using i3lock command. Sets 
#
# @bg   Path to image to be used for the lockscreen wallpaper
lock_screen() {
  local bg="${1:?}"
  # Lock, but remain in foreground so the unlock processes aren't executed yet
  swaylock -i "${bg}"
}


# La fonction primaire
main() {
  blurry_wallpaper='/tmp/swaylockwall.png'
  # Get the program path that will screenshot for the background image
  lock_wallpaper_cmd="$(gen_wallpaper_cmd ${blurry_wallpaper})"

  if [ "${lock_wallpaper_cmd}" = "" ]; then
    echo "Screenshot command not found (grim). Exiting."
    return 1
  fi

  # Screenshot and post-process
  bash -c "${lock_wallpaper_cmd}"

  # Execute the lock screen with the new fancy wallpaper
  lock_screen ${blurry_wallpaper}

  # Cleanup the original screenshot and blurred counterpart
  rm "${blurry_wallpaper}"
}

# Enter the script here
main ${@}